⎇ⓥ⺖㗴ฬ㧦ᤨಽഀ㨄✢࿁᛬ᴺߦࠃࠆࠬࡔࠢ࠹ࠖ࠶ࠢᶧ᥏ߩേ⊛᭴ㅧ⸃ᨆ
⎇ⓥઍ⴫⠪㧦㑐Ỉ๺ሶ(ᣣᧄᄢቇ㨯ℂᎿቇㇱ㨯‛ℂቇ⑼)
⎇ⓥᓥ੐⠪㧦㜞ᯅ↱⟤ሶ(ᣣᧄᄢቇ㨯ℂᎿቇㇱ㨯‛ℂቇ⑼)౒ห⎇ⓥ⠪㧦㘵↰ෘᄦ(KEK,PF)
㜞㊁⦟♿(ᣣᧄᄢቇ㨯ℂᎿቇㇱ㨯‛ℂቇ⑼)㜞ἑᶈ৻(ᣣᧄᄢቇ㨯ℂᎿቇㇱ㨯‛ℂቇ⑼)‫⎇ޣ‬ⓥ⋡⊛‫ޤ‬ᶧ᥏ߦઍ⴫ߐࠇࠆ࠰ࡈ࠻ࡑ࠲࡯ߪᄖജߦኻߔࠆᔕ╵ᕈ߇⦟ߊ‫ޔ‬ዊߐߥᄖ႐ߢᄢ߈ߥ᭴ㅧᄌൻࠍ␜
ߔ‫ߩ࡯࠲ࡑ࠻ࡈ࠰ޕ‬ⓨ㑆⊛ᤨ㑆⊛ᄌൻߩ⹦⚦ࠍᬌ⸛ߒ‫ߩߘޔ‬⒎ᐨᒻᚑㆊ⒟‫⋧ޔ‬ォ⒖ᯏ᭴╬ࠍ⸃᣿ߔࠆߚ߼ߦߪ‫ޔ‬᭴ㅧᄌൻߩㆊ⒟ࠍታᤨ㑆ߢ⋥ធⷰኤߔࠆߎߣ߇ᦸ߹ߒ޿‫ߢߎߘޕ‬FELࠍ↪޿ߚ㨄✢(ࡄ࡜ࡔ࠻࡝࠶ࠢ㨄✢)ߩࡄ࡞ࠬᕈࠍᵴ↪ߒߚᤨಽഀ㨄✢࿁᛬శቇ♽ࠍ᭴▽ߒ‫ࠢ࠶ࠖ࠹ࠢࡔࠬޔ‬ᶧ᥏ߩ㔚႐ᔕ╵ߥߤ‫ߩ࡯࠲ࡑ࠻ࡈ࠰ޔ‬᭴ㅧᄌൻㆊ⒟ࠍⷰኤߔࠆᚻᴺࠍ⏕┙ߔࠆߎߣࠍ⋡⊛ߣߒߚ‫ޕ‬‫⎇ޣ‬ⓥ᭎ⷐ‫ޤ‬㧔㧝㧕ታ㛎Ḱ஻ࡄ࡜ࡔ࠻࡝࠶ࠢࠬ㨄✢ࠍ↪޿ߚᤨಽഀ㨄✢࿁᛬ᴺߩ㐿⊒Ḱ஻ߣߒߡ‫ޔ‬ᶧ᥏ߩ㔚႐ᔕ╵߇ᤨಽഀ㨄✢࿁᛬ᴺߦࠃߞߡⷰኤน⢻ߢ޽ࠆߎߣࠍ⏕⹺ߔࠆߚ߼‫ޔ‬㜞ࠛࡀ࡞ࠡ࡯ടㅦེ⎇ⓥᯏ᭴‫ޔ‬᡼኿శ⎇ⓥ
ᣉ⸳BL-4Aߦ߅޿ߡታ㛎ࠍⴕߞߚ‫ޕ‬ታ㛎ߦߪᤨಽഀࡑࠗࠢࡠࡆ࡯ࡓ㨄✢࿁᛬శቇ♽ࠍ↪޿ߚ‫ߪ⟎ⵝᧄޕ‬ႎ๔⠪ࠄ߇㐿⊒ߒߚ߽ߩߢ޽
ࠆ‫ޕ‬஍ะ㔚⏛⍹߆ࠄߩㅪ⛯X✢ࠍᄙጀ⤑ಽశེߦࠃࠅන⦡ൻ(8 keV)ߒ‫ޔ‬Kirkpatrick- Baezဳశቇ⚛ሶ
2ߦࠃࠅ㓸శߒߡ⹜ᢱ૏⟎ߢߩࡆ࡯ࡓࠨࠗ࠭߇⚂34 μm એਅߦߥࠆࠃ߁⺞ᢛߒߡ޿ࠆ‫ⷺޕ‬ᐲ⊒ᢔߪ
8᳓ᐔ‫⋥ုޔ‬ᣇะߣ߽1.0 mrad⒟ᐲ‫ߪࠬࠢ࠶࡜ࡈࡦ࠻ࠜࡈޔ‬ᾖ኿៊்ࠍ㒐ߋߚ߼10 photons/s⒟ᐲߢ૶
↪ߒߡ޿ࠆ‫ޕ‬૶↪ߒߚᒝ⺃㔚ᕈᶧ᥏ߢߪ5ࡋ࡞࠷ߩਃⷺᵄߦㅊ㓐ߒߡጀ᭴ㅧ߇ᄌൻߔࠆߎߣࠍ⏕⹺ߢ߈ߚ‫߹ޕ‬ߚ‫ޔ‬ታ㛎ߩߚ߼ߦᔅⷐߣߐࠇࠆ⹜ᢱࠬ࠹࡯ࠫߩ࿁ォ࡮ਗㅴゲ߿⹜ᢱ㔚႐૞⵾ᣇᴺߥߤ‫ޔ‬ᔅⷐߣߐࠇ
ࠆၮᧄ⊛ߥታ㛎᧦ઙࠍᛠីߔࠆߎߣ߇ߢ߈ߚ‫ޕ‬㧔㧞㧕ࡄ࡜ࡔ࠻࡝࠶ࠢ㨄✢ࠍ↪޿ߚశቇ♽ߩ㐿⊒Siන⚿᥏߆ࠄ⊒↢ߒߚࡄ࡜ࡔ࠻࡝࠶ࠢ㨄✢ߪᜰะᕈ߇㜞ߊḰන⦡శߢ޽ࠆߩߢ‫⋥ࠍࠇߎޔ‬ធ⹜ᢱߦᾖ኿ߒ‫ޔ‬࿁᛬㨄✢ࠍᓧࠆߎߣߢ㜞ಽ⸃⢻᷹ቯ߇น⢻ߢ޽ࠆ‫ޔ߼ߚߩߎޕ‬ታ㛎ࡎ࡯࡞ౝߩࡄ࡜ࡔ࠻
࡝࠶ࠢ㨄✢ขࠅ಴ߒญㄭறߦ⸳⟎ߐࠇߚࠧ࠾ࠝࡔ࡯࠲ࠍ↪޿‫ᧃ☳ޔ‬㨄✢࿁᛬శቇ♽ߢၮ␆࠺࡯࠲ࠍ
෼㓸ߒߚ‫ޕ‬㨄✢ࠛࡀ࡞ࠡ࡯ߪ10 keV‫ޔ‬13.5 keVߣߒߚ‫ޕ‬ᬌ಴ེߦߪࡐ࡜ࡠࠗ࠼࡮ࡈࠖ࡞ࡓ‫ޔ‬CCD‫ޔ‬ࠪࡦ࠴࡟࡯࡚ࠪࡦ࡮ࠞ࠙ࡦ࠲╬ࠍ↪޿ߚ‫⹜ޕ‬ᢱ߇න⚿᥏ߢ޽ࠆ႐วߪࠪࡖ࡯ࡊߥ࿁᛬✢㧔ࡠࠠࡦࠣࠞ࡯ࡉඨଔ᏷ߢ0.003q⒟ᐲ㧕߇ᓧࠄࠇࠆߎߣ߇ᣧᎹࠄߦࠃߞߡႎ๔ߐࠇߡ޿ࠆ‫ߒ߆ߒޕ‬ᄙ⚿᥏⹜ᢱߦ߅޿ߡߪ࿁᛬ࡊࡠࡈࠔࠗ࡞ࠍᓧࠆߦ⥋ߞߡ޿ߥ޿‫ޕ‬ᬌ಴ེ߇ࡐ࡜ࡠࠗ࠼࡮ࡈࠖ࡞ࡓ‫ޔ‬CCDߩ႐วߦߪᗵᐲߩਇ⿷‫޿⸒ޔ‬឵߃ࠇ߫࿁᛬㨄✢ߩᒝᐲਇ⿷߇ਥⷐߥේ࿃ߩ৻ߟߢ޽ࠆߣ⠨߃ࠄࠇࠆ‫߹ޕ‬ߚ‫ߪߢ࠲ࡦ࠙ࠞ࡮ࡦ࡚ࠪ࡯࡟࠴ࡦࠪޔ‬࿁᛬ⷺ20qએਅߢᭂ߼ߡ㜞޿ࡃ࠶ࠢࠣ࡜࠙ࡦ࠼߇ᬌ಴ߐࠇ‫ޔ‬࿁᛬✢߇ૐⷺᐲߦ⃻ࠇࠆᶧ᥏⹜ᢱߦߪᄢ߈ߥ໧㗴ߣߥࠆ‫ߪ࠼ࡦ࠙࡜ࠣࠢ࠶ࡃޕ‬ਛᕈሶ✢‫ޔ‬ǫ✢ࠍᄙߊ฽ࠎߢ޿ࠆߣᕁࠊࠇࠆ߇‫⃻ޔ‬࿷✢⾰ߩ⺞ᩏࠍⴕߞߡ޿ࠆ‫ߩ࠼ࡦ࠙࡜ࠣࠢ࠶ࡃޕ‬ᕈ⾰߇᣿ࠄ߆ߦ
ߥࠇ߫ㆡಾߥㆤ⭁߿ࡒ࡜࡯‫ޔ‬PHA‫ߡߞࠃߦ╬↪૶ߩ࠲࡯ࡀࡒ࡝ࠢࠬࠖ࠺ޔ‬ലᨐ⊛ߦ㒰෰ߢ߈ࠆ‫ࠪޕ‬ࡦ࠴࡟࡯࡚ࠪࡦ࡮ࠞ࠙ࡦ࠲ߪᐢ޿ࠛࡀ࡞ࠡ࡯▸࿐ߢ㜞ᗵᐲࠍ଻ߜ‫¨ޔ‬E = ᢙ keV⒟ᐲߢ޽ࠆ߇ࠛࡀ
࡞ࠡ࡯ಽ⸃⢻ࠍᜬߟߩߢࡄ࡜ࡔ࠻࡝࠶ࠢ㨄✢ߩᐢ޿ᔕ↪▸࿐ߦኻߒߡ᦭ലߢ޽ࠆ‫ࠣࠢ࠶ࡃߡߞࠃޕ‬࡜࠙ࡦ࠼ࠍૐᷫߒS/Nࠍะ਄ߐߖࠆߎߣߦࠃࠅࠪࡦ࠴࡟࡯࡚ࠪࡦ࡮ࠞ࠙ࡦ࠲ࠍᬌ಴ེߣߔࠆశቇ♽ߩ⏕┙ࠍ⋡ᜰߔ‫ޕ‬߹ߚ‫ޔ‬ノᐲߩะ਄ࠍ࿑ࠆߚ߼‫ޔ‬ᬦ౞ࡒ࡜࡯ߩKirkpatric-Baezࠪࠬ࠹ࡓߦࠃࠆ㓸శࠍⴕ߁੍ቯߢ޽ࠅ‫ޔ‬
4⺞ᢛ߇ㅴࠎߢ޿ࠆ‫ޕ‬㓸శߦࠃࠅノᐲߪ⚂10 ୚ߦߥࠆߣ⷗Ⓧ߽ࠄࠇߡ޿ࠆߩߢ‫ޔ‬චಽߥ࿁᛬㨄✢ᒝᐲ߇ᦼᓙߢ߈ࠆ‫ޔ߼ߚߩߎޕ‬㓸శ♽ᓟᣇߦ⹜ᢱࠍ࠮࠶࠻ߔࠆశቇ♽ߩ᭴▽߽ⴕߞߡ޿ࠆ‫ޕ‬㓸శᓟߩ
2ࡆ࡯ࡓࠨࠗ࠭ߪ10 ×10 μm ⒟ᐲߣߥࠆߚ߼‫⹜ޔ‬ᢱゲߩ੤Ꮕ♖ᐲ߿ࡆ࡯ࡓ૏⟎ߩᬌ಴ᯏ᭴╬ࠍ⠨ᘦߔࠆᔅⷐ߇޽ࠆ‫ޕ‬ߎࠇࠄߩၮᧄ⊛శቇ♽ࠍ⏕┙ߒߚߩߜ‫ޔ‬శḮߩࡑࠢࡠࡄ࡞ࠬߦหᦼߒߚᤨಽഀ᷹ቯ♽ࠍઃടߔࠆ
੍ቯߢ޽ࠆ‫ޕ‬‫ޤ߼ߣ߹ޣ‬ᶧ᥏ߩ㔚႐ᔕ╵ߥߤ࠰ࡈ࠻ࡑ࠲࡯ߩ࠳ࠗ࠽ࡒࠢࠬࠍ⎇ⓥߔࠆᚻᲑߣߒߡᤨಽഀ㨄✢࿁᛬ᴺ߇᦭
ലߢ޽ࠆߎߣ߇⏕⹺ߢ߈ߚ‫੹ޕ‬ᓟߪࡄ࡜ࡔ࠻࡝࠶ࠢ㨄✢ࠍ↪޿ߚᤨಽഀ㨄✢࿁᛬శቇ♽ࠍᣧᦼߦ⏕┙ߒ‫ޔ‬ᶧ᥏⎇ⓥߦㆡ↪ߔࠆߣ౒ߦᔕ↪▸࿐ࠍᐢߍߡⴕߊ‫ޕ‬‫⎇ޣ‬ⓥᬺ❣╬‫ޤ‬࡮⊒⴫⺰ᢥ(1) Atsuo Iida, Yumiko Takahashi, Yoichi Takanishi, Toyokazu Ogasawara, Michi Nakata, Ken Ishikawa
and Hideo Takezoe (2005)

Dynamic and microscopic X-ray characterization of a compound chevron

layer in electroclinic liquid crystals

contributed to Liquid Crystals(2) Yumiko Takahashi, Atsuo Iida, Yoichi Takanishi, Toyokazu Ogasawara, Michi Nakata, Ken Ishikawa
and Hideo Takezoe (2003)

Dynamic local layer response of surface stabilize ferroelectric liquid

crystals to high electric field by time-resolved x-ray micro-diffraction Phys. Rev. E 67, 051706-1 –051706-10(3) Yumiko Takahashi, Atsuo Iida, Yoichi Takanishi, Toyokazu Ogasawara, Michi Nakata, Ken Ishikawa
and Hideo Takezoe (2004) Temperature and electric field dependences of the local layer structure inanti-ferroelectric liquid crystals measured by X-ray micro-diffraction. Ferroelectrics, 311, 41-50(4) A.Iida, Y.Takanishi, Y.Takahashi, M.Nakata, K.Ishikawa and H. Takezoe (2002)

Observation of

dynamic local layer response of smectic liquid crystals by X-ray micro-diffraction Acta Cryst. A 58
(Suppl.), C337
(5) Y.Takahashi, A.Iida, Y.Takanishi, T. Ogasawara and H. Takezoe (2001)

Time resolved X-ray

micro-diffraction measurements of the dynamic local layer response to electric field in antiferroelectricliquid crystals

Nucl. Instr. and Meth. A 467-468, 1001-1004

࡮ቇળ⊒⴫(1) 㜞ᯅ↱⟤ሶ(2004) 㧔෻㧕ᒝ⺃㔚ᕈᶧ᥏ߦ߅ߌࠆዪᚲ᭴ㅧߩ㔚႐ᔕ╵̆ᤨಽഀࡑࠗࠢࡠࡆ࡯ࡓ
㨄✢࿁᛬ᴺߦࠃࠆേ⊛᭴ㅧ⸃ᨆ̆

╙48࿁ℂᎿቇㇱቇⴚ⻠Ṷળ㧔ℂᎿቇㇱ⦁ᯅᩞ⥢㧕(2) 㘵↰ ෘᄦ㧘㜞ᯅ ↱⟤ሶ㧘㜞⷏ 㓁৻㧘ਛ↰ᧂ⍮㧘⍹Ꮉ ⻞㧘┻ᷝ ⑲↵ (2004)ߌࠆጀ᭴ㅧߣಽሶ㈩ะߩേ⊛ᓸዊ㗔ၞX✢࿁᛬ᴺߦࠃࠆ⹏ଔ

㔚௑ലᨐߦ߅

2004ᐕᣣᧄᶧ᥏ቇળ⸛⺰ળ㧔ฬฎደᄢቇ㧘ฬฎደ㧕(3) Atsuo Iida, Yumiko Takahashi, Yoichi Takanishi Michi Nakata, Ken Ishikawa and Hideo Takezoe(2004)

Dynamic local layer structure in the electroclinic effect : Time-resolved X-raythmicro-diffraction 20 International Liquid Crystal Conference (Liubljana, Slovenia)(4) 㘵↰ෘᄦ㧘㜞ᯅ↱⟤ሶ㧘㜞⷏㓁৻㧘ਛ↰ᧂ⍮㧘೑శ߼ߋߺ㧘⍹Ꮉ⻞㧘┻ᷝ⑲↵ (2004)

ᒝ⺃㔚ᶧ᥏ߩSmA⋧㔚௑ലᨐߦ߅ߌࠆዪᚲጀ᭴ㅧߩേ⊛⸃ᨆ╙17࿁ᣣᧄ᡼኿శቇળᐕ࿁࡮᡼኿శ⑼ቇวหࠪࡦࡐࠫ࠙ࡓ㧔ߟߊ߫࿖㓙ળ⼏႐㧘ߟߊ߫㧕(5) 㘵↰ෘᄦ㧘㜞ᯅ↱⟤ሶ㧘㜞⷏㓁৻㧘ਛ↰ᧂ⍮㧘೑శ߼ߋߺ㧘⍹Ꮉ⻞㧘┻ᷝ⑲↵(2003)

SmA⋧

㔚௑ലᨐߦ߅ߌࠆዪᚲጀ᭴ㅧߩേ⊛⸃ᨆ2003ᐕᣣᧄᶧ᥏ቇળ⸛⺰ળ㧔㕍᫪Ꮢᢥൻળ㙚㧘㕍᫪㧕(6) Yumiko Takahashi, Atsuo Iida, Yoichi Takanishi, Michi Nakata, Ken Ishikawa and Hideo Takezoe(2003)

Static and dynamic local layer structure under the electric field in antiferroelectric liquidthcrystal measured by X-ray micro-diffraction 9 International Conference on Ferroelectric Liquid
Crystals (Trinity College, University of Dublin, Dublin)(7) Atsuo Iida, Yumiko Takahashi, Yoichi Takanishi, Michi Nakata and Hideo Takezoe (2003)

Dynamic

local layer response of smectic liquid crystals under the ac electric field by time-resolved X-ray
micro-diffractionth

8 International Conference on Synchrotron Radiation Instrumentation(YerbaBuena Arts Center, San Francisco)(8) 㜞ᯅ↱⟤ሶ㧘㘵↰ෘᄦ㧘㜞⷏㓁৻ਛ↰ᧂ⍮㧘೑శ߼ߋߺ㧘⍹Ꮉ⻞㧘┻ᷝ⑲↵ (2003)ࠬࡔࠢ࠹ࠖ࠶ࠢᶧ᥏㔚௑ലᨐߦ߅ߌࠆዪᚲጀ᭴ㅧᔕ╵㧙ࡑࠗࠢࡠࡆ࡯ࡓX✢࿁᛬ᴺ㧙╙16࿁᡼኿శ
ቇળᐕળ࡮᡼኿శ⑼ቇวหࠪࡦࡐࠫ࠙ࡓ ࠗ࡯ࠣ࡟ᆢ〝㧘ᆢ〝(9) 㜞ᯅ ↱⟤ሶ㧘㘵↰ ෘᄦ㧘㜞⷏ 㓁৻㧘ਛ↰ ᧂ⍮㧘೑శ߼ߋߺ 㧘⍹Ꮉ ⻞㧘┻ᷝ ⑲↵ (2002)㔚

௑ലᨐߦ߅ߌࠆSmA⋧ߩዪᚲጀ᭴ㅧߩᔕ╵2002ᐕᣣᧄᶧ᥏ቇળ⸛⺰ળ㧔ᄹ⦟⋵ᣂ౏ળၴ㧘ᄹ⦟㧕(10) 㜞ᯅ↱⟤ሶ㧘㘵↰ෘᄦ㧘㜞⷏㓁৻㧘ዊ═ේ⼾๺㧘ਛ↰ᧂ⍮㧘⍹Ꮉ⻞㧘┻ᷝ⑲↵ (2002)ࡑࠗ

ࠢࡠࡆ࡯ࡓߦࠃࠆ ෻ ᒝ⺃㔚ᕈᶧ᥏ጀ᭴ㅧߩਇนㅒ⊛࡮นㅒ⊛㔚႐ᔕ╵╙15࿁᡼኿శቇળᐕ
ળ࡮᡼኿శ⑼ቇวหࠪࡦࡐࠫ࠙ࡓ 㧔᧲੩ᄢቇ‛ᕈ⎇ⓥᚲ, ᨰ㧕(11) 㜞ᯅ↱⟤ሶ㧘㘵↰ෘᄦ㧘㜞⷏㓁৻㧘ዊ═ේ⼾๺, ਛ↰ᧂ⍮, ⍹Ꮉ⻞㧘┻ᷝ⑲↵ (2001) ᒝ⺃㔚㧛෻ᒝ⺃㔚ᕈᶧ᥏ߦ߅ߌࠆጀ᭴ㅧߩ㔚႐ᔕ╵ߣశቇᔕ╵2001ᐕ ᣣᧄᶧ᥏ቇળ⸛⺰ળ(ᄢች࠰࠾࠶ࠢࠪ࠹ࠖ࡯,ߐ޿ߚ߹)(12) 㜞ᯅ↱⟤ሶ㧘㘵↰ෘᄦ㧘㜞⷏㓁৻,ዊ═ේ⼾๺, ⍹Ꮉ⻞㧘┻ᷝ⑲↵ (2001)߅ࠃ߮ᒝ⺃㔚ᕈᶧ᥏ߦ߅ߌࠆዪᚲጀ᭴ㅧߩേ⊛㔚႐ᔕ╵ߩኻᔕ෻ᒝ⺃㔚ᕈᶧ᥏

╙48࿁ ᔕ↪‛ℂቇ㑐ଥㅪว⻠Ṷળ (᣿ᴦᄢቇ, ᧲੩)(13) 㜞ᯅ↱⟤ሶ㧘㘵↰ෘᄦ㧘㜞⷏㓁৻, ዊ═ේ⼾๺, ⍹Ꮉ⻞㧘┻ᷝ⑲↵ (2001)䊙䉟䉪䊨䊎䊷䊛䈮䉋䉎෻ᒝ⺃㔚ᕈᶧ᥏ጀ᭴ㅧ䈱ㆊᷰ⊛㔚႐ᔕ╵㩷 㩷 ╙14࿁ ᡼኿శቇળᐕ࿁࡮᡼኿శ⑼ቇวหࠪࡦࡐ
ࠫ࠙ࡓ (ᐢፉᄢቇ, ᐢፉ)PHYSICAL REVIEW E 67, 051706 共2003兲

Dynamic local-layer response of surface-stabilized ferroelectric liquid crystals to a high electricfield by time-resolved x-ray microdiffraction
Yumiko Takahashi*
The Graduate University for Advanced Studies, 1-1 Oho Tsukuba, Ibaraki 305-0801, Japan

Atsuo Iida
Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho Tsukuba,
Ibaraki 305-0801, Japan

Yoichi Takanishi, Toyokazu Ogasawara, Michi Nakata, Ken Ishikawa, and Hideo Takezoe
Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama Meguro-ku, Tokyo 152-8552, Japan
共Received 15 August 2002; revised manuscript received 20 February 2003; published 23 May 2003兲
Time-resolved synchrotron x-ray microdiffraction measurements have directly revealed the dynamic locallayer response to the high electric field in a surface-stabilized ferroelectric liquid crystal. The irreversible layertransformation under the increasing electric field is found to consist of two stages; the initial vertical chevron
structure transforms to the alternate vertical and horizontal chevrons and, with increasing field, the chevron
angle decreases and the horizontal chevron structure develops. The time-resolved microdiffraction measurement has clarified the detailed reversible layer transformation between the mostly horizontal chevron at thehigh field and the so-called quasibookshelf at the low field during the ac field application. The transient layer
response time is about 0.1–0.2 and 0.3–0.4 ms for falling and rising edges, respectively, and is slightly longer
than the optical response time. The layer transformation is discussed in terms of electric torque and surface
anchoring. The local-layer response in the antiferroelectric liquid crystal is also discussed for comparison.
DOI: 10.1103/PhysRevE.67.051706

PACS number共s兲: 61.30.⫺v

I. INTRODUCTION

The local-layer structures of ferroelectric liquid crystals
共FLCs兲 and antiferroelectric liquid crystals 共AFLCs兲 andtheir layer response to an electric field have attracted muchattention both from display device applications and fundamental physics 关1,2兴. When the smectic-A (SmA) phase iscooled down to the chiral smectic-C (SmC * ) phase, the reduction of the layer spacing is compensated by a verticalchevron 共v-chevron兲 structure in a surface-stabilized cell
关2–7兴. Optical and electro-optical phenomena could be interpreted in terms of this v-chevron structure and its modification. Under the high electric field, an irreversible layer transition from the initial v chevron to the so-called
quasibookshelf structure was observed in both surfacestabilized AFLC and FLC cells 关9–11兴. When observed witha polarized optical microscope, the quasibookshelf structureoften accompanies the stripe texture that degrades the opticalcontrast for display applications. The stripe texture has been
discussed with regard to the horizontal chevron 共h-chevron兲
structure 关12兴. The h chevron is realized due to the interaction between the applied electric field and the spontaneouspolarization of the molecule. The h-chevron structures, however, are not restricted to the SmC * under the high-field
treatment, but also they were found in the FLC without thefield treatment 关13兴 and in the electroclinic effect in the SmA
phase 关12,14,15兴. Recently, the v chevron to quasibookshelf*Present address: Nihon University, Surugadai, Kanda, Chiyodaku, Tokyo 101-8308, Japan.
1063-651X/2003/67共5兲/051706共10兲/$20.00

transition has been also studied in detail by x-ray small angle
scattering in relation to the ferroelectric, ferrielectric, andantiferroelectric phases as a function of temperature and theelectric field 关16 –19兴. Since the h chevron is a laterally inhomogeneous layer structure in a cell, a spatially resolved
x-ray technique is indispensable to directly determine thelocal-layer structure. Small angle x-ray scattering with a synchrotron x-ray microbeam is the direct microscopic technique and has proven to be quite effective for the characterization of smectic liquid crystals 关20–25兴.
Obviously, for the study of the electro-optical behavior of
the FLCs and AFLCs, it is important to directly investigate
the dynamic as well as the static layer structure of the v andh chevrons in detail. The x-ray experiments having a millisecond 共ms兲 to microsecond 共␮s兲 time resolution for the liquid crystal layer determination, however, have been limited
in number. The layer responses from a few tens of microseconds to sub-milliseconds were observed even under the relatively low electric field of a symmetric bipolar pulse 关26,27兴.
Recently, the local-layer structure in the AFLCs and its response to the applied electric field were successfully revealedby time-resolved synchrotron x-ray microdiffraction 关28,29兴.
In this paper, the local-layer structure of the FLCs and its
response to the electric field are investigated to reveal the
dynamic interaction of the field with the local-layer structureby x-ray small angle scattering with a few ␮m spatial resolution and a few tens of ␮s time resolution. Furthermore, theorthogonal ␻- and ␹-angular dependences of diffracted intensities are fully utilized to study the field-induced layer transformation. Simultaneous observation of the optical responsewith the x-ray measurement also makes it possible to discuss
the relationship between the molecular and the layer re-

67 051706-1©2003 The American Physical Society

PHYSICAL REVIEW E 67, 051706 共2003兲

TAKAHASHI et al.

FIG. 1. 共a兲 Experimental setup for synchrotron x-ray microbeam
diffraction. 共b兲 Sample coordinates for the smectic layer normal.
The angle ␦ is the tilt angle or the vertical chevron angle. ␥ is thein-plane deflection angle or the horizontal chevron angle when thechevron structure is periodic.

sponse. The quasistatic and transient layer transformations
for the triangular-form and the step-form electric fields, respectively, are reported. The results are also discussed inrelation to the AFLC layer response.
II. EXPERIMENTThe sample was TK-C101 共Chisso兲 关23兴 sandwiched
between ITO-coated glass plates 共150 ␮m thick兲 rubbed
on one side after coating a polyimide alignment film.
The phase sequence of TK-C101 is iso(80 °C)
N*共70 °C兲SmA共56 °C兲SmC*. The experiments were performed in the SmC * phase at room temperature. Most of theexperiments were carried out with one-side rubbing cells,
which is the same alignment condition as previous AFLC
experiments 关28,29兴. The cell gap was about 5– 8 ␮m. For
comparison, an AFLC sample 共S兲-TFMHPOBC 关4-共1trifluoromethyl heptyloxycarbonyl兲phenyl 4⬘-octyloxybiphenyl-4-carboxylate兴 was also measured at the same
sample temperature of T c ⫺10° as previous experiments
关28,29兴, where T c is the phase transition temperature from
SmA to SmC A* 共109 °C兲.
The x-ray diffraction experiments were carried out on
beam line 4A at the Photon Factory 共PF兲. The experimental
detail has been already reported in the previous paper 关28兴,so only a brief description is given here. The beam size wasabout 3(h)⫻4(v) ␮ m2 and the angular divergence of theincident beam was about 1.0 mrad both in the horizontal andin the vertical direction. The incident x-ray energy was 8 keV
共1.55 Å兲. The diffraction geometry is schematically shown in
Fig. 1共a兲. The rubbing direction was set horizontally. The
␹-intensity distribution 共␹ profile兲 on a position sensitive

FIG. 2. Polarized optical micrographs of textures of the initialstage before field application 共a兲, ⫾18 V 共b兲, ⫾28 V 共c兲, and ⫾60 V
共d兲 under the triangular wave form 共5 Hz兲. The sample was TKC101. The cell thickness was about 7.5 ␮m. The measurement wasdone at room temperature. The rubbing direction was set horizontally. White arrows show the direction and the region of the x-ray
measurement shown in Fig. 3. A scale mark is 100 ␮m. 共Weak grayarrows show points of measurements during the experiments.兲

proportional counter was collected simultaneously. The
␻-scan intensity profile 共␻ profile兲 was obtained by rotating
the sample around a vertical axis 共Y兲. The ␻ intensity is theintegrated intensity with respect to ␹ in the present paper. No
absorption correction for the cell glass plates was made. The
layer deflection angles ␦ and ␥ are defined in Fig. 1共b兲.
The optical response was obtained by a photomultiplierattached to an in situ polarized microscope during the x-ray
measurement, though the optical measurement area was
about 100 ␮m in diameter and was much larger than the
x-ray microbeam size.
A triangular-form 共5 Hz, ⫾1–⫾65 V兲 or a step-form 共25–
100 Hz, ⫾45–⫾65 V兲 electric field was applied to thesample. The time-resolved ␻ profile and ␹ profile were obtained with an MCS 共multichannel scaler兲 mode and a gated
MCA 共multichannel analyzer兲 mode, respectively. A minimum dwell time for the MCS mode was 10 ␮s. In the gated
MCA mode, the ␹ profiles at eight sampling points in one
cycle of the applied field were collected with a minimum
time resolution of 10 ␮s. MCS and MCA data were summed
within a measurement time.
III. RESULTS
A. Time integrated spatial distribution of the diffraction
profileThe time integrated spatial distribution of the x-ray diffraction profile from TK-C101 was measured as a function ofan applied voltage 共Fig. 3兲 together with the in situ observation of the texture by a polarized optical microscope 共Fig. 2兲.
Figures 3共1-a兲 and 3共1-b兲 show series of ␻ and ␹ profiles,
respectively, across the narrow wall at an initial state before
the field application. The v-chevron structure 共peaks at␻ ⫽⫾21°) is clearly seen in Fig. 3共1-a兲. The peaks that ap-

051706-2

PHYSICAL REVIEW E 67, 051706 共2003兲

DYNAMIC LOCAL-LAYER RESPONSE OF SURFACE- . . .

FIG. 3. Series of ␻ profiles 共a兲 and ␹ profiles 共b兲 as a function of
the vertical position 共Y direction兲. 共1-a兲 and 共1-b兲 were obtained
before the field application. 共2-a兲 and 共2-b兲, 共3-a兲 and 共3-b兲, 共4-a兲
and 共4-b兲, and 共5-a兲 and 共5-b兲 were obtained during the triangularfield of ⫾18, ⫾30, ⫾40, and ⫾60 V, respectively. 共6-a兲 and 共6-b兲
were obtained after turning off the field. The ␹ profiles were obtained at ␻ ⫽0° except for 共2-b兲 where ␻ ⫽⫺5.8° 共see text兲. The
scanning step in the Y direction was 4 ␮m. The darker part corresponds to the higher diffracted intensity. X-ray intensities were normalized by the highest intensity in each figure.

peared in ␹ profiles 关Fig. 3共1-b兲兴 are due to a pair of thenarrow wall of a zigzag defect observed in Fig. 2共a兲. Thus,
the v-chevron angle 共␦兲 and the in-plane deflection angle atthe narrow wall 共␥兲 are 21° and 22°, respectively.
When the triangular electric field with a frequency of 5
Hz was applied to the sample, most of the narrow walls inthe view field disappeared up to ⫾5 V 关8兴 and the new line
defect 共needle defect 关20,23兴, hereafter兲 appeared above ⫾10
V. The needle defect usually appeared from a broad wall, thetip of a narrow wall or a spacer edge. At ⫾18 V 关Fig. 2共b兲兴,the needle defect develops and the so-called stripe texture isformed. A series of the ␻ profiles 关Fig. 3共2-a兲兴 shows broad
but weak peaks 共␻-bookshelf components, hereafter兲 between the v-chevron peaks. The ␹-intensity distribution 关Fig.

3共2-b兲兴 obtained at ␻ ⫽⫺5.8° 共peak of ␻-bookshelf component兲 shows the alternate intensity variation between the low
and high angles indicating the nearly periodic needle-defectformation 共h-chevron growth兲. The angles ␦ and ␥ are almost
the same as in the initial state.
By increasing the applied voltage, the needle defect further develops and covers the whole area as shown in Fig.
2共c兲. It is also noted that dense focal conics appear in theneedle defect 共or stripe兲 reflecting the strain field. The intensity modulation in Figs. 3共3-a兲 and 3共3-b兲 is about 8 –10 ␮min period, which is close to the cell thickness. Above theapplied voltage of around ⫾30 V, the spatial period of the
␹-profile modulation is almost unchanged. The angles ␦ and␥ become small and the FWHM 共full width at half maximum兲 of the v-chevron peak in the ␻ profile slightly increases up to 1° from the initial one 共about 0.4°兲 indicating
the strain introduction.
Up to ⫾50 V, the stripe texture progressively covers thewhole sample area and the focal conics density increases.
With increasing applied voltage, the angles ␦ and ␥ become
small and the v-chevron intensity further becomes weak asshown in Figs. 3共4-a兲 and 3共4-b兲. It is noted, however, thatthe v-chevron structure still remains at this stage.
Above ⫾50 V, the contrast of the stripe texture becomesvery weak and focal conics disappear 关Fig. 2共d兲兴. The ␻ profiles obtained at ⫾60 V 关Fig. 3共5-a兲兴, which is the highest
applied voltage for this sample show a sharp peak near ␻⫽0° and are almost independent of the position. The ␹ profiles 关Fig. 3共5-b兲兴, however, show the alternate intensity distribution from position to position. The angle ␥ decreases
down to 5° on an average.
When the electric field is turned off, the ␻ profile becomes broad and the angle ␥ becomes small 共3°兲 as shown in
Figs. 3共6-a兲 and 3共6-b兲. Compared to the initial state, thelocal-layer structure is irreversibly transformed. The ␻ profile looks like the quasibookshelf or the strongly modified
v-chevron structure.
A series of time integrated spatial distributions in Fig. 3
has revealed the local-layer structure in a microscopic scale.
The detail of the layer structure, however, seems to dependon the sample and the history of the field application. Figure
4 shows the other typical ␻ and ␹ profiles from a different
sample for the high applied field 关Figs. 4共a兲 and 4共b兲兴 andafter turning off the field 关Figs. 4共c兲 and 4共d兲兴. The ␻ profiles
at the high voltage 共⫾50 V兲 show the single peak 关Fig. 4共a兲兴
similar to Fig. 3共5-a兲, while the ␹ profiles in Fig. 4共b兲 arebroader than those in Fig. 3共5-b兲 and the periodic structure isnot so clear. After turning off the field, this type of thesample shows a single peak in the ␹ profile 关Fig. 4共d兲兴 incontrast to the alternate two peaks shown in Fig. 3共6-b兲,while the ␻ profile 关Fig. 4共c兲兴 is similar to Fig. 3共6-a兲. For allthese differences among samples, the local-layer structure
after turning off the field is characterized by the broadeningof the ␻ profile and the narrowing of the chevron angle ␥ ora single peak in the ␹ profile. Hereafter, the layer structuresin Figs. 3 and 4 are referred to as the type D and type S,
indicating the double and single peaks in the ␹ profile after
turning off the field, respectively.

051706-3

PHYSICAL REVIEW E 67, 051706 共2003兲

TAKAHASHI et al.

obtained after a long time interval 共about four months兲 without electric field application. Poor statistics are due to thelack of the spatial integration in this case. Multiple broad
peaks in the ␻ profile indicate the partial recovery of thev-chevron structure. The layer relaxation seems to proceed
quite slowly.
B. Quasistatic response

FIG. 4. Series of ␻ profiles 关共a兲 and 共c兲兴 and ␹ profiles at ␻
⫽0° 关共b兲 and 共c兲兴 as a function of the vertical position across the
stripe. Under the ⫾50 V field application 关共a兲 and 共b兲兴 and after
turning off the field 关共c兲 and 共d兲兴. The sample thickness was 6 ␮m.

To summarize the layer deformation process, the ␻ and ␹
profiles in Fig. 3 are summed for Y positions 共temporally andspatially integrated profiles, Fig. 5兲. The irreversible v chevron to the quasibookshelf transformation in ␻ profiles 关Fig.
5共a兲兴 well agrees with previous x-ray diffraction experiments
关8,10,17,19兴, while the simultaneous ␹-profile measurement
clearly indicates various stages of the h-chevron formation.
Finally, the layer transformation having a long relaxation
time is mentioned. Uppermost profiles in Fig. 5 共long兲 are

FIG. 5. Summary of the time integrated ␻ profile 共a兲 and ␹
profile 共b兲. From ⫾18 V to E off 共after turning off the electric field兲,the diffracted intensities were obtained by integrating over the position from series of ␻ and ␹ profiles 共Fig. 3兲. For the initial profile,the ␹ profile 共broken line兲 was measured during the ␻-profile measurement at the center of the narrow wall 共integrated over ␻ angle兲.
Uppermost profiles 共long兲 were obtained from a different sample ata single position 共no spatial integration兲 after a long interval without
electric field application.

The time-resolved experiments under the quasistatic condition were performed with a 5-Hz triangular wave for the
sample after the irreversible transition, i.e., time-resolved
measurements of Figs. 3共5-a兲 and 3共5-b兲. Figures 6共a兲 and6共b兲 show the time-resolved MCS-mode ␻ profiles from thesample used in Fig. 3 for one cycle of applied voltage 共⫾60
V amplitude兲 as a function of time for different positions
共8-␮m apart in the Y position兲. In Fig. 6共a兲, a single peaknear ␻ ⫽0° at the high field shifts to the low angle by about
1° and becomes broad at the low field. In Fig. 6共b兲, a weak
hump appears at the low angle side and it shifts to lower
angles with increasing voltage, and the broad double peak
appears at low voltage. These two patterns, Figs. 6共a兲 and6共b兲, appeared from position to position in the Y direction
alternately. Figure 6共c兲 shows the ␻-profile intensity near ␻⫽0° obtained from Fig. 6共b兲 as a function of the applied
voltage 共voltage-dependent profile兲. The intensity has
maxima at around ⫾30 V and decreases at lower and higher
applied voltages. The decrease in the intensity is compensated by the low-angle weak hump at the high field, while,naturally, it is due to the shift and broadening of the ␻-profile
peak at the low field. The layer response is different from theoptical one.
Although Figs. 6共a兲 and 6共b兲 are the typical time-resolved␻ profiles for the triangular wave, several types of the ␻
profile seem to appear at the low field from various samples
and positions: the asymmetric broad peak 关tilted bent bookshelf, Fig. 6共a兲兴, the broad double peak 关modified v chevron,Fig. 6共b兲兴 and the symmetric broad peak 共quasibookshelf兲.
The common feature of these is the broad profile. It is also
noted that the FWHM of the ␻ profile after turning off the
field 关Fig. 3共6-a兲兴 is broader than that at 0 V during the ac
field application. Therefore, the layer response under the triangular field 共5 Hz兲 is a quasistatic process.
The time-resolved MCA-mode ␹ profile shows remarkable profile change during the field application. Figures 7共a兲and 7共b兲 are obtained from different samples. In Fig. 7共a兲,
the angular separation of about 10° of the double peak at thehigh field ( ␥ ⬃5°) decreases down to 4°–5° at the low field( ␥ ⬃2°) while, in Fig. 7共b兲, the double peak at the high fieldchanges continuously to the single peak at the low field.
Figures 7共a兲 and 7共b兲 relate to the type D and type S layertransformations, respectively. In practice, the time dependence of the type S 关Fig. 7共b兲兴 is more frequently observed.
The positional dependence of the time-resolved ␹ profile
showed the alternate low- and high-angle peaks.
The reversible layer response such as shown in Figs. 6
and 7 started when ␦ and/or ␥ became less than ⬃10° or
dense focal conics disappeared. Below that voltage, no con-

051706-4

PHYSICAL REVIEW E 67, 051706 共2003兲

DYNAMIC LOCAL-LAYER RESPONSE OF SURFACE- . . .

FIG. 7. Time-resolved MCA-mode ␹ profiles for a half cycle ofthe triangular wave form 关5 Hz, see the inset of Fig. 6共a兲兴. 共a兲 and共b兲 were obtained for different samples and the maximum applied
voltages were ⫾60 and ⫾50 V, respectively. Both profiles wereobtained near ␻ ⬃0°. 10 ms time resolution. Note that the sampling times 共abscissa兲 are not at equal intervals.

FIG. 6. Time-resolved MCS-mode ␻ profiles for one cycle ofthe triangular wave form 共5 Hz兲 关共a兲 and 共b兲兴. 共a兲 and 共b兲 wereobtained from the sample used in Fig. 3 at positions 8 ␮m apart in
the Y direction. An inset in 共a兲 shows the wave form applied to thesample. The maximum applied voltage was ⫾60 V. The time resolution was 1 ms. The data for the last 2.5% of one cycle are lacking
due to the limitation of the timing control procedure for present
electronics. 共c兲 The applied voltage dependence of the ␻-profile
intensity near ␻ ⫽0° 共voltage-dependence profile兲 obtained from共b兲. The optical transmittance is also shown.

spicuous ␹-profile response to the applied field was observed.
From the time-resolved measurement, the quasistatic reversible layer transformation was revealed for the first time.
C. Transient response

The transient layer response was investigated under astep-form electric field 共25 Hz, ⫾60 V兲. The time-resolved
MCS-mode ␻ profile for one cycle of the field is shown in

Fig. 8共a兲. The ␻ profiles at the high and low fields, time
integrated for 3 ms of Fig. 8共a兲, are shown in Fig. 8共b兲. Astrong peak near ␻ ⫽0° and weak humps near ␻ ⫽⫾4° at
the high field, and a broad single peak at the low field are
seen. The time dependent integrated intensity of the ␻ profile关integrated Fig. 8共a兲 from ␻ ⫽⫺0.6° to ␻ ⫽1.6°] shown in
Fig. 8共c兲 remains nearly constant at the high field, while thatat the zero-voltage region shows the slow fluctuation, up to afew milliseconds after the field change. The corresponding
optical response in Fig. 8共c兲 shows the memory effect whenthe electric field is turned off 共⫹60–0 V, falling edge兲 andthe sharp decrease when the field is turned on 共0– 60 V, risingedge兲. Figures 9共a兲 and 9共b兲 show the detailed intensity
variation at ␻ ⫽0° and 0.4° at the falling edge and the risingedge, respectively. At the falling edge, the decrease of the
␻-profile intensity depends on the ␻ angle, while at the risingedge the intensity increase seems to be independent of the ␻angle. The transient time in the time-resolved ␻ profile,when it is defined by the time interval during which the ␻intensity in Fig. 9 levels off after the electric field change, is
ca. 0.2–0.4 ms for the falling edge and about 0.5 ms for therising edge. The optical transient time is about 30 ␮s at therising edge for this sample 关Fig. 8共c兲兴 and usually less than
0.1 ms; it is shorter than the layer transient time.
The time-resolved ␹ profiles for falling edge and risingedge are shown in Figs. 10共a兲 and 10共b兲, respectively. The
time-resolved ␹ profiles have the double peak and the single
peak at the high and the low voltage, respectively, and theycorrespond well to the quasistatic time-resolved ␹ profile
shown in Fig. 7. The response time in the ␹ profile, during
which the major profile change occurs after the applied fieldchange, is 0.1–0.2 and 0.3–0.4 ms for the falling edge andthe rising edge, respectively. The response time for the ␹
profile is slightly shorter than the transient time for the ␻

051706-5

PHYSICAL REVIEW E 67, 051706 共2003兲

TAKAHASHI et al.

FIG. 9. X-ray intensity near the falling 共⫹60–0 V兲 共a兲 and rising
共0–⫺60 V兲 共b兲 edges obtained from Fig. 8共a兲 for ␻ ⫽0° 共䊊兲 and␻ ⫽0.4° 共䊉兲. Dotted lines show the time when the applied fieldchanges.

plication, the sample showed the stripe texture which was a
combination of the v and the h chevron 关28兴. Figure 11
shows the applied voltage dependences of the angles ␦ and ␥
for TFMHPOBC together with those for TK-C101. A clear
threshold voltage for TFMHPOBC 共AFLC兲 in contrast to thegradual layer change in TK-C101 共FLC兲 agrees with previous experiments 关9,17–19兴. It is noted that not only ␦ but
also ␥ shows the similar voltage dependence. The thresholdvoltage relates to the onset of the ferroelectric state.
During the reversible layer transformation under the triangular wave form 共5 Hz, ⫾65 V兲, the time-resolved MCS ␻
profile 关Fig. 12共a兲兴 shows the triple peak at the low field andthe single peak at the high field. The corresponding timeresolved ␹ profile 关Fig. 12共c兲兴 shows that the two peaks at
the high field 共50 and 140 ms兲, though the low-angle peak
共around ␹ ⬃⫺1.5°) is quite weak in this case, become aFIG. 8. 共a兲 Time-resolved MCS-mode ␻ profiles for the stepform electric field 共25 Hz, ⫾60 V兲. 0.04 ms time resolution. An
inset shows the wave form applied to the sample. 共b兲 ␻ profiles
integrated over 3 ms around 60 V 共solid兲 and 0 V 共broken兲. Arrows
show humps that appeared at ⫹60 V applied voltage. 共c兲 The timedependence of the ␻-profile integrated intensity around ␻⫽0.2° – 1° obtained from 共a兲. An optical transmittance is also
shown.

profile. This might be caused by the following reasons; the ␻
profile is the integrated intensity for the ␹ angle in thepresent experiment resulting in the insensitive response, andthe marked change in the layer structure is closely related tothe h chevron rather than the v chevron 共or the layer deformation around the Y axis兲. In practice, the slow intensity
variation in the ␹ profile 共more than 1 ms兲 was observed andit corresponded to the slowly varying part of the ␻ profile.
D. AFLC response

An AFLC sample TFMHPOBC was also measured withthe same technique. At the initial stage before the field ap-

FIG. 10. 共a兲 and 共b兲 are time-resolved MCA-mode ␹ profiles forthe falling edge 共⫹60–0 V兲 and the rising edge 共0–⫺60 V兲, respectively, of the step-form electric field 共50 Hz, ⫾60 V兲; 0.1 ms time
resolution. Dotted lines show the time when the applied fieldchanges.

051706-6

PHYSICAL REVIEW E 67, 051706 共2003兲

DYNAMIC LOCAL-LAYER RESPONSE OF SURFACE- . . .

FIG. 11. Applied voltage dependences of the chevron angle ␦共䊏,䊐兲 and ␥ 共䊉,䊊兲. 共a兲 and 共b兲 are for TK-C101 共FLC兲 and TFMHPOBC 共AFLC兲, respectively. The bar shows the FWHM of eachpeak.

single peak at the medium field 共60, 80, and 130 ms兲 and thatthe two peaks appear again in the low field 共90–110 ms兲. The
angular separation between the two peaks at the low field iswider than that at the high field. From Figs. 12共a兲 and 12共c兲,the layer structure is approximately described as the h chevron at the high field, the quasibookshelf at the medium field,
and the combination of the h and v chevrons at the low field.
Compared to TK-C101 results and the similarity between the
optical response and the diffraction intensity 关Fig. 12共b兲兴, it
was confirmed that the layer structure of TFMHPOBC appearing in the high and medium fields corresponds to theferroelectric state. The appearance of the low-field h chevronis closely related to the antiferroelectric state due to the fieldinduced phase transition. It is noted that the x-ray diffraction
profile shows the double hysteresis similar to the optical response of AFLCs 关2,9兴, indicating again the important role oflayer motion in the electro-optical response.
The transient layer response under the step-form electricfield 共100 Hz, ⫾45 V兲 shows the different behavior between
the falling and rising edges. At the falling edge 关Figs. 13共a兲and 14共a兲 for ␻ and ␹ profiles, respectively兴, the ferroelectric
structure gradually changes to the antiferroelectric one, whileat the rising edge 关Figs. 13共b兲 and 14共b兲兴 the layer structuresuddenly changes within a present time resolution. The transient time, during which the h chevron of the antiferroelectric and the ferroelectric phases for the falling (T f ) and rising(T r ) edges, respectively, appears after the field change, depends on the sample. Typically, T f and T r were 0.1–0.3 and
0.02–0.08 ms, respectively, and corresponded to the slow
component of the field-induced phase transition 关30兴. The
quick response of T r is closely related to the field-induced
phase transition. The layer transient time was as fast as the
optical response time.

FIG. 12. 共a兲 Time-resolved MCS-mode ␻ profiles for one cycleof the triangular wave form 共5 Hz, ⫾65 V兲 for TFMHPOBC. The
applied wave form is shown in an inset. 0.5 ms time resolution.
共b兲 The applied voltage dependence of the ␻-profile intensity near␻ ⫽0° 共voltage-dependence profile兲 from 共a兲. The optical transmittance is also shown. 共c兲 Time-resolved MCA-mode ␹ profiles obtained at ␻ ⫽⫹0.2°. 5 ms time resolution. The time from 50 to
150 ms corresponds to the applied voltage from ⫹65 to ⫺65 V.
Note that the sampling time 共abscissa兲 is not equal interval. The
sample thickness was 5.5 ␮m.
IV. DISCUSSION
A. Layer structure under the electric field

Since a series of spatially and time-resolved ␻- and␹-diffraction profiles was measured, the irreversible and reversible layer transformations of the surface-stabilized FLCs
under the electric field can be discussed as shown in Fig. 15.
At the initial state, the layer structure is the v chevronwith a zigzag defect 关Fig. 15共a兲兴. The irreversible layer trans-

051706-7

PHYSICAL REVIEW E 67, 051706 共2003兲

TAKAHASHI et al.

FIG. 13. Time-resolved MCS-mode ␻ profiles for the step-form
electric field 共100 Hz, ⫾45 V兲 from TFMHPOBC around the fallingedge 共⫹45–0 V兲 共a兲 and the rising edge 共0–⫺45 V兲 共b兲. 10 ␮stime resolution. Dotted lines show the time when the applied fieldchanges. The sample thickness was about 4 ␮m.

formation with increasing electric field consists of twostages. When the electric field is first applied to the sample,
the electric torque makes the layer upright resulting in theneedle-defect generation 关Fig. 15共b兲兴. The in-plane deflection
angle ␥ is nearly equal to the v-chevron angle ␦ at this stage,
though the layer bends along the depth. With an increasing
applied voltage, the nearly periodic structure consisting of
the alternate v chevron and h chevron is achieved 关Fig.
15共c兲兴. These structures are deduced from the data shown in
Figs. 3共1-a,b兲 and 3共2-a,b兲 and each layer structure has already been discussed 关12,21,22兴.
With further increase of the applied voltage, both ␦ and ␥
reduce gradually and simultaneously. There are, at least, two

FIG. 15. Schematic representation of the local-layer structure in
the FLC cell under the ac electric field. The initial v-chevron structure with narrow walls 共a兲, the generation of the needle defect 共b兲,the development of the needle defect and the formation of the stripe
texture 共c兲, and the transformation of the stripe texture 共d兲. The
reversible layer transformations are shown in 共e兲 and 共f兲 for the high(E high) and low (E low) electric fields, respectively. 共d-1兲–共f-1兲 and共d-2兲–共f-2兲 correspond to the type S and type D layer transformations 共see text兲. All chevron angles are exaggerated and the layer
deformation, especially along the depth, is simplified. Thin dottedlines are a guide for eyes to show the folding direction.

FIG. 14. Time-resolved MCA-mode ␹ profiles for the step-form
electric field 共50 Hz, ⫾45 V兲 from TFMHPOBC for the falling edge
共⫹45–0 V兲 共a兲 and the rising edge 共0–⫺45 V兲 共b兲. 40 and 15 ␮stime resolutions for 共a兲 and 共b兲, respectively. Dotted lines show thetime when the applied field changes. Note that the sampling time
共abscissa兲 is not equal interval.

types of the surface layer structure: either the layer intersection at the substrate surface is straight 关type S, Fig. 15共b-1兲兴
or a part of the surface layer is folded 关type D, Fig. 15共b-2兲兴.
The surface layer of the type D has partly changed to the hchevron. The type S structure is deduced from Fig. 4, in
which the quite broad bookshelf or the deformed v-chevron
structure is realized without the h chevron after turning off
the field. The single peak at the low voltage in a reversible
process in Fig. 7共b兲 also supports this structure. The type D

051706-8

PHYSICAL REVIEW E 67, 051706 共2003兲

DYNAMIC LOCAL-LAYER RESPONSE OF SURFACE- . . .

layer structure is inferred from Figs. 3共5-a兲 and 3共5-b兲 byconsidering that the h-chevron area increases to make up thedecrease in the v-chevron part. The origin of types S and D
might be due to the difference in the surface treatment and/or
the history of the applied field.
The quasistatic reversible layer deformation is illustrated
in Figs. 15共e兲 and 15共f兲 for the high and low fields, respectively 共see Figs. 6 and 7兲. When the quasibookshelf is realized at the low field 共type S兲, the layer bends along the cell
depth 关Fig. 15共f-1兲兴. With increasing field, the bulk layer
tends to be upright while the surface layer stays almost at thesame position, resulting in the appearance of the surface v
chevron at the apex of the h chevron, which enables thesmooth layer connection 关Fig. 15共e-1兲兴. The v-chevron part
corresponds to the small hump appeared in the time-resolved␻ profile. When the layer is the deformed h chevron even at
the low field 共type D兲, the layer response to the electric fieldis the increase in the h-chevron angle and the appearance of
the weak v-chevron component at the high field 关Fig. 15共e2兲兴. The present results directly show the importance of thesubstrate surface effect during the h-chevron formation.
After the electric field is turned off, the type S structure
becomes the broad quasibookshelf or the strongly modified v
chevron as seen in Figs. 4共c兲 and 4共d兲. For the type D structure, the layer is similar to the mostly h-chevron structure
shown in Fig. 15共b-2兲 but with the distortion along the depth.
In Fig. 15, the layer is assumed to be symmetric withrespect to the center of the cell for simplicity. In practice,
however, the layer might be asymmetric due to the differencein the surface treatment, macroscopically and microscopically, for upper and lower substrates.
B. Origins of the layer deformation

The possible origin of the observed layer deformation is
discussed in terms of the electric torque, the substrate surface
anchoring, and the molecular orientation. In the following
discussion, the conservation of the layer spacing is assumed.
1. Stripe texture formation under electric field

For the generation and the growth of the needle defect,
the surface molecule is not necessary to change orientation.
Thus, the needle defect is easy to grow 关12,24兴. With increasing electric field, the angles ␦ and ␥ became small simultaneously 关Fig. 15共d兲兴 in contrast to the proposed layer structure in which the h chevron grows continuously withincreasing applied voltage 关12兴. The layer spacing along the
rubbing direction at the substrate surface ds is given by ds⫽dc * /cos ␦ cos ␥, where dc * ⫽da cos ␪ is the smectic layer
spacing, da is the molecular length, and ␪ is the cone angle.
At the initial and low-field stages, the angles ␦ and ␥ areclose to ␪ indicating ds⬃da. The decrease in both ␦ and ␥ isthe clear and direct evidence of the rearrangement of thesurface molecule; thus ds reduces. This process is induced by
the increasing field-induced torque, which overcomes thesurface anchoring. The competition between the electric
torque and the surface anchoring induces a strain in the bulk
resulting in the appearance of dense focal conics 关Fig. 2共c兲兴.
After the new layer structure forms at higher voltages, focal

conics disappear. It is noted, however, that the surface molecule does not completely follow the applied field due to theresistive anchoring. Thus the perfect bookshelf structure isseldom observed. Furthermore, surface molecules arrange
again after a long interval so that they can become parallel tothe rubbing direction slowly 共uppermost figure of Fig. 5兲.
Various types of so-called stripe textures are observed after
the generation of the needle defect; the layer structure, however, is different among them. The triple peak in the ␻ profile
for the stripe texture obtained with conventional x-ray experiments has been interpreted as the v chevron with thebookshelf at the center of the cell 共double-kink structure兲
关9,17,19兴. From the present results, the bookshelf region
might be interpreted as a part of the h chevron 关Fig. 15共d兲兴 insome cases.
2. Layer structure in the reversible transformation

During the reversible layer transformation process, thelayer at the surface is assumed to stay almost at the same
position due to the surface anchoring, while the bulk layer
共molecule兲 responds to the applied field under this boundary
condition. At the low field, the so-called quasibookshelf
structure seems to be realized 关Figs. 6, 7, and 15共f兲兴. The
low-field structure, however, is expected to be the v chevron,
if constant dc * is assumed, since the high electric field structure is mainly the h chevron 关Fig. 15共e兲兴. Furthermore, evenafter turning off the field, the perfect v chevron as seen in theinitial state was not observed. The layer structure at the low
field is explained as follows. Since the homogeneously bent
layer is energetically unfavorable in the smectic phase, thebroad peak in the ␻ profile indicates the introduction of thelayer imperfection; i.e., the alignment condition is partly destroyed by the high-field treatment. In other words, as is wellknown, the good alignment is necessary to realize the v
chevron. Even when the macroscopic alignment condition isdeteriorated, however, the v chevron may be locally realized
at least near the surface to keep the layer spacing constant.
From these discussions, the quasibookshelf structure observed at the low field seems to be the imperfect v-chevron
structure.
The electric torque makes the layer upright resulting in
the h-chevron formation at the high field, whereas the surface
anchoring tends to align the v-chevron layer. The differencein the transient layer response between the falling and risingedges observed in Figs. 9 and 10 can be explained by these
two forces. At the rising edge, the molecule should overcome
the surface anchoring, while the anchoring force alone exists
at the falling edge. Thus, in the FLCs, the transient time at
the rising edge is slower than that at the falling edge.
Under both triangular- and step-form electric fields, thelayer transformed depending on the electric field, while theoptical response showed the well-known memory effect关Figs. 6共c兲 and 8共c兲兴. In other words, the bulk molecular
position moves while the molecular orientation remains
nearly the same during the layer deformation. The timeresolved diffraction measurement clarified the molecular motion that was not observed by the optical measurement alone.

051706-9

PHYSICAL REVIEW E 67, 051706 共2003兲

TAKAHASHI et al.
V. CONCLUSION

Further studies of the static and dynamic details of theh-chevron structure and its relation to the v chevron are necessary to reveal the mechanism of the stripe texture formation and to study the role of the layer ordering in the electrooptical response. The effects of the polarity and theasymmetry of the electric field on the layer stability are alsoof practical interest. Further experiments are now underway
to clarify these problems.

The time-resolved x-ray microdiffraction measurement
clarified the local-layer structure response in FLC cells to theelectric field. The temporally and spatially resolved ␻ and ␹
profiles can offer the information for the reconstruction of
the time dependent layer structure, which has been estimatedfrom indirect observations. The initial v-chevron structurechanged to the combination of the v chevron and the h chevron at relatively low electric field as the growth of the needle
defect. The chevron angles then reduced continuously withincreasing electric field. After the irreversible layer transformation, the transition between the h chevron with a small
v-chevron part 共high field兲 and the so-called quasibookshelf
共low field兲 occurred reversibly during the ac field application. The low-field quasibookshelf seems to be the imperfectv-chevron structure. The electric torque and the surface anchoring are major driving forces for the reversible layertransformation. Time-resolved measurements also revealed
the difference in the response between the local layer and themolecular orientation. The reversible transformation process
in the FLC cell corresponds well to that in the ferroelectricstate of the AFLC cell.

The authors would like to thank the staff of PF for their
help during experiments. We wish to thank Professor K.
Sekizawa, Professor Y. Takano, and Dr. K. Takase for theircontinuous encouragement during the study. This work was
carried out under the approval of the Photon Factory Program Advisory Committee 共Proposal Nos. 98G341 and
00G279兲. This work was partly supported by a Grant-In-Aid
for Scientific Research on Priority Area 共B兲 共Grant Nos.
2129202 and 12129206兲, the Ministry of Education, Science,Sports and Culture.

关1兴 N. A. Clark and S. T. Lagerwall, Appl. Phys. Lett. 36, 899
共1980兲.
关2兴 S. T. Lagerwall, Ferroelectric and Antiferroelectric Liquid
Crystals 共Wiley, Weinheim, 1999兲.
关3兴 T. P. Rieker, N. A. Clark, G. S. S. Smith, D. S. Parmar, E. B.
Sirota, and C. R. Safinya, Phys. Rev. Lett. 59, 2658 共1987兲.
关4兴 N. Clark and T. P. Rieker, Phys. Rev. A 37, 1053 共1988兲.
关5兴 N. A. Clark, T. P. Rieker, and J. E. Maclennan, Ferroelectrics
85, 79 共1988兲.
关6兴 Y. Ouchi, H. Takano, H. Takezoe, and A. Fukuda, Jpn. J. Appl.
Phys., Part 1 27, 1 共1988兲.
关7兴 H. Orihara, A. Suzuki, Y. Ishibashi, K. Gouhara, Y. Yamada,and N. Yamamoto, Jpn. J. Appl. Phys., Part 2 28, L676 共1989兲.
关8兴 Y. Sato, T. Tanaka, H. Kobayashi, K. Aoki, H. Watanabe, H.
Takeshita, Y. Ouchi, H. Takezoe, and A. Fukuda, Jpn. J. Appl.
Phys., Part 2 28, L483 共1989兲.
关9兴 M. Johno, Y. Ouchi, H. Takezoe, A. Fukuda, K. Terashima, andK. Furukawa, Jpn. J. Appl. Phys., Part 2 29, L111 共1990兲.
关10兴 K. Itoh, M. Johno, Y. Takanishi, Y. Ouchi, H. Takezoe, and A.
Fukuda, Jpn. J. Appl. Phys., Part 1 30, 735 共1991兲.
关11兴 M. Oh-e, M. Isogai, and T. Kitamura, Liq. Cryst. 11, 101
共1992兲.
关12兴 R. F. Shao, P. C. Willis, and N. A. Clark, Ferroelectrics 121,
127 共1991兲.
关13兴 Y. Asao and T. Uchida, Jpn. J. Appl. Phys., Part 2 32, L604
共1993兲.
关14兴 A. G. Rappaport, P. A. Williams, B. N. Thomas, N. A. Clark,
M. B. Ros, and D. M. Walba, Appl. Phys. Lett. 67, 362 共1995兲.
关15兴 R. E. Geer, S. J. Singer, J. V. Selinger, B. R. Ratna, and R.
Shashindhar, Phys. Rev. E 57, 3059 共1998兲.
关16兴 L. S. Matkin, H. F. Gleeson, L. J. Baylils, S. J. Watson, N.

Bowring, A. Seed, M. Hird, and J. W. Goodby, Appl. Phys.
Lett. 77, 340 共2000兲.
关17兴 S. J. Watson, L. S. Matkin, L. J. Baylis, N. Bowring, H. F.
Gleeson, M. Hird, and J. Goodby, Phys. Rev. E 65, 031705
共2002兲.
关18兴 P. Cluzeau, P. Barois, H. T. Nguyen, and C. Destrade, Eur.
Phys. J. B 3, 73 共1998兲.
关19兴 P. Cluzeau, P. Barois, and H. T. Nguyen, Eur. Phys. J. E 7, 23
共2002兲.
关20兴 A. Iida, T. Noma, and H. Miyata, Jpn. J. Appl. Phys., Part 1 35,
160 共1996兲.
关21兴 A. Iida, T. Noma, and H. Miyata, Jpn. J. Appl. Phys., Part 1 38,
2845 共1999兲.
关22兴 A. Iida, T. Noma, and H. Miyata, Jpn. J. Appl. Phys., Part 1 40,
1345 共2000兲.
关23兴 Y. Takanishi, A. Iida, K. Ishikawa, H. Takezoe, and A. Fukuda,
Jpn. J. Appl. Phys., Part 1 35, 683 共1996兲.
关24兴 Y. Takanishi, A. Iida, K. Ishikawa, H. Takezoe, and A. Fukuda,
Jpn. J. Appl. Phys., Part 1 38, 4132 共1999兲.
关25兴 Y. Takanishi, T. Izumi, J. Watanabe, K. Ishikawa, H. Takezoe,and A. Iida, J. Mater. Chem. 9, 2771 共1999兲.
关26兴 H. Gleeson and A. Mors, Liq. Cryst. 21, 755 共1996兲.
关27兴 H. Gleeson, G. Bryant, and A. Morse, Mol. Cryst. Liq. Cryst.
362, 203 共2001兲.
关28兴 Y. Takahashi, A. Iida, Y. Takanishi, T. Ogasawara, K. Ishikawa,and H. Takezoe, Jpn. J. Appl. Phys., Part 1 40, 3294 共2000兲.
关29兴 Y. Takahashi, A. Iida, Y. Takanishi, T. Ogasawara, K. Ishikawa,and H. Takezoe, Mol. Cryst. Liq. Cryst. 365, 853 共2001兲.
关30兴 M. Johno, K. Ito, J. Lee, Y. Ouchi, H. Takezoe, A. Fukuda, andT. Kitazume, Jpn. J. Appl. Phys., Part 2 29, L107 共1990兲.

ACKNOWLEDGMENTS

051706-10

Ferroelectrics, 311: 41–50, 2004
C Taylor & Francis Inc.
Copyright 
ISSN: 0015-0193 print / 1563-5112 online
DOI: 10.1080/00150190490511149

Temperature and Electric Field Dependences of the
Local Layer Structure in Anti-Ferroelectric Liquid
Crystals Measured by X-Ray Micro-Diffraction
YUMIKO TAKAHASHI,1 ATSUO IIDA,2 YOICHI TAKANISHI,3MICHI NAKATA,3 KEN ISHIKAWA,3 and HIDEO TAKEZOE3
1

Department of Physics, College of Science and Technology, Nihon University, 1-8,
Surugadai, Kanda, Chiyoda-ku, Tokyo 101-8308, Japan2
Photon Factory, Institute of Materials Structure Science, High Energy Accelerator
Research Organization, 1-1 Oho Tsukuba 305-0801, Japan3
Department of Organic and Polymeric Materials, Tokyo Institute of Technology,
O-okayama, Meguro-ku, Tokyo 152-8552, Japan(Received in ﬁnal form October 29, 2003)
The local layer of the antiferroelectric liquid crystal has been investigated as a functionof the temperature near the SmA to SmC∗A phase transition by synchrotron X-ray microbeam diffraction. The stripe texture in the SmA phase well above the phase transition
temperature is related to the in-plane layer deﬂection. Just above the phase transition
temperature, the clear stripe starts to grow and the local layer structure becomes the
combination of the vertical-chevron and the horizontal-chevron. With decreasing temperature in the SmC∗A phase, the chevron angle increases. The growth of the chevron
structure is explained by the gradual reduction of the layer spacing. The time resolved
measurement of the local layer structure in the electroclinic effect is also carried out
to characterize the layer response in the SmA phase. The comparison of the chevron
structure between the antiferroelectric and the ferroelectric liquid crystal is made.
Keywords Anti-ferroelectric liquid crystal; stripe texture; chevron local layer structure; electroclinic; synchrotron X-ray microbeam; X-ray micro-diffraction

1. Introduction
Antiferroelectric liquid crystals (AFLCs) have been attracted much attention for theirtristable switching behavior and various sub-phases [1, 2] from both basic and appliedresearches. Smectic sub-phases and the phase transition between them in AFLCs related
closely to the molecular arrangement in adjacent smectic layers. The layer structure characterizes also the smectic sub-phase, as it reﬂects the molecular interaction mainly throughthe layer spacing and the surface effect for the surface stabilized (SS) AFLC. For instance, the bookshelf layer structure is realized in the SS cell in the smectic A phase (SmA),
while the vertical chevron layer structure (v-chevron) is generated in smectic C∗ (SmC∗ )variants due to the layer spacing reduction. Furthermore, a stripe texture running parallel tothe rubbing direction is sometimes observed with a polarized optical microscope in AFLC
and the ferroelectric liquid crystal (FLC) [3] and is thought to be due to the horizontal
chevron (h-chevron, in-plane chevron.). To clarify the relation between these local layer
Address correspondence to Atsuo Iida, Photon Factory, Institute of Materials Structure Science, High Energy
Accelerator Research Organization, 1-1 Oho, Tsukuba 305-0801, Japan. E-mail: atsuo.iida@kek.jp[337]/41

42/[338]

Y. Takahashi et al.

structures and the molecular alignment, small angle X-ray scattering investigations [4–7]have been carried out. Recently the time resolved synchrotron X-ray microbeam has beensuccessfully applied to the AFLC and FLC [8–10] to reveal the dynamic response of thespatially resolved local layer structure under the electric ﬁeld.
In this paper, in order to directly characterize the stripe texture and to investigate its
growth process, the temperature dependence of the local layer structure was measured indetail using synchrotron X-ray microbeam diffraction. The time resolved X-ray diffraction
measurement of the electroclinic effect is also carried out to characterize the layer responsein the SmA phase. The chevron structure in AFLC is compared with that in FLC.

2. Experimental
The experiment was carried out on BL-4A at the Photon Factory. The X-ray energy was 8 keV
and the beam size at the sample was less than 3(vertical) × 4(horizontal) μm2 . The diffracted
intensities were measured as a function of angles ω and χ , which correspond to the layer
orientation with respect to the rubbing direction normal in the cell plane and the surface
normal, respectively. The layer deﬂection angles, δ and γ , are measured from the ideal
bookshelf structure along the depth and in the cell glass plane, respectively. When the vor h-chevron structure is realized, δ or γ is equivalent to the chevron angle. The sample
geometry is shown in Fig. 1. Diffracted X-rays were measured by a position sensitive
proportional counter or an X-ray CCD detector with an image intensiﬁer. The time resolved
measurements were performed by using a timing control system synchronized with anapplied signal to the sample. A detailed description of the experimental system has been
already published elsewhere [8–10].
The samples were homogeneously aligned (R)-TFMHPOBC (AFLC) and was sandwiched between ITO-coated glass plate (150 μm thick) rubbed on one-side after coatinga polyimide alignment ﬁlm. The cell gap was about 9 μm. The sample was set in a conventional temperature control stage. The rubbing direction was set horizontally. The phasetransition temperature (Tc ) from SmA to SmC∗A was 109◦ C [11]. Several samples wereprepared for different experiments to conﬁrm the effect of the thermal history or electricﬁeld treatment.

FIGURE 1 Schematic representation of the experimental setup for the synchrotron X-ray
microbeam diffraction.

Local Layer Structure in Anti-Ferroelectric Liquid Crystals[339]/43

3. Results
The spatial distribution of the X-ray diffraction proﬁle from TFMHPOBC was measured asa function of temperature near the SmA to SmC∗A phase transition together with the in situ
observation of the texture by a polarized optical microscope.
At Tc + 2.9◦ C, the micrograph (Fig. 2(a)) shows the stripe texture of a weak contrast.
Figures 3(a) and (b) show series of ω- and χ -proﬁles, respectively, scanned in the verticaldirection normal to the stripe texture. Both proﬁles show single peaks almost independentof the position. The ﬂuctuation of the peak angular position are within ±1◦ . Above thistemperature, at least up to Tc + 7◦ C, ω- and χ -proﬁles are almost unchanged. By decreasing
the temperature, at Tc + 1.9◦ C, the full width at half maxima (fwhm) of the peak in thespatially resolved ω-proﬁles increases from 1.1◦ (Fig. 3(a)) to 1.7◦ (Fig. 3(c)) on averageand the tail part of the proﬁle is enhanced. The peak angular position in the χ -proﬁle inFig. 3(d) shows the slightly larger angular ﬂuctuation than that in Fig. 3(b). The contrastof the stripe texture (Fig. 2(b)) slightly increases compared to Fig. 2(a). At Tc + 1◦ , in the
ω-proﬁle (Fig. 3(e)), the single or the triple peak (a strong central peak and two weak subpeaks) appears alternately from position to position. The angular position of the sub-peakis about 2◦ from the main peak. At the same time, the angular position of the peak in theχ -proﬁle (Fig. 3(f)) shows the alternate intensity distribution; its spatial period is about

FIGURE 2 Polarized optical micrographs of textures obtained at temperatures (a) Tc +2.9◦ , (b) Tc +1.9◦ , (c) Tc +1.0◦ and (d) Tc −1.0◦ . The rubbing direction was set horizontally.
White arrows show the direction and the region of the X-ray measurement shown in Fig. 3.
A scale mark is 100 μm.

44/[340]

Y. Takahashi et al.

FIGURE 3 Series of ω-proﬁles and χ -proﬁles as a function of the vertical position (Ydirection) at T = Tc + 2.9◦ , (a) and (b), T = Tc + 1.9◦ (c) and (d), T = Tc + 1.0◦ (e) and(f), and T = Tc −1.0◦ (g) and (h). The χ -proﬁles were obtained at ω = 0.6◦ (b), 0.5◦ (d), 0.8◦(f) and 0.8◦ (h). The scanning step in the Y direction was 3 μm. The darker part corresponds
to the higher diffracted intensity. X-ray intensities were normalized by the highest intensity
in each ﬁgure.

Local Layer Structure in Anti-Ferroelectric Liquid Crystals[341]/45

10 μm and the angular difference of the alternate peak position is about 4–5◦ . When thesample is further cooled down to SmC∗A , Tc − 1◦ C (Fig. 2(d)), the triple peak is clearlyobserved in the ω-proﬁle (Fig. 3(g)). The peak intensity for the main (ω = 0◦ ) and subpeaks (ω = ±12◦ ) varies alternately again as a function of the position. The correspondingχ -proﬁle (Fig. 3(h)) also shows the alternate peaks.
Figure 4 shows the peak angular position in the χ -proﬁle at around ω = 0.8◦ , ω =−11.2◦ and ω = 12.0◦ at Tc − 1◦ . The peak of the χ -proﬁle at ω = 0.8◦ shows the nearly
periodic variation, while those at ω = −11.2◦ and ω = 12.0◦ stay constant. The former andthe latter are the typical behavior of the h- and v-chevron, respectively. Furthermore, thealternate appearance of each chevron structures indicates that the local layer structure is the
combination of the h- and v-chevron; i.e. the periodic v-chevron and h-chevron structure isclearly generated at this temperature. The v- and h-chevron angles increased up to 15◦ at
Tc − 10◦ C.
Corresponding to these X-ray diffraction results, the stripe texture in Fig. 2 progressively increases its contrast. Though the stripe texture at high-temperature (Fig. 2(a)) issimilar to that at low-temperature (Fig. 2(d)) except the constrast, the ﬁne structure or theabsolute position of the stripe is slightly different between them. The stripe seems to be
modiﬁed near the defect (white dots in micrographs) around Tc .
The temperature dependence of the layer spacing was also measured with an X-ray
CCD camera. The relative layer spacing as a function of temperature (Fig. 5(b)) was obtained
from the diffraction spot on the CCD (Fig. 5(a)). Tc in this ﬁgure is set at the temperature
where the layer spacing changes abruptly. Naturally, the layer spacing decreases rapidly in
SmC∗A with decreasing temperature due to the increase in the molecular tilt angle, it is also
noted that the layer spacing gradually decreases even above Tc . This type of the temperaturedependence has been also reported in other AFLC materials such as MHPOBC [12].
From the above experiment, it is clariﬁed that the local layer in the SmA is approximately the so-called bookshelf structure and becomes the chevron structure near Tc . In
order to characterize the local layer structure in further detail, the layer response to theelectric ﬁelds (the electroclinic effect) was measured. Figures 6(a) and (b) show series of
ω- and χ-proﬁles, respectively, scanned in the vertical direction normal to the stripe texture at Tc + 1.0◦ C without the electric ﬁeld. The sample was different from that used inFig. 3. Though a lot of defects and domains are seen in an optical micrograph (Fig. 7(a)),
the measured region was in a single domain owing to the small beam size. In this sample, the v-chevron structure is not so clear (Fig. 6(a)) compared to that in Fig. 3(e), while

FIGURE 4 The peak angular position of the χ -priﬁle (Fig. 3(h)) at around ω = 0.8◦ (),ω = −11.2◦ () and ω = −12.0◦ (◦) at Tc − 1◦ .

46/[342]

Y. Takahashi et al.

FIGURE 5 (a) X-ray diffraction spot obtained by an X-ray CCD camera at Tc − 1◦ atω = −11.2◦ . A scale mark shows 0.1◦ in 2θ angle. (b) The relative layer spacing as afunction of temperature. The Tc was set at the temperature where the gradient of the layer
spacing has maximum. The layer spacing in SmA (do ) is assumed to be 34.6 A in this ﬁgure.

the h-chevron is partly realized (Fig. 6(b)). After the application of the triangular electricﬁeld (±60 V, 5 Hz), the angular spread of the ω-proﬁle becomes narrow (Fig. 6(c)). The
time resolved ω-proﬁle (Fig. 8(a)), though quite weak in the intensity, shows that the peak
becomes broad and narrow at the low and high ﬁeld, respectively. The narrow ω-proﬁlein Fig. 6(c) is mainly due to the high ﬁeld layer structure. The time-resolved χ -proﬁleshows the single peak at the low ﬁeld and the double peak at the high ﬁeld (Fig. 8(b)).
The positional dependence of χ -proﬁle at the highest voltage are shown in Fig. 6(d). The
h-chevron formation is clearly seen at the high ﬁeld. Though the alternate change of thepeak angular position is similar to that in Fig. 6(b), the angular separation of the low andhigh angle peaks becomes large. From this ﬁgure, it is found that the electroclinic effectresults in the h-chevron formation which is characterized by the enhancement of the initiallayer undulation. When the applied ﬁeld is turned off, the local layer structure returns tothe structure similar to the initial one (Figs. 6(e) and (f)). Furthermore, when the sample iscooled down to Tc − 10◦ C after the electric ﬁeld treatment (Figs. 6(g) and (h)), the layer
structure becomes again the combination of the v-chevron and the h-chevron. The positionof the h-chevron and the ﬁne structure, however, are slightly different from the initial ones,
indicating the rearrangement of the layer structure.

Local Layer Structure in Anti-Ferroelectric Liquid Crystals[343]/47

FIGURE 6 Series of ω-proﬁles and χ-proﬁles as a function of the vertical position(Y-direction) at Tc + 1◦ C before, (a) and (b), during, (c) and (d), and after, (e) and (f), the triangular electric ﬁeld application (±60 V, 5 Hz). (g) and (h) were obtained at Tc − 10◦ C.
(c) is a time integrated ω-proﬁle, while (d) is a time resolved χ -proﬁle at the high ﬁeld. Theχ -proﬁles (b), (d), (f) and (h) were obtained for ω = −1.8◦ , −0.6◦ , −1.5◦ and ω = 0◦ ,respectively. The scanning step in the Y direction was 3 μm.

4. Discussion
The stripe texture in SmA of a relatively weak contrast is related to the local layer undulation observed in the χ -proﬁle (Figs. 3(b)), which mainly consists of the in-plane layerdeﬂection. With decreasing temperature, the fwhm of the ω-proﬁle (Fig. 3(c)) gradually
increases and the in-plane undulation structure grows (Fig. 3(d)). Just above Tc (Tc + 1◦ .

48/[344]

Y. Takahashi et al.

FIGURE 7 Polarized optical micrographs of the sample obtained during the electric ﬁeld
application at Tc + 1.0◦ (a) and after turning off the ﬁeld at Tc − 10◦ (b). The spacer edge
is shown in the upper part of the ﬁgure.
Figures 3(e) and (f)), the v-chevron and the h-chevron (periodic in-plane deﬂection layer)
appear simultaneously. The temperature dependence of the layer structure is considered tobe due to the reduction of the layer spacing (Fig. 5(b)) in the same way as the well-known
v-chevron formation in the SS FLC. As compared Fig. 2(b) with Fig. 2(c), or Fig. 3(d) with
Fig. 3(f), the ﬁne structure and the position of the stripe is slightly different between thembesides the increase in the contrast of the stripe texture. It seems that the clear stripe in
Fig. 2(c) is related to the defects (white spots).
The appearance of the in-plane layer deﬂection or the h-chevron characterizes the layer
structure in the SmA and SmC∗A phases of this AFLC material, compared to the v-chevron
preference in SmC∗ of FLC materials [10]. The origin of the in-plane layer deﬂection is
discussed in the following. Since most of the stripe seems to relate to the white defect(focal conics) as shown in Figs. 3(e) and (f), geometrical constraint might play a role torealize the h-chevron. Once the h-chevron is generated, it is easy to propagate along the
rubbing direction similar to the needle defect generation and propagation in SmC∗ [15, 16].
Another possibility for the h-chevron generation is the surface electroclinic effect exertingon surface molecules, since the surface ﬁeld is normal to the surface [17]. Furthermore, it is
not excluded that the memory effect of the h-chevron of the low temperature phase remains

Local Layer Structure in Anti-Ferroelectric Liquid Crystals[345]/49

FIGURE 8 Time resolved ω-proﬁle (a) for the triangular wave form (5 Hz, ±60 V) andthe χ -proﬁle (b) for a half cycle of the same wave form. An inset in (a) shows the change
in the applied voltage during measurements. The proﬁle (b) was obtained at ω = −0.6◦ .
1 ms and 10 ms time resolution for (a) and (b), respectively.
in SmA; since the sample was set to the stage after the off-line sample preparation and was
carefully heated from the room temperature, the X-ray measurement was performed for the
sample subjected to SmC∗ sub-phases and the crystalline phase.
In the electroclinic effect, the reversible transition between the bookshelf and the hchevron occurs. The time resolved χ -proﬁle (Fig. 8(b)) is quite similar to the dynamic layer
response observed in the SmC∗ variants under the high ﬁeld [10]. The h-chevron generation
seems to be consistent with the previous macroscopic observation [13, 14] while the weak
tail appeared in the ω-proﬁle (Fig. 6(c)) suggests the existence of the v-chevron. Further
experiments are now underway.
From Figs. 6(c) and (d), the effect of the electric ﬁeld on the stripe is just the enhancement of the existing one. After the electric ﬁeld is turned off (Figs. 6(e) and (f)), thetexture is quite similar to the initial ones (Figs. 6(a) and (b)). The surface molecule seems toremain nearly at the same position and in the same alignment during the ﬁeld application.
This is also consistent with the time-resolved measurement in Figs. 8(a) and (b), where thebookshelf structure is realized at the low ﬁeld.

Acknowledgement
The authors would like to thank the staff of PF for their help during experiments. We wish
to thank Professor K. Sekizawa, Professor Y. Takano and Dr. K. Takase for their continuous
encouragement during the study. This work was carried out under the approval of the Photon

50/[346]

Y. Takahashi et al.

Factory Advisory Committee (Proposal No. 98G341 and 00G279). This work was partly
supported by Grant-In-Aid for Scientiﬁc Research on Priority Area (B) (12129202 and
12129206), the Ministry of Education, Science, Sports and Culture.

References
1. S. T. Lagerwall, Ferroelectric and Antiferroelectric liquid crystals (Wiley, Weinheim, 1999).
2. I. Musevic, R. Blinc, and B. Zeks, The Physics of Ferroelectric and Antiferroelectric Liquid
Crystals (World Scientiﬁc, 2000).
3. M. Johno, Y. Ouchi, H. Takezoe, A. Fukuda, K. Terashima, and K. Furukawa, Jpn. J. Appl. Phys.
29, L111 (1990).
4. L. S. Matkin, H. F. Gleeson, L. J. Baylils, S. J. Watson, N. Bowring, A. Seed, M. Hird, and J. W.
Goodby, Appl. Phys. Lett. 77, 340 (2000).
5. S. J. Watson, L. S. Matkin, L. J. Baylis, N. Bowring, H. F. Gleeson, M. Hird, and J. Goodby,
Phys. Rev. E 65, 31705 (2002).
6. P. Cluzeau, P. Barois, H. T. Nguyen, and C. Destrade, Eur. Phys. J. B 3, 73 (1998).
7. P. Cluzeau, P. Barois, and H. T. Nguyen, Eur. Phys. J. E 7, 23 (2002).
8. Y. Takahashi, A. Iida, Y. Takanishi, T. Ogasawara, K. Ishikawa, and H. Takezoe, Jpn. J. Appl.
Phys. 40, 3294 (2000).
9. Y. Takahashi, A. Iida, Y. Takanishi, T. Ogasawara, K. Ishikawa, and H. Takezoe, Mol. Cryst. Liq.
Cryst. 365, 853 (2001).
10. Y. Takahashi, A. Iida, Y. Takanishi, T. Ogasawara, M. Nakata, K. Ishikawa, and H. Takezoe,
Phys. Rev. E 67, 051706 (2003).
11. Y. Suzuki, T. Hagiwara, I. Kawamura, N. Okamua, T. Kitazume, M. Kakimoto, Y. Imai, Y. Ouchi,
H. Takezoe, and A. Fukuda, Liq. Crys. 6, 167 (1989).
12. A. Suzuki, H. Orihara, Y. Ishibashi, Y. Yamada, N. Yamamoto, K. Mori, K. Nakamura, Y. Suzuki,
T. Hagiwara, I. Kawamura, and M. Fukui, Jpn. J. Appl. Phys. 29, L336 (1990).
13. A. G. Rappaport, P. A. Williams, B. N. Thomas, N. A. Clark, M. B. Ros, and D. M. Walba, Appl.
Phys. Lett. 67, 362 (1995).
14. R. E. Geer, S. J. Singer, J. V. Selinger, B. R. Ratna, and R. Shashindhar, Phys. Rev. E 57, 3059
(1998).
15. R. F. Shao, P. C. Willis, and N. A. Clark, Ferroelectrics 121, 127 (1991).
16. Y. Takanishi, A. Iida, K. Ishikawa, H. Takezoe, and A. Fukuda, Jpn. J. Appl. Phys. 38, 4132
(1999)
17. K. Nakagawa, T. Shinomiya, M. Koden, K. Tsubota, T. Kuratate, Y. Ishii, F. Funada, M. Matsuura,
and K. Awane, Ferroelectrics 85, 39 (1988).

Acta Cryst. (2002). A58 (Supplement), C337

Acta Cryst. (2002). A58 (Supplement), C337

SYNTHESIS AND STRUCTURE OF CaSiN2
F. Ottinger R. Nesper
ETH Zurich Laboratorium Fur Anorganische Chemie Wolfgang-Pauli-Strasse
10 Hci H106 ZURICH 8093 SWITZERLAND

CRYSTAL AND MAGNETIC STRUCTURES OF LAYEREDSr 2MnGaO5+x OXIDES
A.M. Balagurov1 V.Yu. Pomjakushin1 A.M. Abakumov2 E.V. Antipov2 M.V.
2
3
Lobanov P. Fischer D.V. Sheptyakov1,3
1
Joint Institut for Nuclear Research Frank Laboratory of Neutron Physics
Frank Laboratory of Neutron Physics Joint Institut for Nuclear Research
DUBNA MOSCOW REG. 141980 RUSSIA 2Department of Chemistry,
Moscow State University, 119899 Moscow 3Laboratory of Neutron Scattering,
ETHZ&PSI, CH-5232 Villigen, Switzerland

Containing corner-sharing as well as edge-sharing sin4-tetrahedra as the mainbuilding blocks, very complex Si-N-networks are possible in ternary
nitridosilicates. Therefore the structures of nitridosilicates are a significant
extension to the structures found in the family of oxosilicates. Although thesynthesis of casin2 has been reported in the 1960s, the structure of casin2 has
not yet been clarified. Ca7Si4N10 was received as the main product by reactionof casi2 and Ca3N2 at temperatures of 1400 °C in sealed Niobium ampoules.
Crystals of transparent, orange casin2 were obtained as a by-product. These
crystals are embedded in a Calcium matrix, as it is not possible to synthesize
them stoichiometrically from only casi2 and Ca3N2. Moreover, Calcium isacting as a flux and enables the formation of large single crystals. Casin2
crystallizes in the orthorhombic space group Pbca (No. 61) with a = 5.129(3)Å, b = 10.224(1) Å, c = 14.821(4) Å, Z = 1, R(Fo) = 0.0341. Casin2 is isotypicwith KFeO2 and KGaO2 building a 3-dimensional network of SiN4 -tetrahedra
forming sechser rings. All Si-N[2] distances are within the usual range fornitrido-silicates between 1.719 (6) - 1.778 (6) Å. The Calcium-Calcium
distance is 3.052 (1) å.

Crystal and magnetic structures of new complex manganese oxides
Sr2GaMnO5+x (x = 0, 0.4 and 0.5) were studied by neutron powder diffraction.
The crystal structure of the compound with x = 0 belongs to a brownmillerite
type and consists of alternating SrO, MnO2, SrO and GaO1+x layers with Ima2
space symmetry. Mn magnetic moments are aligned antiferromagnetically inall directions below TN=180 K (G-type order). The oxidized compound with x= 0.5 has a perovskite-like crystal structure with a tetragonal unit cell of
P4/mmm space symmetry. The GaO1+x layers are partially filled. Its magnetic
structure (TN = 108 K) preserves AFM ordering within the MnO2 plane,
however, the interlayer coupling becomes ferromagnetic (C-type order). The
average crystal structure of x = 0.4 sample can be satisfactorily described inmonoclinic P2/m space group but two-phase state could not be excluded. The
latter is indicated by two-step magnetic phase transition: appearance G-type
structure at 140 K and then C-type structure at 110 K. Despite the distances
between neighbouring in-plane and out-of-plane Mn atoms are very different(3.8 Å and 8 Å, respectively) a magnetic structure of all compounds has a 3D
character.

Keywords: MANGANITES, LAYERED STRUCTURE, NEUTRONDIFFRACTION
Keywords: NITRIDO SILICATES, NETWORK STRUCTURE, HIGHTEMPERATURE SYNTHESIS

Acta Cryst. (2002). A58 (Supplement), C337

Acta Cryst. (2002). A58 (Supplement), C337

11x
OBSERVATION OF DYNAMIC LOCAL LAYER RESPONSE OF
SMECTIC LIQUID CRYSTALS BY X-RAY MICRO-DIFFRACTION
A. Iida1 Y. Takahashi2 Y. Takanishi3 M. Nakata3 K. Ishikawa3 H. Takezoe3
High Energy Accelerator Research Organization Institute of Materials
Structure Science 1-1 O-Ho TSUKUBA IBARAKI 305-0801 JAPAN1
Photon Factory, Institute of Materials Structure Science, High Energy
Accelerator Research Organization 2The Graduate University for Advanced
Studies 3Department of Organic and Polymer Materials, Tokyo Institute ofTechnology

DETERMINATION OF PHASES AND PHASE TRANSITIONS IN
LIQUID CRYSTALS
A.K. Schaper1 Z. Zhao1 W. Ruland1 B. Albert2
1
Philipps University Materials Science Center Dept of Geosciences HansMeerwein-Str. MARBURG 35032 GERMANY 2Department of Chemistry,
Justus Liebig University, 35392 Giessen, Germany

For the direct determination of the microscopic local layer structure in thesmectic liquid crystal, the synchrotron X-ray microbeam diffraction technique
becomes a powerful tool[1]. The dynamic local layer response of the stripe
texture, which appears in the anti-ferro and ferroelectric liquid crystal (AFLCand FLC), was measured in detail under the high electric field.
The experiment was performed at the Photon Factory (BL4A) by the X-ray
beam. The diffracted intensities were measured as functions of angles, whichcorrespond to the layer orientation with respect to the normal to the rubbing
direction and the surface normal, respectively. The time resolved
measurements were carried out with the time resolution from a few ƒÝs to ms.
The samples used were TK-C101(FLC) and TPMHPOBC (AFLC). The layer
responses in the SmC* and SmCA phase were measured for FLC and AFLC,
respectively. The electroclinic effect is also measured in the SmA phase ofboth materials. for FLC cells, the reversible local layer change from thehorizontal chevron to the quasi-bookshelf structure was confirmed under the
triangular waveform. It was shown that the anchoring effect at the alignment
film played an important role for the layer transformation. The local layer
relaxation time for the step waveform was dependent on the applied electricfield and the sample (AFLC/FLC). The relation of the layer response among
samples and phases was discussed.
References[1] Y.Takahasi et al, Jpn. J. Appl. Phys. 40(2001)3294

Keywords: SMECTIC LIQUID CRYSTAL, X-RAY MICROBEAM,
TIME-RESOLVED MEASUREMENT

From certain liquid crystal (LC) compounds it is known that they pass throughan intermediate hexatic-B (SmBHex) phase during transition from thecrystalline smectic-B (SmB) phase to the liquid-like smectic-A (SmA) phase.
This hexatic phase is characterized by long-range bond orientational order overmacroscopic dimensions, but only short-range positional order propagatingover not more than a few tens of nanometers. The hexagonal bond orientational
order correlations extent over a three-dimensional stack of two-dimensional
hexatic layers which exhibit only weak interlayer coupling. In this paper, direct
proof of the hexatic order in a cyclohexyl derivative of a biphenylic typecompound is provided by in situ low-dose selected area electron diffraction(SAED). Further information on the phase transitional behavior of the LC
material with the bulk transition sequence SmB - SmBhex - SmA - N - I isgained from light microscopy observations, calorimetric measurements, small
and wide angle x-ray scattering (SAXS, WAXS), and from x-ray density
fluctuation measurements, in particular. The particle density fluctuation ofcondensed matter is caused by thermal motion of the atoms or molecules, andis influenced in a definite manner by the presence of structural defects andlattice disorder. Therefore, the relationship between the density fluctuation andthe x-ray scattering intensity extrapolated toward zero angle may serve as
quantitative measure of the state of order and of the strength of particular
defect populations in solids. For the first time, we apply this method tocharacterizing the phase transitional behavior of an LC material.

Keywords: LIQUID CRYSTALS PHASE TRANSITIONSDIFFRACTION AND SCATTERING

Nuclear Instruments and Methods in Physics Research A 467–468 (2001) 1001–1004

Time resolved X-ray micro-diﬀraction measurementsof the dynamic local layer response to electric ﬁeld
in antiferroelectric liquid crystals
Yumiko Takahashia, Atuso Iidab,*, Yoichi Takanishic, Toyokazu Ogasawarac,
Hideo Takezoeca
The Graduate University for Advanced Studies, 1-1 O-ho, Tsukuba 205-0801, Japan
Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization,
1-1 O-ho, Tsukuba, Ibaraki 305-0801, Japanc
Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8552, Japanb

Abstract
The time-resolved synchrotron X-ray microbeam diﬀraction experiment has been carried out to reveal the local layer
response to the electric ﬁeld in the antiferroelectric liquid crystal. The X-ray microbeam of a few mm spatial resolution
was obtained with Kirkpatrick–Baez optics. The time-resolved small angle diﬀraction experiment was performed with atime resolution ranging from 10 ms to a few ms. The reversible local layer change between the horizontal chevron andthe quasi-bookshelf structure was conﬁrmed by the triangular wave form. The transient layer response for the step form
electric ﬁeld was observed. The layer response closely related with an electric ﬁeld induced antiferroelectric toferroelectric phase transition. # 2001 Elsevier Science B.V. All rights reserved.
Keywords: Synchrotron X-ray microbeam; Antiferroelectric liquid crystal; Time-resolved measurements; X-ray micro-diﬀraction

1. Introduction
Antiferroelectric liquid crystals (AFLC) haveattracted much attention from the application
point of view and also from the basic interest in themesophase [1]. Though the macroscopic layerordering in AFLC can be characterized by theconventional small angle diﬀraction technique [2],the X-ray microbeam is necessary to investigate*Corresponding author. Tel.: +81-298-64-5634; fax: +81298-64-2801.
E-mail address: atsuo.iida@kek.jp (A. Iida).

the local layer structure in the texture observed by
an optical microscope. The time-resolved experiment is also needed to reveal the layer response to
the electric ﬁeld [3].
The synchrotron X-ray microbeam diﬀraction
has been successfully applied to the characterization of various textures in the thin surface
stabilized ferroelectric liquid crystals (FLC) [4–6].
Though the stripe texture observed in AFLC,
which runs parallel to the rubbing direction, is
important for understanding the electric ﬁeld
induced phase transition between AFLC and
FLC phases [7,8], the detailed microscopic local

0168-9002/01/$ - see front matter # 2001 Elsevier Science B.V. All rights reserved.
PII: S 0 1 6 8 - 9 0 0 2 ( 0 1 ) 0 0 5 5 1 - 4

1002

Y. Takahashi et al. / Nuclear Instruments and Methods in Physics Research A 467–468 (2001) 1001–1004

layer structure has not yet been clariﬁed. Furthermore, direct evidence of the dynamic local layer
response of AFLC to the electric ﬁeld has not beenreported, though the molecular response has been
investigated by the optical technique [9].
In this paper, the time-resolved X-ray microdiﬀraction technique is described and the results
are presented for the time-dependent local layer
response in the stripe texture of AFLC.

2. Experimental
The X-ray microbeam system at the Photon
Factory (PF) on BL-4A consists of a multilayer
monochromator and Kirkpatrick–Baez focusing
optics [10,11] (Fig. 1(a)). Owing to the emittanceupgrade of the PF 2.5 GeV ring, the focused beam
size was reduced from 5  6 mm2 (former) to3  4 mm2 (present). The setup around the sample
cell is shown in Fig. 1(b). A position sensitive
proportional counter (PSPC) was used. The
diﬀracted intensity was measured as a functionof o and w angle. The o angle corresponds to thelayer tilt angle with respect to the rubbing
direction in the cell surface plane, while the w
angle is that with respect to the rubbing direction
around the cell surface normal. The o intensity
proﬁle was obtained by rotating the sample
around Y-axis, while the w-intensity proﬁle wasobtained simultaneously by the PSPC at a ﬁxed oangle.
The sample used was TFMHPOBC1 (AFLC)
and was sandwiched between ITO-coated glass
plates rubbed one side after alignment ﬁlm coating. The sample thickness was about 5 mm. The
sample temperature was kept at Tc -108 duringexperiments, where Tc was the critical temperatureof the phase transition from SmA to SmC*A(antiferroelectric phase). Due to the limited spacearound the sample, the sample cell was simply
inserted in Cu plates in which a thermofoil heaterand a thermocouple were embedded.
The two types of electric ﬁelds, i.e. the triangularand step wave form, were applied to the sample
14-(1-triﬂuoromethylheptyloxycarbonyl)phenyl-40 -octyloxybiphenyl-4-carboxylate.

Fig. 1. Schematic representation of the experimental arrangement. (a) X-ray focusing system and (b) the experimental setup
around a sample.

cell. Under the triangular ﬁeld of a suﬃciently low
frequency, the local layer response is expected tobe quasi-static. For the step ﬁeld (one period
consists of four constant voltages of equal timeinterval, 50 V ! 0 V ! 50 V ! 0 V), the transient
local layer response for the ﬁeld induced phasetransition can be measured. The high-to-low
electric ﬁeld change corresponds to the ferroelectric to antiferroelectric transition and viceversa. The gate signal from a function generator
via a delay pulser was applied to a router of amultichannel analyzer (time-resolved w-proﬁle).
With this mode, eight sampling points in a period
can be measured. The signals were successively
accumulated during the collection time at each oangle. A multichannel scaler was used to measure
the time-resolved o-intensity proﬁle (MCS mode)
and was controlled by the same trigger signal fromthe function generator. Depending on the responsetime of the local layer to the electric ﬁeld, the time
resolution from 10 ms to a few ms was used.

3. Results and discussion
Typical local layer structures in the AFLC cells
are the vertical chevron (v-chevron) and the

Y. Takahashi et al. / Nuclear Instruments and Methods in Physics Research A 467–468 (2001) 1001–1004

horizontal chevron (h-chevron) as shown in
Fig. 2(a). A pair of peaks is expected for o-proﬁleand w-proﬁles due to the v-chevron and the hchevron, respectively. The horizontal chevron (hchevron) is considered to be related with the stripe
texture.
In the initial state of SmC*A phase, the layer
structure was a combination of the v-chevron andthe h-chevron. When the triangular electric ﬁeld
was increased, the layer structure changed irreversibly to the h-chevron. Time integrated w proﬁlesshown in Fig. 2(b) were obtained by changing theanalyzing position perpendicular to the stripe
texture. The alternative intensity modulation in
the w-proﬁle (10 mm period) clearly indicates the
structure modulation in the stripe texture. A seriesof o-proﬁles showed the v-bookshelf structure
independent of the analyzing position.
For time-resolved microbeam X-ray diﬀraction
proﬁles with triangular wave form, the reversible
local layer change between the horizontal chevron
and the quasi-bookshelf structure was conﬁrmed.
The peak intensity of the o-proﬁle and theh-chevron angle in the w-proﬁle showed thehysteresis corresponding to the ﬁeld-induced ferroelectric to antiferroelectric phase transition [12].
The transient layer response was obtained forthe step form electric ﬁeld. Fig. 3 shows the time

Fig. 2. (a) The vertical chevron and the horizontal chevron
local layer structures of the (anti-) ferroelectric phase. (b) A
series of time integrated w intensity proﬁles during a triangularelectric ﬁeld application (5 Hz,  50 V) as a function of thevertical displacement across the stripe texture with 3 mm/step. wproﬁles were obtained at o ¼ 0:48.

1003

resolved w-proﬁle for the high (50 V) to low (0 V)
step form electric ﬁeld measured at o ¼ 1:38,
which is the bookshelf peak position in the oproﬁle. The initial h-chevron angle (a2:58)
decreases as a function of time. The layer structureis again the h-chevron after 5.3 ms (or 0.3 ms after
ﬁeld change) and the h-chevron angle becomesslightly large (a3:58). The transient time fromthe ferroelectric to antiferroelectric phases was
about 0.3 ms in the present cell. Though the
response time of sub-ms seems to correspond to
the slow process due to the domain motion
observed by the optical response [9], the positional
dependence of the transient time was not conﬁrmed in the present experiment. For the low (0 V)
to high (50 V) step wave form, the layer response
was much faster (less than 40 ms). The diﬀerence inthe transient time between above process reﬂects
the diﬀerence in the driving force of the phasetransition.
In conclusion, the time-resolved micro-diﬀraction experiment revealed the local layer structure

Fig. 3. The time-resolved X-ray diﬀraction w-intensity proﬁlesfor the high (50 V) to low (0 V) electric ﬁeld obtained at
o ¼ 0:38. The ﬁeld change from high to low occurred at 5 ms.
Time resolution was 0.1 ms.

1004

Y. Takahashi et al. / Nuclear Instruments and Methods in Physics Research A 467–468 (2001) 1001–1004

and its response to the electric ﬁeld in the AFLC
for the ﬁrst time. The quantitative analysis of thelayer response and its dependence on the sample
preparing process are now underway.
This work was carried out under the approval of
the Photon Factory advisory committee (Proposal
No. 98G341).

References[1] S.T. Lagerwall, Ferroelectric and Antiferroelectric Liquid
Crystals, Wiley-VHC, Weinheim, 1999.
[2] M. Johno, Y. Ouchi, H. Takezoe, A. Fukuda,
K. Terashima, K. Furukawa, Jpn. J. Appl. Phys. 29(1990) L111.

[3] A. Morse, H.F. Gleeson, Mol. Cryst. Liq. Cryst. 302(1997) 121.
[4] A. Iida, T. Noma, H. Miyata, Jpn. J. Appl. Phys. 35 (1996)
160.
[5] Y. Takanishi, A. Iida, K. Ishikawa, H. Takezoe, A.
Fukuda, Jpn. J. Appl. Phys. 38 (1999) 4132.
[6] A. Iida, T. Noma, H. Miyata, Jpn. J. Appl. Phys. 38 (1999)
2845.
[7] J. Pavel, M. Glogarova, Ferroelectrics 113 (1991) 619.
[8] K. Ito, M. Johno, Y. Takanishi, Y. Ouchi, H. Takezoe, A.
Fukuda, Jpn. J. Appl. Phys. 30 (1991) 735.
[9] M. Johno, K. Itoh, J. Lee, Y. Ouchi, H. Takezoe,
A. Fukuda, T. Kitazume, Jpn. J. Appl. Phys. 29 (1990)
L107.
[10] A. Iida, T. Noma, Nucl. Instr. Meth. B 82 (1993) 129.
[11] A. Iida, T. Noma, K. Hirano, Ferroelectrics 149 (1993)
117.
[12] Y. Takahashi, A. Iida, Y. Takanishi T. Ogasawara, K.
Ishikawa, H. Takezoe, Jpn. J. Appl. Phys., submitted.