無容器法により合成した
超高屈折率ガラスの物性と構造

東京大学生産技術研究所
増野敦信

Institute of Industrial Science, the University of Tokyo

Collaborators
H. Inoue, K. Yoshimoto, Y. Kikuchi, T. Mizoguchi, Y. Watanabe
Institute off Industrial Science, The Universityy off TokyoyJ, Yu, Y. Arai, M. Kaneko
Japan Aerospace Exploration Agency (JAXA)S Kohara
S.
K hJapan Synchrotron Radiation Research Institute
Y Kuroiwa,
Y.
Kuroiwa C.
C Moriyoshi
Hiroshima University
K. OkajimajSaga-LS
A. C. Hannon
ISIS Facility,
F ili Rutherford
R h f d Appleton
A lLaboratory
L b
E. Bychkov
Université du Littoral
Institute of Industrial Science, the University of Tokyo

Introduction

Institute of Industrial Science, the University of Tokyo

Containerless processing
with container

without container

melt

melt

9suppress heterogeneous nucleation from thecontainer wall
9promote deeper undercooling in moltenmaterials

crystallizationfrom the container wall

No crystallization

ΔT~ smallt0

time

temperraturetemperrature

Tm

t0

time

Institute of Industrial Science, the University of Tokyo

Containerless processing on the ground
Various types of levitation furnace

Electrostatic levitation furnace

Aerodynamic levitation furnace

Acoustic wave levitation furnace

Electromagnetic levitation furnace
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Aerodynamic levitation furnace
CCD camera
pyrometer
monitorsamplenozzlePC

Beam splitter
CO2 laser

Mass flow controller

Gas: air, oxygen, nitrogen, argon
Pressure: 1 ~ 3 atm
SampleSl size:i φ = 1 ~ 5 mm
Sample weight: 10 ~ 200 mg

Institute of Industrial Science, the University of Tokyo

Ferroelectric BaTi2O5
Monoclinic,
a = 1.6914 nm,
b = 0.3935 nm,
c = 0.9412 nm
b = 103.11º

stableregion~10 ºCC

N. Zhu and A. R. West, J. Am. Ceram. Soc. 93, (2010) 295.

Y. Akishige et al., Jpn. J. Appl. Phys. 42, (2003) L946.
T. Akashi, et al., Mater. Trans. 44, (2003) 1644.

9High
g ferroelectric transition temperaturep
9Large dielectric constant
9Colorless and transparent
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Glass formation of ferroelectric BaTi2O5
XRD, ND

XANES

1.5 mmJ.Yu et al.,, Chem. Mater. 18,, (2006)() 2169.

The first time glass formation of ferroelectrictitanate without any network former oxides.

RMC simulation

9Glass structure
Distorted TiO5 polyhedra
Edge shared polyhedra
9Crystallization process
Metastable phase formation
Giant dielectric response
J.Yu et al., Chem. Mater. 21, (2009) 259.
Institute of Industrial Science, the University of Tokyo

Metastable phase formation from BaTi2O5 glass
λ = 0.4977 Åγ phaseIntenssity

TP3

Tg

β phaseα phase

Tx1

Tx2
5

Before crystallization at 1150 K of thestablebl ferroelectricfl i γ phase,htwometastable phases α (at Tx1) and β (at Tx2)
appeared in sequence.

10152θ(λ=04977A)

20

25

Paraelectric β phase Ferroelectric γ phase
J.Yu et al., Chem. Mater. 21, (2009) 259.
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Giant dielectric response at Tx1
100 HzTp1
1001 K

Tp31150 K
Tp21038 K

Tg
960 K

Tcry2
Tcry1994 K 1018
0 8K

J.Yu et al., Chem. Mater. 18, (2006) 2169.
Institute of Industrial Science, the University of TokyoNext step
9Optical properties
Transmission
Refractive index
Luminescence properties
9Glass forming region
binar (La2O3-TiO
binaryTiO2)ternary (BaO-TiO2-MOx, La2O3-TiO2-MOx)
9Unusual crystallization process

Institute of Industrial Science, the University of Tokyo

Optical properties

Institute of Industrial Science, the University of Tokyo

Optical properties of BaTi2O5 glasstransmittaance (%)

100

Transmittance region of oxide glasses

80

Bi2O3

60

TeO2

40

Al2O3

0
300

Ge2O3

Opticalpbandgap：3.48
g p
eV

20

P2O5
400

500

600

700

wavelength (nm)

B2O3

800

SiO2

-1

transmittaance (%)

5000 4000
100

wavenumber (cm )
3000

2000

1000

BaTi2O5

100

80

1000

W l
Wavelengthh (nm)
( )

10000

60

BaTi
B
Ti2O5 glass:ltransparent fromf
350 nm to 7.7 μm

40
20
0
2

3

4

5

6

wavelength (μm)

78 9 10A. Masuno et al., J. Appl. Phys. 108, (2010) 063520.
Institute of Industrial Science, the University of TokyoRefractive index of BaTi2O5 glass
BaTi2O5 glass
2.4
2.2
reffractive inddex nD

refrractive index

2.25

2.20

2.15

2.10

400

500
600
700
wavelength (nm)nd − 1ν== 20.5
Abbe numbernF − nc
nF：H F (487 nm)
nd：He d (587.6 nm)
nc：H c (656.3 nm)

20
2.0

Bi, Pb, Te
glasses

1.8
1.6
1.4

70

60

50 40 30
Abbe number ν

20

10

9Conventional highg refractive index
glasses contain Bi, Pb, Te.
9Larger Abbe number of BaTi2O5 glass
among high refractive index glasses
A. Masuno et al., J. Appl. Phys. 108, (2010) 063520.
Institute of Industrial Science, the University of Tokyo

Large oxygen polarizability
9Lorentz-Lorenz equation(n − 1)(n + 2)2

2

gnumber4πα m N A NA: Avogadro’s
αm: molar polarizability=
3Vm Vm: molar volume

Vm = 22.8 cm3/mol/ lSilicate:30 ~ 60 cm3/mol
Borate: 25 ~ 45 cm3/mol
Phosphate: 27 ~ 60 cm3/mol

9Oxygen polarizability

α O = (α m − ∑ α i )(N O )−12−2−NO2-:number of oxygen
αBa2+
αTi4+ = 0.184
0 184 (Å3)∴Σαi = 0.654 (Å3)
= 1.595 (Å3)αO220B2O3-80SiO2

1.434

20Na2O-80B2O3

1.374

25ZnO-75P2O5

1.502

B Ti2O5
BaTi

2 57
2.57

Quite large αO2•High ionicity of oxygen•Large contribution of electrons
around oxygen to the highrefractive index.
These features are different fromconventional oxide gglasses.
A. Masuno et al., J. Appl. Phys. 108, (2010) 063520.
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Origin of high refractive index

Elements in BaTi2O5 glass are highly ionic.
Weaken covalent bond between cations and oxygen
Larger packing density
Higher refractive index

Institute of Industrial Science, the University of TokyoFunctionalization by rare-earth doping
Ba0.7Ln0.3Ti2O5.15
Raman intenRnsity (arb. unnit)

Raman scattering
MaximumMiPhononEnergy829 cm-11

0

200

400

600

800

1000

1200

-1

Raman shift (cm )High concentration of Ln

SiO2 systemt1100 cm-11

B2O3 system

1265

P2O5 system
y1360

GeO2 system

880

TeO2 system

800

BaTi2O5

829

Institute of Industrial Science, the University of TokyoUpconversion of Er3+ doped BaTi2O5 glass

Energy (1003 cm-1)
E

20
15
10

~ 550 nmB 1-xErBa
E xTi2O5+x/2

4

4S

F7/2
2
4
S3/2 H11/2
4
F9/2
4
I9/2
4
I11/2
4

I13/2

5
0

4F
9/2

3/2

x = 0.50
0.40

intensityy (a. u.)980 nm

0.30

0.10
2H

green
4F
9/2

red

0.05

11/2

0.01
400

500
600
700
wavelength (nm)Energy diagram of Er3+

800
2

H11/2

em
mission intensiity (a. u.)

Strong upconversion luminescence4
11/2， S3/2

0.20

4

I15/2

2H

4

S3/2

4

F9/2

Different
composition
dependence

Different
process
0.0

0.1

0.2

0.3

0.4

0.5

x
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Luminescent process of Er3+ doped BaTi2O5 glass
9GreenET: 2 4I11/2 → 4I15/2 + 4F7/2
ESA: 4I11/2 +hν → 4F7/2
and then
4F2
4
7/2 → H11/2 → S3/2
strong luminescence in low
concentration→main
main process is ESA.

9Red

ET: Energy Transfer
ESA: Excited State Absorption

Green process + 4S3/2 → 4F9/2
ET: 4I13/2 + 4I11/2 → 4I15/2 + 4F9/2
ESA: 4I13/2 + hν → 4F9/2
strongtluminescencel iini highhi hconcentration→main: 4S3/2 → 4F9/2 and ET

Institute of Industrial Science, the University of Tokyo

Glass forming region

Institute of Industrial Science, the University of Tokyo

Glass forming region of Ba1-xAxTi2O5
A = Mg，Sr: x ≤ 0.05
A = Ca: x ≤ 0.90

Mg

Exceptionally large glass-forming regionof Ba1-xCaxTi2O5.

Ca
Sr

00
0.0

02
0.2

04
0.4

06
0.6

08
0.8

10
1.0

x
xAO-(1-x)P(1 x)P2O5
Mg xAOM

xAO-(1-x)B
xAO(1 x)B2O3

M
Mg
Ca

Ca

Sr
Ba
0.1

Sr

Glass formingGlfi region：i
Mg < Ca < Sr < Ba
0.2

0.3

x

0.4

0.5

0.0

Ba
0.2

0.4

Almost the same
regardless of thealkali-earth ion
substituted

0.6

x

O. V. Mazurin, M. V. Streltsina, T. P. Shvaiko-Shvaikovskaya (Eds.), Handbook of Glass Data, Physical Science Data 15,
Part B (single-component and binary non-silicate oxide glasses), Elsevier, Amsterdam, 1985.
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Thermal properties of Ba1-xCaxTi2O5 glassesDT
TA (arbb. unit)

x=
0.80
0.70

600

0.60
0.50
0.40
0.30
0.20
0 15
0.15
0.12

800

1000

Temperature (°C)

0.10
0.05
0.03
0.01

Tg and Tx1 increased with x.
x
ΔT = Tx1 –Tg increased with x.
A. Masuno et al., J. Mater. Chem. 21, 17441 (2011).
Institute of Industrial Science, the University of TokyoRefractive index of Ba1-xCaxTi2O5 glassesnd − 1νd =nF − nC

nd：587.6 nm
nF：486.1 nm
nC：656.3 nm

Refractive index
increases with increaseof Ca content.
νd decreases.
Unexpected result

A. Masuno et al., J. Mater. Chem. 21, 17441 (2011).
Institute of Industrial Science, the University of Tokyo

Transmittance of Ba1-xCaxTi2O5 glasses
Optical bandgap Eopt
αhν = A(hν − Eopt )2

α: the absorption coefficienth: the Planck constant
ν: the frequency of light
A: an energy-independent
energy independent constantEopt
p decreases withincrease of Ca content.
ColorlessCl l andd transparent
The absorption edge shifted to longer
wavelength
wavelength.

Unexpected result

A. Masuno et al., J. Mater. Chem. 21, 17441 (2011).
Institute of Industrial Science, the University of TokyoRefractive index dispersion and optical bandgap
Ca substitution?
Eopt decreased
d
d

?
○

nd increasedidSmaller Eopt leads to larger nd.
The problem:
Why does Ca substitution decrease Eopt?

Institute of Industrial Science, the University of Tokyo

Raman scattering spectra of Ba1-xCaxTi2O5 glasses
The bands at 636 cm-1 and 829 cm-1:
one long Ti–O
Ti O bond and four short Ti–O
Ti O bonds
The band at 636 cm-1 does not shift.
→one longl
Ti–O
Ti O bbond
d remains.
i
The peak intensity of the band at 829 cm-1
decreases and that of the band at 780 cm-1
increases.
→the lengths
g of some of the four short bonds
increase→a narrow distribution of the Ti–O bond lengthand relaxing the distorted Ti
Ti–O
O polyhedra.

A. Masuno et al., J. Mater. Chem. 21, 17441 (2011).
Institute of Industrial Science, the University of Tokyo

Bandgap decrease by local structure change
Ti 3d

Ti–O bonding state strongly affects theb d gap.
band
O 2p

a narrow distribution of the Ti–O bond length and relaxing thedi t t dTi O polyhedra
distortedTi–Ol h d byb lengthening
l th i some short
h t Ti-O
Ti O bbondsd→the degree
g of hybridizationyof O 2pp and Ti 3d orbitals decreases→the difference between the bond and anti-bond levels becomes smaller→bandgap decreases→refractive
f ti index
i d increasesi
Structural-relaxation-induced highg refractive index
A. Masuno et al., J. Mater. Chem. 21, 17441 (2011).
Institute of Industrial Science, the University of TokyoRefracctive index nd

The impact of Ca substitution
as the Ca2+ content increases,…

2.2•GlassGl are ththermallyll stabilized.
t bili d•Optical band gap decreases.
•The
The refractive index increases.
increases•The Abbe number decreases.

20
2.0
1.8
1.6
11.44
100

80

60

40

20

Abbe number νd

The changes in the physical properties caused by Ca2+
substitution are mainly due to the local structure relaxation
caused by their different ionic radii.
Structural relaxation induced high refractive index
Structural-relaxation-induced
A. Masuno et al., J. Mater. Chem. 21, 17441 (2011).
Institute of Industrial Science, the University of TokyoFuture work for Ba1-xAxTi2O5 glasses
Mg
Ca
Sr

0.2

0.4

0.6

0.8

1.0

x

Sr is the neighboringgg element of Ba
in the periodic table, and Ca is thesecond neighbor of Ba. Why glassf
formingi region
i is
i narrow ini Sr
substitution but wide in Ca
Structural analysis of undercoolingmelt is necessary.

Aerodynamic levitation furnace at SPring-8
BL04B2 for in-situ XRD
12
Tm-100℃
10
8

T(r)

0.0

6
BaTi2O5

4

Ba0.5Sr0.5Ti2O5

2

Ba0.5Ca0.5Ti2O500

CaTi2O5

SrTi2O5

2

4

6

r (Å)

8

10

Institute of Industrial Science, the University of TokyoLa2O3-TiO2-MOx system
La2O3-TiO2

La2O3-TiO2-ZrO2
ZrO2

LaO3/2
Y. Arai et al., J. Appl. Phys. 103, (2008) 094905.
M. Kaneko et al., J. Am. Ceram. Soc. 95, (2011) 79.

TiO2
H. Inoue et al., Opt. Mater. 33, (2011) 1853.
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Abbe diagram

Reffractivve inddex nd

2.4

La2O3-TiO2-MOx

2.2

Ba1-xCaxTi2O5

2.0
1.8
16
1.6
1.4
100

80

60

40

20

Abbe number νdInstitute of Industrial Science, the University of Tokyo

BaTi2O5 glass
Unusual crystallization process

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Metastable phase formation from BaTi2O5 glass
λ = 0.4977 Åγ phaseIntenssity

TP3

Tg

β phaseα phase

Tx1

Tx2
5

Before crystallization at 1150 K of thestablebl ferroelectricfl i γ phase,htwometastable phases α (at Tx1) and β (at Tx2)
appeared in sequence.

10152θ(λ=04977A)

20

25

Paraelectric β phase Ferroelectric γ phase
J.Yu et al., Chem. Mater. 21, (2009) 259.
Institute of Industrial Science, the University of Tokyo

Giant dielectric response at Tx1
100 HzTp1
1001 K

Tp31150 K
Tp21038 K

Tg
960 K

Tcry2
Tcry1994 K 1018
0 8K

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Measurement of Second harmonic generation
IR filter
Nd/YAG Laser

mirror1064 nm
lens
Monochrometerharmonic
separator

PM
Digital

532 nmoscillometerPCTC

heater

Thermometer
temperature
controller

Institute of Industrial Science, the University of Tokyo

Giant Second harmonic generation at Tx1
SHG appeared at Tx1and disappeared at Tx2.

increasing temp
temp.
decreasing temp.

SH intensityy is 5 times largergthan g phase

This behaviorThi
b h i totallyt t llcorresponds to that ofdielectric constant.

Tc

Direct evidence ofcorrelationl i betweenbαphase crystal structure
aandd giant
g a dielectricd e ec c
responseglass
γ (ferroelectric)αβ γγ (paraelectric)

A. Masuno et al., Appl. Phys. Express 4, (2011) 042601.
Institute of Industrial Science, the University of Tokyo

Mechanism of giant response at Tx1
100 kHzglass

10
ε' ×10-6α phasey
crystallization
Polar nanocrystals are ordered by anelectric field.

5

0
960

980 1000 1020 1040
temperature (K)Grain boundary(Maxwell-Wagner effect)

9Giant SHG response at Tx1: α-BaTi2O5 has non-centrosymmetric (polar) structure.
9The instant dielectric jump at Tx1 was caused by the alignment of polar nanocrystalsof α phase.
9The large
9Thldielectric
di l t i constantt t fromf
Tx1 tot Tx2 was explainedl i d byb theth Maxwell–WagnerMll W
effect at the grain boundaries between the glass and the partially crystallized α phase.
By in-situ SHG observation during crystallization process, we obtained the first direct
evidence that the alignment of polar nanocrystals caused the giant dielectric response.
A. Masuno et al., Appl. Phys. Express 4, (2011) 042601.
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Ba1-xCaxTi2O5 glass
Crystallization of ferroelectric phase

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Single phase crystallization from BaTi2O5 glass

stableregion~10 ºCWe found that crystallization from theglass was useful for single phase
preparation of BaTi2O5.

Control of ferroelectric properties by
substitution for Ba as well as BaTiO3 system.
Previous reports;
N. Zhu and A. R. West,, J. Am. Ceram. Soc. 93,, (2010)() 295.

S B 1-xSr
Sr：Ba
S xTi2O5 (x( < 0.12)
0 12)→ arc-melt method
X. Yan et al., J. Ceram. Soc. Jpn. 115, (2007) 648.

ba

KF：Ba1-xKxTi2O5-xFx (x < 0.05)→ sol-gel + SPS
c

I valueIsol =00.54e/Å
54 /Å3

J. Xu and Y. Akishige, Appl. Phys. Lett. 92, (2008) 052902.

C. Moriyoshi et al., Jpn. J. Appl. Phys. 48, (2009) 09KF06 .
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Results: heat treatment condition
Ba1-xCaxTi2O51000 ºC
C 1000 ºCC
10 min.
12h.

1100 ºCC
10 min.

1200 ºC
C
12 h.

0

○

0.05

○

0.07

○

0 10
0.10

○

○

○

0.12

○

△

○

0.15

○

△

0.20

○

△

0.30

○

△

0.40

×

×

○：single phase△：slight impurity of BaTiO3
×：almost no BaTi2O5 phase0 < x < 0.07
as stable as BaTi2O5
0.10 < x < 0.12
decreasing stability
0 15 < x < 0.30
0.15
0 30
metastable phase
0.40 < x
no Ba1-xCaxTi2O5 phase

Heating rate: 20 ºC/min.
(5 ºC/min.
ºC/ i forf 1200 ºC )Institute of Industrial Science, the University of Tokyo

3000

x=0
0.01
0.05
0.07

2000
1000

500

0
0

dielectricc constant ε'Ferroelectric transition temperatures wereobserved in all Ba1-xCaxTi2O5 phases (x ≤ 0.30)
The peaks were broaden with increase of x.

1 MHz

200
400
temperature (℃)

600

400
0.10
0.12
0.15
0.20
0.30

2500

TP (℃)

dieleectric consttant ε'Results: dielectric constant

300

2000

200

1500
0

100

200 300 400 500
temperature (℃)

600

0.0

0.1

0.2

0.3

x
TP dropped 250 ºC.
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Results: lattice constants
Change ratio of lattice constants

16 90
16.90

Δl

16.85
3.95

c (Å)

9.40

l0

l0：lattice constant at x = 0
lx：lattice constant at x

-0.4
-0.6

a
b
c

-0.8
10
-1.0

103.0

β (°)

(l0 − l x )

-0.2

3.90
9 45
9.45

-1.2
0.0

102.5

605
600

0.1

0.2

0.3

0.4

x

610

V (Å3)

l0

=
00
0.0

Δl/l0 ((%)

b (Å)

a (Å))

Ba1-xCaxTi2O5

0.0

0.1

0.2

x

0.3

0.4

Decrease ratio of b axis is larger than otheraxes.
→affect ferroelectric properties
effectively
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Results: Correlation between TP and b axis length500

Ti2O6 Ti1O6

Ti3O6

TP (℃
℃)

400
Ba1

300

Ba2
Ba1-O12200

Ba2-O123.94 3.92 3.90
b-axis length (Å)

Strong correlation between TP andb axis length

Ba-O bond length distribution in BaO12 polyhedra
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Site selectivity of Ca in Ba0.95Ca0.05Ti2O5
Ba0.95Ca0.05Ti2O5

b
a

Ba/Ca

Atom

g

x

y

z

U [10-2Å2]

Ba1

0.944(1)0.36858(3)-0.002(1)0.01753(6)0.647(7)Ca1

0.056(1)0.36858(3)-0.002(1)0.01753(6)0.647(7)

Ba2

1

0

0.5

0.5

0.67(2)Ti1

1

0 0390(1)0.0390(1)-0.024(1)0 024(1)0 2096(2)0.2096(2)0 83(6)0.83(6)Ti2

1

0.2073(1)0.003(3)0.3724(2)0.70(4)Ti3

1

0.3337(1)0.504(3)0.3044(2)0.77(5)O1

10.0356(3)0.529(3)0.2102(5)0.3(2)

O2

1

0.1108(3)0.028(3)0.4271(5)0.2(2)

O3

1

0.1510(3)0.025(4)0.1836(5)0.2(2)

O4

1

0.1749(3)0.510(8)0.6608(5)0.2(2)

O5

1

0.2344(3)0.518(5)0.3953(5)0.2(2)

O6

1

0.2892(3)0.518(6)0.1249(6)0.6(2)

O7

1

0.4424(3)0.508(8)0.2884(5)0.3(2)

O8

1

00.015450( )0.3(2)

C2, a = 16.9036(1) Å, b = 3.93030(2) Å,c c = 9.40715(6) Å, β = 102.9640(4)°.

Ba
90, RI = 0.0
73, RF = 0.0
0 .
RWP = 0.0
0.0290,0.0173,0.0104.
Ca ions occupy only the distorted Ba1 site.
C. Moriyoshi et al., J. Phys. Soc. Jpn. 81, (2011) 014706.
Institute of Industrial Science, the University of Tokyo

XANES spectra of Ca in Ba1-xCaxTi2O5
Ba1-xCaxTi2O5

calculation
CaTiO3

0.30
0.20

4c

0.10
4050

0.05
0.01

4020

Intensity (arb. unit)

Intennsity (arbb. unit)x = 0.40

2c

4040

4060

E
Energy
(eV)
( V)

4080

4060

4070

4080

4090

Energy (eV)Ca site selectivity is realized only at
low Ca concentration.
In metastable ferroelectric phase, Ca
occupies both 2c and 4c sites.
sites

Fluorescence method at SAGA-LS
Institute of Industrial Science, the University of Tokyo

Crystallization of ferroelectric phase
Ferroelectric phase crystallized from Ba1-x
1 xCaxTi2O5 glass.
Ferroelectric properties depend on b-axis bond length.
0 ≤ x ≤ 0.07: stable phasesite selective Ca doping
0.10 ≤ x ≤ 0.30: metastable pphaserandom site doping of Ca

Ba11-xxCaxTi2O5 gglass is useful as a pprecursor of ferroelectric pphase.
Institute of Industrial Science, the University of Tokyo

Summary: TiO2 glass system
9Optical properties
Colorless and transparent in visible and near IR region
High refractive index > 2.1 and low wavelength dispersion
Strongg upconversionpluminescence due to low pphonon energygy
9Glass forming regionbibinary(La( 2O3-TiOi 2) andd ternary (BaO-TiO(
i 2-MOx, La2O3-TiO
i 2MOx) systems were determined.
Ca doping caused characteristic changes in physical andstructural properties.
9Unusual crystallization process
Giant SHG response at a phase crystallization temperature.
M
Metastable
bl ferroelectricfl i phasehcrystallized
lli d fromfCa
C dopedd d glasses.
lInstitute of Industrial Science, the University of TokyoRefraactive inddex

Nb2O5 system

1 mm

2.6

2.4

2.2
400

600

800

1000

Wavelength (nm)00.30La
30L 2O3-0.70Nb
0 70Nb2O5
spherical glass was preparedby containerless processing.
processing
φ = 2 ~ 3 mm
A. Masuno and H. Inoue,
Appl. Phys. Express 3, 10261 (2010).

ColorlessCl l andd transparentttHigh refractive index over 2.2
suitable for small optics usedin visible and infrared region
e.g. lens, endoscope, fiber collimator
Institute of Industrial Science, the University of Tokyo

New glass system ~ frontier in glass science ~TiO2, Nb2O5 glasses prepared by containerless processing
9Without networkformer
9Large oxygen packing density
9Large oxygen polarizability
Deviation from the classic glass forming rules
Through investigating physical and structural properties,
new and extended glass forming rules should be made.

Institute of Industrial Science, the University of Tokyo

Refferences
1. Glassl Formation
i in
i LaO3/2–TiO2/
i Binaryi
System byb
Containerless Processing
M. Kaneko, J. Yu, A. Masuno, H. Inoue, M. S. V. Kumar, O.
Odawara, S. Yoda
J Am
J.
Am. Ceram
Ceram. Soc.
Soc 95 (2012) 79.
79
2. Site-selective Calcium Substitution in BaTi2O5: Effect on the
Crystal Structure and the Ferroelectric Phase Transition
C. Moriyoshi, Y. Kuroiwa, A. Masuno, H. Inouey Soc. Jpn.
p 81,, (2011)() 014706.
J. Phys.
3. Structural-relaxation-induced high refractive indices of Ba1xCaxTi2O5 glasses
A. Masuno, H. Inoue, Y. Arai, J. Yu, Y. Watanabe
J. Mater. Chem. 21, (2011) 17441.
4. Effect of substituting Al2O3 and ZrO2 on thermal and opticalproperties of high refractive index La2O3-TiO2 glass system
prepared by containerless processing
H. Inoue, Y. Watanabe, A. Masuno, M. Kaneko, J. Yu
Opt Mater
Opt.
Mater. 33,
33 (2011) 1853.
1853
5. Giant second harmonic generation from metastable BaTi2O5
A. Masuno, Y. Kikuchi, H. Inoue, J. Yu, Y. Arai
Appl. Phys. Express 4, (2011) 042601.
y
BaTi2O5
6. Structure of Glassyy and Metastable Crystalline
Fabricated using Containerless Processing
J. Yu, S. Yoda, A. Masuno, H. Natsui, M. Kaneko
Ferroelectrics 402, (2010) 130.
7. High Refractive Index of 0.30La2O3-0.70Nb2O5 Glass
Prepared by Containerless Processing
A. Masuno and H. InoueAppl. Phys. Express 3, (2010) 102601.

8. Refractive
f i index
i d dispersion,dii optical
i l transmittance,iandd Raman
scattering of BaTi2O5 glass
A. Masuno, H. inoue, J. Yu, Y. Arai
J. Appl. Phys. 108, (2010) 063520.
9 Charge Density Study of Metastable State in BaTi2O5 with9.
Fivefold Coordinated Ti
C. Moriyoshi, S. Miyoshi, Y. Kuroiwa, J. Yu, Y. Arai, A.
MasunoJpn.
p J. Appl.
pp Phys.
y 49,, (2010)() 09ME10.
10. Charge Density Study on Phase Transition in BaTi2O5
Ferroelectric
C. Moriyoshi, N. Okizaki, Y. Kuroiwa, J. Yu, Y. Arai, A.
MasunoJpn. J. Appl. Phys. 48, (2009) 09KF06
11. Comprehensive Structural Study of Glassy and Metastable
Crystalline BaTi2O5
J. Yu, S. Kohara, K. Itoh, S. Nozawa, S. Miyoshi, Y. Arai, A.
Masuno H.
Masuno,H Taniguchi
Taniguchi, M.
M Itoh,Itoh M.
M Takata,
Takata T.
T Fukunaga,
Fukunaga S.
SKoshihara, Y. Kuroiwa, S. Yoda
Chemistry of Materials 21, (2009) 259.
12. Thermal stability and optical properties of Er3+ doped BaTi2O5
gglassesA. Masuno, H. Inoue, J. Yu, Y. Arai, F. Otsubo
Adv. Mater. Res. 39-40 (2008) 243.

Institute of Industrial Science, the University of Tokyo