bluuebunny/crossref_metadata_2025 huggingface dataset:
Radiation Chemistry of Fluoronaphthalene as a Candidate for Absorption Enhancement Component of Chemically Amplified Extreme Ultraviolet Resists
Authors: Ikeda Sadatatsu , Okamoto Kazumasa , Yamamoto Hiroki , Saeki Akinori , Tagawa Seiichi , Kozawa Takahiro
Published: September 2010

With the reduction of resist thickness accompanying the miniaturization of feature sizes, increasing the absorption coefficient of extreme ultraviolet (EUV) resists is becoming increasingly important from the viewpoint of the efficient use of incident radiation. The fluorination of the resist polymer is the most effective means of increasing the absorption coefficient. However, it has been pointed out that the dissociative electron attachment of the fluorinated polymer is a problem in the application of the fluorinated polymer to chemically amplified resists used for ionizing radiation. In this study, the electron flow in fluorinated resists was examined using fluoronaphthalene as a possible candidate for suppressing the dissociative electron attachment. The molecular structure dependence of the reactivity with tetrahydrofuran-solvated electrons, the electron transfer from fluoronaphthalene radical anions to triphenylsulfonium-triflate, the dissociation of fluoronaphthalene radical anions, and the charge recombination of fluoronaphthalene radical anions with protons were clarified by the comparison of octafluoronaphthalene, 1-fluoronaphthalene, and naphthalene. The dissociation of fluoronaphthalene radical anions was negligibly slow. Also, the recombination of octafluoronaphthalene radical anions with protons was significantly delayed compared with that of naphthalene radical anions. These results suggest that the molecular structure of fluoronaphthalene is suitable for the molecular design of chemically amplified EUV resists from the viewpoint of the control of electron flow in the acid generation processes.
Monolithic Thermoelectric Devices Prepared with Multilayer Cofired Ceramics Technology
Authors: Hayashi Sachiko Fujii , Nakamura Takanori , Kageyama Keisuke , Takagi Hiroshi
Published: September 2010

Novel monolithic thermoelectric (TE) devices were fabricated using multilayer co-fired ceramics technology and p-type, n-type, and insulator layers of oxide materials. (La1.97,Sr0.03)CuO4 and (Nd1.97,Ce0.03)CuO4 served as p- and n-type thermoelectric materials, respectively. A mixture of Mg2SiO4 and silicate glass was utilized as an insulator sandwiched between p- and n-type layers. The materials constituting a TE device must have mutually matching thermal shrinkage characteristics. The dimensions of a TE device comprising 25 pairs of p–i–n junctions were 9.6 ×6.9 ×5.0 mm3. The observed maximum open-circuit voltage and electric output power of the TE devices were 2.3 V and 40 mW/cm2 at ΔT = 360 K (between 653 and 293 K), respectively.
Fabrication and Characterization of Planar Screen-Printed Ag/AgCl Reference Electrode for Disposable Sensor Strip
Authors: Idegami Koutarou , Chikae Miyuki , Nagatani Naoki , Tamiya Eiichi , Takamura Yuzuru
Published: September 2010

An accurate disposable planar Ag/AgCl reference electrode with an internal electrolyte was successfully fabricated by the screen-printing process. The internal electrolyte layer was also printed by using an electrolyte paste of sodium alginate containing KCl. The potential stability of the electrode was investigated at different operation times and Cl- concentrations in test solutions. Results show that the electrode has long-term potential stability (approximately 60 min), and that its performance does not depend on the Cl- concentration. This electrode can be used to provide various promising applications in sensing techniques based on disposable strips for sensing purposes.
Crystal Structure and Dielectric Property of Bismuth Layer-Structured Dielectric Films with c-Axis Preferential Crystal Orientation
Authors: Mizutani Yuki , Kiguchi Takanori , Konno Toyohiko J. , Funakubo Hiroshi , Uchida Hiroshi
Published: September 2010

Thin films of bismuth layer-structured dielectrics (BLSDs), CaBi4Ti4O15, and SrBi4Ti4O15, were prepared by a chemical solution deposition (CSD) technique on various substrates, such as (111)Pt/TiO2/(100)Si, (100)LaNiO3/(111)Pt/TiO2/(100)Si, and (100)SrRuO3∥(100)SrTiO3substrates. Conductive perovskite oxide LaNiO3with (100) preferential crystal orientation was introduced into the interface between the BLSD film and the (111)Pt/TiO2/(100)Si substrate to control the crystal orientation of BLSD by lattice matching between pseudo-perovskite blocks in the BLSD crystal and the (100)LaNiO3plane with the perovskite structure. The (00l) planes of BLSD crystals were preferentially oriented on the substrate surface of the (100)LaNiO3/(111)Pt/TiO2/(100)Si, whereas randomly-oriented BLSD crystals with lower crystallinity were only obtained on the surface of (111)Pt/TiO2/(100)Si substrate. The (001)-oriented BLSD films exhibited the leakage current densities below 10-7A/cm2at ±50 kV/cm, which is significantly lower than those for randomly-oriented films, above 10-6A/cm2, The room-temperature dielectric constants (εr) of CaBi4Ti4O15and SrBi4Ti4O15thin films on the (100)LaNiO3/(111)Pt/TiO2/(100)Si substrate were both approximately 250, while those on the (100)SrRuO3∥(100)SrTiO3substrate were approximately 220. The temperature dependence of the capacitances for the CaBi4Ti4O15and SrBi4Ti4O15films on the (100)LaNiO3/(111)Pt/TiO2/(100)Si substrate were approximately +17 and +10%, respectively, in the temperature range from 25 to 400 °C. These values were slightly larger than those of epitaxial BLSD films, but smaller than those of (Ba,Sr)TiO3films.
Characterization of (Bi3.25Nd0.75)Ti3O12 Thin Films with a- and b-Axis Orientations Deposited on Nb:TiO2 Substrates by High-Temperature Sputtering
Authors: Kobune Masafumi , Tamura Akihiro , Oshima Hisashi , Imagawa Kazuki , Daiko Yusuke , Mineshige Atsushi , Yazawa Tetsuo , Fujisawa Hironori , Shimizu Masaru , Yamaguchi Hideshi , Honda Koichiro
Published: September 2010

a- and b-axis-oriented (Bi3.25Nd0.75)Ti3O12 (BNT-0.75) films, 3.0 µm thick, were fabricated on conductive Nb:TiO2(101) substrates with 0.001–0.79 mass % Nb at 650 °C by high-temperature sputtering. All the films had a mostly single-phase orthorhombic structure and a- and b-axis orientations. The degree of a- and b-axis orientations was high, with values of ≥96%. BNT-0.75 films grown heteroepitaxially on Nb:TiO2(101) substrates containing 0.79 mass % Nb were comprised of nanoplate-like crystals and exhibited the best hysteresis loop shapes, with a remanent polarization (2P
r) of 29 µC/cm2 and a coercive field (2E
c) of 297 kV/cm.
Improvement in Ferroelectric Properties of Chemically Synthesized Lead-Free Piezoelectric (K,Na)(Nb,Ta)O3 Thin Films by Mn Doping
Authors: Kondo Naoya , Sakamoto Wataru , Lee Bong-Yeon , Iijima Takashi , Kumagai Jun , Moriya Makoto , Yogo Toshinobu
Published: September 2010

Lead-free piezoelectric (K,Na)(Nb,Ta)O3 thin films were prepared by chemical solution deposition. Perovskite single-phase (K0.5Na0.5)(Nb0.8Ta0.2)O3 and Mn-doped (K0.5Na0.5)(Nb0.8Ta0.2)O3 thin films were successfully fabricated at 600 °C on Pt/TiO
x
/SiO2/Si substrates by controlling the excess amounts of K and Na, and Mn by doping. The (K0.5Na0.5)(Nb0.8Ta0.2)O3 thin films showed poor ferroelectric polarizations due to the insufficient insulating resistance at room temperature. The leakage current density of the (K0.5Na0.5)(Nb0.8Ta0.2)O3 films, especially in the high-applied-field region, was markedly reduced by doping with a small amount of Mn. Also, the ferroelectric properties of the (K0.5Na0.5)(Nb0.8Ta0.2)O3 thin films were markedly improved by Mn doping. 0.5 and 1.0 mol % Mn-doped (K0.5Na0.5)(Nb0.8Ta0.2)O3 thin films exhibited well-shaped ferroelectric polarization–electric field (P–E) hysteresis loops at room temperature. The remanent polarization (P
r) and coercive field (E
c) values of the 0.5 and 1.0 mol % Mn-doped (K0.5Na0.5)(Nb0.8Ta0.2)O3 thin films at 1 kHz were approximately 14 and 21 µC/cm2, and 111 and 86 kV/cm, respectively. Furthermore, these films showed a typical field-induced butterfly loop, and the estimated effective d
33 values were 58 pm/V for the 0.5 mol % Mn-doped (K0.5Na0.5)(Nb0.8Ta0.2)O3 thin films and 41 pm/V for the 1.0 mol % Mn-doped (K0.5Na0.5)(Nb0.8Ta0.2)O3 thin films.
Effect of Lattice Strain and Improvement of the Piezoelectric Properties of (K,Na)NbO3 Lead-Free Film
Authors: Suenaga Kazufumi , Shibata Kenji , Watanabe Kazutoshi , Nomoto Akira , Horikiri Fumimasa , Mishima Tomoyoshi
Published: September 2010

(K,Na)NbO3 (KNN) films with very high transverse piezoelectric coefficient d
31, which attained values comparable to those of Pb(Zr,Ti)O3 (PZT) films for the first time, were successfully deposited on Pt/Ti/SiO2/Si φ 4-in. substrates by RF magnetron sputtering. These films were polycrystalline and had pseudo-cubic perovskite structure with a <001> preferred orientation. Furthermore, we focused on the effect of lattice strain on d
31 of KNN to clarify the relationship between the piezoelectric properties and structural parameters apart from orientation. We found that -d
31 increases with decreasing lattice strain c/a ratio of KNN when the in-plane lattice parameter a increases and the out-of-plane lattice parameter c decreases. By controlling the lattice strain c/a ratio strictly and maintaining a homogeneous strain, we achieved a high d
31 (∼-100 pm/V) that can be uniformized on φ 4-in. substrates and with a standard deviation that decreases to about 4 pm/V.
Ferroelectric Properties of (Na0.5K0.5)NbO3–BaZrO3–(Bi0.5Li0.5)TiO3Thin Films Deposited on Pt/(001)MgO Substrate by Pulsed Laser Deposition
Authors: Yamazoe Seiji , Miyoshi Yuzo , Hattori Takafumi , Adachi Hideaki , Wada Takahiro
Published: September 2010

0.92(Na0.5K0.5)NbO3–0.06BaZrO3–0.02(Bi0.5Li0.5)TiO3(NKN–BZ–BLT) thin films with a thickness of about 2.0 µm were fabricated on a Pt/(001)MgO substrate by pulsed laser deposition (PLD). The X-ray diffraction pattern (XRD) showed that the NKN–BZ–BLT thin films that were oriented in both the 001ptand the 101ptdirections [determined by pseudo-tetragonal perovskite (pt)] were grown on the Pt/(001)MgO substrate. A rocking curve measurement revealed that the fluctuations of the crystalline orientation of the 001pt- and 101pt-oriented NKN–BZ–BLT grains are very small. The reciprocal space map and pole figure showed that the 001pt-oriented NKN–BZ–BLT grains epitaxially grew on the Pt/(001)MgO substrate. On the other hand, the 010ptaxis (existing in the in-plane) of the 101pt-oriented NKN–BZ–BLT grains rotated by 45° for the 100 axis (existing in the in-plane) of the (001)MgO substrate. The dielectric constantεrand the dielectric loss tan δ of the NKN–BZ–BLT thin films were 682 and 0.076 at 1 kHz, respectively. TheP–Ehysteresis loops of the NKN–BZ–BLT thin films showed clear ferroelectricity. The remanent polarizationPrand coercive electric fieldEcwere 24.5 µC/cm2and 29.3 kV/cm, respectively. The NKN–BZ–BLT thin films exhibited largerPrvalues than NKN–BZ–BLT ceramics.
Improvement of Sol–Gel Derived PbZrxTi1-xO3 Film Properties Using Thermal Press Treatment
Authors: Kaneda Toshihiko , Kim Joo-Nam , Tokumitsu Eisuke , Shimoda Tatsuya
Published: September 2010

A thermal press treatment was introduced in the sol–gel process of PbZr
x
Ti1-x
O3 (PZT) thin films for the first time and the crystalline and electrical characteristics of the PZT films were investigated. The thermal press treatment was applied to the amorphous PZT gel film before crystallization annealing. It is found that the crystalline orientation and grain size of the PZT film fabricated with the thermal press treatment are different from those of the film fabricated by the conventional sol–gel process without the thermal press treatment, even though the crystallization conditions are exactly the same. It is demonstrated that the electrical properties, especially leakage current density and breakdown field, are significantly improved for the PZT film fabricated with the thermal press treatment. Furthermore, we also demonstrate that the fatigue property is improved by introducing the thermal press treatment.
Orientation Dependence of Transverse Piezoelectric Properties of Epitaxial BaTiO3 Films
Authors: Imai Hideyuki , Kanno Isaku , Yokokawa Ryuji , Wasa Kiyotaka , Kotera Hidetoshi
Published: September 2010

The orientation dependence of the piezoelectric properties of epitaxial BaTiO3 (BTO) films was investigated. The (001), (101), and (111)-oriented BTO films of 2–2.5 µm thickness were deposited on SrRuO3/Pt/MgO or SrRuO3/SrTiO3 substrates by rf magnetron sputtering. X-ray diffraction measurements showed that (001), (101), and (111)BTO films were epitaxially grown on the substrates. The lattice parameters of each BTO film were different from those of the bulk single crystal, and the unit cell volume of the BTO films was larger than that of bulk BTO. The transverse piezoelectric coefficients e
31
*=d
31/s
11 of (001)BTO films was almost independent of applied electric field, whereas e
31
* of (111)BTO increased with voltage owing to the domain motion. The piezoelectric properties of (101)BTO films strongly depended on the in-plane alignment of the crystal structure, and a relatively large e
31
* of -1.3 C/m2 could be achieved by enhancement of the domain motion. Although the absolute values of e
31
* are smaller than theoretical calculation values, we could demonstrate that the optimization of crystal orientation is effective for enhancing BTO-based lead-free piezoelectric films.
Preparation of (Ba,Sr)TiO3 Thick Films with Ni Electrodes by Screen Printing
Authors: Sakai Yuichi , Kakuda Tatsunori , Futakuchi Tomoaki , Adachi Masatoshi
Published: September 2010

The effects of doping MgO into (Ba0.6Sr0.4)TiO3 (BST) fired under a reducing atmosphere were investigated in order to prepare BST thick films with Ni electrodes by the screen-printing method. MgO-doped BST thick films fired under a reducing atmosphere showed insulation resistance. Grain growth in the thick films was advanced by MgO doping. The dielectric constant near T
C of the bulk ceramics and thick films increased with increasing MgO concentration up to 2 and 10 mol %, respectively. Mg ion substitution to the B-site was also observed up to these concentrations. The tunability and tan
δ of thick films with MgO concentrations of 2 and 4 mol % at an electric field of 10 V/µm were approximately 77 and 0.3%, respectively. It is expected that thick films prepared by screen printing will be applicable to tunable devices with Ni electrodes.
Control of Powder Quality as a Method of Improving the Dielectric Properties of (Ba0.6,Sr0.4)TiO3 Thick Films Fabricated by Aerosol Deposition Method
Authors: Popovici Daniel , Akedo Jun
Published: September 2010

(Ba0.6,Sr0.4)TiO3 (BST60) thick films were fabricated on Cu substrates by aerosol deposition (AD) method. The quality of the raw powder was checked and optimized to increase the dielectric constant of the fabricated films without the need of a post-film-formation annealing procedure. The carbonate phase has been observed in the raw powder and it was successfully reduced by thermally treating the powder at 900 °C. The AD-fabricated films obtained from the 900 °C thermally-treated powder show a dielectric constant of 200, which is much higher than that of the AD-fabricated films obtained from the raw powders. The leakage currents in the films fabricated from 900 °C thermally-treated powders stay below 10-7 A/cm2 when the applied electric field is less than 500 kV/cm, being at least one order of magnitude smaller than the leakage values in the AD-fabricated films obtained from the raw powder. The above results indicate that thermally treating the powder at 900 °C is a satisfactory method of improving the electrical properties of the AD-fabricated BST60 thick films.
Ferroelectric Data Recording Using Servo-Controlled Tracking Technique
Authors: Tanaka Kenkou , Cho Yasuo
Published: September 2010

A new method of achieving real information recording with a density above 1 Tbit/in.2 using servo tracking control in ferroelectric data storage systems is proposed. In this system, position control of the read/write head was realized by the scanning nonlinear dielectric microscopy technique. The data bits can be read by only one-line scanning on a one-line data track using high-precision head position control. The tracking accuracy of this system was evaluated to be about 2 nmpp. As a result, actual data composed of 64×64 bits were recorded at an areal density of 1 Tbit/in.2 and the bit error rate was evaluated to be 1.7×10-3.
Leakage Current Properties of Cation-Substituted BiFeO3 Ceramics
Authors: Abe Kazutomo , Sakai Noriyoshi , Takahashi Junichi , Itoh Hidenobu , Adachi Nobuyasu , Ota Toshitaka
Published: September 2010

Cation-doped BiFeO3 ceramics were fabricated by sintering coprecipitated and calcined powders at 700–900 °C to study the effect of cation doping on the leakage current properties of the sintered samples. Among the dopants examined in this study, Ti4+, Sn4+, or Zr4+ doping was found to effectively reduce the leakage current of the samples. In particular, a marked decrease in the leakage current density was achieved at 10% Ti4+ doping, which also resulted in the structure change from rhombohedral to cubic. The codoping of Ti4+/Zn2+ ions or Ti4+/Ni2+ ions brought about a substantial reduction in the leakage current density of the bulk samples by about four or five orders of magnitude at a small doping amount of 2%. This can be explained by the combined effect of Ti4+ doping, which basically contributes to the decreased number of oxygen vacancies in the sample, and Zn2+ or Ni2+ doping, which might assist the homogeneous substitution of Ti4+ ions for the Fe3+ sites.
First-Principles Calculations of Electronic Structure and Solution Energies of Mn-Doped BaTiO3
Authors: Moriwake Hiroki , Fisher Craig A. J. , Kuwabara Akihide
Published: September 2010

Doping with 3d transition metals, particularly Mn, is thought to play an important role in determining the reliability of dielectrics used in multi-layer ceramic capacitors (MLCCs). However, a detailed examination of the electronic structure, solution energies and compensation mechanisms of these systems is lacking. In this paper, the quantitative analysis of the substitution of Mn in perovskite-type BaTiO3 using first-principles calculations in combination with chemical thermodynamics is reported. The solution energies of dopants with vacancy and n-type and p-type charge compensations have been systematically calculated. Substitution onto the two crystallographically different cation sites in cubic BaTiO3 under four different thermodynamic conditions with different chemical potentials is also examined. Mn is found to be stable on Ti sites under all conditions examined, although its charge state varies. In the oxidizing limit, Mn substitutes for Ti as a Mn4+ ion, but in the reducing limit, Mn substitutes for Ti as a Mn2+ ion compensated by the formation of an O vacancy. Depending on the Fermi level of the system, the valence state of Mn varies from Mn4+ under p-type conditions, to Mn2+ under n-type conditions. Mn3+ is not found to be stable. These results agree well with the experimentally determined site preferences and valence states of Mn, and help to further elucidate the features of Mn-doped BaTiO3 at the atomic level.
Size Effect of Nanograined BaTiO3 Ceramics Fabricated by Aerosol Deposition Method
Authors: Hoshina Takuya , Furuta Tsutomu , Kigoshi Yoichi , Hatta Saki , Horiuchi Naohiro , Takeda Hiroaki , Tsurumi Takaaki
Published: September 2010

We demonstrated the size effect of nanograined BaTiO3 ceramics using freestanding BaTiO3 thick films fabricated by the aerosol deposition (AD) method. Dense BaTiO3 thick films fabricated by the AD method were crystallized and detached from the SrTiO3 substrate by annealing treatment at 600 °C, and then the grain size was controlled by reannealing treatment at various temperatures. As a result, freestanding BaTiO3 thick films with various grain sizes from 24 to 170 nm were successfully obtained. Polarization–electric field (P–E) measurement revealed that BaTiO3 ceramics with grain sizes of more than 58 nm showed ferroelectricity, whereas BaTiO3 ceramics with an average grain size of 24 nm showed paraelectricity at room temperature. Dielectric measurement indicated that the permittivity decreased with decreasing grain size in the range from 170 to 24 nm. The decrease in permittivity was due to the decreases in ferroelectricity and domain-wall contributions with decreasing grain size.
Microstructures Related to Ferroelectric Properties in (Bi0.5K0.5)TiO3–BiFeO3
Authors: Ozaki Tomoatsu , Matsuo Hiroki , Noguchi Yuji , Miyayama Masaru , Mori Shigeo
Published: September 2010

Crystal structures and microstructures associated with ferroelectric properties in a lead-free piezoelectric compound, x(Bi0.5K0.5)TiO3–(1-x)BiFeO3, have been investigated mainly by transmission electron microscopy (TEM). Complicated ferroelectric domain structures with a width of approximately ∼200 nm were found in the polar rhombohedral structure of the x = 0.30 compound. On the other hand, a tweed-like contrast, which stems from local lattice distortion, was observed in the pseudocubic structure of the x = 0.40, 0.46, and 0.50 compounds. The present results suggest that the pseudocubic phase is characterized by nanodomain structures consisting of non-polar cubic and polar rhombohedral structures.
Thermal Depolarization Measurement for Na0.5K0.5NbO3 Piezoceramics
Authors: Matsudo Hitoshi , Kakimoto Ken-ichi , Kagomiya Isao
Published: September 2010

The thermal depolarization of Na0.5K0.5NbO3 ceramics was investigated by thermally stimulated depolarization current (TSDC) measurement in a short circuit and under a 0.5 V induced bias. The large current anomaly of the relaxation of oxygen vacancies was observed at approximately 370 °C, as well as sharp pyrocurrent peaks at T
O–T (209 °C) and T
C (417 °C) in a short circuit when the ceramics were poled under 3 kV/cm at 150 °C. The temperature of the start of broad current flow (325 °C) was close to the bending point temperature of the Arrhenius plot of the bias-induced TSDC pattern (313 °C). The temperature corresponded to the temperature at which k
p began to decrease. The degradation of the piezoelectric property of the poled Na0.5K0.5NbO3 ceramics closely correlated to the thermal relaxation of oxygen vacancies.
Switching Dynamics in Ferroelectric Vinylidene Fluoride–Trifluoroethylene Copolymer Thin Film with α,ω-Dihexylsexithiophene Semiconductor Layer
Authors: Nakajima Takashi , Nakamura Marika , Furukawa Takeo , Okamura Soichiro
Published: September 2010

Ferroelectric switching dynamics in thin vinylidene fluoride–trifluoroethylene copolymer films with an organic semiconductor α,ω-dihexylsexithiophene layer have been investigated on the basis of the measurements of the electrical properties including D–E hysteresis loop, switching characteristics, and capacitance changes. The authors elucidate that the full polarization reversal can be accomplished and the depletion is maintained at zero bias field. The time domain measurement together with capacitance measurements enables the evaluation of the close relationship between polarization reversal and carrier behavior in semiconductor layer. Polarization reversal toward the negative side under negative voltage progresses rapidly owing to the accumulation of majority carriers. Polarization reversal toward the positive side proceeds through two-step reversals. The mechanism of the two-step switching is explained by the depolarization field induced by the uncompensated polarization charge due to the formation of the depletion layer.
Microwave Dielectric Properties of CaTiO3–(LiNd)TiO3–(BiNa)TiO3 Ceramics
Authors: Moon Sang Hwan , Kim Jeong Seog , Cheon Chae Il , Kim Eung Soo , Ohsato Hitoshi
Published: September 2010

The microwave dielectric properties of the CaTiO3–(Li1/2Nd1/2)TiO3–(Bi1/2Na1/2)TiO3 (CT–LNT–BNT) ternary ceramics were studied on the basis of their crystal structure. The microwave dielectric constant improved from 139 to 432, and Qf decreased continuously from 3249 to 124 GHz with an increase in BNT content in the 0.4CT–(0.6-x)LNT–xBNT ternary compositions. The crystal structures of 0.4CT–(0.6-x)LNT–xBNT (x=0–0.6) ceramics were confirmed to be perovskite with an orthorhombic crystal system P
c
m
n (No. 62) and the lattice parameter differences between the a- and c-axes became small with increasing BNT content (x). The increase in the dielectric constant with the increase in BNT content could be explained by not only the large polarizability of a Bi ion but also the crystal structure change: increases in bond lengths, volumes of octahedra and cuboctaheda, and the tilt angle of an octahedron. The tendency of the crystal structure to change from paraelectric orthorhombic to ferroelectric trigonal or tetragonal perovskite structure resulted in a decrease in Qf value with increasing BNT content.
High Power Characteristics of (Ca,Ba)TiO3 Piezoelectric Ceramics with High Mechanical Quality Factor
Authors: Tanaka Daisuke , Yamazaki Junichi , Furukawa Masahito , Tsukada Takeo
Published: September 2010

(Ca0.1Ba0.9)TiO3 + x wt % MnCO3 [x=0, 0.2, 0.5, 1.0] (CBT-Mx) ceramics were prepared by conventional sintering, and their dielectric and piezoelectric properties were measured. The mechanical quality factor (Q
m) of CBT was markedly enhanced by Mn addition and reached 2400 when x=0.5. The dielectric loss tangent (tan
δ) was 0.0023 at room temperature. The Curie temperature (T
C) was 133 °C. Then, the high power characteristics of CBT-M0.5 were investigated. The maximum vibration velocity (v
0) of CBT-M0.5 was 1.1 m/s and was higher than that of Pb(Zr,Ti)O3-based ceramics (Hard-PZT). The heat generation of CBT-M0.5 was smaller than that of Hard-PZT at the same v
0. The resonant frequency (f
r) of CBT-M0.5 was stable up to v
0 of 1.1 m/s. Additionally, the temperature stability of f
r was investigated in the practical application temperature range (from -20 to 80 °C). The amount of change in f
r for CBT-M0.5 was larger than that for Hard-PZT below 10 °C.
Evaluation of Ferroelectric Domain Behaviors Using Acoustic Emission Method
Authors: Aburatani Hideaki
Published: September 2010

Two kinds of acoustic emission (AE) signals are used to evaluate the ferroelectric domain behaviors in tetragonal lead zirconate titanate (PZT) ceramics: AE related to the ferroelectric domain and vibro acoustic emission (vibro-AE) caused by sample vibration. The signal level of vibro-AE caused by the sample vibration is suppressed using an external resistor, and the vibro-AE and AE related to the ferroelectric domain are observed simultaneously. It is shown that the vibro-AE measured as an AE signal Vrms reflects the piezoelectricity of the sample. The Kaiser effect in terms of electrical loading is found to be valid for ferroelectric PZT ceramics. From the vibro-AE measurement, it is shown that domain clamping occurs at critical fields at which the vibro-AE signal vanishes. It is also shown that domain-related AE takes place above the coercive field E
c and after domain clamping occurs. From these obtained AE activities, conflicts among ferroelectric domains in the sequence of domain reorientation from the clamped state to the aligned domain state and the resulting stress relaxations are considered to be the origin of AE.
Effect of CuO Doping on (Bi,Na)0.83Ba0.17TiO3 Piezoelectric Ceramics
Authors: Lv Junhua , Karaki Tomoaki , Adachi Masatoshi
Published: September 2010

(Bi0.5Na0.5)0.83Ba0.17TiO3–x wt % CuO ceramics were prepared by a conventional ceramics fabrication method. The effects of CuO doping on densification, microstructure, and electrical properties are presented. The 0.2 wt % CuO-doped sample sintered at 1060 °C for 2 h exhibits good properties: a shrinkage rate of 16.5%, a relative density of 97%, a relative dielectric constant ε
33

T
/ε
0 of 555 and a dielectric loss of 2.10% at 1 kHz, an electromechanical coupling factor k
p of 18.0%, a piezoelectric charge coefficient d
33 of 148 pC/N, a frequency constant N
p of 3096 Hz·m, a mechanical quality factor Q
m of 52, a depolarization temperature T
d of 218 °C, and a temperature corresponding to the maximum dielectric constant T
m of 249 °C.
Poling Field Dependence of Ferroelectric Properties in Alkali Bismuth Titanate Lead-Free Ceramics
Authors: Ogawa Toshio , Nishina Takayuki , Furukawa Masahito , Tsukada Takeo
Published: September 2010

The DC poling field dependence of ferroelectric properties was investigated to evaluate the mechanism of domain alignment in lead-free ceramics of the forms of (1-x)(Na0.5Bi0.5)TiO3–x(K0.5Bi0.5)TiO3 (x=0.08–0.28), 0.79(Na0.5Bi0.5)TiO3–0.20(K0.5Bi0.5)TiO3–0.01Bi(Fe0.5Ti0.5)O3 and (1-x)(Na0.5Bi0.5)TiO3–xBaTiO3 (x=0.03–0.11). From the DC poling field (E) dependence of ferroelectric properties, asymmetrical shapes in piezoelectric constants vs ±E caused by nonuniform mobility of domain alignment in the application of positive and negative poling fields were observed in the small amount substitution by (K0.5Bi0.5)TiO3 (x≦0.11) and BaTiO3 (x≦0.03). On the other hand, symmetrical shapes in piezoelectric constants vs ±E were observed in higher piezoelectricity with lower frequency constant accompanied with typical domain clamping. The effects to improve ferroelectric properties by Bi(Fe0.5Ti0.5)O3 and by BaTiO3 substitutions for (Na0.5Bi0.5)TiO3 were also proved by the measurement of P–E hysteresis loops.
Fabrication and Piezoelectric Properties of Textured (Bi1/2K1/2)TiO3 Ferroelectric Ceramics
Authors: Nagata Hajime , Saitoh Masahiro , Hiruma Yuji , Takenaka Tadashi
Published: September 2010

Textured (Bi1/2K1/2)TiO3 (BKT) ceramics were prepared by a reactive templated grain growth (RTGG) method to improve their piezoelectric properties. Also, a hot-pressing (HP) method was modified on the basis of RTGG method to obtain dense ceramics and promote the grain orientation. The textured BKT ceramics prepared by the RTGG and HP methods exhibited a relatively high orientation factor F of 0.82 and a high density ratio of 95–99%. Scanning electron microscopy (SEM) micrographs of the textured HP-BKT indicated a textured and poreless microstructure. In addition, the resistivity of the textured HP-BKT was 1.73×1013 Ω·cm. The piezoelectric strain constant d
33 determined by means of resonance and antiresonance method was 125 pC/N for the direction parallel to the sheet-stacking direction of the RTGG process. From the measurement of field-induced stain, the normalized d
33
* (=S
max/E
max) at 80 kV/cm were 127 and 238 pm/V on the randomly oriented and textured samples (F=0.82) for the (∥) direction, respectively.
Pressure-Dependent Raman Scattering Spectrum of Piezoelectric (Li,Na,K)NbO3 Lead-Free Ceramics
Authors: Kakimoto Ken-ichi , Sumi Tomoaki , Kagomiya Isao
Published: September 2010

High-pressure Raman scattering experiments have been carried out for (Na0.5K0.5)NbO3 and Li
x
(Na0.5K0.5)1-x
NbO3 (abbreviated as LNKN-100x) ceramics using a diamond-anvil cell (DAC) in the backscattering geometry. Appreciable spectral changes occurred between 2.04 and 3.41 GPa in (Na0.5K0.5)NbO3 ceramics, which was a sign of the orthorhombic (O) to tetragonal (T) phase transition. The Raman modes of T-phase LNKN-6 and LNKN-7 were less affected by increasing pressure, indicating them to be particularly stable against hydrostatic pressure. In LNKN-5.5, however, a pressure-induced phase transition from a polymorphic O–T phase mixture to a single O phase, similar to the case of LNKN-3, was observed at around 2.84 GPa, since the hydrostatic compression might favor the dense O phase rather than the T phase. Accompanying this result, it was newly found that a further important role of Li substitution in LNKN ceramics is the introduction of tensile stress in the crystal structure.
Polarization System and Phase Transition on (Li,Na,K)NbO3 Ceramics
Authors: Hatano Keiichi , Kobayashi Keisuke , Hagiwara Tomoya , Shimizu Hiroyuki , Doshida Yutaka , Mizuno Youichi
Published: September 2010

The polarization system and phase transition on Li0.055(Na0.50K0.50)0.945NbO3 (LNKN) ceramics were investigated to determine the piezoelectric properties, relative permittivities and X-ray diffraction (XRD). The piezoelectric properties and relative permittivities were strongly dependent on the poled state, which poling temperatures were 25 or 150 °C. The XRD did not exhibit orthorhombic–tetragonal phase transition around the phase transition temperature because no orthorhombic phase was observed below the phase transition temperature. The LNKN ceramics had multiple poled states, the origin of the multiple poled states was considered to be attributable to the multiple spontaneous polarization (P
s) direction on perovskite structure. From these results, we proposed that the phase transition on LNKN was not an orthorhombic–tetragonal phase transition but a monoclinic-tetragonal phase transition. The monoclinic perovskite structure [Z=1, P
m, a=3.9825(5) Å, b=3.9438(4) Å, c=4.0217(5) Å, β=90.292(3)°] can provide multiple P
s directions, such as [101]pc and [001]pc.
Anisotropic Polarization Switching in Tungsten Bronze Ferroelectrics in Binary (Bi1/2Na1/2)Nb2O6–BaNb2O6 System
Authors: Watanabe Takayuki , Hayashi Jumpei , Miura Kaoru
Published: September 2010

Randomly oriented (1-x)BaNb2O6–x(Bi1/2Na1/2)Nb2O6 ceramics were prepared by conventional solid state sintering. The ceramics (0.2≤x≤0.7) sintered at 1250 °C consisted of a single phase of a tungsten bronze structure, while the end-member materials did not crystallize into the tungsten bronze structure. The crystal systems of tungsten bronze phases were orthorhombic for 0.2≤x≤0.25 and tetragonal for 0.3≤x≤0.7. The temperatures for the maximum dielectric constant (T
m) measured for orthorhombic crystals were 300 and 190 °C for x=0.2 and 0.25, respectively, and showed no frequency dispersion. However, the T
m for tetragonal crystals was suppressed below 160 °C and showed an obvious frequency dispersion. To evaluate the orientation of spontaneous polarization, (001)- and (h
k0)-oriented fiber-textured ceramics were prepared for x=0.2, 0.25, and 0.3 by slip casting under a strong magnetic field. Clear hysteresis loops of polarization–electric field were observed for (001)-oriented orthorhombic ceramics (x=0.2 and 0.25) at room temperature, while the polarization induced in the (h
k0)-oriented or tetragonal ceramics (x=0.3) varied proportionally to the external electric field. It was concluded that the tungsten bronze crystals, (1-x)BaNb2O6–x(Bi1/2Na1/2)Nb2O6 (x=0.2 and 0.25), are ferroelectric at room temperature with the spontaneous polarization parallel to the c-axis.
Fundamental Study of Piezoelectric Motion of Chiral Polymeric Fibers for Realizing Tubular-Type Polymeric Actuator for Large Macroscale Physical Object
Authors: Itoh Suhei , Sawano Michiya , Hikawa Hiroomi , Maeda Yutaka , Tajitsu Yoshiro
Published: September 2010

The piezoelectric constant of a poly(L-lactic acid) (PLLA) fiber is larger than that of other piezoelectric polymers. It is well known that it is easier to fabricate large devices with a flexible shape using polymer materials than using inorganic materials. Thus, on the basis of the features of polymer materials, we attempted to fabricate a PLLA actuator for a large macroscale physical object using PLLA fibers. We consider how to bundle PLLA fibers into a tubular-type polymeric actuator (PLLAFTTPA) with electrodes for producing piezoelectric motion under the application of voltage. Then, by thermal welding, a PLLAFTTPA with electrodes on its inner and outer surfaces was manufactured. Finally, we succeeded in producing a PLLAFTTPA with a diameter of 1 cm and a length of 12 cm. We observed that, under the application of an ac voltage of 2 kV, the PLLAFTTPA could be tilted 20 µm in the fixed direction when the base of the PLLAFTTPA was mounted.
Effect of Alumina Film on Surface Acoustic Wave Properties of ZnO Thin Film Surface Acoustic Wave Devices
Authors: Shih Wen-Ching , Wang Tzyy-Long , Wang Hui-Min , Wu Mu-Shiang
Published: September 2010

ZnO films with c-axis (0002) orientation have been successfully grown by RF magnetron sputtering on Al2O3/SiO2/Si substrates. The alumina films were deposited on SiO2/Si substrates by electron beam evaporation. Crystalline structures of the films were investigated by X-ray diffraction, atomic force microscopy, and scanning electron microscopy. The phase velocity of the surface acoustic wave (SAW) device with a 8-µm-thick alumina film was measured to be about 4733 m/s, which is much higher than that (4069 m/s) of the ZnO/SiO2/Si structure and approaches (89.6%) that (5283 m/s) of ZnO/sapphire. The coupling coefficient and temperature coefficient of the frequency of the ZnO/Al2O3/SiO2/Si structure with 8-µm-thick alumina film were close to those of the ZnO/sapphire structure. The experimental result is beneficial to the replacement of the expensive single-crystalline sapphire substrate with alumina film at lower cost for high-frequency SAW devices, and is also useful for integrating the semiconductor and high-frequency SAW devices on the same Si substrate.
Field-Induced Phase Transition between Tetragonal and Rhombohedral Phases in Pb(Zn1/3Nb2/3)O3–8%PbTiO3
Authors: Iwata Makoto , Iijima Naoya , Ishibashi Yoshihiro
Published: September 2010

The field-induced phase transition between the rhombohedral and tetragonal phases was investigated in Pb(Zn1/3Nb2/3)O3–8%PbTiO3 by dielectric constant and electrostriction loop measurements. The temperature-electric-field phase diagram was clarified, and physical properties near the field-induced phase transition were discussed using the Landau-type free energy function.
Gigahertz Range Relaxation in Relaxor Ferroelectric Sr0.75Ba0.25Nb2O6
Authors: Tsukada Shinya , Kojima Seiji
Published: September 2010

The dynamic response of Sr0.75Ba0.25Nb2O6 uniaxial relaxor ferroelectrics is investigated in the GHz–THz range through broadband Brillouin spectroscopy, to clarify the ferroelectric phase transition. The spectra show the temperature and polarization dependent relaxation, which relate to the order–disorder mechanism along the tetragonal z-axis. As a result of the polarization fluctuating along the z-axis, the acoustic phonons related to the z-axis show a marked temperature dependence. The relaxation time is determined in the timescale of 10-11 s, and its temperature dependence shows an anomaly at approximately 430 K (130 K higher than T
C). We show the relaxation to be polar, and interpret the relaxation with the general concept of liquid–glass transitions.
Ferroelectric Phase Transition and Photoinduced Cooperative Phenomena in Bi-Layered Perovskite Pb2Bi4Ti5O18 Ceramics Studied by Brillouin Scattering
Authors: Takesada Masaki , Ueki Ayaka , Onodera Akira , Noguchi Yuji , Miyayama Masaru
Published: September 2010

The ferroelectric phase transition mechanism and ultraviolet (UV) photoexcition effect have been investigated in the bismuth layered perovskite Pb2Bi4Ti5O18 by Brillouin scattering using a Sandercock-type tandem Fabry–Perot interferometer. The temperature dependences of Brillouin spectra both with and without UV irradiation were observed around phase transition points. The observed Brillouin spectra include a central peak component that shows an anomaly in the ferroelectric phase transition point T
C=450 K. The central peak spectra show narrowing under UV irradiation. The correlation length of the ferroelectric dipole fluctuation should be enhanced with the UV irradiation effect below T
C.
Noncentrosymmetric Structure of LuFeO3 in Metastable State
Authors: Magome Eisuke , Moriyoshi Chikako , Kuroiwa Yoshihiro , Masuno Atsunobu , Inoue Hiroyuki
Published: September 2010

The crystal structure of metastable LuFeO3 synthesized by containerless processing has been revealed to be a non-centrosymmetric structure (space group P63
c
m) by analyzing the high-energy synchrotron-radiation powder-diffraction data using the maximum entropy method (MEM)/Rietveld method. The structural characteristics are found in the FeO5 trigonal bipyramid distorted and tilted from the c-axis, which is cause by the hybridization of atomic orbitals between the O atom constituent of the polyhedron and the neighboring Lu atom. The spontaneous polarization expected from the polar structure is estimated at about 5 µC/cm2.
First Principles Calculation Study of the Origin of the Tetragonal Structure of BiCoO3
Authors: Okuno Yukihiro , Sakashita Yukio
Published: September 2010

We have investigated the electric state of BiCoO3 in various crystal and magnetic structures by first-principles calculation method to clarify the origin of the tetragonal structure of BiCoO3. The ferroelectric displacement of Co in the tetragonal crystal is larger than that in the rhombohedral one. Because of the large ferroelectric displacement, the energy levels of the Co's d6 localized electrons are lowered and the crystal tends to be tetragonal. Moreover, we calculated the electric state of BiCo0.5Fe0.5O3, BiCoO3–BiFeO3 solid solution. In this solid solution, the effect of Co's d6 localized electron is effective and the crystal also tends to be tetragonal.
Local Structure of Li-Substituted (Bi0.5Na0.5)TiO3
Authors: Yoneda Yasuhiro , Hiruma Yuji , Nagata Hajime , Takenaka Tadashi
Published: September 2010

The local structure analysis of Li-substituted (Bi0.5Na0.5)TiO3 was carried out by a synchrotron radiation X-ray pair-distribution function (PDF) method. The PDF peak is resolved as a doublet owing to the presence of two phases with distinct local structures, namely, the rhombohedral and tetragonal phases. The coexisting local structure is very similar to the orthorhombic structure. A martensitic phase transformation occurred at the deporalization temperature (T
d) because of the similarity of the local structures.
Late Jurassic-early Cretaceous reef trends on the continental margin SW of the British Isles
Authors: Masson D.G. , Roberts D.G.
Published: September 2010

SUMMARY: Multichannel seismic reflection data has been used to outline the distribution of reefs or carbonate banks on the continental margin SW of the British Isles. This distribution is discussed in terms of regional structure and stratigraphy. All the reefal bodies are pre-Aptian in age, with evidence for both late Jurassic and early Cretaceous phases of reef development. Reef growth was contemporaneous with rifting prior to the occurrence of sea-floor spreading in the Bay of Biscay. The distribution of reefs suggests that shallow marine conditions persisted in the Goban Spur area until middle Cretaceous time, while a deeper embayment may have occupied the Bay of Biscay as early as the late Jurassic.
Strain factorizations from lapilli tuff, English Lake District
Authors: Bell A.M.
Published: September 2010

SUMMARY: Two existing and two new methods of strain analysis have been used on samples of accretionary lapilli tuff from the English Lake District. Results from each method are presented for comparison. Factors responsible for lapilli shape are itemized and discussed. Regional studies indicate that lapilli ellipsoids contain initial, compaction and tectonic components. The most reliable results indicate that compaction of 66% of original thickness normal to bedding during diagenesis was followed by tectonic strains due to folding and cleavage formation. The effects of folding on lapilli shape are thought to be small. Slaty cleavage was produced by strains close to plane strain, indicating a shortening of SO-70% normal to the cleavage plane. It is concluded that slaty cleavage does not form perpendicular to the maximum total shortening of the rock, but perpendicular to the short axis of a strain ellipsoid associated solely with cleavage formation and computation of three-dimensional progressive deformations.
Primary bedding-parallel fabrics in structural geology
Authors: Maltman A.J.
Published: September 2010

SUMMARY: Many phyllosilicate minerals gain greatest mechanical stability on sedimentation by orienting themselves parallel to bedding. Loss of water during the initial stages of compaction also promotes or enhances such a preferred alignment. If the mineral is then buried in the absence of tectonic stress, static mimetic recrystallization will be prompted, so that the fabric becomes metamorphic in appearance while retaining its bedding-parallel orientation.

Such a fabric, in its various stages of evolution, appears not to have received due attention in structural geology. Examples are given where problems associated with microstructures in slump sheets, the early stages of cleavage generation, the development of early schistosities and the interpretation of structural sequence, can be alleviated by the recognition of a primary fabric.
Subcellular localization-dependent decrements in skeletal muscle glycogen and mitochondria content following short-term disuse in young and old men
Authors: Nielsen Joachim , Suetta Charlotte , Hvid Lars G. , Schrøder Henrik D. , Aagaard Per , Ørtenblad Niels
Published: September 2010

Previous studies have shown that skeletal muscle glycogen and mitochondria are distributed in distinct subcellular localizations, but the role and regulation of these subcellular localizations are unclear. In the present study, we used transmission electron microscopy to investigate the effect of disuse and aging on human skeletal muscle glycogen and mitochondria content in subsarcolemmal (SS), intermyofibrillar (IMF), and intramyofibrillar (intra) localizations. Five young (∼23 yr) and five old (∼66 yr) recreationally active men had their quadriceps muscle immobilized for 2 wk by whole leg casting. Biopsies were obtained from m. vastus lateralis before and after the immobilization period. Immobilization induced a decrement of intra glycogen content by 54% ( P < 0.001) in both age groups and in two ultrastructurally distinct fiber types, whereas the content of IMF and SS glycogen remained unchanged. A localization-dependent decrease ( P = 0.03) in mitochondria content following immobilization was found in both age groups, where SS mitochondria decreased by 33% ( P = 0.02), superficial IMF mitochondria decreased by 20% ( P = 0.05), and central IMF mitochondria remained unchanged. In conclusion, our findings demonstrate a localization-dependent adaptation to immobilization in glycogen and mitochondria content of skeletal muscles of both young and old individuals. Specifically, this suggests that short-term disuse preferentially affects glycogen particles located inside the myofibrils and that mitochondria volume plasticity can be dependent on the distance to the fiber border.