bluuebunny/crossref_metadata_2025 huggingface dataset:
X-ray Study on the Intermediate Phase of Quartz
Authors: Kato N. , Gouhara K.
Published: March 2014

This article reviews our recent work on the α-β phase transition of quartz. The transition occurs on the four levels of spatial scale, namely through the structural change within the unit cell, the incommensurate modulation (150∼300 Å), the super modulation (30∼100 µm) and the formation of a domain structure (∼mm). The usefulness of X-ray topography or the combination with goniometry is emphasized. The incommensurate modulation waves are essentially a set of transversal acoustic waves which, however, is modified by a coupling with optical modes particularly near the α phase.
Constrained Process Near the Critical Point
Authors: Okada Kenkichi , Suzuki Ikuo
Published: March 2014

Processes of constant entropy, volume and polarization of a combined system of a lattice and an ordering system in the classical potential are calculated. In an isentropic process, the first order transition does not take place if the coexistence line is not parallel to the temperature axis. An expected double hysteresis loop just above the transition point may or may not appear depending upon the lattice heat capacity in an isentropic process. The three types of relaxation after constrained processes are discussed in parallel, with connection to the critical slowing down.
New Relevant Invariants in the Renormalization Group Study of Ferroelectric Transitions
Authors: Hatch Dorian M. , Felix Jeffrey W.
Published: March 2014

New invariant gradient terms are discussed within renormalization group (RG) methods as applied to solids. We specify under what conditions such terms are allowed by symmetry and indicate that such terms are relevant in RG. For the considerations of three component (n=3) order parameters the irreducible representations are listed which allow such terms and we list the associated electric species type. For n=2, 6 we also claim such terms are relevant whenever usual RG results yield a stable fixed point.
Recent Developments in the Structure, Properties, and Applications of Ferroelectric Polymers
Authors: Lovinger Andrew J.
Published: March 2014

Rapid progress is continuing to be made in the field of ferro-electric polymers. The last few years have seen detailed structural determinations of PVF2 and its copolymers, convincing evidence for Curie transitions, and development of theories that successfully predict the observed ferroelectric behavior. In the field of processing, manufacture of mm-thick polarized PVF2 sheet has been achieved, and a continuous method for simultaneous orientation and poling of PVF2 film and tube has been developed. New piezoelectric polymers have been under study, some of these showing ferroelectric hysteresis. Among applications, ultrasonic transducers in the form of hydrophones, sonar arrays, and focussed medical sensors are attracting wide current attention, while imaginative new uses for these polymers are under continuing investigation.
Fluctuations, Disorder, and Tricritical Behavior of Impure Crystals
Authors: Sokolov A. I.
Published: March 2014

The joint influence of the order parameter fluctuations and lattice imperfections on tricritical behavior is studied within renormalization group approach. The five-dimenional flow diagram is analysed, and the runaway of phase trajectories is revealed within the tricritical sector. The phenomenon is argued to indicate the smearing of phase transitions close to the tricritical point. Instead of this point, the domain of smeared transitions occurs in a phase diagram of imperfect crystal which separates the line of continuous phase transitions from that of first-order ones.
Statistical Mechanics of a Finite Ferroelectric with a Constant Interaction
Authors: Müser H. E. , Siems R.
Published: March 2014

The statistical mechanics of a finite ferroelectric described by an \varOmega=0 pseudo-spin Hamiltonian with constant interactions is treated by analytic, by direct summation, and by Monte Carlo methods. Explicit particle number and temperature dependences of thermodynamic functions are derived and crossover effects are discussed.
Use of Group Theory in Charge Density Calculations of ABO3 Compounds
Authors: Weyrich K. H. , Siems R.
Published: March 2014

Group theory was used to simplify LMTO charge density calculations of complex structures. To profit by the full crystal symmetry also at atoms with a lower site symmetry, the angular distribution functions of local charges at different sites are written as components of a suitable tensor function. The method was explicitly applied to the perovskite structure.
Chemical Trends in ATiO3 Perovskites from Self Consistent LMTO Calculations
Authors: Weyrich K. H. , Siems R.
Published: March 2014

First principles electronic structure calculations, based on density-functional-theory and the linear-muffin-tin-orbital method, were performed for SrTiO3, BaTiO3 and PbTiO3. The valence band density of states, the charge densities, the cohesive energies and the lattice constants were calculated and were used to discuss the chemical trends. A good agreement between theoretical and experimental data was found.
Phase Transitions in KNbO3: Successive Displacive/Order-Disorder Crossovers
Authors: Fontana M. D. , Kugel G. E.
Published: March 2014

Deviations from classical displacive and order/disorder pictures are found in the soft mode behaviour of KNbO3. A model based on the coexistence of a soft phonon and a relaxational central peak is proposed in order to explain the various anomalies. The large discrepancy between the clamped measured data and the LST calculated values of the dielectric constant,together with the special sequence of phase transitions,are explained in this framework.
Effect of Electric Boundary Conditions on Morphotropic Pb(Zr, Ti)O3 Piezoelectrics
Authors: Amin A. , Cross L. E.
Published: March 2014

A phenomenological free energy function which we developed earlier is used to calculate the effect of electric boundary conditions upon the relative stability points, and the rhombohedral (R3m)-tetragonal (P4mm) degeneracy required for the morphotropy at Zr:Ti ratio approximately equal to 1:1. The free energy–composition phase diagram under applied dc fields is discussed in terms of the morphotropic phase boundary behavior.
Piezoelectric Polymers–Materials and Manufacture
Authors: Ohigashi Hiroji
Published: March 2014

Recent progress in improvement of the piezoelectric activity in ferroelectric polymers of technical importance is reviewed with relation to manufacturing process of polarized films. The polymers described are PVDF (polyvinylidene fluoride), P(VDF–TrFfE) (copolymers of vinylidene fluoride and trifluoroethylene), P(VDF–TeFE) (copolymers of vinylidene fluoride and tetrafluoroethylene), and P(VDCN–VAc) (copolymer of vinylidene cyanide and vinylacetate). To increase the piezoelectric activity it is most important to enhance crystallinity and orientation of the polar axis in the thickness direction of the film. This is realized in P(VDF–TrFE) with VDF molar content of 60–85%. The maximum electromechanical coupling factor for thickness extensional mode attains about 0.3 in these copolymers.
Pressure and Temperature Dependence of Dielectric Properties of Pb(Co1/2W1/2)O3
Authors: Hachiga Tadashi , Fujimoto Sanji , Yasuda Naohiko
Published: March 2014

The pressure (0 to 5 kbar) and temperature (-150 to +60°C) dependence of dielectric properties (permittivity, dielectric loss tangent and phase transition temperatures) of ceramic Pb(Co1/2W1/2)O3 were measured, and the pressure-temperature phase diagram was obtained. The dielectric properties associated with the paraelectric-antiferroelectric phase transition was fairly explained in terms of a phenomenological theory.
Optical Anomalies in LiNbO3 Crystals
Authors: Wang Huafu , Hu Xinghua , Zhou Wenzhuang
Published: March 2014

Strong anomalies of the intensity of transmitting light through the z-axis of LiNbO3 crystals between cross Nicols and the conoscopic patterns have been found during continuous heating (or cooling) from room temperature to 140°C. The optical anomalies disappeared for the crystal kept at constant temperature below 140°C. An anomalous broad peak of pyroelectric current has been found along the y-axis over the above temperature range. The anomalies are ascribed to the tertiary pyroelectric effect arising from the thermal stress due to temperature gradient in the crystals.
Optical Deflector Using PLZT Ceramics
Authors: Utsunomiya Toshio , Nagata Kunihiro , Okazaki Kiyoshi
Published: March 2014

Optical deflectors utilizing the electro-optic effect have simple construction, while the deflection angle is small. Aiming at larger deflection angle, we propose a new type of deflector, which consists of a PLZT rectangular solid and triangular electrodes on its top and bottom surfaces. This deflector has the deflection angle more than 1 degree at the electric field 600 V/mm. It is considered that this deflector is as promising for the practical use as the prism-type deflector we have reported.
Bragg A–O Deflector Using a Piezoelectric PLZT Thin Film
Authors: Adachi Hideaki , Mitsuyu Tsuneo , Yamazaki Osamu , Wasa Kiyotaka
Published: March 2014

Bragg deflection of waveguided light by SAW has been observed in an epitaxial PLZT thin film on sapphire structure. Thin film of PLZT was successfully grown with high transparency and piezoelectricity by rf magnetron sputtering. Present PLZT thin film will be one of the most promising candidates to make integrated optic devices using E–O and A–O properties.
Structural Phase Transition in BaPb1-xBixO3
Authors: Oda M. , Hidaka Y. , Katsui A. , Murakami T.
Published: March 2014

The room temperature crystallographic properties and the structural temperature changes of a distorted perovskite system BaPb1-x
Bi
x
O3 were investigated by using X-ray diffraction analysis. It was found that the room temperature structure is orthorhombic in the range of 0≤x\lesssim0.9 and monoclinic in 0.9\lesssimx≤1. In the x\lesssim0.4 samples structural transitions from an orthorhombic to a monoclinic phase were observed at low temperature. While, in the x>0.4 range such transitions were not observed. The x-dependence of the monoclinic angle y was almost the same with that of the superconducting transition temperature. This result indicates that the superconductivity of this system is closely related to the low temperature structure.
Observation of Boundary Structure in Perovskite Type Superconducting Thin Films
Authors: Hidaka Yoshikazu , Suzuki Minoru , Murakami Toshiaki
Published: March 2014

The direct observation of Boundary Josephson Junctions are performed in BaPb1-x
Bi
x
O3 films on sapphire and SrTiO3 single crystal substrate by a high resolution electron microscope. It was revealed from the lattice image of these films that the potential barriers are exactly located at grain boundaries and the origin of the potential barriers is surface states at the grain boundaries.
Oxygen Deficiency in Perovskite-Type Superconductiong BaPb1-xBixO3-δ
Authors: Shikano Koji , Hidaka Yoshikazu , Murakami Toshiaki
Published: March 2014

This paper presents the determination of oxygen, barium, lead and bismuth in the ceramic BaPb1-x
Bi
x
O3-δ using activation analysis and isotope dilution method. The oxygen concentration is close to the theoretical value in the range of 0.0≤x≤0.3, being minimum at x=0.4 and larger than the value at 0.6≤x≤0.8. It is also found that lead is lost through volatilization, that barium is excess and that the bismuth content, x, is different before and after preparation of BPB. Oxygen deficiency, δ, is 0. 19 at x=0.4 and 1.0. The oxygen deficiency might in fact be related to metal-semiconductor transition.
Single-Crystal Thin-Film Growth and Properties of BaPb1-xBixO3
Authors: Murakami Toshiaki , Suzuki Minoru
Published: March 2014

Single-crystal thin films of BaPb1-x
Bi
x
O3 (x=0 to 0.4), a perovskite-type oxide superconductor, have been epitaxially grown by magnetron sputtering. The films (x=0.3) grown on SrTiO3 substrates exhibited a sharp superconducting transition at about 10 K without annealing process. The Hall mobility (300 K) of BaPb1-x
Bi
x
O3 is found to decrease with increasing x from 55 cm2/Vsec at x=0 to 0.2 cm2/Vsec at x=0.35. The results also indicate the carrier localization tendency depending on the Bi content and the amount of oxygen vacancies.
Switching Phenomenon in I-V Curves for Superconducting BaPb1-xBixO3 Films
Authors: Moriwaki Kazuyuki , Suzuki Minoru
Published: March 2014

A novel voltage switching effect has been reported for superconducting polycrystalline BaPb0.7Bi0.3O3 (BPB) films possessing two dimensional boundary-Josephson-junctions (BJJ) arrays. I-V curves are measured for a BPB film with a perpendicular control-current flow pattern. Two I-V curve phenomena are observed. One is a voltage switching effect by an integral multiple of the superconducting energy gap voltage. The other is that the voltage states in the I-V curves are elongated beyond the V-axis. The switching phenomena are investigated in detail by varying the control current and the line width of the BPB cross patterns. The results obtained verify the hypothesis that the voltage switching is caused by diagonally connected BJJs in the voltage state due to electromagnetic coupling among the BJJs.
Penetration Depth into Perovskite Structure Superconducting BaPb1-xBixO3 Films
Authors: Yoriume Y. , Murakami T.
Published: March 2014

Penetration depth into perovskite structure BaPb1-x
Bi
x
O3 films at x=0.3 was measured using a resonator composed of a uniform planar superconducting transmission line consisting of a strip-line. Penetration depth was about 2 µm or a little greater, which was greater than ordinary superconductors. The large penetration depth was attributed to the small mean free path and low carrier density of the BaPb1-x
Bi
x
O3.
Conduction Band Structure of SrTiO3
Authors: Uwe Hiromoto , Yoshizaki Ryozo , Sakudo Tunetaro , Izumi Akio , Uzumaki Takuya
Published: March 2014

Shubnikov de Haas(SdH) oscillations have been measured for the semiconducting single domain SrTiO3 with Carrier concentration of 3.4×1018 cm-3 and 5.9×1018 cm-3. From the temperature dependence of the SdH amplitude, the cyclotron mass values are determined for the [001] and [110] magnetic field directions. We have found, from the angular dependence of the SdH oscillation, that there exist several branches of the frequencies among which the highest and lowest branches originate from the Fermi spheres at the Brillouin zone center, and the other ones from the extremal area which is interconnected through the magnetic breakdown tunneling paths. Energy band parameters based on the k
p perturbation method are determined.
Low Frequency Optical Studies of Boracite Improper Ferroelectrics
Authors: Moopenn A. , Coleman L. B.
Published: March 2014

The infrared and far-infrared (20–4000 cm-1) reflectivity of single crystal nickel bromide and copper chloride boracites has been measured in the ferroelectric and paraelectric phases. In the ferroelectric phase, an anomalous increase of the linewidth of a low-frequency band in the Ni–Br boracite is observed near the transition temperature. A similar temperature dependence is also seen in the linewidth of the anti-symmetric stretch mode of the BO3 group in both boracites. This behavior is interpreted as the result of an enhanced couping to a low frequency soft mode. Our observations suggest that the microscopic origin of the improper ferroelectric phase transition in these materials is both of an order-disorder and displacive nature.
Successive Structural Phase Transitions in TRMCC and TRMCB
Authors: Kashida S.
Published: March 2014

The successive structural phase transition of a linear chain compounds (CH3)3NHCdCl3 (TrMCC) and (CH3) 3NHCdBr3 (TrMCB) were studied by X-ray diffraction methods. The transition sequence of these compounds which were obtained in the heating process were as follows;
TrMCC: Pbnm(1×√3)-Pbnm(2×√3)-P6̄(3×3)
TrMCB: Pbnm(1×√3)-Pbnm(2×√3)-P6̄(3×3)-P6̄2m(√3×√3)

The newly found (√3×√3) phase was discussed as composed of partially disordered state which is equivalent to that observed in the two-dimensional triangular Ising lattice.
Rotational Mode and Curie Temperature in Tungsten Bronze Ferroelectrics
Authors: Varaprasad A. M.
Published: March 2014

The Curie temperature (T
c) data on a number of tetragonal tungsten bronze (TTB) ferroelectrics are successfully explained on the basis of the rotational mode proposed recently.1) The mode arises out of the localized dynamical configurations viz. TTB and perovskite and couples with one of the low frequency lattice modes. This lattice mode presumably is the conventional soft mode that is known as the vibration of the cationic sublattice against the anionic sublattice. The mode is identified with increased Raman spectral widths with increasing Li+ ion concentration in the 12 co-ordinated A-cation site for the compositions Li5La5Ti10O30 and Li6La4 Ti8Nb2O30 and is compared with a similar phenomena observed in morphotropic PZT composition PbZr0.51Ti0.49O3.
Ferroelectricity and Antiferroelectricity in Partially Deuterated Betaine Arsenate
Authors: Rother H. J. , Albers J. , Klöpperpieper A. , Müser H. E.
Published: March 2014

Ferroelectric betaine arsenate (BA) becomes antiferroelectric by deuteration. Complete miscibility of BA and deuterated betaine arsenate (DBA) allows the growth of crystals in which the effective interaction, deciding about the transition to a ferroelectric or to an antiferroelectric state, goes to zero. Tc, however, shifts monotonically with the Dcontent, indicating that this interaction is not responsible for the transition itself. Dielectric and caloric data of some crystals with different deuteration degrees are presented.
Mechanism of the Ferroelectric Phase Transition in Tris-Sarcosine Calcium Chloride
Authors: Nakamura Eiji , Itoh Kazuyuki , Deguchi Kiyoshi , Mishima Naoyuki
Published: March 2014

Consistency between the Debye dispersion in the close vicinity of T
c and the resonant type dispersion of TO soft phonon mode observed in TSCC was examined through comparison of the dynamical and the static quantites by extrapolation. Noticeable discrepancy was found between the two dispersions. X-ray crystal structure analysis revealed a disordered structure above T
c. The structure below T
c is well approximated with one of the two of atomic configurations above T
c. Soft mode contribution was not detected in the mean square thermal amplitude in consistent with the small extrapolated value of the static dielectric constant of the resonant type dispersion.
Thin Films of Amorphous PbTiO3 and LiNbO3 Prepared by Sputtering Deposition
Authors: Kitabatake Makoto , Mitsuyu Tsuneo , Wasa Kiyotaka
Published: March 2014

Amorphous states of PbTiO3 and LiNbO3 were prepared by sputtering deposition and studied their structure and electrical properties. Two types of the amorphous PbTiO3 were prepared under various substrate temperature. One (a1-PbTiO3 deposited at <200°C) contained Pb crystallites and the other (a2-PbTiO3 deposited at <200°C) did not. The
amorphous PbTiO3 crystallized to perovskite by annealing above 520°C. The a2-PbTiO3 annealed below 520°C partially crystallized to perovskite and pyrochlore. The partially crystallized perovskite crystallites in the a2-PbTiO3 is in a “stress-free state”. The amorphous LiNbO3 exhibited high dielectric constant (∼ 8000). This dielectric constant could be explained by dielectric relaxation which was attributed to a Li ion motion.
Solid-Phase Epitaxy of PbTiO3 Thin Films on SrTiO3 Single Crystal
Authors: Kushida Keiko , Takeuchi Hiroshi
Published: March 2014

PbTiO3 films were prepared by rf magnetron sputtering at relatively low temperature (200–300°C) and subsequent annealhig The composition of the sputtered films was investigated in detail and was found to strongly depend on the sputtering gas (Ar-10%O2) pressure. The films fabricated at about 4 Pa had stoichiometry and a perovskite structure under a wide annealing temperature range. Under these conditions, epitaxial growth of PbTiO3 film on SrTiO3 single crystal was attempted. From RHEED patterns and transmission electron micrographs, it was confirmed that epitaxial films with high crystalline quality were obtained.
Poling Treatment of Sputter-Deposited PZT Films
Authors: Fukami Tatsuo , Fujii Shinji , Tsuchiya Hidetoshi
Published: March 2014

Ferroelectric PZT films were successfully fabricated by reactive magnetron sputtering using a composit metal target. The films often showed asymmetric hysteresis loops which were brought about by a spontaneous internal biasing field. The field also affected stability of the poled film during application of a high ac voltage. In some cases, films without poling treatment showed evident pyroelectric response.
Electrical and Optical Properties of SbSI Films
Authors: Rao T. Sudersena , Mansingh Abhai
Published: March 2014

Thin films of antimony sulphoiodide (SbSI) have been grown by flash evaporation. Structural studies revealed that films have a tendency to grow with the c axis oriented at 6° to the substrate. The measured relative dielectric constant (ε') for a 1.0 µm thick film at 100 kHz, 300 K was ∼73. Reproducible ferroelectric-to-paraelectric phase transitions were observed for films thicker than 0.2 µm. Thermoelectric power measurements indicated p-type conduction in the annealed films. Pyroelectric activity was also observed in these films. The refractive index and band gap for a 1.0 µm thick film were found to be ∼4 and ∼1.97 eV respectively.
Preparation and Dielectric Properties of Mixed-Sintering Ceramics
Authors: Takahara Hideyuki
Published: March 2014

A novel mixed-sintering technique for obtaining new ceramics with a large dielectric constant (ε) and small temperature dependence is studied. In this technique, ceramic mixtures called mixed-sintering ceramics (MSCs) are formed by combining two or more perovskites which are calcined at a given temperature and ground into powder.
This paper discusses the preparation method and dielectric temperature dependence of MSCs using x=0.1 and x=0.5 in a pseudobinary xPb(Fe2/3W1/3)O3–(1-x)Pb(Fe1/2Nb1/2)O3 system.
The resulting MSCs exhibit a large ε≃12,000 and, compared to conventionally sintered ceramics, the temperature dependence in MSCs can be significantly reduced in the range of -25° to 85°C without using additives.
Low Temperature Crystal Growth and Ceramic Sintering of BaTiO3–Type Oxyfluorides
Authors: Ravez J. , Chaminade J. P. , Sekiya T. , Benziada A. , Houttemane C. , Pouchard M.
Published: March 2014

The interest of LiF as additive to BaTiO3 has been pointed out for sintering dielectric oxyfluoride ceramics at low temperature (t
sint=930°C). The understanding of the corresponding sintering process leads us to characterize ceramics and single crystals prepared at t<1000°C. Ceramic grains and crystals have a composition Ba(Ti1-x
Li
x
)O3-3x
F3x
.
The whole composition of the ceramics (grain and grain boundaries) is compared to that of crystals. This study per formed on many samples allows to prove the existence of a grain boundary phase, with low melting temperature, facilitating the grain coalescence. The diffuse character of the phase transition and the grain composition gradient induce a large maximum of the ceramic permittivity at T
c, result of great interest for dielectric capacitors.
Hot-Pressing of Barium Titanate Prepared by Oxalate Method in Ethanol
Authors: Yamamura Hiroshi , Haneda Hajime , Watanabe Akio , Shirasaki Shin-ichi
Published: March 2014

Barium titanyl oxalate was prepared by addition of ethanol solution of oxalic acid to barium-titanium (1:1) solution. The oxalate thus obtained was transformed to perovskite-type barium titanate by calcination above 800°C in air. The calcined powder was hot-pressed at 1150 to 1250°C under 300 to 600 kg/cm2 in flowing oxygen. The maximum relative density of the hot-pressed sample was up to 99%. The polished specimens showed translucency. The maximum transmittance was 28% at 870 nm in wavelength of source light. Grain size was estimated to be around 1.0 µm by SEM observation. Dielectric constant increased with increase in the relative density, and the value of the sample having maximum relative density reached 4000. This anomalously high dielectric constant was understood by intimate contact of the fine grains in highly dense ceramics.
Effects of Calcining Temperature on Resonance Characteristics of PZT
Authors: Chung Su-Tae , Lee Wu-Il , Cho Sang-Hee
Published: March 2014

The effects of calcining temperature ranging from 700°C to 1000°C on the resonance characteristics of Pb(Zr0.53Ti0.47)O3 doped with Nb2O5 has been investigated. The anti-resonance frequency, f
a, of the sample increased with the calcining temperature up to 900°C and decreased beyond that temperature, while the resonance frequency, f
r, was almost unaffected by the calcining temperature. Therefore, the planar coupling factor, k
p, was related strongly on the f
a rather than the f
r.
Studies on Macroscopic Property and Microstructural Changes in PLZT Ferroelectric Ceramics
Authors: Yin Z. W.
Published: March 2014

The macroscopic property and microstructural changes correlated with the so-called α-β transition are presented with emphasis on the eletro-optic and TEM studies.
The results of electro-optic measurement show that in the temperature range between the β-α transition point T
t and 10–15°C below T
t a definite reverse electric field can induce the ferroelectric β phase back to nonferroelectric α phase and the transmittance of the sample will rise sharply to near the transmittance of the thermally depolarized specimen. From TEM study microregions were observed in α phase PLZT grains, it would be a forceful verification of polar microregions concept for relaxor ferroelectrics.
Theoretical Equations for Dielectric and Piezoelectric Properties of Ferroelectric Composites Based on Modified Cubes Model
Authors: Banno Hisao
Published: March 2014

This paper describes mainly theoretical considerations for the dielectric and piezoelectric constants of ferroelectric composite types 1–3, 0–3 and 3–0. There is a newly derived theoretical equation for the piezoelectric d
31 constant of 1–3 type parallel model, which is distinguished from that of the conventional 2–2 type parallel one.
The d

h
-equation of the 0–3 type piezorubber composites, ellipsoidal ceramic particles arrangement in the PVDF-PZT composites, and the porosity dependencies of the dielectric and piezoelectric constants of porous ceramics are discussed based on the modified cubes model.
Glass Bonded Crystalline Boracite Composites for Pyroelectric Applications
Authors: Bhalla A. S. , Cross L. E. , Newnham R. E.
Published: March 2014

Polymer and glass bonded crystalline boracite composites are prepared for large area device applications. The glass bonded composites show large pyroelectric figure of merit at room temperature and at 65°C the value becomes larger than that of TGS single crystal (1×10-5 C/m2K) measured at room temperature. Larger area boracite composites can be prepared. Such composites are easier to pole, give quite reproducible results and give higher pyroelectric figure of merit
(p/K values) than the earlier reported values on Fe-I boracite single crystals.
Fundamental Consideration of Piezoelectric Ceramic Multi-Morph Actuators
Authors: Tomikawa Yoshiro , Masamura Koichi , Sugawara Sumio , Konno Masashi
Published: March 2014

This paper deals with a piezoelectric ceramic multi-morph actuator. Included in the first part is investigation of its force factor and electro-mechanical coupling factor in static operation. The force factor can be made large in proportion to the layer number of piezoelectric ceramics. But its electro-mechanical coupling factor is improved little. Second part contains new displacement devices as an application of the actuator. In the third, description of its force factor in dynamic operation is also made and some dynamic applications are added.
Piezoelectric Vibratory Gyro
Authors: Konno Masashi , Sugawara Sumio , Tomikawa Yoshiro
Published: March 2014

The equivalent circuits for a piezoelectric vibratory gyro are introduced, and some conditions in designing are given. Moreover, some new constructions of the gyro are derived from the equivalent circuit.
A Continuous Warming Computer-Controlled Calorimeter Using a Pyroelectric Thermometer
Authors: Lang Sidney B. , Ikura Michio , Brunet Jean
Published: March 2014

A computer-controlled adiabatic calorimeter for use in the continuous warming mode was designed, constructed, and tested. Since its intended use was in measuring the singularities in specific heats near critical solution temperatures, a thermometric sensor capable of yielding accurate values of \dotT at very slow temperature scan rates was required. A pyroelectric thermometer was selected for the purpose. Details of the design of the calorimeter, the pyroelectric thermometer, the
platinum resistance thermometer, and the computerized data acquisition and control system are presented. Preliminary measurements of the singularity of the specific heat of the triethylamine-water system are discussed.
Soft Mode in the Ferroelectric Phase Transition of Li2Ge7O15
Authors: Wada Mitsuo , Fujita Kazuhiko , Sawada Akikatsu , Ishibashi Yoshihiro
Published: March 2014

The ferroelectric phase transition of Li2Ge7O15 was investigated by means of dielectric, ferroelectric, Raman scattering and far-infrared measurements. In the ferroelectric phase a totally symmetric soft phonon mode and in the paraelectric phase the associated polar B
1u soft phonon mode have been observed. This soft mode has a very small oscillator strength even in the vicinity of the transition point. It is suggested that there exists another relaxational mode which should give rise to the dielectric anomaly at the transition point.
Raman Spectral Study on Polar Phonons of Piezoelectric Molecular Solids
Authors: Kobayashi Masamichi , Tashiro Kohji , Yagi Noriko
Published: March 2014

Angular dispersion (LO-TO splitting), polariton dispersion, and scattering profile of the Raman bands due to the polar phonons in piezoelectric trioxane crystal are analyzed quantitatively in terms of oscillator strengths measured by infrared absorption intensities on the basis of the Lyddane-Sachs-Teller equation. Remarkable angular dispersion is observed in the Raman spectra of the ferroelectric phase of triglycine sulfate. Rayleigh wing appears and has the maximum intensity in the vicinity of the Curie point (49°C).
High-Pressure Raman Study of the Deuterium Bonded Crystalline DCOOD
Authors: Shimizu Hiroyasu
Published: March 2014

The Raman spectra of crystalline deuterated formic acid (DCOOD) have been measured up to 100 kbar at 300 K in a gasketed diamond anvil cell. The frequencies of intramolecular O–D and C=O stretching modes decrease strongly with increasing pressure. These softening are due to the increasing strength of the deuterium bonds which link DCOOD molecules to form infinite planar chains. The pressure-induced phase transition at about 45 kbar is presented by the characteristic high-pressure behavior of the stretching O–D, the stretching C=O, and the bending C–D modes. This is discussed at the stage of the conformational phase transition associated with the deuteron transfer
Raman Spectrum in Monoclinic BiVO4
Authors: Jang M. S. , Park H. L. , Kim J. N. , Ro J. H. , Park Y. H.
Published: March 2014

A boule of BiVO4 single crystal was grown by Czochralski technique and annealed for 24 hours at 500°C. The Laue and conoscopic image techniques were used to determine the crystallographic axes of BiVO4 single crystal. The Raman spectrum of c(bb)c̄ geometry of monoclinic BiVO4 was obtained and the Ag symmetry mode appearing at 56 cm-1 at room temperature was softened as the temperature approached to the ferroelastic-paraelastic phase trasition point (255°C). The disappearing of soft Ag mode at phase transition temperature indicates that it is closely related to the ferroelastic strain which controlles the phase transition, i.e., ferroelastic-paraelastic phase transition in BivO4.
Raman Scattering Study of Calcium Orthovanadate Crystal
Authors: Li Cong-zhou , Yang Wen-huang , Chang Ying-chuan
Published: March 2014

This paper presents the Raman scattering of Calcium Orthovanadate crystals. The crystals show strong internal vibrational bands and weak external vibrational bands. We analyzed these vibrational modes in terms of the correlation method.1)
Pattern Dynamics in Ordering Kinetics
Authors: Kawasaki Kyozi
Published: March 2014

Kinetics of phase changes often involves states with broken translational symmetry typified by domain walls which may generally be called patterns. Here we present a brief review of our works in this area emphasizing pattern evolution in incommensurate modulated systems. We show that the idea of phase dynamics introduced recently in hydrodynamics combined with defect dynamics is very useful in describing slightly disturbed modulated states. Otherwise, the equations of motion of discommensurations and dislocations must be solved to obtain pattern evolution.
Use of the Synchrotron X-Ray Topography for Ferroelectric Crystals
Authors: Takagi Mieko , Tokugawa Yohko , Suzuki Shigeo
Published: March 2014

Synchrotron X-ray topography was applied to highly strained c-plates of NaNO2 in which new domains had been formed by application of an A. C.electric field. A precise determination on orientation of the lattice in the domain was made by analyzing the topographs. The study displays an example of the effective application of the topography to the ferroelectric crystals with complicated domain structure.
Study by Scanning Electron Microscopy of Ferroelectric Domain Structure versus Temperature on Pulled BaTiO3 Crystals
Authors: Beudon Didier , Bihan Raymond Le
Published: March 2014

The study of domain structures of BaTiO3 crystals grown by pulling method is interesting because the purity of these crystals is better than for crystals grown by Remeika method. By SEM we have observed cleaved surfaces. The variation of ferroelectric domain structure from room temperature to 150°C is studied; 180° and 90° domains disappear at different temperatures. This suggests a difference in energy for modify the two kinds of domains.
Acoustic Imaging and Propagation Characteristics of Ferroelastic Crystals
Authors: Kojima Seiji
Published: March 2014

Acoustic Microscopy has been applied to the study of ferroelastic crystals. The propagation characteristics of LRW and SSCW have been investigated by utilizing a line-focus lens. The factors of acoustic material signatures are discussed. Acoustic observations of ferroelastic domains and domain walls have been made. The contrast in acoustic micrographs are discussed with regard to the ray theory.
Laser Interferometric Studies on KDP Ferroelectric Domains
Authors: Ha Dong-Han , Kim Jong-Jean
Published: March 2014

High quality laser diffraction patterns are obtained from optically flat and plane parallel c-cut samples of KDP in the ferroelectric phase. Sample thickness t dependence of domain width D was measured between t=0.7 mm and 4.6 mm, which agrees very well with theory D∝√t. Very interesting polarization characteristics of diffraction beams may have some applications.
Deflection of Light and Domain Structure in KH3(SeO3)2 and NaH3(SeO3)2
Authors: Tsukamoto Takeyo , Sato Tsuneo , Hatano Jun , Tamano Noriko , Futama Hideo
Published: March 2014

Properties of the light deflected by ferroelastic domains in KH3(SeO3)2 and NaH3(SeO3)2 were examined. Above a critical angle of incidence, five deflected beams were observed with a He–Ne laser incidence for a y-cut plate of KH3(SeO3)2 and z- and y-cut plates of NaH3(SeO3)2. Only two deflected beams appear at the incident angle of 0°; the deflection angles are ±21.0°, ±31.4° and ±26.0° for the y-cut plate of KH3(SeO3)2 and the z- and y-cut plates of NaH3(SeO3)2, respectively. The intensity of the deflected beams in both crystals increases abruptly just below the transition points on warming process. It was found that the increase of the intensity is due to the formation of a number of fine domains in the vicinity of the transition points.
Piezoelectric Ceramics for Filter and Resonator Applications
Authors: Fujishima Satoru
Published: March 2014

Piezoelectric ceramics are widely used for filter and resonator applications in the audio to UHF frequency range. The most suitable vibration mode differs for each frequency range mainly by the spurious frequency response and fabrication techniques. Many examples of filters and resonators using PZT and PbTiO3 ceramics are described hereafter. It should be noted that a ZnO thin-film is not ferroelectric but piezoelectric ceramics, and components utilizing this technique are available for transducers of LF to UHF range resonators. Also, ZnO thin-film on glass is a suitable structure for SAW filters. Using a high sonic velocity substrate, ZnO thin-film has a high SAW coupling coefficient at the third overtone.
Domain Walls in Pseudo Spin Systems with Competing Interactions
Authors: Tentrup T. , Weyrich K. H. , Siems R.
Published: March 2014

The structure of domain walls was studied within the frame of a generalized ANNNI-type pseudo spin model with a non zero tunneling constant. Temperature dependences of free energies, migration barriers, and profiles of the walls were calculated and shown to be sensitive functions of tunneling constants and interaction ratios. In some parts of the phase diagram there is an oscillatory approach of the wall polarization to the bulk value.
Crystal Structures of Rb2SeO4 and Rb2BeF4
Authors: Onodera Akira , Takahashi Isao , Ishii Shoji , Shiozaki Yoichi
Published: March 2014

The structures of Rb2SeO4 and Rb2BeF4 have been determined at room temperature by X-ray diffraction, of which space groups are Pnam and Pna21, respectively. The final discrepancy factors are 0.039 for Rb2SeO4 and 0.037 for Rb2BeF4. Because large anisotropic thermal parameters are observed for oxygen atoms in SeO4 group, a correction for rigid-body thermal motion has been carried out. The SeO4 is an almost regular tetrahedron, whereas the BeF4 is distorted as the same order as the BeF4 in a ferroelectric (NH4)2BeF4. The SeO4 is linked by three contact O–Rb bonds. In Rb2BeF4, the Rb(2) atom is linked to four F atoms tightly whereas the Rb(1) is very loosely surrounded. Compared with isomorphous A
2
B
X
4-type ferroelectrics, the relative isotropic thermal motions of SeO4 are found.
Electronic Structure of BaPb1-xBixO3
Authors: Mattheiss L. F.
Published: March 2014

The results of linear augmented-plane-wave electronic structure calculations for the perovskite-type compounds BaPb1-x
xBi
x
O3 are reviewed in the light of recent experimental measurements of the x-dependent electronic properties near E
F(x). In the metallic regime x<0.35, satisfactory agreement is found between the calculated density of states N(E
F,x) and specific-heat data. The experimental-theoretical ratio suggests an electron-phonon enhancement factor (1+λ) ≈2. A similar comparison between the calculated and observed free-carrier plasma energies \varOmegap(x) yields ∼ 10% agreement over
the entire alloy series.
X-ray Diffraction Study of Polar Crystal IBr under Pressure –Structural evidence for molecular dissociation–
Authors: Fujii Yasuhiko , Ohishi Yasuo , Onodera Akifumi , Takemura Ken-ichi , Reichlin R. L.
Published: March 2014

The interhalogen molecular crystal iodine-monobromide has been found to undergo the molecular dissociation at 39±2 GPa, where the I–Br bond length becomes equal to the nearest intermolecular distance so that a new monoclinic lattice is formed in its high-pressure phase.
The Crystal Growth of Bi2(MoO4)3
Authors: Jang M. S. , Lee H. C. , Lee J. H. , Park Y. H.
Published: March 2014

The Bi2(MoO4)3 powder was prepared by the solid state reaction of the constituent oxides at 600°C for 12 hours. The single crystal of Bi2(MoO4)3 was grown by Czochralski technique. The optimum conditions for pulling and rotation rates were 2 mm/hr and 12 rpm respectively. Laue patterns were obtained in (010) and (001) faces at room temperature.
Temperature dependent electrical properties were studied for different crystal orientations and found that it has a phase transition temperature at (475±5)°C.
New Compounds on the Base of Niobium and Tantalum Oxyfluorides
Authors: Kalinnikov V. T. , Agulyansky A. I.
Published: March 2014

Synthesis and some properties of double fluorides and oxyfluorides of niobium (or tantalum) as well as of chain and some transition metals are described. Primary attention is given to the compounds of a coordination-type structure.
Proton NMR of the Ferroelectric Phase Transition in (CH3NH3)HgCl3
Authors: Milia F. , Giannacopoulos E.
Published: March 2014

A first order ferroelectric phase transition has been recently found to take place at T
c=61°C in (CH3NH3)HgCl3. The spin-lattice and spin-spin relaxation times T
1 and T
2 have shown that the ferroelectric transition is closely connected with reorientation of the CH3NH3 groups rather than with –CH3 and –NH3 rotations. The spin-lattice relaxation time T
1 has a discontinuity at T
c connected with an abrupt change in the 35Cl NQR frequency thus demonstrating the occurrence of a phase transition, connected with a dynamic disordering of the CH3–NH3 groups as in the layer structure perovskites.
Nuclear Magnetic Resonance of 51V in BiVO4 Single Crystals
Authors: Choh S. H. , Moon E. Y. , Park Y. H. , Jang M. S.
Published: March 2014

Nuclear magnetic resonance spectra of 51V (I=7/2) in ferroelastic BiVO4 single crystals grown by the Czochralski method have been investigated by employing a wide-line Varian spectrometer. The seven line structure due to the quadrupole interaction was measured at a fixed frequency of 15 MHz in three mutually perpendicular crystal planes at room temperature and 77 K, well below its ferroelastic Curie temperature of 523 K. From the experimental data the quadrupole coupling constant, e
2
q
Q/h, and asymmetry parameter, η, are determined: e
2
q
Q/h=4.856 MHz and η=0.380 at room temperature, and 5.062 MHz and 0.459, respectively, at 77 K. The principal axes of the electric field gradient tensor are X=c, Y=a, and Z=b, where a,b, and c are crystal axes with β=90.38°. The twin structure of some of the crystals is also observed.
Temperature Dependence of the Proton Spin-Lattice Relaxation Time Near Ferro- and Antiferroelectric Phase Transitions; Application to Squaric Acid
Authors: Hochstraßer D. , Petersson J. , Siems R.
Published: March 2014

On the basis of an explicit calculation of the critical relaxation rate T
1
-1 for proton NMR in hydrogen bonded crystals, the influence of the groundstate symmetry and the range of interaction on the critical temperature dependence of T
1 is examined for uniaxial systems. Furthermore an evaluation of T
1 in squaric acid is presented which gives new information on the jumping rate of the proton in the hydrogen bond.
ESR Studies of TGS:Fe3+ Crystals
Authors: Ferrer-Anglada N. , Filippini V. , Franco G. , Bandet J.
Published: March 2014

ESR spectra of ferroelectric TGS:Fe3+ crystals are investigated at different temperatures. Changes in the spectra near T
c are noticeable but they are poorly resolved over room temperature. We analyzed the angular dependence of lines at 23°C and at -180°C. The Fe3+ ions are located at two different positions, one of them with orthogonal symmetry. For this center we used the habitual Spin Hamiltonian to obtain the B2
0 parameter. The values found indicate that the crystal field is strongly axial and increase when lowering the temperature.
Incommensurate-Commensurate Transitions in Solid and Liquid Crystalline Ferroelectrics in External Fields
Authors: Blinc R. , \uZek\us B. , Prelov\usek P. , Levstik A. , Filipi\uc C. , Carlsson T. , Mu\usevi\uc I.
Published: March 2014

The phase diagrams of proper and improper incommensurate solid ferroelectrics in external electric fields and of ferroelectric liquid crystals in external magnetic fields are reviewed. It is shown that the Landau model for solid improper ferroelectrics with n=4 is isomorphous to the model for ferroelectric liquid crystals in an external magnetic field allowing for the existence of a Lifshitz point. The experimental results are reviewed and a new model for ferroelectric liquid crystals is proposed.
Optical Absorption in the Near Ultraviolet Region Band Structure and Phase Change of BaTiO3
Authors: Castet-Mejean L. , Godefroy G. , Hafid L.
Published: March 2014

The optical absorption behavior of BaTiO3 at the para-ferroelectric phase change and the anisotropies, in the vicinity of the interband absorption edge for pure monodomaine crystals are investigated from experimental measurements and tight-binding computations. The characteristic features are connected with the energy band structures and with the interband transition moments.
Electronic Structures of Fe2+ and Fe3+ Impurities in BaTiO3 and LiNbO3 Ferroelectric Hosts
Authors: Michel-Calendini F. M. , Hafid L. , Godefroy G. , Moretti P.
Published: March 2014

The spin-unrestricted Xα method is used to obtain the energy level diagrams of Fe2+ and Fe3+ impurities trapped in ferroelectric BaTiO3 and LiNbO3 hosts at room temperature. The mechanisms of ligand-metal, intervalence and crystalfield transitions are analysed and compared to experimental optical data.
ESR Studies of Dipole Impurities in Incipient Ferroelectric KTaO3: Li
Authors: Vugmeister B. E. , Glinchuk M. D. , Pechony A. P.
Published: March 2014

The concentration, temperature and orientational dependences of axial center Fe3+ ESR line width have been studied in incipient ferroelectric K1-x
Li
x
TaO3 (0.01\leqslantx\leqslant0.05).
The contributions in total line broadening due to electric and stress fields created by off-center Li+ ions were found. It was shown that observed nonlinear ESR line width dependence on Li+ ions concentration is connected with manifestation of the long range part of dipole-dipole interaction in strongly polarizable crystals because of the occurance correlative polarization regions in such crystals.
The effective dipole moment d
* of off-center Li+ ions and their reorientation frequency were determined.
Elastic Anharmonicity of NH4Cl, NH4Br and NH4Cl1-xBrx near λ-Point
Authors: Yamashita Haruyasu , Tatsuzaki Itaru
Published: March 2014

Third order elastic constans of NH4Cl, NH4Br and NH4Cl1-x
Br
x
near λ phase transition temperature were obtained from pressure derivatives of second order elastic constants measured under hydrostatic and uniaxial pressures. It is found that the coefficients (C111+6C112+2C123)/54 and (C111-3C112+2C123)/24√3 of strains in the free energy of NH4Cl show quite different temperature dependence from those of NH4Br and NH4Cl1-x
c
BR
x
. Acoustic mode Grüneisen parameters of NH4Cl also show quite different behavior from those of NH4Br.
Acoustical Activity and Ferroic Crystals
Authors: Bhagwat K. V. , Wadhawan V. K. , Subramanian R.
Published: March 2014

Two theoretical formulations for explaining acoustical activity, namely the first-strain-gradient theory and the rotation-gradient theory, are described and compared. In the first-strain-gradient theory acoustical activity is determined by a fifth-rank tensor d, called the acoustic gyrotropic tensor. A new fourth-rank pseudotensor G has been defined by us which is completely equivalent to the tensor d. We also introduce the term “pure ferroacoustogyrotropy” to describe the effect in which the acoustic rotatory power of a crystal can be switched in sign (without change of magnitude) for transverse acoustic waves travelling along acoustic axes (axes of 3-fold or higher rotational symmetry). This effect can occur in ferroic crystals only. Twenty-nine Aizu species allowing it are identified. A number of crystals are predicted to exhibit this effect, the most convenient to study being lead germanate.
Ferroelastic Phase Transitions in Elpasolites A2BB3+X6
Authors: Aleksandrov K. S. , Bovina A. F. , Voronov V. N. , Gorev M. V. , Iskornev I. M. , Melnikova S. V. , Misjul S. V. , Prokert F. , Flerov I. N.
Published: March 2014

Ferroelastic phase transitions (PT's) have been found, studied and confirmed in chlorides of Cs2NaB3+Cl6 and fluorides of A2BDyF6 types with the elpasolite structures. Symmetry of distorted phases has been determined. Behaviour of thermodynamic properties was analyzed in frames of the phenomenological theory. Coefficients of thermodynamical potential were obtained.