bluuebunny/crossref_metadata_2025 huggingface dataset:
An In Vivo Technique for Estimation of Size and Relative Sound Velocity of Breast Tumor using Distorted Image in Ultrasonic Tomogram
Authors: Soetanto Kawan , Ohtsuki Shigeo , Okujima Motoyoshi
Published: March 2014

A technique is proposed for estimation of size and sound velocity of a massive tissue relative to its surroundings that is larger with ultrasonic beam width. This technique is based on a distorted image of a plane reflector behind a massive tissue in an ultrasonic tomogram, which is caused by ultrasonic refraction. An example of a breast tumor with an obscure boundary is shown to demonstrate the usefulness of this technique.
Measurement of Tubular Living Cell Using Ultrasonic Waves Emitted by Arched IDTs
Authors: Kikuchi Tsuneo , Shiokawa Shouko , Moriizumi Toyosaka , Yasuda Tsutomu
Published: March 2014

This study was on the fluctuations of ultrasonic characteristics caused by activities in a living cell which were determined by the phase detection method. Sample and reference ultrasonic beams were emitted from arched interdigital transducers (IDT) on a piezoelectric substrate (PZT), and the phase difference between the two beams was detected. Nitella, a tubular plant cell which shows an excitation phenomenon, was placed in the sample beam and showed small phase fluctuation and spike-like ultrasonic phase changes.
Observation of Dislocation Lines in a Transistor by Electron-Acoustic Microscopy
Authors: Takenoshita Hiroshi , Managaki Masahiro , Mizuno Kaoru
Published: March 2014

Electron acoustic images, EAIs, by electron-acoustic microscopy were studied by in situ observation at the same area of a Si transistor-chip Tr-chip under several bias conditions applied between the collector and the emitter. The results confirmed that the EAI contrast varies depending not only on the difference in the materials and the flatness of the surface but also on the bias conditions. Dislocation lines were clearly observed at the base region of the Tr-chip and were induced by the thermal diffusion process of the base layer production. However, dislocation lines were not observed from the structually same emitter region.
Magnetic Field Dependence of the Vibronic Interactions in KTaO3 and SrTiO3 at Low Temperatures
Authors: Lawless W. N. , Clark C. F. , Swartz S. L.
Published: March 2014

Vibronic interactions in KTaO3 and SrTiO3 were investigated by measuring changes in the dielectric constants (ε) with magnetic field up to 15 T at 20.4 K (liquid hydrogen immersion). Two new features were found: (1) Changes Δ(1/ε) with field are of opposite signs in KTaO3 and SrTiO3; and (2) Anomalous plateaus in Δ(1/ε) appear in both materials at about 10 T. The induced changes in the Curie temperatures with intense magnetic field are orders of magnitude smaller than predicted: ∼12 mK in KTaO3 and ∼-6 mK in SrTiO3 at 10 T.
Mobile Charged Point Defect Contribution to the Low Frequency Dielectric Response of LiNbO3 below Tc
Authors: Prieto C. , Arizmendi L. , Gonzalo J. A.
Published: March 2014

Low frequency dielectric constant data for LiNbO3 in the range from 20 Hz to 20 kHz, at temperatures from 400 to 900°C, show a pronounced increase in ε'(ω) at the low frequency side, similar to that previously reported for LiTaO3 at T above T
c. Making appropriate corrections to the analysis of the data, applicable also to the LiTaO3 data previously reported, it is shown that this behavior may be attributed to collective charged defect migration under the influence of the low frequency a
c field.
Low Sintering Temperature Dielectrics with Composition Derived from Pb(Fe0.50Nb0.50)O3
Authors: Ravez Jean , Simon Annie , Rossignol Jean-François , Hagenmuller Paul
Published: March 2014

The investigation of the Pb(Fe0.50Nb0.50)O3–BaLiF3 system has allowed to obtain a perovskite solid solution for compositions close to that of the oxide. The ferroelectric Curie temperature decreases as the substitution rate increases from Pb(Fe0.50Nb0.50)O3. The ceramic with composition (Pb0.93Ba0.07)(Fe0.465Nb0.465Li0.07)O2.79F0.21 (PB7) has a Curie temperature close to 280 K. A mixture of Li2CO3 and eventually LiF has been added to that material for allowing low temperature sintering. The highest permittivity value has been obtained by sintering a starting mixture 0.94PB7+0.06Li2CO3 at 900°C for two hours (ε
r'=17860 and tan δ≃2×10-2 at room temperature). The curves giving the thermal dependence of ε
r' have shown some of the materials being type II dielectrics and of W(Z5U) class.
Switching Observation of Magnetite by Magnetoelectric Effect
Authors: Inase Toshio , Miyamoto Yoshiko
Published: March 2014

The magnetoelectric effect of magnetite was measured over the temperature range from 4.2 K to 50 K, and an anomaly was found at about 45 K in magnetically induced electric polarization along the triclinic b axis, or P
b, when the magnetization rotated in the ac plane. On the contrary, when the magnetization rotated in the bc plane, no anomaly was observed at that temperature.
This anomalous behavior of the magnetoelectric effect is considered to be due to the switching of the a to b axis in magnetite by the external magnetic field. This is the first observation on a-b switching of magnetite by means of the magnetoelectric effect.
Photosensitivity and Imaging Characteristics of Ion-Implanted PLZT Ceramics
Authors: Land Cecil E.
Published: March 2014

We reported in previous papers that both the near-UV and the visible photosensitivities of ferroelectric-phase PLZT (lead lanthanum zirconate titanate) ceramics are increased by as much as four orders of magnitude by ion implantation or a combination of thermal diffusion of Al and ion implantation. New results are presented here on high-energy (1 MeV) implants of Al and Ni and coimplants of Al+Ne and Ni+Ne, and these results are compared with earlier 500 keV implants of Al and Cr and coimplants of Al+Ne and Cr+Ne as surface modification techniques for increasing the visible photosensitivity of PLZT. The important role of grain size in determining optimum contrast and resolution of stored optical information is described in terms of new experimental results.
Ni–I Boracite: Latent Antiferromagnetism and Improper Ferroelectricity-Ferroelasticity
Authors: Tolédano P. , Schmid H. , Clin M. , Rivera J. P.
Published: March 2014

A theoretical model of the 61.5 K transition in Nickel-iodine boracite is presented. Based on a six-dimensional irreducible corepresentation of the F4̄3cl' paramagnetic group, it shows, within the framework of the Landau theory, that the simultaenous onset of the magnetic ferroelectric and ferroelastic properties can be foreseen from the symmetry of the transition order-parameter. The primary order-parameter is identified as a latent antiferromagnetic ordering. The weak magnetization, polarization and strain components originate in an improper coupling of these quantities with the antiferromagnetic sublattice magnetization. The corresponding magnetic, dielectric, elastic and magnetoelectric anomalies, are briefly discussed.
Use of Microcomputers for Fast Monte Carlo Calculations
Authors: Müser Horst E. , Rys Franz S.
Published: March 2014

The use of microcomputers (Personal Computers, Home Computers) for sophisticated scientific calculations is exemplified. A fast Monte Carlo program is applied to simulate a whole class of statistical models on the two-dimensional square lattice in the critical region. Specifically, results on the critical behaviour of the loop gas model order parameter are presented, which show that the model lies in the Ising universality class.
Ab Initio Calculations of the Effect of Non-Rigid Ions on the Statics and Dynamics of Oxides
Authors: Boyer L. L. , Mehl M. J. , Flocken J. W. , Hardy J. R.
Published: March 2014

The potential induced breathing of oxygen ions in a crystal, which plays a major role in explaining the violation of the Cauchy relations and the splitting of the longitudinal and transverse optic frequencies in alkaline earth oxides, is analyzed for BaTiO3 in the perovskite structure and the distorted structure corresponding to the tetragonal phase. The results indicate that nonspherical ions are required to describe the ferroelectric transition.
A Phenomenological Theory for the PbZrO3: PbTiO3 Solid Solution System with the Spontaneous Polarization and Oxygen Octahedral Tilt Angle as Order Parameters
Authors: Haun M. J. , Halemane T. R. , Newnham R. E. , Cross L. E.
Published: March 2014

The Landau: Ginsburg: Devonshire (LGD) theory for the singlecell region of the PZT solid solution system developed by Amin, et al.
1) has been extended to include the low temperature rhombohedral phase field, which exhibits compositions having both ferroelectric polarization and tilted oxygen octahedra. An additional term has been added to the elastic Gibbs free energy to account for this tilting. The coefficients of the energy function were determined from a combination of phase boundary requirements and experimental data. The spontaneous polarization and tilt angle were calculated
as a function of composition and temperature.
Phonons State Density in Perturbed Perovskite Structures
Authors: Godefroy L. , Benzagouta A. , Derouiche A. , Khatib D.
Published: March 2014

Two different methods are used for computing the density of states (DOS) of phonons for BaTiO3. The influence of impurities is briefly discussed. Raman spectrum is deduced from the results.
Phase Transitions in RbCaF3 and KCaF3
Authors: Flocken J. W. , Guenther R. A. , Hardy J. R. , Boyer L. L.
Published: March 2014

Calculations have been performed to determine the lowest static energy configurations associated with R-pint lattice instabilities in RbCaF3 and KCaF3. Minimum static energies and ionic displacements have been obtained for rotations of the Fluorine octahedra about the [1, 0, 0] [1, 1, 0] and [1, 1, 1] directions. Lattice configurations and energy minima will be discussed and compared with experimental values.
Soft Mode Calculations of KTa1-xNbxO3 Solid Solutions in the Cubic Phase
Authors: Kugel G. E. , Fontana M. D. , Kress W.
Published: March 2014

The temperature dependence of the ferroelectric soft mode has been calculated in mixed KTa1-x
Nb
x
O3 crystals for various niobium concentrations within the framework of a non-linear shell model, in which the fourth-order anharmonic electron-phonon interaction is taken into account in the self-consistent phonon approximation. The variation of the soft mode frequency with temperature for different niobium concentrations(0<x<100%) is reproduced by our model, in which only two parameters related to the linear and non-linear polarizability of the oxygen ion along the oxygen-metal (Ta or Nb) chains depend on x.
Soft Mode and Long-Range Polar Order in KTa1-xNbxO3 for Low Niobium Concentrations
Authors: Kugel G. E. , Fontana M. D. , Mesli H. , Rytz D.
Published: March 2014

The nature of the structural phase transitions in KTa1-x
Nb
x
O3 solid solutions for low niobium concentrations has been recently the object of many controversial discussions. In order to help clarifying the situation we present Raman scattering results from room temperature to 8 K performed on crystals with x=0.008, 0.012 and 0.020 The data are interpreted in the framework of a dynamical model used for calculations of the densities of phonon states and of second-order Raman processes. Conclusions on the nature of the phase transitions in the KTN system are given.
The Micro-Analysis for Composition in DPT Ferroelectrics
Authors: Yuhuan Xu , Hong Wang
Published: March 2014

A DPT ferroelectric ceramics system of (Ba1-x
La
x
)(Ti1-y
Zr
y
)O3 and a DPT-SPT ferroelectric single crystal series of K0.2Na0.2(Sr
p
Ba1-p
)0.8Nb2O6 have been studied. The dielectric constants as function of temerature of these materials have been measured. The semiquantitative point-analyses for composition distribution have been obtained by the technique of SEM and EDAX. The inhomogeneity of composition distribution was discovered in both DPT ceramics and crystal, but no such fluctuation was found in SPT crystal. This provided an experimental support to Smolensky's composition fluctuation model. The theoretical calculations of dielectric constant have been achieved by use of two kinds of form of ε'(T, T
c) and agree well with experiments.
Polarization Optical, Electric and Neutron Scattering Studies of the Perovskite Pb2CoWO6
Authors: Brixel W. , Werk M. L. , Fischer P. , Bührer W. , Rivera J. -P. , Tissot P. , Schmid H.
Published: March 2014

Flux grown single crystals of the elpasolite-like perovskite Pb2CoWO6 have been characterized by polarized light microscopy, electric conductivity, ferroelectric polarization, elastic and inelastic neutron scattering, and DSC. A sequence of four phases is found: cubic, Fm3m (I) \overset∼298 K\longleftrightarrow monclinic, incommensurate (II) \overset∼235 K\longleftrightarrow ferroelectric (III) \overset∼9 K\longleftrightarrow ferromagnetic/ferroelectric (IV). The transitions II/III and I/II are of first order with the respective latent heats: 290 and 840 Jmole-1 Pb2CoWO6. The structure of phase I has been refined with the Rietveld system program, using the 306 K neutron diffraction data. In this phase a soft phonon mode with wave vector q along Σ has been observed and which condenses near the zone boundary point X. -Phases III and IV are probably ferroelectric.
Ferroelectric Behavior in Hexagonal Type Barium Titanate
Authors: Sawaguchi Etsuro , Akishige Yukikuni , Kobayashi Masakazu
Published: March 2014

An investigation on dielectric anomalies in a hexagonal modification of barium titanate has revealed that this crystal is also ferroelectric as in the well known perovskite type barium titanate. The hexagonal single crystals have been grown successfully. The dielectric constant along c-axis ε
c shows two distinct peaks at 222 K and 74 K; a general feature of ε
c vs temperature relation is in agreement with that of ceramic samples (J. Phys. Soc. Jpn. 54 (1985) 480). Above 74 K Curie-Weiss law holds with the curie constant C=1.2×104 degrees. The dielectric constant perpendicular to c-axis is constant ε
⊥∼70. Below about 74 K ferroelectric hysteresis loop occurs. The c-component of the spontaneous polarization is ∼2×10-2 C/m2 at 5 K. Barium titanate affords a rare and an interesting example that both polymorphic states show strong ferroelectric activity despite the quite difference in crystal structures.
Optical Properties and Linear Electro-Optic Effect in Ferroelectric Single Crystal KNSBN
Authors: Yuhuan Xu , Huanchu Chen , Liu S. T.
Published: March 2014

The experiments for optical and linear electro-optic properties in tungsten-bronze type ferroelectic single crystal KNSBN [(K
x
Na1-x
)0.4(Sr
y
Ba1-y
)0.8Nb2O6 with 0.5<x<0.75, 0.30<y<0.90] are described. This crystal has large birefringence with transparency range from 4000 Å to 5.6 µm. The refractive indices n
0 and n
e of 2.3358 and 2.2747 at 5610 Å are given. The low half-wave voltage in KNSBN gives the high value n
0
3·r
c of 730×10-12 m/V, which is figure of merit for EO modulator materials. The thershold energy of 618 MW/cm2 (4pps) for laser damage makes KNSBN attractive for large power laser modulation.
The Magnetophotovoltaic Effect in the Crystals without a Centre of Symmetry
Authors: Fridkin V. M. , Lazarev V. G. , Shlensky A. L.
Published: March 2014

The influence of the magnetic field on the linear and circular bulk photovoltaic effect in the piezoelectric crystals Bi12GeO20 and Bi12SiO20 is investigated. The Hall component of the circular photovoltaic current is measured. The mobility of the nonthermolized electrons is obtained from the Hall measurements. For linear photovoltaic current the Hall component is absent. The possibility of the separation of the ballistic and shift mechanisms of the bulk photovoltaic effect by means of the Hall measurements is predicted.
Anisotropic Photoconductivity and Magnetic-Field-Induced Photogalvanic Effect in Pb5Ge3O11
Authors: Esayan S. K. , Ivchenko E. L. , Lemanov V. V. , Maksimov A. Yu. , Pikus G. E.
Published: March 2014

The anisotropic photoconductivity and magnetic-field-induced photogalvanic effect in ferroelectric Pb5Ge3O11 crystals have been investigated. From comparison of experimental results with theoretical calculations the mobility of the nonthermalized carriers and the coefficient of the photocarrier alignment are determined.
A PTCR BaTiO3 Ceramic Icing Probe for Helicopters
Authors: Osbond P. C. , Whatmore R. W. , Ainger F. W.
Published: March 2014

The structural build-up of ice presents a severe problem for helicopters when flying in super-cooled water cloud below 0°C and probes are required to provide pilot warning. The present generation of probes are accretion sensors using the growth of ice layers to measure the effect. These probes do not indicate liquid water content (LWC) above 0°C, working best in strongly icing conditions. This paper describes a new type of icing sensor which exploits the properties of positive temperature coefficient of resistance (PTCR) BaTiO3 ferroelectric ceramic. The probe works equally well above and below 0°C, and possesses a short time constant (1 to 2 sec.). Hence, it is a device which can be used to give rapid warning of the entry of icing conditions as the critical region around 0°C is traversed.
Structural Transitions in Boracites: One or Two Order-Parameters?
Authors: Toledano P. , Schmid H. , Clin M. , Rivera J. P.
Published: March 2014

At the light of the structural and dielectric data available for 23 boracites, a phenomenological approach of the sequences of ferroelectric-ferroelastic phases observed in this family of compounds, is proposed. It makes use of a single six-dimensional order-parameter, in agreement with the theory of Dvorak and Petzelt, and Gufan and Sakhnenko and in contrast to the two-order-parameter model claimed by Levanyuk and Sannikov. A new interpretation is suggested for the temperature dependences of the polarization and dielectric permittivity, which involves two coupling terms, linear in
the polarization components, and respectively quadratic and cubic in the order-parameter components.
Phase Transitions in N(CH3)4IO3 and N(CH3)4NO3
Authors: Yamaguchi Toshihisa , Suzuki Haruhiko , Shimizu Fuminao , Sawada Shozo
Published: March 2014

Single crystals of N(CH3)4IO3 and N(CH3)4NO3 were prepared by the evaporation method. A clear phase transition was found in each substance by means of the DSC and the DTA and the dielectric measurements. They have the transition temperatures at 207°C and 10°C, respectively. We should say at the present stage that ferroelectricity of N(CH3)4IO3 may exist or may not. There is no evidence of ferroelectric activity in N(CH3)4NO3.
Ferroelectric-Superionic Conductor Phase Transitions in Crystals MeNbWO6·nH2O (Me=Tl, Rb)
Authors: Stefanovich S. Yu. , Yanovsky V. K. , Astafyev A. V. , Voronkova V. I. , Venevtsev Yu. N.
Published: March 2014

Crystals TlNbWO6·0.24H2O and RbNbWO6·0.13H2O with pyrochlorelike structure are obtained by flux method and their dielectric, ion-conductive and non-linear optical properties are studied. The crystals of Tl- and Rb-pyrochlore undergo phase transition from ferroelectric to superionic phase at about 50°C and 100°C respectively, the exact temperature of the phase transition depending on the water content in the crystal. The effect of water content as well as of high cationic mobility on properties of crystals and phase transitions are discussed.
Dielectric Study in Microwave Region and Mechanism of Ferroelectric Phase Transition in (CH3NHCH2COOH)3·CaCl2 (TSCC)
Authors: Sawada Akikatsu , Horioka Masakiyo
Published: March 2014

Complex dielectric constants of (CH3NHCH2COOH)3·CaCl2 crystal in microwave region have been measured around the ferroelectric transition temperature. Remarkable dispersion of dielectric constants has been found between 4 GHz and 35 GHz. It is suggested on the basis of the dielectric spectra that the ferroelectric phase transition of (CH3NHCH2COOH)3·CaCl2 can be described by a phonon-relaxator coupled model on the assmption that a soft phonon is the driving force of the phase transition.
Dielectric Constants of Deposited BaTiO3 Thin Films
Authors: Iijima Yoshio
Published: March 2014

Thin films of BaTiO3 were deposited on a platinum substrate using a tungsten heater as the evaporation source, and the characteristics of the films were found to vary with the deposition conditions. The films with the most favorable characteristics, including a high dielectric constant, were obtained at a substrate temperature of 1000°C and a heat-treatment temperature of 1000°C or greater. Films with substrate temperatures between 600°C and 800°C can be used in making memory elements.
Electrical Properties of Perovskite Type Oxide Thin-Films Prepared by RF Sputtering
Authors: Kuwata Jun , Fujita Yosuke , Matsuoka Tomizo , Tohda Takao , Nishikawa Masahiro , Abe Atsushi
Published: March 2014

Oxide thin-films with perovskite structure are prepared by rf magnetron sputtering in argon-oxygen mixed gas at substrate temperature below 500°C using the Sr(Zr, Ti)O3 and Ba(Sn, Ti)O3 solid solution ceramic targets. The dielectric properties and the microstructure of the sputtered thin-films depend on the substrate temperature, oxygen partial pressure, and target compositions. The dielectric constant and the electrical breakdown strength of the thin-films sputtered by using Sr(Zr0.2Ti0.8)O3 and Ba(Sn0.2Ti0.8)O3 targets is about 100 and 3 MV/cm, respectively. These thin-films with the high dielectric constant and the high electrical breakdown strength are useful for the dielectic layer of the ac TFEL panel.
Optical Detector Using Superconducting BaPb0.7Bi0.3O3 (BPB) Thin Films
Authors: Enomoto Youichi , Murakami Toshiaki
Published: March 2014

Highly sensitive optical detectors have been fabricated by using perovskite type superconductor BaPb0.7Bi0.3O3 (BPB) thin films. Optical signals create quasi-particles and induce changes in the superconducting order parameter. These changes are measured by tunneling junctions along grain boundaries in the BPB polycrystalline thin films. The sensitivity is about 103 V/W in the 1.0∼10 µm wavelength range and they can respond up to 600 MHz at the wavelength of 3.2 µm. The observed results suggest that the BPB detectors are suitable for application in optical communication systems and infrared spectrometers.
A Composite Heat Sensor
Authors: Nakagawa K. , Yanagida T. , Tokuta H. , Fukase T.
Published: March 2014

A pyroelectric heat sensor has been developed. The sensing element installed is a composite film in which the particles of modified PbTiO3 are so dispersed that they can be aligned in a single layer and are bound together by polyamidimid resin. Both the top and bottom portions of the particles are scraped allowing them to come into contact with the electrodes provided on the film. Thus the composite film has the parallel structure. The sensor equipped with the composite film is found to exceed the ceramic one in the responsivity, R
v, by a factor of 2. In the case of detecting induced charge, the sensor output increases as the particle content and the area/thickness of the film increase in a wide range. The sensor equipped with the composite film of high particle content and having a large area and a small thickness exceeded the ceramic sensor in output voltage.
Light Scattering Study of Phase Transitions in KLiSO4
Authors: Ganot F. , Kihal B. , Farhi R. , Moch P.
Published: March 2014

Raman and Brillouin scattering studies have been performed on KLiSO4 single crystals. At room temperature our results well agree with the previously proposed structure (P63-phase I). Between T
1≈250–265 K and T
2≈190–200 K, the spectra are consistent with the simultaneous occurrence of two phases (I and II). Below T
2 a single phase is obtained (phase III). For phases II and III, a conventional analysis of the Raman selection rules does not lead to crystallographic structures already reported in the literature.
Pressure Dependence of the Raman Spectra of TSCC
Authors: Roth R. , Schaack G. , Hochheimer H. D.
Published: March 2014

We have studied the polarized Raman spectra of tris-sarcosine calcium chloride under hydrostatic pressure (p<500 MPa) at low temperatures (100 K<T<180 K). The pressure and temperature-dependence of the soft mode in the ferroelectric phase near T
c has been determined, the spectra have been fitted to a damped harmonic-oscillator model and to a correlation function derived from a coupled pseudospin-phonon model assuming an order-disorder type transition.
Submillimetre Dielectric Spectra of Superionic Conductors
Authors: Volkov A. A. , Kozlov G. V. , Mirzoyants G. I. , Petzelt J.
Published: March 2014

Using the BWO spectrometry, both real perimittivity and conductivity spectra in the 3–10 cm-1 range as a function of temperature have been determined independently of each other for several Ag+ and Na+ superionic conductor (Agl, (AgI)
x
A.(Ag2WO4)1-x
ceramics, RbAg4I5, Na-β-Al2O3, Na-β''-Al2O3 ceramics, Na3Sc2(PO4)3 ceramics). Two rather general features are established: (a) above the room temperature in all compound an extra relaxation-type dispersion is present in the 3–10 cm-1 region with roughly temperature independent relaxation time; (b) at low temperatures a rich splitting of the “attempt” vibrational mode into many lines is observed which is obviously connected with ordering of the conducting ions in several inequivalent crystallographic sites.
The 90°-Domains Grown in c-Plates of NaNO2
Authors: Tokugawa Yohko , Takagi Mieko
Published: March 2014

By application of a gradually increasing A. C. electric field to c-plates of NaNO2 crystal, formation of b-domains in which the polar b-axis is nearly parallel to the c-axis of the plate was observed. The formation was confirmed by optical and by the D-E hysteresis loop observations. Effect of the strain field due to the electrodes on the formation of the domain is discussed.
X-ray Plane-Wave Topography for Use in the Study of Domain Structure of Rochelle Salt
Authors: Umezawa Kikuo , Takashima Masaki , Ogawa Takashi , Ishida Kohtaro , Takagi Satio
Published: March 2014

Domain structure of Rochelle salt has been studied by X-ray plane-wave topography. Fine stripe patterns of domain boundaries are found in topographs of a-plates in ferroelectric state. These patterns are caused by strains near the boundary, due to atomic displacements parallel to the boundary. For c-plates, separate three topographs have been obtained for three incident angles corresponding to three peaks in the rocking curve due to c-domain and to two sets of crystal
orientation in b-domain.
TEM of the Relaxor Material Pb(Sc0.5Ta0.5)O3
Authors: Chan H. M. , Harmer M. P. , Bhalla A. , Cross L. E.
Published: March 2014

The transmission electron microscope (TEM) was used to directly observe ordered microdomains in Pb(Sc0.5Ta0.5)O3 (PST). The microstructure of both single crystal and polycrystalline PST was studied as a function of S, the degree of order (which was controlled by thermal treatment). The observed domain sizes were in good agreement with the results of prior X-ray studies. It was found that the domain coarsening kinetics are much slower for the single crystal than the polycrystalline material. Also evidence was obtained for the presence of short range order within PST.
Domain Freezing of KH2PO4 Single Crystal
Authors: Kuramoto Kazuoki , Motegi Hiroshi , Nakamura Eiji , Kaneishi Yoshiro
Published: March 2014

Effects of crystal defects on the domain freezing of KH2PO4 single crystal are investigated by measuring the complex dielectric constant at frequencies between 10 Hz and 10 MHz. Freezing temperature T
F, defined as the temperature at which \varepsilone'' has its maximum, decreases for more defective samples. Dielectric dispersion observed around T
F is far different from the typical relaxational type. An extremely wide distribution of the relaxation times is expected, which is quite similar to that seen in the dipole glasses.
Effect of Samarium Doping on Some Properties of Ferroelectric Lead Germanate Pb5Ge3O11
Authors: Dhuley C. V. , Katpatal A. G.
Published: March 2014

Pure and 0.1 wt% Sm doped lead germanate crystals were grown by controlled cooling of the melt. Unit cell parameters a=b=10.264 Å, c=10.687 Å in pure crystals have changed to a=b=10.276 Å, c=10.722 Å in doped crystals, without affecting the crystal structure. Sm doping results in a significant shift in the transition temperature by 28°C (from 177°C to 205°C). It also reduces room temperature conductivity from 10-8 Ω-1 m-1 to 10-9 Ω-1 m-1. At higher temperature conductivity of these crystals is more than that of pure crystals. Sm doped crystals exhibit enhanced activation energies both in ferroelectric (0.31 eV to 0.36 eV) and paraelectric (0.54 eV to 0.66 eV) phases. Doping has also resulted in lowering of the threshold voltage associated with low frequency electroluminescence (EL) and in enhanced EL intensity. Results are discussed in terms of the defects created through valancy compensation in the substitution of some of the divalent lead ions by trivalent samarium ions.
Crystal Growth and Liquid Phase Epitaxy of KNbO3 from a K2O–V2O5 Flux
Authors: Bohac P. , Buchmann P. , Melchior H.
Published: March 2014

The phase diagram of the pseudobinary KNbO3–KVO3 system was determined by DTA and KNbO3 films have been grown for the first time on KNbO3, KTaO3, SrTiO3 and spinel substrates by liquid phase epitaxy from a K2O–V2O5 flux. Preliminary results on the fabrication of microstructures for rib waveguide applications by wet chemical and reactive ion etching of KNbO3 are reported.
Shear Acoustic Waves in Piezoelectric Crystals Near the Proper Ferroelectric Phase Transition
Authors: Kessenikh G. G. , Shuvalov L. A.
Published: March 2014

The temperature dependences of the bulk shear wave velocity and that of surface Bleustein-Gulyaev wave are theoretically investigated near the phase transition 4̄3mFmm2 for some direction. It is shown that the bulk wave velocity in an infinite crystal changes near the phase transition slowly, meanwhile the surface wave velocity decreases to zero in paraelectric phase on the mechanically free and electrically shorted surface.
Coset-Decomposition Analysis and Optical and X-Ray Investigations on Ferroelastic Thallous Nitrate
Authors: Wadhawan V. K. , Somayazulu M. S.
Published: March 2014

Thallous nitrate crystals exhibit ferroelastic switching, the domain walls being easily created and moved parallel to {221} planes. It is shown that for the motion of these walls, the sum of displacement vectors of the bulky thallium ions has the smallest value. This result follows from a detailed computation of atomic displacement vectors for the 40 different modes of ferroelastic switching. The pseudosymmetry relations governing these modes are derived by carrying out a left coset decomposition of the prototype space group Pm3m with respect to the space group Pnma of the roomtemperature ferroelastic phase.
Measurement of birefringence and lattice parameters as a function of temperature reveals the possible occurrence of two new phase transitions at 36°C and 56°C.
Period-Doubling Nonlinear Piezoelectric Oscillations in KH2PO4 Crystal near Ferroelectric Transition
Authors: Park Yong-Jik , Huang Jung-Yun , Kim Jong-Jean
Published: March 2014

45° c-cut KDP crystal is observed to form a nonlinear RCL circuit, which shows period-doubling phenomena. The period doubling in KDP was best observed at temperature near T
c, at frequencies of anti-resonance piezoelectric oscillation, and either at high driving voltages or under d.c. bias.
Piezoelectric Studies of Acoustic Softening in KH2PO4 Crystal
Authors: Koo Ja-Yong , Kim Jong-Jean
Published: March 2014

Long wavelength limit of acoustic x

y
-shear mode in KDP crystal was studied by use of piezoelectric excitation. This piezoelectric limit of the acoustic soft-mode, the piezoacoustic oscillator, was analyzed in terms of a damped harmonic oscillator model. Possible contributions from this piezoacoustic mode to both the central peak intensity and the dielectric anomaly of ε'(T≃T
c)≃104
ε'(T≫T
c) were discussed in terms of the piezoacoustic mode parameters.
The Role of Electrostriction in the Determination of Nonlinear Piezoelectric Constants of Quartz
Authors: Kittinger E. , Tichý J. , Friedel W.
Published: March 2014

Starting from the rotationally invariant equations of electroelasticity, the initial derivative of the natural sound velocity with respect to the magnitude of a static electric biasing field is obtained. This initial slope depends on the propagation parameters and second-order material coefficients and, in addition, on third-order stiffnesses and permittivities as well as on non-linear piezoelectric and electrostriction constants. While the contribution of third-order permittivities to this effect is negligible, it is shown that electrostriction is not negligible in general. From time of flight measurements of ultrasonic pulses nonlinear piezoelectric constants were determined. A tentative value is also presented for the electrostriction constant ł11.
Piezoelectric Properties of (Ba, Ca)TiO3 Doped with SiO2, Al2O3 and MnO2
Authors: Sung Yeon Woo , Lee Moon Ho , Yang Cheul Kee
Published: March 2014

The dielectric and piezoelectric properties of Ba0.917Ca0.083TiO3 ceramics doped with SiO2, Al2O3 and MnO2 were
studied as a function of SiO2 and/or Al2O3 contents, and Mn content. The addition of SiO2 and/or Al2O3 deteriorates the piezoelectric coupling factor (kp) and the mechanical quality factor (Qm). On the other hand, the addition of MnO2 improves the deteriorated piezoelectric properties (i.e., kp and Qm) of the (Ba, Ca) TiO3 ceramics doped with SiO2 and/or Al2O3. A high kp of over 40% was found at the doping of 3.0–6.0% MnO2. From the analysis of EDS results, it is supposed that the increase of kp and Qm is related with the distribution of Mn in grain interior or boundary.
Pyroelectric and Piezoelectric Properties of Lithium Tetraborate Single Crystal
Authors: Bhalla A. S. , Cross L. E. , Whatmore R. W.
Published: March 2014

Pyroelectric. piezoelectric and dielectric properties of single crystal Li2B4O7 (LTB) are measured in the temperature range from 50°C down through -150°C. At room temperature LTB has dielectric constant K
3∼10 (at 100 KHz) and dielectric tan
δ∼1 (10 KHz). At liquid nitrogen temperatures, the tan
δ decreased to ∼10-3. Pyroelectric coefficient at room temperature measured ∼30 µC/m2-K which increased to -120 µC/m2-K at -150°C and showed the pyroelectric figure of merit p/K comparable to the value obtained on TGS at room temperature. Primary and secondary components of pyroelectricity are separated and the results suggest that the major contribution comes from the primary effect in Li2B4O7.
Piezoelectric measurements show high values of g
33≃270×10-3 V-m/N and g
h≃100×10-3 V-m/N indicating potential application of Li2B4O7 in the area of pressure sensors.
Effect of Uniaxial Stress on the 130 K and 93 K Phase Transitions in K2SeO4
Authors: Billesbach D. P. , Ullman F. G. , Hardy J. R.
Published: March 2014

The uniaxial stress dependencies of the 130K(T
i) and 93 K(T
c) transitions in K2SeO4 were determined from measurements of birefringence anomalies at T
i, and capacitance anomalies at T
c. At T
i, for crystal axes defined as c<a<b, we obtain: -17.0±0.2 K/kbar for stress along “c”, 3.1±0.2 K/kbar for stress along “a”, and 7.7±0.2 K/kbar for stress along “b”. Summing these three values gives the hydrostatic pressure dependence of -6.2 K/kbar, close to the reported experimental values of about -6.5 K/kbar. Capacitance vs temperature data, for stress along “c” only, in the vicinity of 93 K were fitted to a Curie-Weiss law to determine the transition temperatures. A value of about -25 K/kbar for the c-axis stress dependence of T
c was found.
Optical and Nonlinear Optical Properties of Rb2ZnCl4 in the Incommensurate and Ferroelectric Phases
Authors: Sanctuary R. , Jundt D. , Funariu O. M. , Baumert J. -C. , Günter P.
Published: March 2014

The incommensurate-commensurate phase transition in Rb2ZnCl4 has been investigated by means of refractive index measurements and second-harmonic generation experiments. The anomalies of the refractive indices n1, and n3 at the phase transition temperature T
c can be explained by assuming Bloch type light waves propagating in the incommensurate structure, vanishing gradient terms in the Landau expansion of the free energy density and a discontinuity of the amplitude of the order parameter at T
c. In the incommensurate phase the observed second-harmonic signals are generated by the symmetry-allowed coefficients of the ferroelectric phase and are explained to be due to the presence of a defect-induced unipolar domain structure. In the ferroelectric phase the nonlinear optical coefficients d32, d33, and d24 are shown to be proportional to the spontaneous polarization.
Nature of the Phase Transition in KTaO3 with Random Site Impurities
Authors: Samara G. A.
Published: March 2014

Recent results, including high pressure data, on the low temperature properties of KTa1-xNbxO3 (KTN) are presented and discussed. Most of the emphasis is on the question of whether the low temperature polar phase in dilute KTN (x≈0.02) arises from the spontaneous displacement of ions below T
c (i.e. a static structural phase transition) or from the freezing of impurity-induced dipolar motion. Much of the evidence argues against a bulk equilibrium phase transition and suggests the coexistence of random dipole freezing and slowly relaxing ordered clusters which grow with decreasing T. The likelihood of a pressure-induced crossover from normal ferroelectric ordering to dipolar glass behavior in soft T
O mode systems is discussed and possible evidence for such a phenomenon is presented.
Electron Microscope Study of Incommensurate Phase in Quartz
Authors: Yamamoto Naoki , Tsuda Kazuya , Yagi Katsumichi
Published: March 2014

Electron microscope observation showed a detailed structure of microdomains of the Dauphiné twin appearing in the incommensurate phase between the α and β phases. The triangular microdomains form a hexagonal domain lattice in orientations slightly deviating from the {10.0} planes by angles ±φ, which gives rise to a `macrodomain' structure. From the contrast analysis of the domain boundary, a relative lattice displacement parallel to the boundary is expected between the neighbouring domains, and a model was proposed. A dynamic process of the α-β phase transition was observed using a TV camera system attached to the electron microscope.
The Investigation of Successive Phase Transitions in Cadmium Pyroniobate Crystal
Authors: Smolensky G. A. , Krainik N. N. , Kamzina L. S. , Salaev F. M. , Tarakanov E. A. , Sher E. S.
Published: March 2014

The dielectric properties, birefringence, domain structure, electrooptic and pyroelectric effects, specific heat and electroacoustic echo have been investigated in Cd2Nb2O7 at successive phase transitions. Physical properties in different phases have been discussed. The thermoactivated reorientations of polarization at the diffuse phase transition temperatures contribute not only to ε, electrooptic and pyroelectric effects, but also influence the electroacoustic echo relaxation time due to the spectral diffusion mechanism.
The Incommensurate Phase of Betaine Calciumchloride-Dihydrate
Authors: Brill W. , K. H.Ehses K. H.Ehses
Published: March 2014

Betaine Calciumchloride-Dihydrate (BCCD), (CH3)3NCH2COO·CaCl2·H2O, is the first member of the (TGS, TSCC)-family which shows incommensurate behaviour. The phase transitions were investigated by conventional X-rays Double axis diffractometer “AMADEUS”, Saarbrücken) and by synchrotron radiation (two-axis-diffractometer Hasylab/DESY, Hamburg). Above 164 K there is a high temperature phase and below 43 K a ferroelectric phase In between, the incommensurate phase can be described as an “incomplete devil's staircase”. The temperature dependence of the satellite intensity can be fitted by a critical exponent 2β=0.85. The half width of the satellite reflections exhibits anomalous behaviour at the transition temperatures. The modulation vector is influenced in a very special manner by an external electric field.
Influence of a Frozen Defects Density Wave on the Incommensurate Modulation in Barium Sodium Niobate
Authors: Kiat J. M. , Calvarin G. , Schneck J.
Published: March 2014

It is shown by means of an X-ray scattering technique that the memory effect in incommensurate Barium Sodium Niobate is associated to the freezing of the modulation wave vector over a wide range of temperature. This result is consistent with the existence of defects induced locked phases. In addition two unexpected phenomena have been observed; a splitting of the modulation into two components and a specific temperature evolution of the ferroelastic domains pattern which can be related to the behaviour of the modulation. The possible origins of these phenomena are discussed.
Thermodynamic Studies on Incommensurate Biphenyl and Related Substances
Authors: Saito Kazuya , Chihara Hideaki , Atake Tooru , Saito Yasutoshi
Published: March 2014

As the temperature decreases, the heat capacity of biphenyl decreases less steeply than those of p-terphenyl and p-quaterphenyl, and crosses them at about 12 K, and at about 6 K, respectively. A simple model calculation of lattice vibration spectra shows that the large heat capacity of biphenyl at low temperatures is attributed to the twisting mode of low frequency of the phenyl rings in biphenyl. However, the heat capacity measurements on 4,4'-difluorobiphenyl which Should have rather large heat capacity at low temperatures according to this explanation reveals that the crossover occurs at about 12 K. An attempt is described to account for the relative magnitude of the heat capacities of biphenyl and 4,4'-difluorobiphenyl by calculating the crystal energies for the planar and the twisted molecular conformations.
Domain Structure and Surface Electrons of Ferroelectrics in Incommensurate State
Authors: Kinase Wataru , Makino Wako , Takahashi Kunio , Naka Hideki
Published: March 2014

The periodicity of the incommensurate state in ferroelectrics is explained by considering that the area of the surface neutralization by one electron corresponds to the area of the microdomain in ferroelectrics, namely, NaNO2, K2SeO4 and Sr2Nb2O7. The state of the surface electrons is obtained quantum-mechanically, and the incommensurate phase transition is also discussed taking account of the interaction between the surface electrons and the ionic lattice.
Orientation in Piezoelectric Tartaric Acid Composites
Authors: Krug William P.
Published: March 2014

The relative volume of oriented tartaric acid crystals, determined by X-ray measurements, was directly proportional to the hydrostatic voltage coefficient, gh, of the piezoelectric composite.
Chirality Induced Pyroelectricity in the Liquid Crystal p-DiMethylAminoBenzaldehyde
Authors: Anand Miss V. , Tiwary H. V.
Published: March 2014

Films of p-DiMethylAminoBenzaldehyde exhibit pyroelectricity in the temperature range 58° to 77°C and indicates the presence of a phase with spontaneous polarization. The origin of pyrocurrent can be attributed to the reorientation of two dipole groups CHO and (CH3)2N around the long molecular axis. The high value of pyroelectric coefficient 6.8×10-8 C/cm2/°C around 63°C showing a maxima, is thought to be due to the combined effect of the reorientation of these two dipole moments. The molecular contribution from the CHO group is expected to be larger here and has more temperature dependence.
Switching Characteristics of Ferroelectric Liquid Crystal DOBAMBC (II)–Temperature Dependence and Scaling Rule–
Authors: Orihara Hiroshi , Ishibashi Yoshihiro
Published: March 2014

The dependence of the switching characteristics of DOBAMBC on the temperature and the applied voltage to the SSFLC cell was observed. From the results obtained a scaling rule was found, i.e., the switching time, the number of nuclei and the domain wall velocities are only the functions of the applied voltage scaled by the temperature difference from the transition point. On the basis of it, we showed that the activation voltage, defined as the voltage over which the nucleation occurs, is proportional to the temperature difference from the transition point.
Recent Topics in Ferroelectrics at Low Temperatures: Quantum, Vibronic, and Glasslike Properties
Authors: Lawless W. N.
Published: March 2014

Recent developments in the quantum, vibronic, and glasslike properties of ferroelectrics at low temperatures are reviewed, primarily from an experimental viewpoint.
The KTa1-x
Nb
x
O3 quantum system has been most thoroughly investigated, and recent work has been done on the Sr1-x
Ca
x
TiO3 and (Cd1-x
Pb
x
)2(Nb1-y
Ta
y
)207 quantum systems.
The vibronic theory predicts significant shifts in the soft-mode frequency of displacive ferroelectrics with magnetic fields. Two sets of contradictory experiments have appeared: Large shifts in modest fields, and small shifts in very intense fields. The sign of the shift is different for outermost 3d and 5d orbitals at the B-site.
Some inorganic ferroelectrics, antiferroelectrics, and pyroelectrics display glasslike thermal and dielectric properties at low and ultralow temperatures, and the magnitudes of the coupling coefficients are the same as in glasses. Domain walls and ceramic grain boundaries do not cause the glassy behavior, nor can very large electric fields influence this behavior. The evidence to date suggests that the glasslike properties may be due to an interaction between the spontaneous polarization and minor defect levels.
Short-Range Interaction Explanation of Ferroelectric, Antiferroelectric and Proton Glass Behavior in Pure RDP, ADP, and Mixed RDP-ADP Crystals Respectively
Authors: Schmidt V. Hugo , Wang J. T. , Schnackenberg P.
Published: March 2014

A unified model is presented for Rb1-x
(NH4)
x
H2PO4 crystals over the whole range x=0 (RDP) to x=1 (ADP). Two short-range interactions are postulated. One is the Slater energy ε
0 which is kept at the value for RDP for all x. The other is an interaction ε
a between two hydrogens in O-H…O bonds across an NH4
+ ion from each other. It is responsible for the off-center positions observed for ammonium ions in the antiferroelectric phase of ADP. Its strength is assumed proportional to x. By minimizing the free energy, one finds a range of x for which no transition occurs, but instead proton glass behavior sets in. Fox x near 0 and 1 respectively, first-order ferroelectric and antiferroelectric transitions are predicted. Both phase boundaries are close to those observed experimentally.
Dielectric Dispersion of Rb1-x(NH4)xH2PO4
Authors: Takashige Masaaki , Terauchi Hikaru , Miura Yuichi , Hoshino Sadao , Nakamura Terutaro
Published: March 2014

The frequency dispersion of the dielectric constants of mixed crystals of Rb1-x
(NH4)
x
H2PO4 was investigated over the full range of the concentration. For 0.25≤x≤0.8, a remarkable frequency-dispersion was found, which supports the existence of a glasslike phase. For 0≤x≤0.2, two kinds of dispersions, which are distinct from those observed for 0.25≤x≤0.8, were found.
Low Temperature Dipole Freezing in KI1-x(NO2)x
Authors: Yamamoto Ikuo , Ohtani Noboru , Hirotsu Shunsuke
Published: March 2014

The temperature and the frequency dependence of the dielectric constant of KI1-x
(NO2)
x
was measured for concentrations of x=0.05 and 0.10. Both the real and the imaginary parts show maxima at low temperatures which depend on the measuring frequency. Two successive dielectric anomalies were observed for x=0.10. The results are discussed in terms of the distribution of the activation energies and it is suggested that the presence of the clustering tendency of the impurity dipoles appreciably affects the reorientation process of NO2
- ions.