bluuebunny/crossref_metadata_2025 huggingface dataset:
The Temperature Dependence of the Polarizing Effect
Authors: Zelenka Jiří
Published: March 2014

The results of the measurement of temperature dependence of the resonant frequency change caused by the application of the dc electric field to the piezoelectric resonators prepared from a Bi12GeO20 crystal are given in the paper. The temperature coefficient of the nonlinear piezoelectric coefficient is calculated from the measured values.
Electrostrictive Tensor Components of PZT-Ceramics Measured by X-ray Diffraction
Authors: Zorn G. , Wersing W. , Göbel H.
Published: March 2014

The electrostrictive tensor components Q
11, Q
12 and Q
44 of Pb0.83Sr0.12Ba0.05 [Zr0.6Ti0.38Nb0.02]O3-ceramic were measured separately above Curie temperature with a time-resolved X-ray diffraction technique. The results were corrected for the influence of ceramic parameters. The corrected values are considered to be the same as single-crystal values. This was proven by comparison of values from measurements on BaTiO3-ceramics with the known values for BaTiO3 singlecrystals. The electrostrictive coefficients of the above mentioned ceramic were measured in a temperature range between 420K (Curie temperature) and 470K. The results were independent of temperature: Q
11=3.0·10-2 m4/C2, Q
12=-1.6·10-2 m4/C2 and Q
44=6.2·10-2 m4/C2. In the ceramic system Pb0.83Sr0.12Ba0.05[Zr
x
Ti0.98-x
Nb0.02] O3 the electrostrictive coefficients were found to vary linearly with variation of x. Our measurements are compared with those of other authors.
Comparison of Piezoelectric Constants of PZT Ceramics with Values Calculated from Electrostrictive Coefficients
Authors: Wersing W. , Zorn G. , Lubitz K. , Mohaupt J.
Published: March 2014

The piezoelectric and elastic behavior of ferroelectric perovskites can be understood by considering parameters such as the permittivities, spontaneous polarization and electrostrictive effect. We recently succeeded in measuring the single-crystal electrostrictive coefficients of Pb0.83Sr0.12Ba0.05 [Zr
x
Ti0.98-x
Nb0.02]O3. From these results and the spontaneous strain measurements together with the temperature dependence and aging of permittivity we were able to calculate the dielectric and piezoelectric single-crystal constants of these ceramics. Averaging these values yielded material constants that deviate from the ceramic constants measured by standard resonance methods. The differences are considered to be due to the domain wall contributions to these material constants.
Properties of Grain-Oriented Lead Germanate Ceramics
Authors: Nagata K. , Uchida Y. , Okazaki K. , Schmitt H.
Published: March 2014

Grain-oriented lead germanate ceramics were prepared by hot-pressing method. The microstructure and the electrical and optical properties of grain-oriented samples were measured. The anisotropies of about two times in the permittivity and pyroelectric coefficients were found between the parallel and perpendicular direction to the hot-pressing direction. It was found that grain-oriented lead germanate ceramics have highly active pyroelectric effect. Hot-pressed samples showed a transmittance of about 60% at a wave-length of 6 µm (0.2 mm in thickness).
Applicaton of a Simple Model with Frustration to Incommensurate Crystal Phases in TMA-Compounds and Biphenyl
Authors: Janssen T.
Published: March 2014

A simple model for incommensurate orystal phases (IC) in insulators is applied to a number of compounds for which such a phase has been observed experimentally. It is shown that in these cases the origin or the incommensurability is probably frustration and the relevant parameters are discussed. Moreover, the model explains the symmetry of the phases, even in those cases where the modulation wave vector becomes commensurate.
Structural Properties of Glassy Phases
Authors: Terauchi Hikaru
Published: March 2014

Glass-transition phenomena occurring in crystalline states of orientational and positional disorders, random-site electric-dipoles and competing ferro-antiferroelectric interactions are reviewed and the structural properties of the glassy phases are discussed. Especially systematic studies of the temperature dependences of dielectric constants, lattice parameters and X-ray diffuse scattering profiles and of the frequency dependence of dielectric constants in a competing ferro-antiferroelectric system are reported. Analogues of spin-glasses are seen in the dielectric glassy phases.
Influence of Defects on the Commensurate-Incommensurate Transition of A2BX4 Crystals
Authors: Jannot B. , Benhmida M. , Fahli M. , Dumas C. , Jannin M. , Gits S. , Ribet M. , Godefroy G.
Published: March 2014

Most of the physical properties of crystals which belong to the A2BX4 family, are closely connected with the growth method, and also with the thermal and mechanical treatments applied to the samples. It is the case for the dielectric response which shows a large thermal hystresis over a wide temperature range including the commensurate-incommensurate region.1,2,3)
In this paper, we report the results of the dielectric measurements performed on Rb2ZnCl4 and (N(CH3)4)2ZnCl4 crystals (or TMA)2ZnCl4) grown by various methods, and propose an interpretation of the different observed behaviours, involving the presence of defects which appear during and after the crystal growth.
Dielectric Dispersion and Ultrasonic Velocity in (NH4)2ZnCl4
Authors: Osaka Toshio , Ichikawa Masaaki , Makita Yasuharu
Published: March 2014

The complex dielectric constant of (NH4)2ZnCl4 above room temperature was measured in a frequency range between 11 MHz and 500 MHz, and the ultrasonic velocities at 10 MHz were measured by a pulse echo superposition technique. It was found that the crystal shows dielectric dispersion near the IC-C phase transition point of 91°C. The dispersion is suggested to be originated from discommensuration in the IC-phase. (NH4)2ZnCl4 exhibits anomalies in the ultrasonic velocities of c
11, c
22 and c
66-modes at the N-IC transition point of 133°C, but it does not show any anomaly at the IC-C transition point of 91°C.
Structural Change at the Incommensurate-Commensurate Phase Transition in (NH4)2BeF4
Authors: Yamada Noboru , Ikeda Takuro
Published: March 2014

The incommensurate-to-commensurate phase transition in (NH4)2BeF4 has been investigated by X-ray diffraction. Structural analyses were made at T
c+1 K and T
c-4 K. The profile of satellite reflection was observed with decreasing temperature and the increase of both integrated intensity and half-width was elucidated. As the satellite went to a commensurate reflection at T
c, the intensity rapidly increases just below T
c. This is consistent with the excessive change of modulation amplitude of BeF4 groups expected from the structural aspect.
Effect of Electric Field on the IC-C Phase Transition in K2SeO4
Authors: Ookubo Hiroaki , Fukui Minoru , Abe Ryuji
Published: March 2014

The effect of electric field on the IC-C phase transition in K2SeO4 has been investigated by measuring the ESR spectra and the crystal current in the ESR circuit. It has been found that time development of the crystal current after the application of static electric field shows two different time dependencies; one is rapid and reversible and the other is slow and irreversible. The slow change of the crystal current can be represented well as t
0.21. The peak of the crystal current which corresponds to that of the dielectric loss shifts to higher temperature with increase of the frequency of applied microwave. From the quantitative analysis of the shift, it is shown that the polarization fluctuation around T
c in K2SeO4 can be explained by the relaxational model with a temperature dependent activation potential.
Lattice Vibrations and Incommensurate Phase Transitions in K2SeO4, Rb2ZnCl4 and K2ZnCl4
Authors: Echegut P. , Hauret G. , Gervais F. , Massa N. E.
Published: March 2014

The temperature dependence of the dielectric function of K2ZnCl4 deduced from infrared reflection spectra is reported over the PE, INC and FE phases. Whereas differences in the transition mechanisms at T
l between K2SeO4 and K2ZnCl4 and Rb2ZnCl4 are recognized, the origin of the dielectric constant anomalies at T
l and T
C are discussed within the context of a same model in particular the lock-in transition is understood as an instability of the lattice against correlated discommensuration sliding fluctuations. In the INC phase, the spectra of the three compounds show the increase of additional modes. Their number is compatible with incipient tripling of the PE unit cell along the pseudo-hexagonal axis. No additional mode is observed in the FE phase and no significant change of regime occurs around T
C in the temperature dependence of mode intensities.
Birefringence in an Incommensurate Structure: Rb2ZnCl4
Authors: Kroupa Jan , Fousek Jan
Published: March 2014

Spontaneous birefringence δs
Δ
n in the INC and C phases of Rb2ZnCl4 crystals has been evaluated and shown to consist of contributions proportional to <r
2> and <r
6>, r denoting the order parameter modulus. Jump-like changes in Δ
n of the order of 10-6 are observed at the INC-C transition. It is shown that they can be explained by a change D/\cong0.25% and by the occurrence of another contribution in the INC phase. The latter could originate from the fact that the light propagation may be affected by spatial modulation of optical permittivities. If temperature is cycled in the INC phase only, no hysteresis in Δ
n is observed. This shows that-unlike static permittivity-optical properties of Rb2ZnCl4 are not sensitive to  which is proportional to soliton density.
Phase Fluctuations in the IC-Phase of Rb2ZnCl4
Authors: Ehses Karl-Heinz
Published: March 2014

The dependence of the satellite intensities of Rb2ZnCl4 on the temperature, the scattering vector Q, and the order m of the satellites has been investigated by means of X-rays (Double-Crystal-Diffractometer AMADEUS, Saarbrücken, λ=1.54 Å) and Synchrotron-Radiation (Two-Axis-Diffractometer, HASYLAB, Hamburg, λ=0.35 Å). The results are in accordance with the structure factor for incommensurate phases given by Axe and Adlhart. Higher order satellites are considerably influenced by a `phason temperature factor' of the form exp
(-m(m-1)C
T).
Weakening of Pinning Effect in Purified Rb2ZnCl4 Crystal
Authors: Hamano Katsumi , Sakata Hideaki , Izumi Haruhiko , Yoneda Kan , Ema Kenji
Published: March 2014

Single crystals of Rb2ZnCl4 were grown by slow evaporation of an aqueous solution which had been purified by repeated recrystallization. Special care was taken to remove impurities having a tendency to enter into crystal in crystallization. The dielectric constant of the purified crystal showed thermal hysteresis of only 0.2 K in the incommensurate phase. The dielectric dispersion frequency of domain wall motion in the commensurate phase was lowered to 200 kHz from 1 MHz in the unpurified crystal. The switching time of the field-induced commensurate-to-incommensurate transition was shortened extremely in the vicinity of T
c. These indicate the weakening of the pinning effect in the purified crystal.
Structural Study of La2Ti2O7 by Convergent-Beam Electron Diffraction and Electron Microscopy
Authors: Tanaka M. , Sekii H. , Ohi K.
Published: March 2014

A convergent-beam electron diffraction study has revealed that the space group of the room temperature phase of La2Ti2O7 is P21. A dark-field electron microscopy has made clear a twinned domain structure in this phase. C BED patterns obtained at above 1053 K were compatible with the space group Cmc21. An incommensurate phase exists between 993 K and 1053 K. The incommensurate reflections are characterized with the vector q̄=((1/2)-δ)ā
0
* from the fundamental reflections of the high temperature phase, a
0
* being the reciprocal lattice parameter of the high temperature phase. The value of δ increases from 0.015 to 0.017 as the temperature is raised. The transition between the room temperature phase and the incommensurate phase is of the first order, and that between the latter phase and the high temperature phase is of the second order.
Successive Phase Transitions and Their Soft Modes in Ferroelectric Sr2Nb2O7
Authors: Ohi Kikuo , Kojima Seiji
Published: March 2014

The soft optic modes responsible for the successive phase transitions of Sr2Nb2O7 have been observed by the Raman scattering measurement. The characteristics of the soft modes are discussed in connection with the macroscopic properties of the successive phase transitions.
Effect of a Hydrostatic Pressure on the Incommensurate Phase of Barium Sodium Niobate
Authors: Savary H. , Tolédano J. C. , Schneck J.
Published: March 2014

Through measurements of the optical birefringence, we have examined the influence of a hydrostatic pressure, up to 3 kilobars, on the range of stability of the incommensurate phase of Ba2NaNb5O15, using two types of experimental procedures, one of which involves the preliminary ordering of defects in the sample. We also point out some characteristics of the pressure hysteresis.
Diffraction Study of Solid Solution [Thiourea]1-x[Urea]x
Authors: Shiozaki Yoichi , Onodera Akira , Takahashi Isao , Kato Yoshitake , Fujiwara Yasuhiro
Published: March 2014

Study of the incommensurate phase of solid solution [thiourea]1-x
[urea]
x
is made by means of X-ray diffraction. The modulation wave of the incommensurate phase is affected by the replacement of thiourea molecule with urea molecule, so that the two equivalent modulated sublattices become non-equivalent ones and slight polar atomic arrangements are resulted. Hydrogen donds in thiourea crystal take a share in the short range interactions necessary for the appearance of the modulation wave.
Model for the Splitting of an Incommensurate Modulation under the Influence of a Frozen Defect-Density-Wave
Authors: Errandonéa G. , Schneck J.
Published: March 2014

We report a theoretical study of the influence of a defect-density-wave on an incommensurate modulation by considering a model in which the modulation is submitted to two competing lock-in potentials with different periodicities. We show that our model can be transformed into the Frenkel-Kontorowa problem. As consequences, the modulation can be described as a solitons distribution whose spacing is not constant but modulated. The temperature dependence of the solitons density is represented by a devil's staircase and the Fourier spectrum of the modulation splits into several components. The case of Rb2ZnBr4 is discussed.
Crystalline Ferroelectrics with a Glassy Polarization Phase
Authors: Burns Gerald , Dacol F. H.
Published: March 2014

We have studied several different ferroelectric crystal systems where the long range translational symmetry is strongly broken. From measurements of the temperature dependence of the optic index of refraction, n(T), we find that far above the ferroelectric transition temperature, T
c, there is a temperature T
d where local polarization occurs. For systems such as PLZT, i.e., (Pb1-3x/2La
x
)(Zr
y
Ti1-y
)O3, T
d is several hundred degrees above T
c and independent of La-concentration. In this system we can account for T
d quantitatively (in terms of T
c of PZT, i.e., zero La concentration). The model emphasizes local polarization effects from clusters of a few unit cells.
Switching Phenomena in Thin Films of Ferroelectric Polymers
Authors: Tajitsu Yoshiro , Furukawa Takeo
Published: March 2014

Ferroelectric switching characteristics of vinylidene fluoride/trifluoroethylene copolymers have been investigated in relation to their higher order structures and compositions. The amount of reversed polarization increases with increasing crystallinity and drawing. This is consistent with the assumption that the switching occurs as a result of rotations of molecules around their chain axes in the crystalline regions. The switching time follows an exponential law at fields from 50 to 500 MV/m. Extrapolation to the infinite field predicts the switching time of 1–10 nsec.
Diffuse Phase Transition in Ferroelectric Polymers and Its Irradiation Effect
Authors: Odajima Akira , Takase Yoshihiko , Ishibashi Teruo , Yuasa Kimihiro
Published: March 2014

The ferroelectric phase transition was investigated in the VDF/TrFE copolymer films before and after irradiations by means of dielectric, X-ray diffraction, IR and gel content measurements. The diffuse phase transition was explained in terms of the Ginzburg-Landau theory, in which the domain boundary effect was taken into account. On irradiation, the peak temperature on the ε'-Tcurve shifted to lower temperatures, but did not decrease below 40°C even irradiated with more than 200 Mrad. On the other hand, the result of X-ray diffraction measurement exhibited a radiation-induced
phase transition at room temperature after irradiation with 120 Mrad. This discrepancy may be attributed to the phase coexistence over a wide temperature range.
Dielectric Properties due to Interfacial Interaction in Ferroelectric Liquid Crystal
Authors: Kai Shoichi , Hashimoto Tetsuya , Nomiyama Miyuki , Imasaki Masahide
Published: March 2014

Interfacial effects on the dielectric properties like a coercive field E
c, a residual polarization P
r and D–E hysteresis loop, are studied in ferroelectric liquid crystal DOBAMBC. The strong relation between the pitch Z of the surface disclination (the stripe pattern) and P
r is observed, that is, P
r increases with increase in Z. E
c becomes larger as the thickness of the cell d decreases and tends to be infinite toward d=0. This suggests the existence of the surface layer in DOBAMBC. Moreover no change of Z is observed for the change of the instantaneous field (a triangular wave) of 60 Hz, supporting that the stripe pattern can only repond to the low applied frequency. Z changes however when the effective field intensity is varied. From these results, it can be said that the -dielectric properties of surface layer (and/or the surface disclination) are obtained from the study of P
r- hysteresis.
Helicoidal Structure and Spontaneous Polarization in the Mixtures of Ferroelectric Liquid Crystal with Its Racemate
Authors: Tsuchiya Tsuyoshi , Ouchi Yukio , Ishikawa Ken , Takezoe Hideo , Fukuda Atsuo , Kondo Katsumi , Era Susumu , Mukoh Akio
Published: March 2014

Some phenomena that critically depend on the helicoidal pitch and spontaneous polarization in ferroelectric liquid crystals are studied. These quantities are changed by mixing active DOBAMBC with its racemate. The phenomena investigated are: (1) Directions of the spontaneous polarization at the bounding surfaces, (2) Critical thickness for realizing bistability, (3) Two types of fringe patterns corresponding to the helicoidal pitch, (4) Disclination lines in the middle of a cell, (5) Unwinding of the helicoidal structure induced by an electric field, and (6) Winding of the helicoidal structure near the phase transition to Sm A.
Order-Disorder Model of PO4 Dipoles for KDP and ADP
Authors: Tokunaga Masaharu
Published: March 2014

The order-disorder models of PO4 dipoles are examined for KDP type ferro- and antiferroelectrics. The Fourier transforms of dipole-dipole interactions between PO4 dipoles have been numerically computed. As far as this interaction is concerned, the dipolar arrays of the minimum energy are the KDP type ferroelectric array for the “upper” and “lower” dipoles, and the Nagamiya type antiferroelectric one for ”lateral” dipoles. The Slater type model and the Ising spin type model have been reexamined in the light of recent experimental results, and their validities are discussed with reference to the ice constraint.
Dynamical Mechanism of Ferroelectric Phase Transition in KH2PO4 by Raman Scattering Study
Authors: Tominaga Yasunori , Tokunaga Masaharu , Tatsuzaki Itaru
Published: March 2014

The dynamical mechanism of the ferroelectric phase transition in KH2PO4 has been confirmed as the “order-disorder dynamics” of locally distorted PO4 dipoles by Raman scattering studies. Through the analysis of the internal vibration modes, the local site symmetry of PO4 tetrahedrons in the paraelectric phase has been determined to be C
2 which is the same site symmetry as that in the ferroelectric phase. The very low frequency central component of the x(y
x)y Raman spectra has been attributed to the relaxational type polarization fluctuation of PO4 dipoles. The relaxation time of an isolated PO4 dipole has been evaluated as τ0=0.13×10-12 sec by the analysis in terms of a Debye type susceptibility.
A Structual Study of the High-Pressure Antiferroelectric Phase of CsH2PO4
Authors: Schuele Paul J. , Thomas Robert
Published: March 2014

A three-dimensional neutron diffraction study has been carried out on the pressure induced antiferroelectric phase of CsH2PO4. At 100.7 K and a hydrostatic pressure of 3.6 kbar the unit cell parameters are a=15.625(9), b=6.254(2), c=4.886(1) Å, β=108.08(3)° and Z=4. Atomic parameters were determined using full-matrix least-squares methods which yield final agreement indices: R(F
2)=0.0715, R
W(F
2)=0.0807 and S=2.13. The structure is nearly consistent with the monoclinic space group P21/a but refinement in P21 yields a slightly better fit. The structure is markedly different from those of the paraelectric and ferroelectric phases with large relative displacements (nearly 1 Å) of Cs+1 and PO4
-3 groups in the x-z plane. Hydrogens bonding in b-chains, which are disordered in the paraelectric phase, show antiferroelectric order.
Calculation of the Parameters for the Vertex Model of Squaric Acid
Authors: Müser Horst E.
Published: March 2014

The antiferroelectric phase transition occurring in Squaric Acid at 100°C is often described by a pseudo-one-dimensional Ising model. We tried to simulate by Monte Carlo calculations simultaneously the well-known temperature dependence of order parameter, specific heat, and dielectric susceptibility both for the Ising model and for a more general 16-vertex model. A satisfying agreement between experimental and calculated results can be reached only for the vertex model. The parameters for the best simulation are presented. It is shown that a three-dimensional interaction is essential for the phase transition.
Randomly Mixed Ferroelectric and Antiferroelectric; Cs1-xTlxH2PO4
Authors: Sakashita Hirofumi , Hayase Shuichi , Terauchi Hikaru
Published: March 2014

X-ray diffraction and dielectric constant measurements have been carried out in a one-dimensional ferro- and antiferroelectric mixed crystal Cs1-x
Tl
x
H2PO4 with a concentration range from x=0 to x=1. In the Cs rich region (0≤x<0.15), the crystals undergo a paraelectric to a ferroelectric phase transition, while a paraelectric to an antiferroelectric phase transition occurs in the Tl rich region (0.3<x≤1). A new phase is found to appear in the intermediate concentration region (0.15<x<0.3). It becomes evident that the transitions are diffusive.
Dielectric and Raman Studies of (KDP)1-x(KDA)x Mixed Crystal
Authors: Choi Byoung-Koo , Lee Kwang-Sei , Kim Jong-Jean
Published: March 2014

Dielectric and Raman studies were made in mixed crystals of (KDP)1-x
(KDA)
x
for varying KDA concentrations of x\lesssim0.24 near the phase transition. Transition temperature T
c was observed to decrease with increasing x at the rate of dT
c/dx≃-60 K, which was fitted well by the model of the pseudo-spin with transverse field. Domain wall freezing temperature T
f was also lowered as x was increased in the range of x\lesssim0.05 but the dielectric plateau anomaly disappeared at higher concentration of x\gtrsim0.05.
Recrystallizing Processes and Dielectric Properties in BaTiO3–SiO2 Glass System
Authors: Tanaka Masahiro , Makino Yoshimi
Published: March 2014

Amorphous BaTiO3–0.27SiO2 was prepared by roller-quenching method. Crystallization was examined by DTA and X-ray diffraction. The crystals appeared are barium titanate and fresnoite; activation energies of crystals are estimated to be respectively 5 eV and 7eV. Lattice parameters of crystals were found to depend on the size of crystals. The temperature corresponding to the cubic-tetragonal phase transition of barium titanate was also found to depend on the size of barium titanate crystals.
Static and Dynamic Behaviour of the CN Molecules in the Quadrupolar Glass Na(CN)xCl1-x Studied by 23Na and 35Cl NMR
Authors: Elschner S. , Petersson J.
Published: March 2014

The freezing process of the CN dumbbells in the orientational glass Na(CN)
x
Cl1-x
was studied by 23Na and 35Cl NMR for several concentrations x. The systems with x\gtrsim0.7 undergo structural phase transitions, whereas systems with x\lesssim0.7 stay cubic on the average down to lowest temperatures. For concentrations x≈0.65, the temperature dependences of the NMR line widths give evidence that the transition into the glass state essentially consists in a deformation of the local potentials leading to a formation of preferential directions for the orientations of the CN ions. The temperature dependence of the spin lattice relaxation time T
1 shows that the motions of the CN ions in their deformed potentials remain fast. With decreasing concentration x, the influence of the collective interactions between the CN ions becomes less pronounced and a gradual transition to systems with decoupled CN ions can be observed.
On the Two-Dimensional Model of Biological System
Authors: Mitsui Toshio , Sugata Kazuhiro , Morita Kenichi
Published: March 2014

Von Neumann succeeded in embedding abstract biological systems in two-dimensional cellular space. His theory is outlined and compared with Ising's two-dimensional model of phase transitions remarking similarities and dissimilarities between them. In von Neumann's theory, a living thing is regarded as an automaton and discussion is made on the basis of Turing's thesis. His theory suggests that the modern mechanistic view of life may be stated in the condensed form: Any function of biological systems can be simulated by a Turing machine. Questions and answers are given about self-reproduction, orthogenesis (evolution in a definite direction), irreversibility of biological systems, and reduction of number of parameters in von Neumann's model.
Epitaxial Growth of PbTiO3 on MgAl2O4/Si Substrates
Authors: Matsubara Shogo , Shohata Nobuaki , Mikami Masao
Published: March 2014

Lead titanate (PbTiO3) thin films are successfully sputter-deposited onto (100)MgAl2O4/(100)Si substrates at 480–550°C sputtering temperatures. It is confirmed, from X-ray and electron diffraction analyses, that the PbTiO3 films grow epitaxially on MgAl2O4 films. The crystal properties of PbTiO3 films depend on those of MgAl2O4 films strongly. The PbTiO3 films are composed of c-axis and a-axis oriented domains. The ratio of the c-axis oriented domain to the a-axis oriented domain is controllable by the cooling rate of the substrate. The dielectric constant of the PbTiO3 film is estimated to be about 100, based on C-V measurements with a metal-insulator-semiconductor structure.
Electrical Properties of Grain-Oriented Ba and La Modified Lead Niobate Ceramics from Molten Salt Synthesized Powders
Authors: Nagata Kunihiro , Uchida Yutaka , Okazaki Kiyoshi , Nam Hyo-Duk
Published: March 2014

Needle-shaped (Pb1-x
Ba
x
)1-y
La2y/3Nb2O6 powders are prepared in the presence of molten slat, and one directional grain-oriented ceramics are made from these powders by two-stage hot-pressing technique. The morphology of powder and the dielectric and piezoelectric properties of ceramics are also examined. The obtained grain-oriented ceramics have a large anisotropy in both permittivity and coupling factor depending on the first and second hot-pressing directions. The substitution of Ba or La has remarkable effect not only on morphology of the powder but on electrical properties of the ceramics.
Effect of Pb Content on d-Constant of Pb(Ni, Zn, Nb)·Ti·ZrO3 Ceramics
Authors: Fujii Hiromitsu
Published: March 2014

Effect of Pb content on lattice parameters and piezoelectric properties was investigated in Pb(Ni, Zn, Nb)O3–PbTiO3–PbZrO3 solid solution system. High d
33-constants, as maximum value of 640×10-12 C/N, were obtained as a result of exact Pb content control. A bimorph vibrator and multilayer vibrator composed of these materials were confirmed having high performance.
Measurement of Internal Stress in PTC Ceramics
Authors: Michiue Masakuni , Igarashi Hideji , Okazaki Kiyoshi
Published: March 2014

The temperature dependence of internal stress in PTC ceramics with various Curie points was successfully measured by a microindentation and a X-ray diffraction techniques. At ferroelectric phase region, the internal stress decreased with approaching to Curie temperature and reached to almost zero at paraelectric phase region. The effects of internal stress on PTC behavior were discussed with potential barrier related to an effective permittivity.
Temperature Stability of Piezoelectric Ceramics
Authors: Ogawa Toshio , Wakino Kikuo
Published: March 2014

This paper reports an investigation into the fundamental temperature stability of piezoelectric ceramics through thermal aging and thermal shock tests. The dependence of piezoelectricity on thermal aging and thermal shock of low Q
m and high Q
m materials was clarified. The surface charges generated by the thermal shock caused depolarization of the ceramic elements. In particular, it was found that space charges promoted depolarization in the high Q
m materials. A resistor inserted in parallel with the element for the thermal shock test improved piezoelectricity by causing quick relaxation of the induced charges.
Electrochromic Absorption Spectra of MocW1-cO3 Films
Authors: Yamada Shoji , Hiruta Yoichi , Suzuki Nobuyuki , Urabe Kazuo , Kitao Michihiko , Toyoda Koichi
Published: March 2014

Evaporated films of Mo
c
W1-c
O3 including MoO3 and WO3 have been prepared, and the electrochromic absorption spectra have been analyzed on the basis of the small polaron absorption model. Thermomodulation spectroscopy measurements are performed in order to make the analysis precisely. The polaron and phonon energies are determined in the case of the MoO3 and WO3 films. In the mixed films, low energy region of the spectra is represented well by either spectrum of WO3 or MoO3 film. Peak photon energy of the absorption band in the mixed film depends on both the Mo fraction and the amount of injected charges.
Electric and Optical Properties of PLZT Ceramic Shutter Array
Authors: Takubo Yoneharu , Horibe Yasutaka , Yamanishi Nobue , Okinaka Hideyuki
Published: March 2014

This paper is concerned with a light-shutter array of PLZT transparent ceramics utilizing newly-developed electrode structure. Relationships between shutter characteristics and electrostrictive effect of the PLZT are investigated. The electrode structure plays significant roles on the reliability of the shutter characteristics. Thus, by introducing a double layer electrode structure coated with resin, the highly stable light-shutter array is obtained to a long time drive. Furthermore, small temperature dependent shutter array can be also realized by controlling each width of the electrode and light-shutter aperture.
Prism-Type 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 prism-type optical deflector using PLZT 9/65/35 ceramics as an elector-optic material.
Processing the PLZT ceramics into a prism with twin electrodes sputtered on its top and bottom surfaces, we fabricate a prism-type optical deflector, which has the deflection angle up to 1.2 degree at the electric field 900 V/mm.
Ceramic Films of Pb4.95Ba0.05Ge3O11 by Printing Technique and Their Pyroelectric Characteristics
Authors: Takamatsu Keiji , Kobayashi Nobuo , Tsujimura Tomio , Matsumoto Kazutoshi , Takada Ko , Ichimura Hiroshi
Published: March 2014

Printing technique was applied to preparing pyroelectric elements of infrared detectors. Completely sintered ceramic films were obtainable using only pastes that were made from raw powders as fine as 1.0 µm. The films indicated ferroelectricity. The measured pyroelectric coefficient, resistivity and relative permitivity were nearly same as those obtainable on the bulk ceramics formed by conventional sintering technique.
High-Energy Oxygen Atoms in ZnO Film Preparation by Reactive Sputtering of Zn
Authors: Tominaga Kikuo , Kume Michiya , Yuasa Takayuki , Tada Osamu
Published: March 2014

Using Zn metal disk target, ZnO films were prepared in Ar+O2 mixed gas by both DC planar magnetron sputtering and RF diode sputtering. The dependence of c-axis orientation of ZnO film on O2 partial pressure was examined from the view point of the bombardment of film by energetic oxygen atoms. For DC planar magnetron sputtering, the c-axis orientation of film does not depend on the O2 partial pressure, but for RF diode sputtering, the c-axis orientation becomes high at r=10–20%, where r is the percent ratio of O2 partial pressure to total pressure. It is found that there exists a correlation between the dependence of c-axis orientation on O2 partial pressure and the film bombardment by energetic O atoms.
Bias Effect in Rf Sputtering of PbTiO3 Thin Film
Authors: Okuyama Masanori , Ueda Toshiyuki , Hamakawa Yoshihiro
Published: March 2014

PbTiO3 thin films have been prepared by rf sputtering under bias application to the substate. Relationships of the plasma potential to the bias voltage have been discussed. Some of the thin films prepared under the substrate bias are highly-oriented and the dielectric properties become better with increase of the bias voltage. The film surface is very smooth because the deposition rate of the horizontal face is high but the inclined plane is etched off very much.
Preparation and Properties of Rapid Quenched (BaO)1-x·(TiO2)x Amorphous Ribbons
Authors: Shoji Kazuo , Uehara Yasuo
Published: March 2014

Amorphous ribbons of (BaO)1-x
·(TiO2)
x
are prepared by rapid quenching method using a twin-roller apparatus. Transparent ribbon-like thin samples are obtained for the composition range 0.60≦x≦0.75. For as-quenched samples with composition 0.55≦x≦0.80, exothermic peaks in DTA curves are clearly observed at 600–820°C. The dielectric constant for each amorphous sample is about 25 at room temperature, and independent of compositional change. Changes in dielectric behavior of quenched samples with x=0.68 by heat treatment are also discussed.
Crystallization of Amorphous Oxides: Li2O–GeO2
Authors: Maeda Masaki , Seino Hiroaki , Kurita Kazue , Sato Hidetaka , Ikeda Takuro
Published: March 2014

Rapid-colled amorphous specimens with composition 3/8 and 1/7 in the Li2O–GeO2 system have been investigated. The crystallization occurs twice successively in 1/7. Crystallization temperatures rise with increasing heating-rate in DTA-measurement, and the Kissinger analysis enables us to estimate activation energies for the crystallization. The sound velocity was measured at various temperatures with time and the temperature dependence of relaxation time permits us to evaluate an activation energy for the nucleation of crystallites.
Spontaneous Polarization and Electrical Field Response of Surface Disclination in Ferroelectric Liquid Crystals
Authors: Kai Shoichi , Hashimoto Tetsuya , Nomiyama Miyuki , Imasaki Masahide
Published: March 2014

Visual observations of a chiral smectic C phase were made simultaneously with the measurement of the spontaneous polarization to understand the relation between the stripe pattern (the surface disclination) and the polarization reversal process. The polarization reverse is not directly related to the dynamical change of the stripe pattern. During the polarization reverse, the bright and chaotic pattern were observed independent of the stripe pattern.
Some Properties of Ferroelectric Liquid Crystals and Their Mixtures
Authors: Sakurai Takao , Mikami Naoko , Yoshino Katsumi
Published: March 2014

Some ferroelectric properties, especially spontanious polarization directions and phase diagram of (R)-DOBA-1-MBC, (S) and (R)-DOBA-1-MPC and (S)-HDOBAMBC , have been examined. Relation between spontaneous polarization direction and molecular structure have been discussed.
Dependence of Switching and Memory Times of Optical Switching Element Utilizing Ferroelectric Liquid Crystals on Thickness of Cell and Material
Authors: Yoshino Katsumi , Ozaki Masanori , Sakurai Takao , Honma Masao
Published: March 2014

Switching times rise time, decay time and memory time, of various electro-optic effects in ferroelectric liquid crystals are found to be strongly dependent on the molecular structure, cell thickness and temperatures. Especially in TSM (transient scattering mode) operation, the rise time becomes shorter in liquid crystals with larger spontaneous polarization, at high temperatures and in thinner cell. The decay time is also shorter at higher temperatures, in thinner cells and also in materials with higher relaxation frequency of dielectric constant.
Electrical Properties of PbTiO3 Thin Films by Thermal Decomposition of Organometallic Compounds
Authors: Ariizumi Akira , Kawamura Kiyoshi , Kikuchi Ichiro , Kato Iwao
Published: March 2014

PbTiO3 thin films were deposited by thermal decomposition of organometallic compounds and their electrical properties were studied. The dielectric constant of these films was estimated to be about 200. D–E hysteresis loops were observed in the films deposited on Pt plates. Remanent polarization and coersive force were about 37µC/cm2 and 130 kV/cm, respectively. Measured pyroelectric coefficient (dPr/dT) after applying a field of 150 kV/cm was 1×10-8 C·cm-2·K-1.
Exoelectron Emission Accompanying Phase Changes in Age-Hardenable Aluminium Alloys
Authors: Górecki Tadeusz , Górecki Czesław
Published: March 2014

Results of previously performed investigations of exoelectron emission accompanying the structural transformations in age-hardenable aluminium alloys as well as the results of our own experiments demonstrate the feasibility to exploit the exoelectron emission technique for programming and monitoring the ageing and reversion procedures for these alloys.
Development of Low Temperature Exoemission (EEE) Studies in Poland
Authors: Sujak Bodgan
Published: March 2014

A review is given of the development of low temperature EEE studis in Poland. Basic difficulties associated with this type of research are discussed. Important types of cryostats are discussed. A nearly complete list of references concerning Polish workers is attached.
PSEE-Related Phenomena Indicative of the Meaning of Two-Process Model Parameters for Mechanically Deformed Aluminum
Authors: Shigekawa Hidemi , Fujiwara Yuichiro , Ando Yuji , Kumagai Akiko , Hyodo Shin-ichi
Published: March 2014

In order to examine the physical meaning of the parameters involved in the two-process model previously proposed by the authors, the following experimental studies were conducted for scratched Al specimens. (1) It was found that the statistical fluctuation in the PSEE yield obeys a Poisson distrubution. This indicates that not only the exo-emission process but also the process of reactivating inactive emission sources should be regarded as a stochastic process. (2) The rate of exo-activation was found to be insensitive to specimen temperatures between 100 and 300 K, and to agree well with the theoretical value obtained from a simple tunneling model. (3) Abrasion did not affect the frequency of the photoluminescence at peaks which were observed at 2.6, 3.0, 3.8 and 4.8 eV. The peak intensity, however, increased after abrasion and then gradually decreased. This is similar to the intensity change in a PSEE yield.
Thermally Stimulated Exoelectron Emission and Thermoluminescence of Alpha Alumina Single Crystals
Authors: Lee Choon Ho , Kim Byung Ho , Du Ha Yung
Published: March 2014

The TSEE and TL from Al2O3 single crystals, subjected to X-ray and UV irradiation in a vacuum, were studied. Four TSEE and PL peaks were observed after X-ray irradiation. For UV excitation, two peaks were observed in a TSEE glow curve and only one prominant peak for TL. TSEE and TL glow curves for Al2O3 showed much similarity regarding the position of peaks and temperature shifts, regardless of the type of excitation. Thus, there is a close relation between TSEE and TL mechanism concerning Al2O3 single crystals.
TSEE from Some Copper Alloys
Authors: Shimada Hisashi , Nakajima Kohichi
Published: March 2014

TSEE from Cu-primary solid solutions which were abrabed was measured using a GM counter. The glow curve of a Cu solution involving Zn or Al could hardly be observed after one heating. This result indicates that the alloy surfaces were covered with a ZnO or Al2O3 film. The formation of a ZnO or Al2O3 film was due to a displacement reaction during the oxidations of the alloy surface. This lead to an enhancement of the solute atom concentration on the oxide surface. The oxygen concentration change with the solute content in Cu–Zn and Cu–Al could be interpreted in terms of the starting temperatures and activation energies determined from the glow curves. The TSEE of Cu–Ni and Cu–Ge had similar profiles and developed within the temperature range of the pure Cu glow curve.
Exoion Emission from Various Types of Corroded Steel
Authors: Krylova I. V. , Lunin E. V.
Published: March 2014

Various types of maraging Ni-alloyed stainless steel were subjected to prolonged corrosion tests in a sodium chloride solution and resulting exoion emissions were studied. Both the behavior of the emission intensity versus time and the glow curve of thermostimulated (negative) ion emission were found to vary remarkably for the specimens which differed in the concentration of retained austenite. With the aid of Auger electron spectroscopy, oxide layers of the specimen surfaces were analyzed for a depth of up to about 700 Å. It was concluded that oxygen which penetrates into the surface oxide or an hydroxide film in the form of either O-, O2- or OH- might be responsible for the activity of exoion emission from various types of steel subjected to corrosion tests.
On the Mechanisms of Exoelectron Emission from Alkali Halides X-Irradiated at Low Temperatures
Authors: Kamada Masao , Tsutsumi Kenjiro
Published: March 2014

A collective report is given on the recent studies of the energy spectra of thermally stimulated exoelectrons from alkali halides irradiated with X-rays at 77 K. To obtain significant information regarding the exoelectron emission mechanism, the energy spectra and the surface potential were simultaneously measured in a clean high vacuum. On the basis of an identification of the origin of exoelectrons, the observed energy spectra are compared with previously proposed exoelectron emission models. It is stressed that the space charge and the patch field play important roles in the transport and escape processes of exoelectrons after they are released from color centers through thermal or Auger process.
Thermostimulated Exoelectron Emission from Oxide Monocrystals in UHV
Authors: Vorst W. Maenhout-Van der
Published: March 2014

Thermostimulated exoelectron emission (TSEE) from different oxide single crystals, such as Al2O3, TiO2 and ZnO, is described. After X-ray excitation in ultra high vacuum (UHV) at room temperature, the crystals were warmed through a linear process. The influence of the storage time in UHV along with the pretreatment of specimens in pure dry oxygen and oxygen saturated with water vapor was observed. The reproducibility of the intensity of the TSEE peaks of Al2O3, TiO2 in an UHV was very good. The influence of adsorption species was very low and the surfaces recovered after a certain digestion time. This did not seem to be the case for ZnO single crystals.
Exoelectron Emission of Na2CO3 in Vacuum
Authors: Bonev Boncho
Published: March 2014

The exoemission of some carbonates appeared in the air after the intensive processing of a negative crown discharge. It was established that some induction is a necessary condition for obtaining the decay of exoelectron emission (EE) and thermostimulated exoelectron emission (TSEE).
The experiments were carried out with Na2CO3 in a vacuum at a pressure of 2.7×10-3 Pa and showed a great difference in the appearance and character of the exoemission.
Dislocation Climb Rate and Activation Energy of Relaxation Processes in Dislocations at Temperatures ca. 100 K.
Authors: Duś-Sitek M. , Olszowski Z. , Sujak B.
Published: March 2014

On the basis of the data obtained during experiments regarding the kinetics of EEE phenomenon from metals deformed at low temperatures (T
d∼100 K), a hypothesis concerning the dislocation mechanism of vacancies transported by dislocation climbing and its rate was confirmed. The relaxation times of energy-dissipation processes at dislocation were determined. Also the possibility of determining the vacancy bonding energy in a Cottrell atmosphere was demonstrated.
TSEE from MgO Single Crystals Introduced by Cleaving
Authors: Seiyama T. , Kawabata K. , Okuda S.
Published: March 2014

TSEE from MgO single crystals, undoped (3-nine and 4-nine purities) and doped with titanium (240 ppm), was observed after cleaving without any other excitation. The TSEE peaks were at 110, 180, 210, and 330°C, except crystals with a 4-nine purity. These showed only 110 and 330°C peaks. The peak intensity at 110°C decayed to one half the initial value after the sample was kept at room temperature for about an hour. (The initial value was determined several minutes after cleaving.) An analysis of this decay process shows 2nd-order kinetics. Intense MgO:Ti (240 ppm) TSEE was observed at temperatures of 180, 210, and 330°C.
Two-Process Model for a Comprehensive Interpretation of Photostimulated Exoelectron Emission
Authors: Shigekawa Hidemi , Hyodo Shin-ichi
Published: March 2014

In order to explain several PSEE time-related phenomena regarding scaratched metals, the authors have proposed a reaction-kinetic model (the Two-Process model), in which particular attention is given to activating inactivated emission sources. On the basis of this model the authors have succeeded in elucidating such PSEE phenomena (mostly observed for scratched aluminum) as a storage effect, the relation between the peak intensity and the ambient pressure, and the dependence of the intensity on the stimulation intensty. In a discussion regarding the parameters involved in the model it is suggested that glow curves produce useful information about the PSEE emission mechanism as well as TSEE measurements.
TSEE from Surfaces of LiF and CaF2 Crystals
Authors: Aoki Masayoshi , Okabe Shigeru , Nishikawa Tsuguo
Published: March 2014

The TSEE glow peaks from a LiF crystal after being exposed to ionizing radiation were observed at 125, 180 and 230°C with a Q-gas flow counter. For irradiation with X-rays (20 R), the TSEE glow peak at 125°C was more dominant than the other peaks. We found that the 125°C peaks for the (110) and (111) surfaces were more intense than for the (100) cleaved surface. When methane was used as a counting gas, the glow peak of the (100) surface at 125°C was weaker than for the case of Q-gas, and the ratio of these intensities was less than one tenth.
The TSEE glow peaks from a CaF2 crystal were observed at 85, 180 and 270°C after X-ray excitation. The TSEE intensity at 85°C for CaF2 cleaved surfaces showed almost the same tendency as for LiF with regard to the effects of crystal orientation.
Efficiencies of TSEE Excited by Various Types of Ionizing Radiation
Authors: Okabe Shigeru , Aoki Masayoshi , Nishikawa Tsuguo
Published: March 2014

The efficiency of thermally stimulated exoelectron emission (TSEE) was studied for the surfaces of exoelectron materials excited by α, β and γ-rays. The measured efficiencies correspond reasonably well with the mean dE/dx of a surface thin layer. There remain problems regarding the counting efficiency of the 2π flow counter system and the number of the missing exoelectrons that escaped before a measurement. Regarding the β-ray excited group, it can be concluded that the origin of the observed exoelectrons was in a thin surface layer with a thickness of several hundred angstroms and that the contribution of the bulk origin was negligible.