Showing papers in "Ferroelectrics Letters Section in 1986"
TL;DR: Flexible piezoelectric composites made from PZT and polymer with 0-0-3 connectivity were fabricated using several types of Eccogel polymer in this paper.
Abstract: Flexible piezoelectric composites made from PZT and polymer with 0–0–3 connectivity were fabricated using several types of Eccogel polymer. The conductivity of the composite is controlled by adding small amounts of a semiconductor filler such as carbon, germanium or silicon. By controlling conductivity, poling can be carried out very rapidly at low voltages, resulting in properties comparable to composites prepared without a conductive phase. For composites optimized for hydrophone performance, the hydrostatic voltage coefficient [gbar]h and hydrostatic figure of merit [gbar]h[dbar]h are an order of magnitude larger than those of single phase PZT.
109 citations
TL;DR: In this article, the Raman spectra of bismuth sodium titanate in its rhombohedral, tetragonal, and cubic phases were measured, with special attention paid to the phase transitions at 584K and 837K (heating).
Abstract: We have measured the Raman spectra of bismuth sodium titanate in its rhombohedral, tetragonal, and cubic phases, with special attention paid to the phase transitions at 584K and 837K (heating). Both transitions appear to be order-disorder and strongly first order, with large thermal hysteresis. The phonon spectra at temperature slightly below the tetragonal phase are remarkably similar to BaTiO3 with A1(To) modes at 130, 269, and 541 cm−1 (compared with 170, 270, 520 cm−1 in BaTiO3) and an E(TO) at 52 cm−1.
100 citations
TL;DR: In this paper, the ferroelectric first order phase transition at 367 K has been discovered in TMACA crystals, which is presumably related to a motion of trimethylammonium cations.
Abstract: The ferroelectric first order phase transition at 367 K has been discovered in TMACA crystals, which is presumably related to a motion of trimethylammonium cations.
64 citations
TL;DR: An ester-type ferroelectric chiral liquid crystal has been studied in thin cells using a modified Diamant-bridge method, and spontaneous polarization has been measured as a function of temperature as discussed by the authors.
Abstract: An ester-type ferroelectric chiral smectic liquid crystal has been studied in thin cells. Using a modified Diamant-bridge method the spontaneous polarization has been measured as a function of temperature. In the same set-up the smectic tilt angle is determined optically, and electro-optical characteristics are measured. Moreover, the dielectric anisotropy is accessible by achieving two orthogonal smectic layer orientations in the measuring cell.
40 citations
TL;DR: In this article, the coercive field of KNO3 films 75 to 400nm thick is found to satisfy the empirical relation EC ∼d −1.3, where d is the thickness, in agreement with earlier work on BaTiO3 by Stadler and on TGS by Hadni et al.
Abstract: The coercive field of KNO3 films 75 to 400nm thick is found to satisfy the empirical relation EC ∼d −1.3, where d is the thickness, in agreement with earlier work on BaTiO3 by Stadler and on TGS by Hadni et al. The switching times for large area devices (20Ox200μm) vary as E−1.5 in agreement with early work on BaTiO3 by Stadler and Zachmanidis, and indicate that the limiting parameter is the velocity of domain growth perpendicular t o the applied field.
22 citations
TL;DR: In this article, the first experimental data of the temperature dependence of e′c and e″c for Rb1−x (NH4)x H2AsO4 was presented.
Abstract: We have presented the first experimental data of the temperature dependence of e′c and e″c for Rb1−x (NH4)x H2AsO4. The results are demonstrated by the presence of a glassy state in Rb1−x (NH4)x H2AsO4 for x = 0.31.
20 citations
TL;DR: In this article, specific heat capacity, thermal conductivity and complex dielectric constant of BaTiO3 ceramic have been measured to temperatures as low as 0.1 K. No influence of an applied electric field on specific heat o r thermal conductivities has been detected.
Abstract: Specific heat capacity, thermal conductivity and complex dielectric constant of BaTiO3 ceramic have been measured to temperatures as low as 0.1 K. No influence of an applied electric field on specific heat o r thermal conductivity has been detected. After removing of an applied static electric field a logarithmic time dependence of the dielectric constant has been observed.
12 citations
TL;DR: In this paper, a microscopic model for the mixed crystal Rb1−x(NH4)xH2PO4 is introduced which takes into account the acid protons as well as the NH4 groups.
Abstract: A microscopic model for the mixed crystal Rb1−x(NH4)xH2PO4 is introduced which takes into account the acid protons as well as the NH4 groups. Using Monte Carlo simulation, the topology of the experimentally determined phase diagram is reproduced rather well, including the onset of freezing into a glasslike state.
10 citations
TL;DR: In this article, the anomaly of LiNbO3 in the vicinity of 75°C has been studied by various X-ray diffraction methods and an abrupt change of axial ratio (c/a) was measured.
Abstract: The anomaly of LiNbO3 in the vicinity of 75°C has been studied by various X-ray diffraction methods. An abrupt change of axial ratio (c/a) was measured. Internal friction peak associated with this change shows characteristic of first order phase transition. A step-like change in all elastic constant Cij occurs near 75°C.
9 citations
TL;DR: In this paper, the dc conductivity of NaKSO4 crystal was investigated along various crystallographic axes in the temperature range from 300 to 500 K and two segments were observed in temperature dependence of electric conductivity at Tc=453 K.
Abstract: The dc conductivity of NaKSO4 crystal is investigated, along various crystallographic axes in the temperature range from 300 to 500 K Two segments are observe in the temperature dependence of electric conductivity at Tc=453 K The spontaneous strain η1s, η2s and η3s, deduced from measurements of the linear thermal expansion coefficients along various crystallographic axes a, b and c showed linear temperature dependence below the transition temperature
9 citations
TL;DR: The dielectric constant of PZT ceramics modified with 0.3 weight % MnO2 was determined in dependence of temperature and frequency, Similar as in the case of plain PZTs and of a technical composition (NSM) containing a ternary component and the same Mn concentration, only one dispersion region was found at room temperature with the relaxation frequency being independent of the [Ti]:[Zr] ratio.
Abstract: The dielectric constant (DC) of PZT ceramics modified with 0.3 weight % MnO2 was determined in dependence of temperature and frequency, Similar as in the case of plain PZT and of a technical composition (NSM) containing a ternary component and the same Mn concentration, only one dispersion region was found at room temperature with the relaxation frequency fr being independent of the [Ti]:[Zr] ratio, but as in the case of NSM one order of magnitude higher than measured in plain PZT.
TL;DR: Ferroelastic and ferroelectric domain structure in lithium ammonium sulphate and its deuterated analogue are observed with the scanning electron microscope in this article, where samples are cut perpendicularly to the three main crystallographic directions.
Abstract: Ferroelastic and ferroelectric domain structure in lithium ammonium sulphate and its deuterated analogue are observed with the scanning electron microscope. Samples are cutted perpendicularly to the three main crystallographic directions. The pictures of all these faces in ferroelectric and ferroelastic phases are presented.
TL;DR: In this paper, the I4N and 170 quadrupole couplings in diglycine nitrate have been determined by proton 14N and proton 170 double resonance.
Abstract: The I4N and 170 quadrupole couplings in diglycine nitrate have been determined by proton- 14N and proton-170 double resonance. The O─H──O bonded proton is moving between two off-centre sites in the H─bond above TC and is frozen out in an off-centre site below TC. The results show that the basic phase transition mechanism is a biasing of the flipping of the ─NH3 groups around the C─N bondbetween two equilibrium orientations separated by ∼ 60° connected with a corresponding rotation of the NO3 −; ions, an exchange of the ionic character of the two glycine molecules and a transfer of the O─H──O bonded proton.
TL;DR: In this paper, precise dielectric measurements of NH4HSeO4 were performed in vicinity of phase transition at 250 K. The existence of the thermal hysteresis of dielectrics permittivity, typical for incomensurate-commensurate phase transition was found.
Abstract: The precise dielectric measurements of NH4HSeO4 were performed in vicinity of phase transition at 250 K. The existence of the thermal hysteresis of dielectric permittivity, typical for incomensurate-commensurate phase transition was found.
TL;DR: Amorphous lead titanate powder was prepared using a sol-gel process and the powder was fired to temperatures ranging from 500°C to 1200°C and soaked for various lengths of time.
Abstract: Amorphous lead titanate powder was prepared using a sol-gel process. The powder was fired to temperatures ranging from 500°C to 1200°C and soaked for various lengths of time. X-ray diffraction confirmed that the fired powders were tetragonal PbTiO3. Surface area measurements indicated that the specific surface area of the powder decreased with increasing heat treatment. The powders were mixed with Eccogel polymer to make composites in which the ceramic phase constituted 60 percent by volume. Piezoelectric coefficients were found to be greatest for those composites containing powder fired to 1100°C and soaked for 1 hour. The dhgh value obtained for this heat treatment was 540×10−15m2N−1.
TL;DR: In this paper, the ground state of the Cu2+ ion in C4V symmetry was found to be 2B1 from the g-values, and the octahedral and tetragonal field parameters and the spin-orbit reduction parameters were evaluated.
Abstract: EPR and optical absorption studies of Dioptase have been carried out at room and low temperatures. The observed, absorption bands have been attributed to Cu2+ ion in C4V symmetry. From the g-values, the ground state of Cu2+ is found to be 2B1. The octahedral and tetragonal field parameters and the spin-orbit reduction parameters have been evaluated. The NIR and IR spectra have also been reported.
TL;DR: Vibrational spectra of EuAsO4 crystal have been recorded at R.T. and discussed in this article, and optical absorption measurements of the crystal have also been reported.
Abstract: Vibrational spectra of EuAsO4 crystal have been recorded at R.T. and discussed. Optical absorption measurements of the crystal have also been reported.
TL;DR: In this article, a direct method for measuring the second harmonic of the nonlinear pyroelectric current is described, and it is shown that second order oscillations exist even for low and medium infrared radiation powers.
Abstract: A direct method for measuring the second harmonic of the nonlinear pyroelectric current is described. It is also shown that the second order oscillations of the nonlinear pyroelectric current exist even for low and medium infrared radiation powers.
TL;DR: In this paper, it was observed that thin 1-3 composites have thickness resonance frequencies ft lower than the original ceramic discs and ft decreases as the width of the PZT columns in the composite increases.
Abstract: It is observed that thin 1–3 composites have thickness resonance frequencies ft lower than the original ceramic discs and ft decreases as the width of the PZT columns in the composite increases. The characteristic acoustic impedance Z of thin composites are determined by the echo-shift and the resonant methods. No significant variation of Z w.r.t. frequency can be observed in the range from .5 MHz up to 7.5 MHz. Thinning tests movement of resonance peaks.
TL;DR: In this paper, solid solution crystals of Sb3+(Sbx 5+Nb1−x 5+)O4 (x=0-0126) were grown hydrothermally in the Sb2O3-Sb 2O5- Nb2 O5 -H2O-KH2F2-H 2O2 system by controlling the composition by means of the redox potential end the pH values.
Abstract: Solid solution crystals of Sb3+(Sbx 5+Nb1−x 5+)O4 (x=0–0126) were grown hydrothermally in the Sb2O3-Sb2O5- Nb2O5 -H2O-KH2F2-H2O2 system by controlling the composition by means of the redox potential end the pH values. An increase of x decreases the ferroelectric Curie temperatures.
TL;DR: In this paper, single crystals of Lithium Caesium Sulphate doped with Co2+ ions were grown by slow evaporation of an aqueous solution of lithium-cesium-sulphate and caesium sulfate to which Cobalt Sulphates is added as dopant.
Abstract: Single crystals of Lithium Caesium Sulphate doped with Co2+ ions were grown by slow evaporation of an aqueous solution of Lithium Sulphate and Caesium Sulphate to which Cobalt Sulphate is added as dopant. Electronic absorption spectra have been recorded at room and liquid nitrogen temperatures on Cary-17 Spectrophotometer. When the crystal is cooled to liquid nitrogen temperature changes in intensity and band position are observed and some of the bands are splitted. From the nature and position of the bands a successful interpretation of all the observed bands have been made and identified as those belonging to Co2+ ion in an octahedral crystal field. The crystal field parameters derived for room temperature are Dq = 870 cm−1, B = 900 cm−1 and C = 3150 cm−1 and for liquid nitrogen temperature are Dq = 880 cm−1, B = 900 cm−1, C = 3150 cm−1 and ζ = 500 cm−1.
TL;DR: In this paper, the non-linear dielectric properties in the paraelectric phase of γ-irradiated TGS crystal are studied and the temperature dependence of nonlinearity coefficient B is found.
Abstract: The non-linear dielectric properties in the paraelectric phase of γ-irradiated TGS crystal are studied. The temperature dependence of non-linearity coefficient B is found. It is claimed that the non-linearity depends on orientation of effective field with regard to bias field. It is also shown that the time dependence of e at dc field as well as the observed hysteresis of e(E) dependence can be explained assuming existence of the bias soft component.
TL;DR: In this paper, a model of diffused phase transition in terms of nucleation of polar regions within the original nonpolar phase is discussed and numerical estimations for the temperature dependences of the radius and the concentration of the nuclei as well as their contribution to the static dielectric constant.
Abstract: A model of diffused phase transition is discussed in terms of nucleation of polar regions within the original nonpolar phase Expressions are obtained for the temperature dependences of the radius and the concentration of the nuclei as well as their contribution to the static dielectric constant. Numerical estimations are carried out for PLZT 8/65/35 ceramic.
TL;DR: In this article, a large-displacement modulator was constructed from two thin pieces of PZT ferroelectric ceramic and an elliptic steel cylinder by utilizing the piezoelectric effect, vibrations were excited in the steel cylinder and the displacement was measured simultaneously.
Abstract: A new type of large-displacement modulator was constructed from two thin pieces of PZT ferroelectric ceramic and an elliptic steel cylinder. By utilizing the piezoelectric effect, vibrations were excited in the steel cylinder and the displacement was measured simultaneously. This modulator can produce a displacement larger than 0.65 mm which is two or three orders of magnitude larger than those of common piezoelectric devices. The non-parallelism of the vibrating plane is less than 0.1%. The working frequency is 420 Hz. The device is used in a far infrared Fabry-Perot interferometer for plasma diagnosis and it can be applied in other similar equipment.
TL;DR: In this paper, the dielectric constant (K) and loss (tanδ) of KNbO3 single crystals were measured E II a-axis as a function of frequency from 102 to 106 Hz and in the temperature range 30°-355°C.
Abstract: The dielectric constant (K) and loss (tanδ) of KNbO3 single crystals have been measured E II a-axis as a function of frequency from 102 to 106 Hz and in the temperature range 30°–355°C These measurements have also been taken after irradiating the crystals with X-rays or γ-rays K at 30°C for these crystals decreases with frequency reaching a constant value of 725 beyond 105Hz; tanδ, having moderately large values at low frequencies decreases with frequency X-ray irradiation is found to decrease the frequency-dependent K value of KNbO3 significantly but has practically no effect on its high frequency value Dielectric loss (tansδ) values, particularly at low frequencies, decrease appreciably on X-ray irradiation of these crystals X-ray Irradiation also reduces the peak K and tanδ values at 102 Hz at the curie temperature (225°C) but does not have effect on these parameters at 106 Hz γ-ray irradiation is found to bring about similar results; however the decrease in K and tanδ values are more pr
TL;DR: Ferroelectric phase transition was detected in monoclinic RbD2 PO4 at TC3 =313K and TC2 =319K in this paper, and the spontaneous polarisation is about Psy = 6.10−4 μC/cm2 at 280K.
Abstract: Ferroelectric phase transition was detected in monoclinic RbD2 PO4 at TC3 =313K in addition to the known antiferroelectric phase transition at TC2 =319K. The almost saturated value of the spontaneous polarisation is about Psy = 6.10−4 μC/cm2 at 280K.
TL;DR: In this paper, the direction of the polarization is alternately changed from plus to minus, and the experimental results of surface acoustic wave (SAW) excitation with this crystal are also described.
Abstract: This report discusses crystals with multi-domain layers in which the direction of the polarization is alternately changed from plus to minus. The experimental results of surface acoustic wave (SAW) excitation with this crystal are also described.
TL;DR: In this article, the optical absorption spectrum of Ni2+ ion in octahedral symmetry associated with spin-orbit coupling is recorded on CARY-14 spectrophotometer at laboratory and liquid nitrogen temperatures.
Abstract: Nickel doped single crystals of rubidium magnesium sulphate hexahydrate are grown by slow evaporation technique, The optical absorption spectrum is recorded on CARY-14 spectrophotometer at laboratory and liquid nitrogen temperatures. The spectrum is characteristic of Ni2+ ion in octahedral symmetry associated with spin-orbit coupling. The inter-electronic repulsion (B, C), crystal field (Dq) and spin-orbit (∊) parameters are evaluated.
TL;DR: In this paper, the fundamental absorption edge in TlInS2xSe2(1−x) solid solutions in the energy region hν = 1.8−3.0 eV at T=100−300 K including phase transition region has been investigated.
Abstract: The fundamental absorption edge in TlInS2xSe2(1−x) Solid solutions in the energy region hν = 1.8−3.0 eV at T=100−300 K including phase transition region has been investigated in present paper. Temperature behaviour of energy gap near the phase transition region has been analyzed.