Abstract: Some of device applications of the Pb(Mg1/3Nb2/3)O3-based electrostrictors are reviewed, including displacement transducers for controlling optical pathlength (sensitive AC interferometer, bistable optical device and deformable mirror), and mechanical position actuators (micro-angle adjusting device and servovalve flapper for controlling oil pressure).

Abstract: Polyvinylidene Fluoride PVF2 presents a strong piezoelectric activity under specific conditions of crystallization and polarization. Studies of the ferroelectric polarization, of the physical and piezoelectric characteristics and of the behavior of PVF2 under dynamic pressure are of fundamental interest. The piezoelectric activity of PVF2 depends on the polarization process as it is presented in the studies of the hysteresis loops P(E) (P: polarization, E: electrical field). The remanent polarization attains 10 μC/cm2 for bi-axially stretched films from Rh˘ne Poulenc Films. Results obtained on uniaxial stretched films from Pennwalt Corporation are reported. Properties under static pressure are presented. Applications to ballistic transducers are described. The dynamic behavior of piezoelectric PVF2 under shock wave is surveyed. Study of shock loaded electric energy released from PVF2 films will be reported. Results with PVF2 transducers for weak or strong shock waves and applications of PVF2 to s...

Abstract: A series of random copolymers of vinylidene fluoride and trifluoroethylene containing 52, 65, 73, and 78 mol % VF2 has been shown by X-ray and dielectric techniques to undergo Curie transi...

Abstract: This paper surveys the temperature, microstructural and environmental variations of the fracture properties of ferroelectric ceramics. Earlier work shows that fracture toughness decreases on heating through the Curie temperature. There is also anomalous behavior in the strength at small crack sizes, indicative of a grain size effect. Further, the strength properties are known to be adversely affected by the presence of water in the atmosphere. Data from recent indentation studies on barium titanate are used to investigate these phenomena.

Abstract: Interconnected porous Pb (Zr0.53 Ti0.47)O3 ceramics, with controlled porosity up to 0.73, were prepared. The piezoelectric coefficient, 933, measured using a resonant method and a Berlincourt d33 meter increased as the porosity increased. The d33 and 933 of the porous PZT ceramic/ silicone rubber composite were almost the same as that of porous PZT.

Abstract: Piezoelectric compositions Pb(MnuNbvNiwTixZry)O3 where u+v+w+x+y = 1.0 were studied by means of X-ray powder diffractometry, scanning electron microscopy and thermal analytical techniques. These studies showed that Mn is incorporated into the tetragonal lattice as trivalent ions at the Ti, Zr octahedral (B) sites.

Abstract: There is no simple experimental method which allows the separation of the dielectric constant in contributions of the bulk and those of 90°-domain wall motions The contribution of the bulk is calculated in this paper for the specific domain configuration in large grains which was revealed by etch patterns The volume contribution is of the order of ervol ≈ 1000 whereas the measured values of er are about 1700 Thus the domain wall contribution is of the order of 40% The slight increase of e33 with poling is caused by volume effects Domain wall contributions, however, support this increase at low polarizations

Abstract: Monoclinic telluric acid ammonium phosphate (TAAP) is shown to be a new class m ferroelectric with a Curie temperature close to ambient (48°C). Emphasis is placed on dielectric and thermal properties, but some optical results are also reported. The material behaves closely like TGS and, from a practical point of view, could be useful in pyroelectric applications.

Abstract: Lanthanum modified lead titanate, (Pb0·775La0·15)TiO3 ceramics with a tetragonality of c/a = 1·024 were hot-pressed and the anisotropy of internal stress generated by applying a poling field were measured using a microindentation technique. In this specimen with a grain size of Gs=3·0 μm, the internal stresses in the directions perpendicular and parallel to the DC poling field were 151 and 35 MN/m2, respectively. The results are explained by the crack-extentional and compressive forces, respectively.

Abstract: A modified alanine doped triglycine sulphate (ATGS) crystal has been grown with partial substitution of H2SO4 with H3PO4. Growth of the ATGSP crystal from a unipolar ATGS seed in the temperature range 30-40°C gives a unipolar bulk crystal with lower permittivity (er ∼ 30) and higher pyroelectric coefficient (6.5·10-4 c/k.m2) than pure TGS. In the doping range used, the higher pyroelectric coefficient is traced to a significantly larger spontaneous polarization Ps (∼5 μc/cm2 at room temperature). Tangent δ is below 0.01 over the whole frequency range from 100 Hz to 100 KHz.

Abstract: The depolarization behavior of ordered and disordered lead scandium-tantalate (PST) ceramics has been studied by Byer-Roundy and Chynoweth method. A sharp decrease of the spontaneous polarization takes place in a narrow temperature range very close to the Curie temperature Tc for the ordered PST materials. For the disordered PST materials, however, the depolarization takes place within a wide temperature range much lower than the temperature of maximum dielectric constant Tm. Evidence of microdomain activities has been observed in disordered materials. The reversible pyroelectric effect is discussed in terms of the micro-macro transition of the domains in disordered PST materials.

Abstract: The temperature dependence of dielectric permittivities, shear moduli and internal friction of LiCsSO4 crystals were measured Large anomalies were found in G1 and G2 shear moduli and in the internal friction Q-1 for the samples in a and b directions, near the Curie point Tc = 202 K The temperature dependence of stress-strain hysteresis loops was also studied In the samples cut out along the a direction a single loop was found while in the b direction a double hysteresis loop was observed

Abstract: Piezoelectric PZT-polymer 1-3 and 1-3-0 composites were transversely reinforced with glass fibers to increase the hydrostatic piezoelectric coefficients for possible use in hydrophone applications Modeling of these composites theoretically showed that the dhgh figure of merit is a function of the volume fractions of PZT rods, glass fibers, and polymer porosity, and of the Poisson's ratio and compliance of the polymer matrix Experimental results showed significant enhancements of the dhgh figure of merit with the addition of glass fibers Comparisons of the theoretical predictions and the experimental results were made

Abstract: Hot-pressed ceramics in the PbZrO3-Pb2FeNbO6-PbTiO3 system have been shown to possess a combination of pyroelectric and dielectric properties which make them very suitable for use in pyroelectric infra-red detectors. The use of uranium as an off-valent dopant ion gives control of the electrical resistivity in the system and permits the elimination of high value gate bias resistors as discrete components. This paper discusses the mechanism by which conduction occurs in these ceramics. It is concluded from measurements of DC and AC conductivity that the uranium ions act as electron donors with conduction being via a hopping mechanism. The modelling of the AC conductivity and its use in describing device Johnson noise is discussed.

Abstract: This paper discusses some aspects of the physics of piezoelectric ceramics which depend considerably on the presence of mixed ferroelectric phases in these materials. The data which are available and problems which are yet to be studied may be divided into several categories. A more complete understanding of problems arising in some of these categories awaits growth of good quality single crystals of lead zirconate titanate (PZT).

Abstract: This paper reviews the recently described process of proton exchange in LiNbO3 and reports some current results. Only results directly applicable to integrated optics will be described, although other applications are possible, and much of the work is interesting from a more fundamental point of view.

Abstract: We summarize some of our recent measurements of the temperature dependence of the optic index of refraction, n(T), in several different classes of ferroelectrics. The common thread between these different materials is that in all of them the translational symmetry is strongly broken. Far above the usual ferroelectric transition temperature Tc up to a temperature Td, we show that the crystals possess a local, randomly oriented, nonreversible polarization. Using a simple model for this behavior, we can account for it qualitatively and in some systems quantitively understand Td. We believe this model contains the basic physical understanding of ferroelectrics that have a diffusive phase transition.

Abstract: An utilization of metal alkoxide is one of the high potential methods for preparing electroceramic powders. The advantage of powder preparation from metal alkoxides is that the ultrafine, monodispersive and compositionally homogenous powder is obtained easily by a simple hydrolysis reaction. Powder preparations from metal alkoxides are discussed in comparison with other conventional techniques.

Abstract: The electrical degradation of BaTiO3 of different Ba/Ti ratios and different grain sizes has been studied. TiO2 −rich compositions degrade more rapidly than stoichiometric or BaO-rich samples. Variation in grain size from 1–10 μm has no effect on the degradation rate of undoped BaTiO3 with Ba/Ti = 1.000.

Abstract: Sintering characteristics, dielectric properties, and electrostrictive Q12 coefficients are reported for fourteen dopant cations incorporated in the perovskite A(B', B′′)O3 structure of lead magnesium niobate [Pb(Mg1/3Nb2/3)O3]. Two trends in the dielectric properties were found: the maximum permittivity appears to be directly proportional to the transition temperature, and secondly, the percent change in capacitance at 20 kV/cm is proportionally larger for the higher permittivity samples. Two methods to estimate the frequency dependence of the diffuseness of the phase transition showed good correlation with each other, but revealed no general trend with ionic size or valence of the modifier cations. Electrostrictive Q12 coefficients were found to generally decrease with increasing diffuseness of the phase transitions.

Abstract: Piezoelectric ceramics are rather exactly specified for small signal applications by the linear elastic, dielectric and piezo electric coefficients. However, an unambiguous characterization of ceramics, which are to be operated at high mechanical or electric power level, cannot be given by these means. There is still an urgent need to improve the characterization of piezoelectric ceramics.

Abstract: Electromechanical and surface acoustic wave (SAW) properties of PbTiO3, ceramics modified by partial substitution of rare-earth for the Pb, specifically (Pb, Ln) (Ti, Mn)O3 (Ln=La, Ce, Pr, Nd, Sm, Eu, or Gd) ceramics, are extensively investigated. The SAW delay time temperature coefficient is found to be minimum when Ln=Nd. A zero temperature coefficient can be achieved in the (Pb, Nd) (Ti, In, Mn)O3 system with appropriate compositions. High frequency SAW filters are fabricated using these ceramics. It is also found that (Pb, Sm) (Ti, Mn)O3 ceramics have exceptionally large electromechanical anisotropy (ratio of electromechanical coupling factor for thickness vibration to that for planar vibration is above 15). A 7.5MHz linear array ultrasonic probe employing these ceramics is developed for medical use.

Abstract: The dynamics of ferroelectric phase transition of KH2PO4 (KDP) have been clarified by means of Raman scattering experiments. The locally and momentarily distorted PO4 tetrahedrons play the main role on the ferroelectric phase transition in KH2PO4. The broad mode below ∼150 cm-1 in x(yx)y spectrum above the transition temperature Tc and the corresponding sharp mode at about 150 cm-1 below Tc have been assigned to the libration modes of the PO4 tetrahedrons. From this result the very low frequency central component (≤20 cm-1) of x(yx)y Raman spectra at T≥Tc has been explained by the order-disorder dynamics of the distorted PO4 tetrahedrons. These results exclude the usual role of the proton dynamics on the KDP problem.

Abstract: Ferroelectricity as a cooperative phenomenon is strongly influenced by the structure of the material. In recent years we have come to understand most of the physical mechanisms involved. Thus we are now able to use this knowledge together with our technological experience and insight to develop tailor-made ceramics for special applications.

Abstract: The electrical properties of triglycine sulphate (TGS) single crystal plates are completely modified when the thickness is decreased down to 1 μm. The dielectric constant at the Curie temperature T0 is reduced by two orders of magnitude, coercive field is increased in the same ratio, and hysteresis loops are observed at several degrees above T0. Phenomenologically these observations can be explained in the frame of Devonshire's theory by assuming an internal electric bias Eb ≃ 1 MV/m for the thinnest plates.To explain such a high bias field we have been led to a tentative model with a surface layer where spontaneous polarization is smoothly decreasing from the bulk value PSB to a finite one PSB at the crystal surface. It is in this layer that a high polarizing field is calculated at room temperature. Its values may be slightly reduced when free charges of opposite sign are assumed to be injected by each electrode (Schottky barriers). These free charges will partially stay when temperature is raised above ...

Abstract: Croissance de monocristaux par recirculation de la solution dans un cristalliseur a deux recipients. Presentation de la morphologie et du maclage des monocristaux. Mise en evidence par attaque chimique des dislocations et domaines ferroelectriques

Abstract: This paper comprises three lectures given at the School on Acoustic Phonons in Varna, Bulgaria, from September 23 to October 2, 1982. Anomalous dispersion of sound velocities, both transverse (TA) and longitudinal (LA), is discussed for ferroelectric insulators near their incommensurate/commensurate phase-transition temperatures. In BaMnF4 the LA dispersion has characteristic time 10-10s and is attributed to amplitudons; the LA frequency behavior satisfies the defect theory of Hochli and Bruce. The TA dispersion has characteristic time 10-9s and is attributed to phasons. The anomalous temperature dependence of the pyroelectric coefficient near T1 in BaMnF4 reported by Negran is also discussed and related to specific-heat and sound-velocity behavior. Results are summarized for BaMnF4, Ba2NaNb5O15, NaNO2, SC(NH2)2, RbH3(SeO3)2, K2SeO4 and Rb2ZnCl4.

Abstract: Te(OH)6 2NH4H2PO4 (NH4)2HPO4 is monoclinic Pn with the following unit cell dimensions: a = 15.66(5), b = 6.314(5), c = 9.818(5) A, β = 105.49(5)°, Z = 2. The crystal structure has been solved and refined with a final R value .033 for 2531 independent reflections.As in all previously described examples of phosphate-tellurates the main feature of this atomic arrangement is the existence of two different kinds of anion groups TeO6 and PO4 in the unit cell.Crystal data for two isostructural compounds: Te(OH)6 2KH2PO4 K2HPO4 and Te(OH)6 2NH4H2AsO4 (NH4)2HAsO4 are given.

Abstract: Single crystals of Sr2KNb5O15 (SKN), approximately 5-8 mm in diameter and 10-20 mm long, have successfully been grown by the Czochralski technique. The crystal has a ferroelectric tetragonal tungsten bronze structure with a Curie temperature of about 150°C. The dielectric and electromechanical coupling constants for this crystal have been established: the polar axis dielectric constant, K33, exceeds 20,000 at the Curie temperature while the coupling constants are K33 = 0.52 and K31 = 0.19, respectively. High frequency dielectric properties of SKN samples were also determined between 90-100 GHz. These measurements indicate that the bulk of the polar axis permittivity has relaxed below 90 GHz, implying that the low frequency dielectric response is not soft-mode controlled.