E. G. Fesenko

Domain structure of multiaxial ferroelectric crystals

Abstract It has been shown and exemplified by model crystals, that domain structure is a consequence of the mechanical, electrical and thermal effects occurring in a two-phase (paraelectric/ferroelectric) crystal. General rules that goven domain structure formation have been formulated.

Phase transitions and electric properties of Pb2InNbO6 and Pb2ScNbO6 crystals with differing degree of ion ordering in the sites of the crystalline lattice

Abstract The effects of the compositional ordering on the properties of Pb2ScNbO6 and Pb2InNbO6(PIN) crystals were studied. For PIN an order-disorder transition temperature of 1010°C is yielded.

Composition-structure-properties dependences in solid solutions on the basis of lead-zirconate-titanate and sodium niobate

Abstract The regularities relating electrophysical and structural parameters of solid solutions on the basis of lead-zirconatetitanate and sodium niobate are considered. An important structural peculiarity of these systems is a morphotropic region (MR)-region of morphotropic phase transition between tetragonal and rhombohedral (rhombic) phases. Understanding of the considered regularities makes easier the prediction of piezoceramic composition with the given properties for different applications.

Rendering barium titanate semiconductive by doping with rareearth elements

Abstract Distribution of doping cations between A and B sites of perovskite ABO3 structure obeys certain conditions derived in terms of energy. These can be applied to predict semiconducting BaTiO3-based compositions, to account for yet unexplained anomalies in concentrational dependencies of electrical resistivity and Curie temperature, and to understand the relatively unimportant effect of doping in the case of solid solutions such as Ba1−x Sr x TiO3 and Ba1−x Ca x TiO3.

On problems of search for novel Bi-containing layered perovskite-like high-Tc ferroelectrics

A crystallochemical analysis of structural parameters of Bi-containing layered perovskite-like oxides (BLPO) of the type Am-1Bi2BmO3m + 3 is given. The morphotropic series, the technique of calculations of unit cell parameters and existence conditions are considered for the first time.

Different kinetic types of phase transformation in lead titanate

Abstract The kinetic features of plane phase-boundary movement in lead titanate crystals were studied. The dependence of the average velocity of the interface motion on cooling rate, ranging from 0. 02 to 1. 2°C. S-1 fit exponential function with the exponent α < 1. A cinematography of the phase transition process allowed to establish that the interface motion is jerky and consists of alternating motions and stops. The jerky character of interface motion is considered to be connected with the non-uniformity of the interphase dislocation movement. It was experimentally found that the kinetics of the new phase growth in PbTiO3 crystals alternates from the thermally activated to the martensitic kinetics. The effect of various peculiarities of phase transition on the domain structure of PbTiO3 crystals is discussed.

Photoelectric phenomena in single crystals of some perovskite oxides

Photoconductivity (PQ and thermally stimulated conductivity (TSC) were investigated on some single-crystal perovskite oxides. Using PC spectral dependence, band gap and impurity-level depths were found. The TSC method gave further information about the energy spectrum of local levels. Due to a significant PC and deep local levels, a photoelectret state was achieved in crystals of some compounds. Illumination of lead titanate crystals by light from the intrinsic photoconductivity region was found to induce screening of spontaneous polarization by non-equilibrium carriers.

Phase transition behavior in the morphotropic region of(x)pbtio3−(0. 98−x)Pbzro3−0. 02 (PbWO.5Cdo. 5O3

Abstract A relation between structural and electrophysical properties of (x)PbTiO3− (0.98−x) PbZrO3−0, 02 (PbWo.5Cdo.5O3) solid solution system is examined. It is found that the extent of phase transition diffuseness in the morphotropic region depends on the spontaneous deformations, phase compositions and relative unit cell volumes of the tetragonal and rhombohedral phases. The diffuseness of the phase transitions is largely determined by severity of residual local stresses at domain boundaries.

The switching of PbTiO3 crystals

Abstract The interrelation is ascertained between the character of 180° switching in PbTiO3 single crystals and the type of dependencies in pulsed fields.

Heteroepitaxial films of (Ba,Sr)TiO3

Abstract Experimental data about certain peculiarities of ferroelectric phase transition revealed by the temperature dependences of unit cell parameters and domain structure specificity are presented.