O. E. Fesenko

The structural phase transitions in lead zirconate in super-high electric fields

The paper describes the E, T phase diagram of lead zirconate in electric fields up to 1,400 kV/cm.

Crystal structure of the electric-fieldinduced ferroelectric phase of NaNbO3

The structure of electric-field-induced ferroelectric phase of NaNbO3 has been studied by means of X-ray diffraction method. Crystal cell is orthorhombic (P21 ma) with parameters: a = 5.569. b = 7.790, c = 5.518 A, V = 239.38 A3, Z = 4. Field-induced phase transition mainly results in reversal of atomic shift directions relative to the cubic perovskite atomic positions in one half of initial orthorhombic cell. Increasing of NbO6 octahedra tilts and additional displacements of some oxygen atoms are accounted for electric field effect.

Optic and dielectric study of lead zirconate crystals

The paper describes twinning of PbZrO3 crystals and their behaviour in the orthorhombic phase under external stress and field.

Phase T,E-diagram of barium titanate

Abstract The T,E-diagram of three ferroelectric phases of BaTiO3 crystals in the temperature range from 0°C to −170°C has been experimentally determined up to 600 kV/cm.

Mechanical stresses and three-phase states in perovskite-type ferroelectrics

Abstract A crystallographic theory has been proposed that takes into account an elastic matching of the polydomain (twinned) phases and allows to predict an evolution and interchange of three phases in perovskite-type ferroelectric single crystals. A diagram connecting these phases with the possible domain structures and their reconstruction has been discussed.

Growth of PbZr1-xSnxO3 single crystals and their phase T,x-diagram

Abstract Single crystals of PbZr1-xSnxO3 have been grown and their phase T,x-diagram have been drawn.

Phase transitions and twinning in NaNbO3 crystals

An improved version of the electric field (E)-temperature (T) phase diagram of NaNbO3 crystals is presented. Field-induced phase transitions are considered for crystals with different types of twinning.

Phase transitions induced in NaNbO3 crystals by varying the direction of an external electric field

The anisotropic behavior of the electrostatic field characterizing the phase transition from an antiferroelectric state to a ferroelectric state is studied for the first time with NaNbO3 as an example. Structural changes taking place in the crystal as the direction of the electrostatic field is varied are studied and electrostatic field magnitude-direction phase diagrams are determined.

Nonlinear properties of barium titanate in the electric field range 0≤E≤5.5×07 V/m

X-ray structural studies and dielectric measurements of BaTiO3 single crystals were performed in the dc electric field range 0≤E≤5.5×107 V/m. The field dependence of the tetragonal cell parameter obtained was used to calculate the field dependence of the piezoelectric modulus d33. The piezoelectric modulus d33 and the dielectric permittivity vary in magnitude by a factor of two with the field varied in the above range. The observed nonlinear behavior is shown to fit well to a relation connecting the dielectric with the electromechanical characteristics of the crystal.

An x-ray diffraction and EXAFS study of the electric-field-induced ferroelectric phase

A structural study of a electric-field-induced ferroelectric phase has been performed using single-crystal x-ray diffraction and EXAFS techniques. The polar axis was found to be orthogonal to the direction of atomic displacements in the initial antiferroelectric phase. The ferroelectric properties of the phase are due to a Pb displacement of about 0.17 A relative to the oxygen framework along the polar axis. The Zr atoms are disordered between two symmetry-related positions and shifted mainly orthogonally to the polar axis. The results obtained by the two methods of crystal structure investigation are in good agreement.