I. A. Sluchinskaya

Direct evidence for off-centering of Mn impurity in SrTiO3

Mn-doped SrTiO3 samples (3% Mn) with different deviations from stoichiometry have been investigated using XAFS spectroscopy. It was shown the under various preparation conditions manganese atoms can sub-stitute A and B sites of the perovskite structure and are in them in different charge states. Impurity Mn4+ ions that substitute Ti sites occupy on-center position in the lattice, whereas Mn2+ ions that substitute Sr sites are off-center and are displaced from the lattice sites by a distance of 0.32Å.

Ferroelectric phase transitions in IV-VI semiconductors associated with off-center ions

Abstract New ferroelectric phase transitions were found in ternary and quaternary solid solutions of IV-VI semiconductors. Their analysis shows that offcenter ions play important role in the appearance of ferroelectricity in these crystals.

Low-temperature phase transitions in some quaternary solid solutions of IV-VI semiconductors

Abstract Samples of PbS x Se y Te 1- x - y , Pb 1- x Sn x Te 1- y Se y and Pb 1- x Sn x Te 1- y S y quaternary solid solutions were investigated in the 4–200 K temperature range using electrical and X-ray methods. The regions where low-temperature phase transitions take place were established. It is shown that phase transitions in these solid solutions are associated with off-center S and Sn ions. The dependence of the phase transition temperature on the composition of solid solutions can be qualitatively described taking into account the influence of substitutional disorder on ordering and tunneling of off-center ions.

Structural instability in BaZrO3 crystals: Calculations and experiment

Phonon spectrum of cubic barium zirconate is calculated from first principles using the density functional theory. Unstable phonon mode with the

Crystal structure, local structure, and defect structure of Pr-doped SrTiO3

R_{25}

Structural position and charge state of nickel in SrTiO 3

symmetry in the phonon spectrum indicates an instability of the cubic structure with respect to rotations of the oxygen octahedra. It is shown that the ground-state structure of the crystal is

XAFS Studies of the Local Environment of Pb Impurity Atoms in Barium, Strontium, and Calcium Titanates

I4/mcm

EXAFS studies of the local environment of lead and selenium atoms in PbTe1−xSex solid solutions

. In order to find the manifestations of the predicted instability, EXAFS measurements at the Ba

Structural position and oxidation state of nickel in SrTiO3

L_{\rm III}

XAFS studies of the local structure and charge state of the Pr impurity in SrTiO3

-edge are used to study the local structure of BaZrO