ANOMALOUS OF STRUCTURE AND PHASE TRANSITION OF PEROVSKITES. N.Kulagin, TU Kharkov, pr. Pravda 7 - 87, 310022 Kharkov, Ukraine

This report deals with a new phenomena in ABO₃ single crystals: disappear of ESR signal during 1200 - 3600 s for some doped SrTiO₃ crystals under 105K, anomalous of optical data for other crystals [1]. We study spectral properties: optical, ESR, X-Ray shift and Raman scattering connected with defests of structure of perovskites. For definite crystals, doped by V, Cr, Mn and another 3d- ions with C= lO^-3 - lO^-2) wt % we registrated anomaly of optical and dielectric parameters. For some SrTiO₃ crystals we studied shift of T_c and so-called expansion phase trasition [2]. There are calculated the electronic structure of clusters of doped and regular ions and defects for perovskites [3].

1. N. Kulagin, V. Sandulenko, L. Korostel. Proc. VIII Int. Conf. Ferroelect. Maryland. 1993. 428

2. N. Kulagin, D. Sviridov. Methods of Electronic Structure Calculations. Moscow. Nauka. 1986.

3. N. Kulagin, D. Sviridov. Introduction to Doped Crystals Physics. Kharkov. 1990.