Strontium titanate:: valency of Ti+n and dielectrical properties of doped single crystals

This paper presents the results of a study of electronic structure, dielectric and spectral parameters of pure and doped strontium titanate single crystals under T = 10-300 K. The change of an electronic state of some part of Ti+4 ions into Ti+3 ones, formation of the clusters with Ti+3 and Me+3 ions is the basis of anomaly of separate properties of SrTiO3, crystals. Charge transfer, tunnelling current, and transition into new electronic state of the crystal may be causes of anomaly of the spectral properties, and temperature dependence of epsilon(0), and tan delta which are discussed in this paper. (C) 1999 Elsevier Science B.V. All rights reserved.