Localization of electrons in LaCuO3- deltaand BaPb0.75Bi0.25O3- delta

Abstract

Changes are considered in the electronic spectrum of crystals caused by their elongation and expansion. Situations are examined when, owing to crystal deformation, the electrons are localized in alternate planes or alternate atomic sublattices. It has been shown that in both cases forbidden gaps may, under certain conditions, arise in the electronic spectrum. The results of the work are discussed in the light of experiments in which it has been found that the increase of delta in LaCuO_{3- delta} and BaPb_0.75Bi_0.25O_{3- delta} leads to the metal-semiconductor transition.