Crystallographic Features and Nature of Luminescence Centres of the Niobate and Tantalate Compounds with Layered Perovskite-Like Structure

Abstract

Aim and Objectives The ultrafine powders of the perovskite-like layered AII3LaM3O12 (AII = Sr, Ba; M = Nb, Ta) compounds have been synthesized by heat treatment of co-precipitated hydroxy-carbonates. The luminescence of these compounds is reported for the first time. Methods: Luminescence spectra of all studied compounds are complex and contain two main wide bands with maxima near 2.9 and 2.5 eV. These luminescence bands were assigned to radiation electron transitions in the MoO67- molecular groups of different symmetry located in the various lattice positions. Conclusion: The energy levels scheme of the MoO67- group and related radiation and absorption transitions had been proposed.