Preparation of divalent rare earth ions in air by aliovalent substitution and spectroscopic properties of Ln 2+

Abstract

When alkaline earth ions in borates, phosphates or borophosphates [SrB 4O 7, SrB 6O 10, BaB 8O 13, MBPO 5 (M=Ca,Sr)] are substituted partially and aliovalently by trivalent rare earth ions such as Sm 3+, Eu 3+, these rare earth ions can be reduced to divalent state by the produced negative charge vacancy V M″. The matrices must have appropriate structure containing a rigid three-dimensional network of tetragonal AO 4 groups (A=B,P). These groups can surround and isolate the produced divalent RE 2+ ions from the reaction with oxygen. Therefore, this reduction reaction can be carried out even in air at high temperature. The produced divalent rare earth ions can be detected by luminescence and XANES methods and their spectroscopic properties are discussed.