Eu-doped pollucite CsAlSi₂O₆ was synthesized by the sol–gel method and heated in an air atmosphere. The crystal structure and the microstructure of the phosphors were investigated by X-ray powder diffraction and SEM images, respectively. The photoluminescence spectra and temperature dependent decay curves were measured. An abnormal reduction phenomenon of Eu³⁺ → Eu²⁺ was reported when Eu³⁺ ions were doped in alkaline metal cation sites in CsAlSi₂O₆ prepared in an oxidizing atmosphere. The abnormal mechanism was discussed on the basis of the charge compensation model and a rigid three-dimensional framework structure of CsAlSi₂O₆. The luminescence color centers were investigated by luminescence decay lifetimes and thermal stabilities of Eu²⁺ ions. The defect complexes of [(Eu³⁺_Cs)^••–2V_Cs′] or [(Eu³⁺_Cs)^••–O_i″] induced by the substitution of Eu³⁺ on Cs⁺ were suggested in the lattices. Eu²⁺ ions could be regarded as Eu³⁺ ions combining with the released electrons from defects O_i″ or V_Cs′ in close vicinity of Eu³⁺ (Eu³⁺ + e); the electrons cannot enter the atom track of Eu²⁺ presenting luminescence of Eu²⁺ ions. The results indicate that several defect traps can be attributed to the abnormal reduction mechanism of Eu³⁺ to Eu²⁺ ions in a matrix.

Publications with shared reference:

0 publications found