New amorphous nanophosphors obtained by evaporation of silicates and germanates REE

Abstract

Amorphous nanophosphors have been produced by pulsed electron beam evaporation of bulk phosphors of rare earth elements (REE) silicates and germanates with oxyapatite structure activated with europium. The processes of crystallization of amorphous nanopowders (NP) have been studied by differential scanning calorimetry and thermogravimetry (40-1400°C) methods. A modification of the Raman and IR spectra of the samples was found when the particle size decreased from bulk to nanostate due to insignificant polymerization of Si(Ge)O4 tetrahedra. The spectral and luminescence characteristics of the bulk samples as well as nanoamorphous samples have been examined. It was established that Eu3+ forms two types of optical centers. Upon the transition of Sr2Gd8(SiO4)6O2:Eu3+ phosphor from bulk state to nanostate during laser excitation, the luminescence intensity of Eu3+ ions increases 10 times. Blue and white amorphous nanophosphors have been obtained for the first time by evaporation of Ca2M8(SiO4)6O2:Eu (M=Y, Gd) and Ca2La8(GeO4)O2:Eu phosphors. Radiation reduction of ions Eu3+→Eu2+ in electron beam has been presumably found. © 2017 IUPAC & De Gruyter.