Optical properties of Eu 2 (CO 3 ) 3 4H 2 O entrapped in silica sol gel glass

Abstract

Preparation of silica glasses containing Eu<SUB>2</SUB>(CO<SUB>3</SUB>)<SUB>3</SUB> 4H<SUB>2</SUB>O by means of sol-gel technology was described. The absorption, emission, and excitation of Eu<SUB>2</SUB>(CO<SUB>3</SUB>)<SUB>3</SUB> 4H<SUB>2</SUB>O compounds in powder and entrapped in silica sol-gel glass were measured in a broad temperature range. It was found that the optical properties of europium ion direct environment were not preserved in silica glass. A broad band, in UV range, characteristic to Eu<SUP>2+</SUP> ions or C-T transition, was also observed. The intensity of this broad band is controlled by temperature an concentration of the active ions. Following the energy diagram of f-f transitions derived from Eu<SUB>2</SUB>(CO<SUB>3</SUB>)<SUB>3</SUB> H<SUB>2</SUB>O system, the symmetry of Eu<SUP>3+</SUP> ion was discussed in precursor and gel spectra. The effect of anisotropy of europium ion was considered, too.