Luminescence of Bi 3+ ions and energy transfer from Bi 3+ ions to Eu 3+ ions in silica glasses prepared by the sol-gel process

Abstract

Luminescence of Bi 3+ ions and energy transfer from Bi 3+ ions to Eu 3+ ions in silica glasses prepared by the sol-gel process have been investigated. The results showed that the excitation band of Bi 3+ ions corresponds to the 1S 0 → 1P 1 transition and emission spectra consists of a single broad band without structure centred at 395 nm, which corresponds to 3P 1 → 1S 0 transition. When a small amount of Bi 3+ ions was introduced to 1 mol% Eu 3+ ions the doped silica gel glass emission intensity of Eu 3+ ions got significantly stronger, which suggests very efficient energy transfer from Bi 3+ ions to Eu 3+ ions. It can be assigned to significant energy overlap between the emission band of the Bi 3+ ion and the excitation band of the Eu 3+ ion. However, due to a larger energy overlap between emission and excitation bands of Bi 3+, when Bi 3+ ion concentration in silica gel glasses was more than 0.5 mol% the probability of energy transfer between Bi 3+ ions increased rapidly and the probability of energy transfer from Bi 3+ ions to Eu 3+ ions decreased relatively. As a consequence, the sensitized effectiveness of the Bi 3+ ion on the emission spectrum of the Eu 3+ ion drastically decreased with increasing Bi 3+ ion concentration.