Narrow Energy Gap between Triplet and Singlet Excited States of Sn2+ in Borate Glass.

Transparent inorganic luminescent materials have attracted considerable scientific and industrial attention recently because of their high chemical durability and form ability. However, photoluminescence dynamics of ns²-type ions in oxide glasses has not been well examined, even though they can exhibit high quantum efficiency. We report on the emission property of Sn²⁺-doped strontium borate glasses. Photoluminescence dynamics studies show that the peak energy of the emission spectrum changes with time because of site distribution of emission centre in glass. It is also found that the emission decay of the present glass consists of two processes: a faster S₁-S₀ transition and a slower T₁-S₀ relaxation, and also that the energy difference between T₁ and S₁ states was found to be much smaller than that of (Sn, Sr)B6O10 crystals. We emphasize that the narrow energy gap between the S₁ and T₁ states provides the glass phosphor a high quantum efficiency, comparable to commercial crystalline phosphors. [ABSTRACT FROM AUTHOR]