Influence of Crystallization on the Conversion of Sm 3+ → Sm 2+ in SrO – Bi 2 O 3 – K 2 O – B 2 O 3 Glass‐Ceramics

Sm 3+ ‐doped glass 13 SrO –2 Bi 2 O 3 –5 K 2 O –80 B 2 O 3 was fabricated by the conventional melt‐quenching technique. The glass‐ceramics were obtained by heating the as‐prepared glasses in air atmosphere at selected temperatures 550°C, 600°C, 615°C, and 650°C, respectively. The luminescence spectra of both Sm 3+ and Sm 2+ were detected in the ceramic heated at 650°C where crystalline phase is formed. The as‐prepared glass and the ceramics heated at 550°C, 600°C, and 615°C show only the emission due to Sm 3+ . In the sample heated at 650°C in air atmosphere, however, part of Sm 3+ ions was converted to Sm 2+ , giving rise to sharp emission lines which are characteristic of Sm 2+ in crystalline state. It is suggested that Sm 2+ ions are located at Sr 2+ site in the ceramic while Sm 3+ ions are located at Bi 3+ sites. The Sm 2+ ‐doped glass‐ceramic has a high optical stability because the fluorescence intensity decreases by only about 8% of its initial value upon excitation at 488 nm Ar + laser.