Investigation on Crystallization and Optical Properties of Ca 1 −x La x F 2 +x Glass‐Ceramics

Transparent oxyfluoride glass‐ceramics containing Er 3+ , Yb 3+ : Ca 1 −x La x F 2 +x nanocrystals, which may have potential applications in the fields of solid‐state laser and luminescence, were prepared. Crystallization of Ca 1 −x La x F 2 +x and behavior of Yb 3+ and Er 3+ during the heat treatment was investigated. Results showed that alumina content had a significant effect on crystallization of Ca 1 −x La x F 2 +x in the SiO 2 – Al 2 O 3 – CaF 2 – LaF 3 system. Due to the size of phase‐separated areas, the size of the crystals during the heat treatment did not change significantly. After crystallization of Ca 1 −x La x F 2 +x in the glass, the majority of Er 3+ ions incorporated into the Ca 1 −x La x F 2 +x crystals during the heat‐treatment process. Time‐resolved luminescence of Er 3+ ions in the samples around 842 nm showed that the solubility of Er 3+ ions in Ca 1 −x La x F 3 crystals is higher than pure CaF 2 crystals. The glass undergoes an enormous phase separation, which keeps the Yb 3+ ions within the other separated phase. Therefore, only at high temperatures (790°C) or with a long heat‐treatment time (72 h), there is a possibility for Yb 3+ ions to be incorporated into the fluorine phase.