Crystallization of lead-based and lead-free oxyfluoride germanate glasses doped with erbium during heat treatment process.

Abstract Oxyfluoride lead-based and lead-free germanate glasses were heat-treated in order to fabricate transparent glass-ceramics. Cubic β-PbF 2 nanocrystals are well formed during crystallization of lead germanate glass. The up-conversion luminescence spectra of Er3+ ions in lead germanate glass-ceramic system are enhanced significantly due to partial incorporation of the optically active ions into fluoride crystalline phase. These effects are not significant in oxyfluoride lead-free germanate glass after heat treatment process. The crystallization of barium gallo-germanate glass with BaF 2 is more complex and the presence of four crystalline phases BaF 2 , BaO, Ba 3 Ga 2 Ge 4 O 14 and GeO 2 was verified by X-ray diffraction measurements. Highlights • Er3+-doped germanate glasses before and after heat treatment have been examined. • PbF 2 nanocrystals are formed during heat treatment of lead germanate glass. • Four crystalline phases were identified in lead-free germanate glass-ceramic. • Up-conversion emission spectra of Er3+ in glass and glass-ceramic were compared. [ABSTRACT FROM AUTHOR]