Technological aspects of borate glass–ceramics preparation doped with transition metals for optoelectronic applications

Abstract

Chromium-doped borate glass-ceramics are prepared at different temperatures via bulk crystallization of the borate glass matrix. The temperature influence on the spectral and operational characteristics of the material is observed. Rod-shaped LiAl7B4O17 crystals nucleate in a glassy matrix during two stage heat treatment. Borate glass-ceramics possess luminescence in the 650–800 nm region when excited with “green” light. An increase in the annealing temperature of glass-ceramics lead to several changes: (1) the luminescence quantum yield increase from 13% to 50%, (2) color coordinates of glass-ceramics luminescence shift towards to the red spectral region, (3) hardness and resistance to acid solutions of glass-ceramics increase. XRD experiments are carried out within the direct heating of a glass sample. The results show that the maximum size of nanocrystals was reached at a temperature of 600 °C, which coincided with the maximum of the exothermic region on the DSC curve. Thus, the spectral and operational properties of borate glass-ceramics exceed those of the initial borate glass, which makes borate glass-ceramics doped with chromium ions promising material for creating red and near infra-red emitters .