Crystallization of GeO 2 –Al 2 O 3 –Bi 2 O 3 Glass

In the presented work, two kinds of germanium oxide glass with different compositions, namely GeO 2 and GeO 2 –Al 2 O 3 –Bi 2 O 3 , were investigated. After controlled crystallization of a glassy sample, the emission in the NIR-range was determined (1165 nm with excitation at 470 nm). To better understanding the kinetics of the glass crystallization, the activation energy was also determined by applying the Kissinger method. The obtained results show that in the case of GeO 2 –Al 2 O 3 –Bi 2 O 3 , activation energy value was 400 and 477 kJ/mol, which means that such values are significantly larger than for pure GeO 2 (254 kJ/mol). The investigations also show that two phases crystallized in the complex glass matrix: the mullite-like phase and germanium oxide.