Thermochimica Acta, Vol.404, No.1-2, 55-61, 2003
Non-isothermal devitrification of sodium germanate glasses
The devitrification behavior of sodium germanate glasses, examined by Fourier transform infrared spectroscopy, differential thermal analysis and X-ray diffraction is reported. The glass compositions are expressed by the general formula: xNa(2)O.(1-x)GeO2 with x = 0.100; 0.125; 0.200; 0.250 and 0.333. The glass transition temperature values do not change linearly with the increase in Na2O content but go through a maximum at x = 0.200. The phases crystallizing during DTA runs were identified and devitrification mechanisms proposed. The effect on devitrification processes of the specific surface area of the samples was also pointed out. (C) 2003 Elsevier Science B.V. All rights reserved.