Nucleation behavior of Na2O-SiO2 glasses with small amount of additive

Nucleation in 49Na(2)O.49SiO(2).2ZrO(2) and 47Na(2)O.51SiO(2).2ZrO(2) glasses were investigated by differential thermal analysis measurement after heat-treatments at 400-580 degrees C for 0-123 h. The addition of ZrO2 increased crystallization peak temperature, T-C, and shifted the temperature, T-max, at which nucleation rate is maximum to higher temperatures. The relationship between the number density of nuclei formed during the heat-treatment and Te was calculated. The variation of the number density of nuclei was obtained from the comparison between the calculated Te and the observed Te as a function of heat-treating time. The transient time for nucleation of 47Na(2)O.51SiO(2).2ZrO(2) glass was 42 h at 430 degrees C. From these results, we found ZrO2 has an effect on the nucleation kinetics of Na2O-SiO2 glass. (C) 2000 Elsevier Science B.V. All rights reserved.