辅助电场下TeO_2-Nb_2O_5-AgCl系统玻璃的核化与析晶机理研究

Nucleation and Crystallization Mechanism of TeO_2-Nb_2O_5-AgCl Glass under Auxiliary Electric Field

在玻璃材料热处理过程中施加辅助电场,如果玻璃相的介电常数小于析出晶相的介电常数,则对玻璃的核化、晶化过程起促进作用;反之则起抑制作用.本文推导了辅助电场与温度场共同作用对玻璃核化、析晶过程的影响机理,研究了辅助电场对TeO2-Nb2O5-AgCl系统玻璃核化与析晶过程的促进作用.结果发现,辅助电场能帮助玻璃在稍低于核化和晶化温度区域的温度下成核和析晶,它可以成为控制玻璃核化和晶化过程的一个"开关",有可能用以精确控制玻璃中纳米晶体的生长.

To control nucleation and crystallization of glass exactly is one of key steps for preparing nano-crystalline embedded glass. The auxiliary electric field, applied on the glass, which is in thermal treatment process, may accelerate nucleation and crystallization of glass when the dielectric coefficient of the glass is less than that of crystalline. On the contrary, the nucleation and crystallization of glass will be inhibited. The auxiliary electric field, whether it plays an accelerating or inhibiting effect on glass, can be used to control nucleation and crystallization exactly when preparing nano-crystalline embedded glass. The mechanism of effects of auxiliary electric field and temperature field on nucleation and crystallization of glass was deduced. Their effects on TeO2-Nb2O5-AgCl glass were also studied in this paper. The results show that the electric field can aid the glass to nucleate in the temperature little lower than traditional nucleation region. The speed of crystallization can be accelerated under auxiliary electric field. The electric field can stimulate nucleation and crystallization of TeO2-Nb2O5-AgCl glass under little below corresponding temperature, which can not provide with enough activation energy for nucleation and crystallization. The characteristic of very fast loading and unloading of auxiliary electric field will become a kind of ' switch ' to control the nucleation and crystallization of the glass. The ' switch ' will be used to control the growth of nano-crystallines in the glass accurately.