The quantitative determination of the effectiveness of nucleating agents

Abstract

Consideration is given to the assessment of the effectiveness of nucleating agents in promoting heterogeneous crystal nucleation in glass. A quantitative measure of nucleation potency Q is the ratio of the free energies required to form a critical radius with and without nucleating agents present in the glass. Previously employed methods to determine Q are laborious and often require unverified assumptions concerning the nature of the nucleation process. A simple alternative scheme is proposed and illustrative calculations are presented for platinum induced nucleation of lithium disilicate glass. Further, it is shown that the combined use of this method and other techniques for determining Q could verify the hypothesis that temperature variation of glass-crystal surface tension is the cause of the discrepancies between the Classical Nucleation Theory and experimental data for homogeneous nucleation rates in simple silicate glasses.