Influence of Dopants on Nucleation and Growth of High-Quartz Solid Solution in Lithium Aluminosilicate Glass

The kinetic parameters of nucleation and crystal growth of high-quartz solid solution in multicomponent lithium aluminosilicate glasses doped with various transition-metalions were studied by nonisothermal DTA. The crystallization of glasses nucleated at different temperatures was carried out, and plots of the DTA peak versus the nucleation temperatures were used to determine the maximum nucleation rate temperature. Peak temperature data of nucleated samples at varying heating rates (5–20 K/min) were used to determine the activation energy for crystallization via the JMA equation. The temperature of maximum nucleation rate depends greatly on the doped transition- metal ions present. The activation energy for crystallization obtained for undoped glass or glasses doped with Fe₂O₃ is of the same order as that already published, and the Avrami exponent is consistent with predominantly three-dimensional crystal growth. The much higher activation energy values for glasses doped with CoO could be a consequence of two crystallization processes proceeding simultaneously.