Notes. Crystallization of amorphous silica into quartz

Abstract

Crystallized quartz has been obtained from amorphous silica prepared by the hydrolysis of silicon alkoxide containing calcium or magnesium alkoxide (10 mol %). The crystallization of CaSiO₃ and MgSiO₃ is observed prior to that of quartz. Crystallization isotherms are described by the contracting cube equation 1 –(l –f)^⅓=k(t–t₀) and activation energies have been determined as 435 and 498 kJ mol^–1 in the presence of Ca²⁺ and Mg²⁺ respectively.