Kinetics of polymorphic transitions in tetrahedral structures. Part 1.—Experimental methods and the transition γ→β Li2ZnSiO4

Abstract

Possible methods are discussed for studying the kinetics of polymorphic transformations in oxides that have tetrahedral structures. Quantitative powder X-ray diffraction methods have been developed for analysing the amounts of β- and γ-polymorphs in samples of Li₂ZnSiO₄ and these methods applied to determine the kinetics of the γ→β transformation. The kinetics were studied isothermally between 572 and 855°C and at each temperature are deceleratory throughout. The reaction approximates to first order kinetics at several temperatures (734–802°C) but orders as low as 0.5 were observed at other temperatures.