Kinetic studies of the crystallization of Te92Pb8 thin films

Abstract A method to obtain the crystallized volume fraction X and the time taken for crystallization t is proposed. The Avrami equation X = 1 − exp(− kt n ) is used to calculate the time exponent n and rate constant of crystallization k . The nucleation mechanism, nucleation rate and the growth rate of nuclei of Te 92 Pb 8 are discussed in relation to different n and k values. It is found that the nucleation at the start of the transformation, plus continuing nucleation at grain boundaries or grain edges, determine the kinetics at lower temperatures. Both the nucleation and the growth rate of nuclei are low at 32° C. They increase slowly with temperature below 46° C. From 46° C, the nucleation rate increase rapidly. Its maximum may be in the temperature region between 65° C and 80° C. The maximum growth rate of nuclei is at a temperature higher than 80° C. A nonlinearity in the plots of lnln 1/(1 − X ) vs ln t caused by the variation of n is also found and discussed. The amorphous state of Te 92 Pb 8 is unstable. The possibility of using it as erasable phase change optical recording material is evaluated.