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The isothermal crystal growth kinetics in Se70Te30 thin films was investigated using the microscopy and in situ X-ray diffraction (XRD) measurements. Plate-like crystals grew linearly with time which is the sign of liquid-crystal interface kinetics. In the studied temperature range, from 68 °C to 88°C, crystal growth rates exhibit simple exponential behavior with an activation energy of crystal growth EG=168±12 kJ mol-1. The growth data obtained from the microscopy measurements were combined with viscosity data, melting parameters and the appropriate crystal growth model was assessed. The relation between the kinetic coefficient of crystal growth and viscosity (uαn) is described in detail, and a correction of the standard growth model is suggested. The crystal growth data obtained from the in situ XRD measurements were described using the Johnson-Mehl-Avrami nucleation-growth model with the Avrami exponent m=2.2±0.2. The activation energy of the overall crystallization process EA was estimated and its value is 171±11 kJ mol-1. [ABSTRACT FROM AUTHOR]

The crystal growth velocity of spherulitic As2Se3 in a supercooled melt of the same composition was studied by optical microscopy and thermoanalytical methods in isothermal and nonisothermal conditions. The time dependence of crystal size is linear, which suggests the crystal growth is controlled by interface kinetics. Crystal growth velocity was determined as the slope of these linear dependences. The experimental results presented in this paper considerably extend the previously reported range of crystal growth velocity. All isothermal crystal growth velocity data can be well described by the standard two-dimensional surface nucleated growth model (2Dsg) including crystal growth viscosity decoupling (ξ = 0.647). The activation energy of crystal growth for microscopic experiments is in a good agreement with values obtained from thermoanalytical experiments, and the ratio of the activation energy of crystal growth and the activation energy of viscous flow well corresponds to an independently determined decoupling parameter. The same model successfully describes also crystalline layer thickness and growth pattern at the amorphous As2Se3 surface in nonisothermal conditions. [ABSTRACT FROM AUTHOR]