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C. Buchner, W. Schneider:
"Explosive crystallization in thin amorphous layers on heat conducting substrates";
Journal of Applied Physics, 117 (2015), S. 24530101 - 24530112.

A model for explosive crystallization in a thin amorphous layer on a heat conducting substrate is presented. For the thin layer, the energy equation is used in a one-dimensional approximation. Heat conduction into the substrate and thermal contact resistance at the interface between layer and substrate are taken into account. Four rate equations are used to describe the kinetics of the homogeneous amorphous-crystalline transition. The whole process is examined as a plane wave of invariant shape in a moving frame of reference. Heat conduction in the substrate is described by introducing a continuous distribution of moving heat sources at the interface. This gives an integral representation for the temperature in the substrate in terms of the unknown source distribution. The integral term implies that there is a non-local influence of the temperature distribution in the layer on the heat loss. A coupled system of an integro-differential equation and four ordinary differential equations is obtained and solved numerically. The propagation velocity of the wave is obtained as an eigenvalue of the system of equations. Varying a non-dimensional heat loss parameter, a critical value is found beyond which no crystallization wave of invariant shape is possible. This can also be interpreted as a certain minimum layer thickness. Temperature and crystallinity distributions are shown for some interesting configurations. Predictions of crystallization-wave velocities and minimum layer thicknesses are compared with experimental values for explosive crystallization in germanium.

crystallization, waves, heat conduction

http://dx.doi.org/10.1063/1.4922787

Projektleitung Wilhelm Schneider:
AIC Androsch International Management Consulting GmbH Forschung auf dem Fachgebiet Strömungsmechanik und Thermodynamik