Speakers: Robert Král (Institute of Physics ASCR)
Place: Library, Institute of Physics ASCR, Cukrovarnická 10, Praha 6
Presented in Czech
Organisers:
Department of Optical Materials
he subject of this lecture is the study of growth conditions influence (temperature gradient in the furnace and pulling rate of the ampoule through the temperature gradient) on the position and shape of the crystal/melt interface during simulated growth of lead halide and ternary alkali lead halide single crystals by the vertical Bridgman method. Study of the influence of the growth conditions during simulated crystal growth by the vertical Bridgman method under stationary (zero pulling rate) and dynamic conditions (pulling rate of 1 and 3 mm/hour) were performed using following experimental methods: (i) direct observation of the position and the shape of the crystal/melt interface, (ii) striations inducing, (iii) temperature field measurement in the growth ampoule under simulated Bridgman crystal growth of PbCl2 as a model compound.
Experimental methods provided information about dependence of the position and the shape of the crystal/melt interface on various crystal growth conditions. Temperature field measurements provided valuable data in growth system in three ampoule positions in four temperature gradients. Obtained temperature data were used as boundary conditions in the numerical modeling.
Apart from the experimental methods, a numerical modeling of studied system was performed as well using commercially available software Comsol Multiphysics. Calculated numerical models described the temperature field and flow of the melt and surrounding atmosphere in the furnace in the studied system. Crystal growth conditions were adjusted and optimized, based on the obtained results of both experimental and numerical study, and single crystals of above mentioned compounds were grown.
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