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Problems of heat conduction are of vital interest for crystal growing. Construction of a plant necessitates pre-knowledge on the corresponding temperature distribution to be expected on basis of geometry, material properties a.s.0. As these information are in general not easily gained by measurement or calculation, modelling by means of electric analogy is offered as a tool. Results are given, indicating that this method is not only simple and versatile, but also of sufficient accuracy.

This paper describes an equipment for growth of single crystals by slow cooling of a saturated flux. Automation, low cooling rates and the use of a Sic-furnace for high temperatures allow good reproducibility, accurate experimental conditions and application of the described method to growth of high-melting oxids.The growth of ZrO, (melting point 2715 "C) was carried out in molten salt solvents, especially in borax and Li,MoO, . x MOO, fluxes with x = 1 and 2 respectively. The morphology (forms and habit) of grown ZrO, crystals (Baddeleyite) depends on temperature (cooling range) and the composition of the flux. Structural features for example twinning and the role of phase transformation during cooling are studied. The influence of the phase transition from the tetragonal to the monoclinic system and the mechanism of "re-entrant corner" on growth is discussed.