Effect of the ceramic tube shape on global heat transfer, thermal stress and crystallization front in low thermal gradient (LTG) Czochralski growth of scintillating BGO crystal

Abstract

The effect of ceramic tube on thermal field, thermal stress and crystallization front have been experimentally and numerically analyzed for a low thermal gradient (LTG) Czochralski growth of crystal. The governing equations have been solved using 2D steady state finite element method. To do it, a real growth setup with three different shapes of the ceramic tube (cylindrical, legged cylindrical and conical) were simulated in order to compare the numerical results with experimental findings of crystal–melt interface. It was found that the best LTG conditions above the melt surface, namely, the lowest thermal stress and the crystallization front with the smallest deflection height, relate to the case of conical ceramic tube due to the lowest internal radiation exchange within the BGO crystal.