Mercurous bromide <TEX>$(Hg_2Br_2)$</TEX> crystal growth by physical vapor transport and characterization

Mercurous bromide (<TEX>$Hg_{2}0Br_{2}$</TEX>) crystals hold promise for many acousto-optic and opto-electronic applications. This material is prepared in closed ampoules by the physical vapor transport (PVT) growth method. Due to the temperature gradient between the source and the growing crystal region, the buoyancy-driven convection may occur. The effects of thermal convection on the crystal growth rate was investigated in this study in a horizontal configuration for conditions ranging from typical laboratory conditions to conditions achievable only in a low gravity environment. The results showed that the growth rate increases linearly with Grashof number, and for 0.2 <TEX>$leq$</TEX> Ar (transport length-to-height, L/H)<TEX>$leq$</TEX>1.0 sharply for Ar=5 and <TEX>$Delta$</TEX>T=30 K. We have also shown that the magnitude of convection decreases with the Ar. For gravity levels of less than <TEX>$10^{-2}$</TEX>g the non-uniformity of interfacial distribution is negligible.