Journal of Crystal Growth, Vol.262, No.1-4, 202-211, 2004
Heat transfer in growing Bi4Ge3O12 crystals under weak convection: I -thermophysical properties of bismuth germanate in solid and liquid state
Thermal conductivity and spectral absorption coefficient of bismuth germanate Bi4Ge3O12 are measured in crystalline state and in melt within temperature range 750-1350 K. It is discovered that thermal conductivity of the melt is low and close to those of thermal insulation (0.2 W/m K). Thermal conductivity of the crystal at melting point is not high; it is equal to 1.15 W/m K. It is stated that the single crystal is transparent till melting point while melt is practically opaque for thermal radiation. Due to these features of the Bi4Ge3O12 melt and crystal, heat transfer mechanism in the liquid phase drastically differs from that in solid. (C) 2003 Elsevier B.V. All rights reserved.