Directional solidification and characterization of Hg 0.89Mn 0.11Te

Abstract

Two boules of Hg 0.89Mn 0.11Te (MMT) were solidified by the vertical Bridgman–Stockbarger method using translation rates of 0.09 and 0.18 μm/s. The influence of growth rate on axial compositional homogeneity in the MMT boules was evaluated experimentally through precision density measurements on radial slices from each boule. In addition, plane front solidification theory and segregation coefficient ( k) data for the Hg 1− x ,Mn x Te system were used to fit theoretical composition profiles to the measured MMT axial composition profiles. The strong correlation between the measured and calculated MMT axial composition profiles indicated diffusion dominated axial solute redistribution in the boules under the applied growth conditions. The analysis of the MMT axial composition profiles allowed the calculation of the effective diffusion coefficient ( D eff=3.75×10 −5 cm 2/s) for MnTe in molten MMT. The k-values for the Hg 1− x Mn x Te system and the D eff were used to show that both boules were solidified under conditions which did not exceed the constitutional supercooling criteria under ideal conditions. Finally, an initial comparison of the radial compositional variations in each boule, as determined by a Fourier transform infra-red spectroscopy (FTIR) technique, was made.