Investigations on the homogeneity of single crystals of materials with variable composition grown by chemical transport reactions

To investigate the problem of homogeneity in crystals grown by chemical transport reactions (CTR) solid solutions Fe_1-yCo_yS, Fe_1-yNi_yS, and Zn_1-yCo_yO were choosen as model substances. Relative concentration profiles of Co and Ni, respectively, were measured by electron-probe microanalysis and light absorption (in Zn_1-yCo_yO only). No significant deviations from homogeneity were found for Fe_1-yMe_yS, whereas in Zn_1-yCo_yO the Co contents increase in the growth direction. A qualitative explanation due to different diffusivities in the solids can be given.