A method for the production of thallium telluride of the composition tl te or isomorphic mixed crystal compounds on the basis of tl te

摘要

In the production of thallium telluride, Tl2Te3, or an isomorphous mixed crystal wherein part of the thallium and/or of the tellurium is replaced by another element, by heating the component elements or compounds supplying them, at a temperature below the decomposition temperature of Tl2Te3 (about 238 DEG C.), as described and claimed in the parent Specification, crystal nuclei of a compound isomorphous with Tl2Te3 are incorporated in the reactant mixture before or during the heat treatment. Such nuclei, preferably Tl2Te3 itself, may be added in amounts up to 1% and are preferably formed in situ. This may be effected by preheating the mixture between 238 DEG and 243 DEG C., for about 30 minutes and then cooling below the decomposition temperature. According to Examples: (1) Tl and Te in proportions corresponding to Tl2Te3 were melted at 350 DEG C. then cooled to 239 DEG C. and maintained at this temperature for an hour. Crystal nuclei of Tl2Te3 where thus formed and the mixture was cooled to 235 DEG C. and kept there for 3 hours. (2) Tl and Te were melted in an argon atmosphere at 300 DEG -350 DEG C. and cooled to 237 DEG C. Crystal nuclei were added as the temperature fell from 250 DEG to 237 DEG C. (3) TlTe and Te, corresponding to Tl2Te3 were ground with Tl2Te3 crystal nuclei and shaped under 1 ton/cm.2 pressure. The body formed was heated at 230 DEG C. for 15 hours to form Tl2Te3. The thallium and/or the tellurium may be partially replaced by gallium or indium and by sulphur or selenium respectively.