CRYSTAL-GROWTH AND X-RAY STRUCTURAL INVESTIGATION OF 2 FORMS OF HGGA2TE4

We have synthesized the HgGa2Te system in two different forms showing cubic and tctragonal symmetry, respectively. Single crystals of alpha-HgGa2 Te 4 suitable for X-ray investigations were obtained by crystallization of the polycrystalline compound using KBr as flux. The X-ray analysis showed a cubic blende-type structure with cations and vacancies disordered on the metallic sites, in agreement with the model proposed by Hahn. Single crystals of beta- HgGa2Te4 were prepared by chemical vapour deposition. The x-ray structural investlgation indicated a partially ordered defect chalcopyrite structure.