Pressure-induced phase transitions in cadmium thiogallate CdGa2Se4

The high-pressure behavior of semiconducting cadmium thiogallate CdGa2Se4 w ith the defect chalcopyrite structure (I (4) over bar, Z = 2) is studied by in situ angle-dispersive synchrotron X-ray powder diffraction and optical reflectivity measurements in a diamond anvil cell at room temperature. At 2 1 GPa an order-disorder phase transition to the rock-salt structure (F (4) over bar 3m, Z = 4) occurs. Upon decompression, the metallic NaCl-type poly morph transforms into zinc-blende (Fm (3) over barm, Z = 4) at pressures of 7.5-4 GPa. The recovered metastable semiconducting material is of the zinc -blende type. (C) 2001 Academic Press.