The structure Tl 3SbS 3, Tl 3SbSe 3, Tl 3SbS 3− xSe x, and Tl 3Sb yAs 1− ySe 3

Abstract

The space group symmetry and crystal structure of Tl 3SbS 3− x Se x compounds in the composition range 0 < x < 3 have been determined by a combination of powder X-ray diffraction, electron diffraction, and high-resolution electron microscopy. The incongruently melting compound Tl 3SbSe 3 has been shown to crystallize in cubic space group P2 13 with a = 9.435Å in a structure related to that of Langbeinite. The convergent beam electron diffraction pattern of Tl 3SbS 3 is in accord with the space group R3 m determined by X-ray diffraction. The cubic Langbeinite-type structure is found for Tl 3SbS 3− x Se x for 0.5 < x < 3 and for Tl 3Sb y As 1− y Se 3 for 0.077 < y < 1.0. A five-component compound Tl 3Sb 0.5As 0.5Se 1.5S 1.5 was also found to be cubic.