Sn 3 S 4 : a new mixed-valence tin sulfide

Single crystals of Sn 3 S 4 of about 0.1 mm in linear size were synthesized by using the method of chemical vapour transport catalyzed by Ag 2 S. The crystal structure of this new mixed-valence tin sulfide was established using single-crystal X-ray diffraction. The crystal has a regular Fd 3̄ m space group symmetry with the unit cell parameter a = 10.5018(1) Å and eight Sn 3 S 4 formula units in the unit cell. Two types of Sn atoms are present in the structure of Sn 3 S 4 . They differ by the number of coordinated S atoms. Integration of atomic basins revealed that the charge at Sn atoms with the octahedral arrangement is +1.27e, and that at the tetrahedral is +1.54e. The sulfur atom has an integrated charge equal to −1.02e. Transmission electron microscopy images show ideal matching with the X-ray refined structure.