Syntheses and structures of six compounds in the A2LiMS4 (A=K, Rb, Cs; M=V, Nb, Ta) family

Six new compounds in the A2LiMS4 (A=K, Rb, Cs; M=V, Nb, Ta) family, namely K2LiVS4, Rb2LiVS4, Cs2LiVS4, Rb2LiNbS4, Cs2LiNbS4, and Rb2LiTaS4, have been synthesized by the reactions of the elements in Li2S/S/A2S3 (A=K, Rb, Cs) fluxes at 773 K. The A and M atoms play a role in the coordination environment of the Li atoms, leading to different crystal structures. Coordination numbers of Li atoms are five in K2LiVS4, four in A2LiVS4 (A=Rb, Cs) and Cs2LiNbS4, and both four and five in Rb2LiMS4 (M=Nb, Ta). The A2LiVS4 (A=Rb, Cs) structure comprises one-dimensional chains of image tetrahedra. The Rb2LiMS4 (M=Nb, Ta) structure is composed of two-dimensional image layers. The Cs2LiNbS4 structure contains one-dimensional image chains that are related to the Rb2LiMS4 layers. The K2LiVS4 structure contains a different kind of image layer.