Crystal structures of the R3Mg0.5GeS7 (R = Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho and Er) compounds

Abstract The crystal structures of the R 3 Mg 0.5 GeS 7 (R = Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho and Er) compounds (La 3 CuSiS 7 structure type, space group P 6 3 , Pearson symbol hP 23) were determined by means of X-ray powder diffraction: a  = 0.9788(1) nm, c  = 0.57745(5) nm, R Bragg  = 0.0814 (Y 3 Mg 0.5 GeS 7 ); a  = 1.0262(2) nm, c  = 0.57849(7) nm, R Bragg  = 0.0687 (Ce 3 Mg 0.5 GeS 7 ); a  = 1.01249(3) nm, c  = 0.58040(2) nm, R Bragg  = 0.0832 (Pr 3 Mg 0.5 GeS 7 ); a  = 1.00701(3) nm, c  = 0.58047(3) nm, R Bragg  = 0.0636 (Nd 3 Mg 0.5 GeS 7 ); a  = 0.99500(3) nm, c  = 0.57872(3) nm, R Bragg  = 0.0870 (Sm 3 Mg 0.5 GeS 7 ); a  = 0.99319(3) nm, c  = 0.57083(3) nm, R Bragg  = 0.0901 (Gd 3 Mg 0.5 GeS 7 ); a  = 0.98007(5) nm, c  = 0.57843(4) nm, R Bragg  = 0.0859 (Tb 3 Mg 0.5 GeS 7 ); a  = 0.97698(4) nm, c  = 0.57675(5) nm, R Bragg  = 0.0931 (Dy 3 Mg 0.5 GeS 7 ); a  = 0.9735(2) nm, c  = 0.57941(7) nm, R Bragg  = 0.0763 (Ho 3 Mg 0.5 GeS 7 ); a  = 0.9694(2) nm, c  = 0.57994(7) nm, R Bragg  = 0.0724 (Er 3 Mg 0.5 GeS 7 ). The R-centered trigonal prisms, Mg-centered octahedra and Ge-centered tetrahedra can be selected in the crystal structure of the R 3 Mg 0.5 GeS 7 compounds.