Crystal structure of the R 7Cu 3Te 12 (R = Tb, Dy, Ho, Er and Tm) compounds

Abstract

The crystal structures of the R 7Cu 3Te 12 (R = Tb, Dy, Ho, Er and Tm) compounds (space group R 3 ¯ m, Pearson symbol hR27-5) were determined by means of X-ray single crystal diffraction: a = 0.43020(6) nm, c = 4.1720(8) nm, R I = 0.0498 (Ho 7Cu 3Te 12) and X-ray powder diffraction: a = 0.43279(3) nm, c = 4.1896(3) nm, R I = 0.0932 (Tb 7Cu 3Te 12); a = 0.43114(5) nm, c = 4.1779(8) nm, R I = 0.0891 (Dy 7Cu 3Te 12); a = 0.42802(2) nm, c = 4.1575(2) nm, R I = 0.0849 (Er 7Cu 3Te 12); a = 0.42709(3) nm, c = 4.1540(3) nm, R I = 0.0858 (Tm 7Cu 3Te 12). The close packed Te layers in …hhcc … stacking exists in the crystal structure of the R 7Cu 3Te 12 (R = Tb, Dy, Ho, Er and Tm) compounds. The R atoms occupy 7/12 of octahedral interstices, whereas the Cu atoms occupy 1/8 of tetrahedral interstices.