Crystal structures of the R3.33CuPb1.5S7 (R = Tb, Dy, Ho, Er and Lu) compounds

The crystal structures of the R3.33CuPb1.5S7 (R = Tb, Dy, Ho, Er and Lu) compounds (space group Cm, Pearson symbol mC25.67) were determined by means of X-ray powder diffraction: a = 1.3129(2) nm, b = 0.39791(6) nm, c = 1.2176(2) nm, β = 104.96(1)° (Tb3.33CuPb1.5S7); a = 1.3079(2) nm, b = 0.39591(6) nm, c = 1.2119(2) nm, β = 104.996(8)° (Dy3.33CuPb1.5S7); a = 1.3047(2) nm, b = 0.39462(5) nm, c = 1.2090(2) nm, β = 104.885(7)°, RI = 0.0982 (Ho3.33CuPb1.5S7); a = 1.3011(1) nm, b = 0.39313(3) nm, c = 1.20606(9) nm, β = 104.884(4)°, RI = 0.0834 (Er3.33CuPb1.5S7); a = 1.29262(9) nm, b = 0.38948(2) nm, c = 1.19916(8) nm, β = 104.794(4)°, RI = 0.0925 (Lu3.33CuPb1.5S7). The unit cell of R3.33CuPb1.5S7 can be obtained by combination of the unit cells of RCuPbS3 (space group Cmcm) and Sc2S3 (space group Fddd). Layers of S atoms and vacancies (in ratio 7:2) of hexagonal topology can be discerned in the R3.33CuPb1.5S7 (R = Tb, Dy, Ho, Er and Lu) compounds.