A novel data on Ag5SbS4 and CuPbSbS3 probed by antimony NQR spectroscopy

Abstract

Investigations of Sb-based chalcogenides, stephanite Ag5SbS 4 and bournonite CuPbSbS 3, have been performed by 121,123Sb nuclear quadrupole resonance (NQR). In stephanite a phase transition at 140 K and internal diffusion motions with an activation energy of 0.29 eV have been experimentally detected. The analysis of experimental results for bournonite revealed two crystal-chemical positions of Sb in the unit cell with distinct local symmetry. The NQR frequencies ν and line-widths Δν data indicate that Sb(A)S3 complex has almost axial symmetry, but Sb(B)S 3 complex is substantially distorted.