A structural and ${}^{121}$Sb Mössbauer-spectroscopic study of PrPdSb and NdPdSb

Phase-pure samples of the antimonides PrPdSb and NdPdSb were prepared by arc-melting pieces of the elements and subsequent annealing. The samples were investigated by powder and single crystal X-ray diffraction: NdPtSb type, space group P6${}_3$mc, a = 458.70(5), c = 780.55(6) pm, wR2 = 0.0272, 244 F${}^2$ values, 11 variable parameters for PrPdSb and a = 458.18(4), c = 771.25(6) pm, wR2 = 0.0317, 229 F${}^2$ values, 11 variable parameters for NdPdSb. The palladium and antimony atoms form slightly puckered Pd${}_3$Sb${}_3$ hexagons which are rotated by 60° in every other layer. The rare earth (RE) atoms are coordinated by two Pd${}_3$Sb${}_3$ hexagons with the RE–Pd shorter than the RE–Sb contacts. The ${}^{121}$Sb Mössbauer spectra at T = 5 K confirm the antimonide character with isomer shifts of −7.55 (PrPdSb) and −7.47 mm $\cdot$ s${}^{\text{â}\text{ˆ}\text{’}1}$ (NdPdSb). In agreement with the crystal structures, each spectrum could be fitted with one quadrupole split signal.