THE RARE-EARTH TRANSITION-METAL PHOSPHIDE OXIDES LNFEPO, LNRUPO AND LNCOPO WITH ZRCUSIAS TYPE-STRUCTURE

The compounds LnFePO (Ln = La-Nd, Sm, Gd), LnRuPO (Ln = La-Nd, Sm, Gd) and LnCoPO (Ln = La-Nd, Sm) crystallize with the tetragonal ZrCuSiAs type structure (P4/nmm, Z = 2), which was refined from single-crystal X-ray data of PrFePO (a = 391.13(6) pm, c = 834.5(2) pm, R = 0.026) and CeRuPO (a = 402.6(1) pm, c = 825.6(2) pm, R = 0.018). The refinement of the occupancy parameters showed the oxygen position to be fully occupied in both compounds. The oxygen content of the samples was also proven by EDAX analyses. The structures of the compounds SmFePO and LaCoPO were refined by Rietveld analyses of X-ray powder data.