THE CRYSTAL-STRUCTURE OF NDFE1-XSB2 AND ISOTYPIC COMPOUNDS RE(FE, CO)1-XSB2 (RE-EQUIVALENT-TO-LA, CE, PR, SM, GD)

New compounds REFe1-xSb2 and RECo1-xSb2 (RE = La, Ce, Pr, Nd, Sm, Gd) were synthesized by argon arc melting elemental mixtures followed by annealing at 800-degrees-C for 7 days. The crystal structure of NdFe1-xSb2 was determined from single-crystal X-ray counter data. NdFe1-xSb2 crystallizes in the ZrCuSi2-type structure with the centrosymmetric space group P4/nmm. The tetragonal lattice parameters are a = 0.43514(6) nm and c = 0.96518(13) nm; Z = 2. For 273 reflections (\F(o)\ > 2sigma) the residual values are R(F) = SIGMA\DELTAF\/SIGMA\F(o)\ = 0.0532 and R(w) = 0.0516. Compounds with the light rare earth elements La, Ce, Pr, Sm and Gd were found to be isotypic with NdFe1-xSb2.