New ternary phosphides Ln(25)Ni(49)P(33) (Ln = Ce, Pr, Nd, Sm, Gd, Tb, Dy,Ho, Er)

New ternary phosphides Ln(25)Ni(49)P(33) (Ln = Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er) have been synthesized by are melting of pure components. Crystal st ructure has been determined for Sm25Ni49P33 using X-ray powder diffraction data and the Rietvelt method: P (6) over bar m2, a = 22.096(4), c = 3.8734( 9) Angstrom, R = 0.096. Crystal structure of Sm25Ni49P33 is of a new type a nd belongs to large family of ternary compounds with trigonal-prismatic coo rdination of the smallest size atoms and metal to nonmetal ratio equal or c lose to 2:1. It is a member of homologous subseries of the compounds with u nit cell contents described by general chemical formula (RnM(n+2)X(n+1)-32) -M-2-X-2. Lattice parameters of the isotypic compounds Ln(25)Ni(49)P(33) ha ve been refined using X-ray powder diffraction data.