Synthesis and crystal structure of new quaternary sulfides BaLn(2)FeS(5)(Ln = La, Ce, Pr, Nd, Sm)

New quaternary sulfides. BaLn(2)FeS(5)(Ln = La, Cc. Pr, Nd, Sm) were synthe sized by a solid state reaction at 900 or 950 degreesC. These compounds cry stallize in the tetragonal structure (space group I4/mcm) with Z = 4. The r efinement of the X-ray diffraction data was carried out by the Rietveld met hod. They have a layered-structure composed of Ln-S layers and Ba-Fe-S laye rs, which are perpendicular to the c-axis. In these compounds. barium, lant hanide, and iron cations are located in 4a (0, 0, 1/4), 8h (x, x + 1/2, 0), and 4b (0, 1/2, 1/4) sites, respectively. Sulfur anions occupy two differe nt sites, S(1) and S(2) in 4c (0, 0, 0) and 16l (x, x + 1/2, Z), respective ly. BaSm2FeS5 is a new compound in a series of BaLn(2)MS(5) (M : 3d transit ion metal). (C) 2001 Elsevier Science Ltd. All rights reserved.