La3Ru8B6 and Y3Os8B6, new members of a homologous series R(A)(n)M3n-1B2n

摘要

Two new compounds. La3Ru8B6 and Y3Os8B6, were synthesized by arc melting the elements. Their structural characterization was carried out at room temperature On as-cast samples by Using X-ray diffractometry. According to X-ray single-crystal diffraction results these borides crvstallize in Fmmm space group (no. 69), Z = 4, a = 5.5607( 1) angstrom, b = 9.8035(3) angstrom, c = 17.5524(4) angstrom, rho = 8.956 Mg/m(3), mu = 25.2 mm(-1) for La3Ru8B6 and a 5.4792(2) angstrom, b = 9.51339(4) angstrom, c = 17.6972(8) angstrom, rho = 13.343 Mg/m(3), mu = 128.23 mm(-1) for Y3OsB6. The crystal Structure of La3Ru8B6 was confirmed front Rietveld refinement of X-ray powder diffraction data. Both La3Ru8B6 and Y3Os8B6 compounds are isotypic with the Ca3Rh8B6 Compound and their structures are built up from CeCo3B2-type and CeAl2Ga2-type structural fragments taken in ratio 2:1. They are the members of structural series R(A)nM(3n-1)B(2n) with n = 3 (R is the rare earth metal. A the alkaline earth metal, and M the transition metal). Structural and atomic parameters were also obtained for La0.94Ru3B2, compound from Rietveld refinement (CeCo3B2-type structure, P6/mmm space group (no. 191), a = 5.5835(9) angstrom, c = 3.0278(6) angstrom). (C) 2007 Elsevier Inc. All rights reserved.