SYNTHESIS, CRYSTAL-STRUCTURE, AND MAGNETIC-PROPERTIES OF COMPLEX OXIDES CU2BSBO6 (B=MN, FE, A) WITH A BIXBYITE STRUCTURE

New complex oxides Cu2BSbO6 (B = Mn3+, Fe3+, Ga3+) with a body-centered cubic elementary cell (the bixbyite type structure) and parameters 9.5667(3), 9.5622(3), and 9.5237(3) angstrom, respectively, have been synthesized in air at 950-degrees-C from simple Cu, Sb, Mn, Fe, and Ga oxides. Rietveld's method of full-profile analysis was employed to refine the structure parameters of one of the obtained compounds, Cu2FeSbO6. Sb occupies 8b sites and Cu and Fe are in 24d sites. From cation-oxygen and oxygen-oxygen interatomic distances, it was shown that Sb occurs within an almost regular SbO6 octahedron (R(Sb-O) = 2.00 angstrom), while Fe and Cu are located inside strongly distorted octahedra (R(M-O) (angstrom) = 1.938, 2.020, and 2.311). Magnetic susceptibility chi of the compounds was measured. For Cu2GaSbO6, chi(T) obeys the Curie-Weiss law in the temperature range 77-300 K. For Cu2+, the values of Weiss's constant and the magnetic moment (c = 0.42, mu = 1.81mu(B)) are close to the theoretical ones. A transition to the antiferromagnetic state was observed at 15.6 K for Cu2FeSbO6 and at 5.9 K for Cu2MnSbO6. (C) 1994 Academic Press, Inc.