Synthesis, Crystal Structure, and Magnetic Properties of Complex Oxides Cu2BSbO6 (B = Mn, Fe, Ga) 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) Å, respectively, have been synthesized in air at 950°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 (RSb-O = 2.00 Å), while Fe and Cu are located inside strongly distorted octahedra (RM-O (Å) = 1.938, 2.020, and 2.311). Magnetic susceptibility χ of the compounds was measured. For Cu2GaSbO6, χ(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, μ = 1.81μB) 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.