Synthesis, crystal structure and magnetic properties of Sr 5(CrO 4) 3(Cu 0.586O) with apatite-like structure

Abstract

The crystal structure of apatite Sr 5(CrO 4) 3(Cu 0.586O) was solved using X-ray diffraction data with GSAS program in the space group P6 3/m with hexagonal unit cell parameters: a = 10.0292(1), c = 7.4623(1) Å, V = 650.033(8) Å 3, and Z = 2. This compound is stable up to 1473 K in air. It was found that copper in the form of Cu + cations is located in infinite linear (CuO) -1 chains inserted into the tunnels parallel to the hexagonal c axis. The chains contain about 40% vacancies in copper positions. The experimental value of the effective magnetic moment (μ eff) for the 1 Cr atom in formula Sr 5(CrO 4) 3(Cu 0.586(4)O) (1.671 μ B) is slightly smaller than the theoretical moment (1.732 μ B) calculated in the assumption that all chromium is present as Cr 5+ cations and copper as Cu +. © 2012 Elsevier B.V. All rights reserved.