Synthesis, crystal structure and magnetic properties of Sr5(CrO4)3(Cu0.586O) with apatite-like structure

Abstract: The crystal structure of apatite Sr5(CrO4)3(Cu0.586O) was solved using X-ray diffraction data with GSAS program in the space group P63/m with hexagonal unit cell parameters: a =10.0292(1), c =7.4623(1)Å, V =650.033(8) Å3, and Z =2. This compound is stable up to 1473K 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 1Cr atom in formula Sr5(CrO4)3(Cu0.586(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 Cr5+ cations and copper as Cu+. [Copyright &y& Elsevier]