Structural and magnetic characterisation of CoSb2O4, and the substitution of Pb2+ for Sb3+

The nuclear and magnetic structures of the synthetic schafarzikite related material CoSb2O4 have been determined from neutron powder diffraction data. The compound is tetragonal (P42/mbc) with refined lattice constants at 300 K of, a=8.49340(9) Å, c=5.92387(8) Å. The magnetic ordering is shown to be consistent with a C mode with moments aligned along [0 0 1]. Magnetic susceptibility measurements indicate a canted antiferromagnetic ground state, for which the ferromagnetic component shows unusually high coercivity. The thermal stability of CoSb2O4 in air is reported. The substitution of Pb2+ for Sb3+ has been investigated and found to cause oxidation of both Co2+ to Co3+ and Sb3+ to Sb5+.