Ammonium-cobalt-nickel phosphates, NH4[Co1-xNixPO4] • H2O

The ammonium-cobalt-nickel phosphates, NH4[Co1-xNixPO4]center dot H2O (x=0.00, 0.34, 0.59, 0.70,1.00), and the deuterated forms, ND4[Co1-xNixPO4]center dot D2O D20 (x=0.00, 0.38, 0.48, 0.69, 0.85), have been synthesized under mild hydrothermal conditions and characterised using X-ray and neutron diffraction, chemical and thermal analysis, and magnetic measurements. Their crystal structures, including hydrogen positions, were determined by Rietveld refinement using single-crystal X-ray and neutron powder diffraction data. The space group of these orthorhombic crystals modifies as a function of their composition. The magnetic susceptibility and magnetization measurements of these ammonium-cobalt-nickel phosphates show antiferromagnetic behaviour, and the Neel temperature evolves from 55 K (x=0.00) up to 13.2 K (x=1.00). (C) 2013 Elsevier Inc. All rights reserved.