Magnetic properties of Co2-xCux(OH)PO4 (x=0, 1 and 2)

The isostructural Co_2-xCu_x(OH)PO₄ (x=0, 1 and 2) phases have been prepared from hydrothermal synthesis and characterized from powder X-ray diffraction. The structure consists of a three-dimensional framework in which M(1)O₅-trigonal bipyramid dimers and M(2)O₆-octahedral chains are simultaneously present. Magnetization measurements of Co₂(OH)(PO₄) show the existence of two maxima attributed to a three-dimensional antiferromagnetic ordering at 70 K and a spin-glass-like state at 12 K. When Co²⁺ is substituted by Cu²⁺ions, the spin-glass behavior disappears and the magnetic order is decreased.