Magnetic properties of the LiMPO(4) (M=Co, Ni) compounds

Powder samples of LiNiPO4, LiCoPO4 together with LiMgPO4 doped with 0.1% of Co2+ were prepared by solid state reactions. Magnetic susceptibility measurements of the LiNiPO4 and LiCoPO4 compounds are consistent with 3D antiferromagnetic behaviour. The magnetic exchange value for the LiNiPO4 phase is -5.61 K, with a g-value of 2.15. The EPR study of LiMgPO4 doped with 0.1% of Co2+ shows the large magnetic anisotropy of the Co2+ ion in a distorted octahedral geometry. The obtained values at 4.2 K for the spin Hamiltonian parameters are g(1) = 6.16, g(2) = 4.14, g(3) = 2.53 and A(1) = 246 x 10(-4), A(2) = 89 x 10(-4) and A(3) < 20 x 10(-4) cm(-1).