Magnetic spin glass properties of the bi-layer hydrate Na0.3NiO2·1.3H2O

The magnetic properties of the new metal oxide bi-layer hydrate Na0.3NiO2·1.3H2O were investigated. DC and AC magnetic susceptibility measurements revealed the compound to be a spin glass at low temperatures with a freezing point of Tf∼3.5 K. Using the Vogel–Fulcher relationship an activation energy of Ea/k∼71.6 K, a Vogel–Fulcher temperature of To∼1.9 K and a frequency dependence of the freezing temperature consistent with a frustrated magnetic spin-glass rather than a RKKY spin glass were determined. Ni K-edge X-ray absorption spectroscopy (XAS) show an absorption edge shift toward higher energies in Na0.3NiO2·1.3H2O compared to Na0.7NiO2 and suggests that Ni occurs in two possible electronic configurations: a combination of 3d7 (S=1/2) and 3d6 (S=0) or 3d7L states, with L representing a hole in the oxygen p-states.