Neutron diffraction studies of magnetic ordering in Ni-doped LaCoO

Research in rare earth cobaltite has recently been intensified due to its fascinating magnetic properties. LaCoO ₃, an important cobaltite, exhibits two prominent susceptibility features at ~90 K and 500 K in low field measurement. The magnetic behavior below 100 K is predominantly antiferromagnetic (AFM), but absence of pure AFM ordering and emergence of ferromagnetic coupling on further decreasing temperature made situation more intricate. The present work of studying the effect of Ni substitution at Co site in polycrystalline LaCo _1−xNi _xO ₃ (0≤ x ≤0.3) is motivated by the interesting changes in magnetic and electronic properties. For lucid understanding, temperature dependent neutron diffraction (ND) study was carried out. ND patterns fitted with rhombohedral structure in perovskite form with R-3c space group, elucidated information on phase purity. Further temperature dependent cell parameter, Co–O bond-length and Co–O–Co bond angle were calculated for the series of Ni doped LaCoO ₃ . The results are explained in terms of decrease in the crystal field energy which led to the transition of cobalt from low Spin (LS) state to intermediate spin state (IS).