Crystal structure and electrical transport properties of single layered perovskite LaSrCoO₄

We present here investigations on the influence of structure on electrical transport properties of polycrystalline LaSrCoO₄ that is single layered perovskite with K₂NiF₄ type structure synthesized using solid state reaction route. Using Reitveld refinement of X-ray diffraction (XRD) data, it is found that the sample is in single phase with tetragonal structure (space group I4/mmm). Electrical resistivity performed in the temperature range 140-300K shows semiconducting character of the sample. Considerable contrasts in the Co-O bond length is associated with the intermediate spin (IS) state of Co ion that correlates the structural and transport properties. Detailed analysis indicates that the temperature dependent electrical resistivity follows the three-dimensional variable range hopping (VRH) model in low temperature region below 225K. The high temperature (225-300K) resistivity data has been found to follow the thermally activated behaviour.