High temperature electrical transport properties of nanophasic Ba^ sub 1-X^ Sb^ sub X^ MnO^ sub 3^

摘要: Nano-phasic Ba1-XSbXMnO3 have been synthesised through sol-gel citrate route. The XRD pattern has been found to be having some brown millerite phase along with pervoskite due to doping induced anti-site effect. The dependence of electrical transport at high temperatures have been studied employing thermal activation model, variable range hopping (VRH) and small polaron hopping model (SPH) to account for the experimental observation due to disorder induced localisation. The VRH parameters To, α throw light on the nature of grain boundary formation to achieve high MR in manganite. Decrease of To, with concentration and temperature is related to disorder in the lattice, which in turn connected to the conduction process across the grain boundaries. Higher activation energy of SPH is linked to increased barrier height for polaron hopping which arises out of mismatch of ionic radii of Ba to Sb is due to doping induced structural disorder (σ2).