Size effects in magnetotransport in sol–gel grown nanostructured manganites

Abstract

We report the results of the studies on polycrystalline nanostructured La0.7Pb0.3MnO3 (LPMO) manganites synthesized using sol–gel method employing metal acetate precursor route. Interestingly, it is observed that crystallite size decreases with increase in sintering temperature while microscopic investigations reveal the second grain growth in all the samples. A correlation between the grain morphology and secondary grain growth with the transport and magnetotransport in LPMO manganites has been established. Observation of large temperature sensitivity (~−28.29 %/K @ 0 T; >300 K) and field sensitivity (~−48.70 %/T @ 0.2 T; 5 K) in the samples sintered at higher temperature (~1150 °C) has been understood in the light of observed secondary grain growth in the form of nanosized grains over the surface of primary grains.