Abstract
AbstractNanocrystalline La0.67Ca0.33MnO3 powders were prepared from organic precursors using a microwave synthesis technique. A variation of the precursor solution pH and annealing temperature was found to change the effective Mn4+ concentration which leads to variations in electronic behavior. In all the cases however, a single phase microstructure was observed showing the stability of orthorhombic manganite. The nanocrystalline manganite prepared from a solution with a pH of 10.5 has the lowest Mn4+ and accordingly low electrical and magnetic transition temperatures. The electrical transport behavior of powders prepared from precursor solutions with pH of 11.5 and 12.5 could be modeled using an effective medium approach across the whole temperature range, 30 K to 300 K. The magnetoresistance in these nanocrystalline manganites increases with decreasing temperature, an effect of increased grain boundaries. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Published Version
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