Soft chemical synthesis and transport properties of La0.7Sr0.3MnO3 granular perovskites

The thermal decomposition of a precursor complex, using ethylenediaminetetr aacetic acid (EDTA) as a complexing agent, was introduced to synthesize La0 .7Sr0.3MnO3 granular perovskites. The dependence of crystallization, grain size and surface morphology on calcination temperature was investigated. Sp in-dependent interfacial tunneling magnetoresistance corresponding to micro structure was observed. Our results indicate that decreasing grain size lea ds to broadening of the ferromagnetic-paramagnetic transition and enhanceme nt of the extrinsic magnetoresistance caused by grain boundaries. Further d ecrease in grain size will result in the disappearance of the metal-insulat or transition and weakening of the magnetoresistance effect at room tempera ture. (C) 2000 Elsevier Science Ltd. All rights reserved.