Microwave synthesis of magnetoresistive La0.7Ba0.3MnO3 using inorganic precursors

We report here the use of inorganic precursors as good microwave absorbers, by virtue of its polarity and high dielectric constant, to synthesize high temperature stable rare earth manganite, La0.7Ba0.3MnO3. Compared to other wet chemical methods, the oxides prepared by microwave assisted route give fine particle oxides (< 30 nm) with effective BET surface area of similar to 25 m(2)/g. Two factors contribute to the rapid synthesis of these high t emperature phases. Firstly, the dielectric constant of the precursors emplo yed increases the microwave power loss in the material and this leads to a local heating effect. Secondly decomposition of these precursors, lead to f ormation of finely divided oxides often accompanied by an exothermic reacti on which provides the needed energy to effect the formation of the product. This method offers a new approach to employ inorganic precursors as starti ng materials to realize fast and effective reaction in microwave assisted m aterial synthesis. (C) 2001 Kluwer Academic Publishers.