PREPARATION OF LA1-XSRXMNO3 POWDERS BY COMBUSTION OF POLY(ETHYLENE GLYCOL) METAL NITRATE GEL PRECURSORS

La1-xSrxMnO3 powders were prepared by auto-ignited combustion of poly( ethylene glycol) (PEG)-metal-nitrate gel precursors. The thermal behav iour of the precursors strongly depends on the ratio of PEG to metal n itrate, which is closely related to the ratio of fuel to oxidizer. The burning behaviour in a furnace was successfully explained by valence concepts normally encountered in propellant chemistry. The formation o f a pure perovskite phase was significantly influenced by the homogene ity of the gel precursor. Perovskite structured oxides were formed thr ough two different paths, one of which was direct formation from the b urning of a gel precursor and the other was a subsequent structural ev olution by heat treatment after burning. The formation procedure of th e perovskite and the morphology of powders could be explained in terms of the burning behaviour of the precursor and the role of organic res idue.