MICROSTRUCTURAL EVOLUTION OF NANOSIZED LAFEO3 POWDERS FROM THE THERMAL-DECOMPOSITION OF A CYANO-COMPLEX FOR THICK-FILM GAS SENSORS

Nanosized, single-phase perovskite-type LaFeO3 powders are prepared by the thermal decomposition at 600 degrees C of a hexacyanocomplex, La[ Fe(CN)(6)].5H(2)O. The formation of LaFeO3 and its microstructural evo lution with the temperature have been studied by simultaneous thermogr avimetric and differential thermal analysis (TG/DTA), x-ray diffractio n (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). LaFeO3 is formed by the decomposition of the comple x with a peculiar morphology, consisting of nanosized particles in sof t agglomerates with the same size and shape of the complex grains. The nanosized particles are free of pores, making the powders suitable fo r application in thick film fabrication, after disruption of the agglo merates, for their use as active elements for gas sensors. Preliminary experiences are encouraging the use of this sensor for NO2 detection in the real environment. (C) 1997 Elsevier Science S.A.