COMBUSTION SYNTHESIS OF PEROVSKITE LNCRO(3) POWDERS USING AMMONIUM DICHROMATE

Fine-particle LnCrO(3) perovskites, where Ln=rare earths, have been prepared by the exothermic redox decomposition of ammonium dichromate, lanthanum nitrate and glycine mixtures. The self-redox decomposition of ammonium dichromate enabled LnCrO(3) to be formed by combustion synthesis using less glycine than mixtures containing chromium nitrate. Autoignition temperatures for precursor mixtures containing ammonium dichromate were lower than those containing chromium nitrate (<170 degrees C versus 180 to 210 degrees C, respectively). Ammonium dichromate-containing precursors combusted at lower temperatures and produced powders having higher surface areas than precursor solutions containing chromium nitrate.