Synthesis of La0.9Sr0.1Ga0.8Mg0.2O2.85 by successive freeze-drying and self-ignition of a hydroxypropylmethyl cellulose solution

The present paper reports the synthesis of La0.9Sr0.1Ga0.8Mg0.2O2.85 perovskite powders by a method combining freeze-drying and self-ignition of an aqueous solution of metallic nitrates containing hydroxypropylmethyl cellulose. The precursor powder obtained after self-ignition was submitted to various thermal treatments and the resulting powders were characterized by X-ray diffraction, electron microscopy, nitrogen adsorption-desorption isotherm analysis, mercury porosimetry and laser granulometry. It turns out that this synthesis method yields single-phase powders with good homogeneity and sinterability properties. The precursor powder treated at 1200 °C presents a coral-like structure which collapses under application of low uniaxial pressure, resulting in a narrow grain size distribution suitable for sintering (98.8% relative density for a pellet sintered at 1400 °C during 1 h). The fact that no milling step is necessary is an additional advantage of this method, which shows promising prospects for the synthesis of other multicationic oxides.