Combustion synthesis and characterization of nanocrystalline LaAlO3 powders

Pure LaAlO3 powder was prepared by a combustion synthesis processing using a concentrated solution of nitrates of lanthanum and aluminate as oxidiser, and glycine acid as fuel, with the aim of obtaining nanosized crystallites of this material with high specific area at relatively low temperature. Precursor powders and calcined powders were characterized by differential thermal analysis (DTA), thermogravimetry analysis (TG), X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The results demonstrate that pure perovskite LaAlO3 powder formed at 700 °C for 2 h and the particle size ranges 78–100 nm. The specimen sintered at 1500 °C for 12 h shows the maximum bulk density and gave the best microwave dielectric properties: ɛr = 23 and Qf = 38,000 GHz.