Low temperature synthesis of microwave dielectric LaAlO3 nanoparticles: effect of chloride on phase evolution and morphology

A novel chemical synthesis route has been developed to prepare LaAlO3 from low cost inorganic precursors, by gelation–precipitation technique. Phase evolution, morphology, agglomeration and surface area were studied as a function of chloride content and heat treatment temperature. The samples containing chloride crystallized at 1100 °C with the formation of intermediate phases. The product was highly agglomerated and had low surface area. On the contrary, the as-synthesized chloride-free samples crystallized directly to pure LaAlO3 perovskite phase at 600 °C, which is the lowest crystallization temperature achieved so far. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) of chloride-free samples reveal very fine clusters of nanosized spherical particles. The as synthesized and calcined chloride-free samples have a high surface area and are thermally stable upto 1600 °C without decomposition.