Chemical vapour synthesis of lanthanum gallium oxide nanoparticles

Lanthanum-gallate nanoparticles have been prepared via chemical vapour synthesis (CVS) starting from metal acetylacetonates as solid precursors evaporated using a CO2-laser. The temperature in the CVS reactor has significant influence on crystallinity and phase composition of the as-synthesized particles. Higher temperatures (1100 °C and 1300 °C) result in nanocrystalline particles with monoclinic La4Ga2O9 and trigonal La2O3 as main phases due to gallium-oxide sublimation in the reactor. Lower temperatures (800 °C and 900 °C) limit evaporation, inhibit crystallization and yield amorphous particles. At 800 °C the volatility of Ga2O3 is low enough to generate nanoparticles containing an almost stoichiometric ratio of gallium to lanthanum of 1:1. Subsequent calcination is required to remove organic residues, however, the nanoscaled structure of the particles is preserved. Ceramics of lanthanum gallium oxide obtained by sintering CVS particles contain closed pores after sintering at 1300 °C and a microstructure with close to theoretical density after sintering for only 1 h at 1400 °C.