Chemical gelation of cerium (III)-doped yttrium aluminium oxide spherical particles

A novel low-temperature (900 °C) chemical gelation method was developed to synthesize spherical and nonagglomerated Ce3+-doped yttrium aluminum oxide particles (YAG:Ce3+). This represents a process with a much lower processing temperature than current solid-state reaction processes (1400 °C). Characterization of the particles via x-ray diffraction and thermoanalytical methods showed that calcination at 900 °C for 2 h allowed direct crystallization from the amorphous phase, inferring that this process allows homogeneous mixing and increased precursor reactivity. Electron microscopy results showed that the spherical particles (∼100 to ∼3 μm) were the flocks of crystallites. The crystallite sizes (Rietveld refinement) grew linearly from 27 nm (900 °C) to 114 nm (1300 °C). The surface area decreased from 40 m2/g (900 °C) to 5 m2/g (1300 °C) because of the coagulating and growing of crystallites to bigger grains at 1300 °C. Single-crystal nanoparticles (around 100 nm) were obtained with this process and their atomic structures were revealed via high-resolution transmission electron microscopy.