Nd:Y2O3 nanopowders for laser ceramics

Nanopowders of Nd-doped yttrium oxide were obtained by chemical co-precipitation method using nitrate salts solutions and different precipitant agents - urea, ammonium carbonate and oxalic acid. Precursor and oxide particles agglomeration, particle form, particle size and specific surface area depend critically upon experimental conditions. Plates and rods were formed with hydroxycarbonate and oxalates precipitation correspondingly, whereas hydroxynitrates gave more uniform spherical particles’ shapes. Calcination at 900–1200 °C gave oxide powders with specific area in the range 15–50 m2/g. High energy ball milling was used to decrease grain agglomeration. Powders with around 100 nm size were used to prepare pellets by slip casting into porous moulds using PMMA or PAA additives to reduce viscosity of the slurries with high powder contents. The pellets density around 0.48–0.52 of the theoretical value was obtained. Vacuum sintering of the pellets at 1700–1800 °C gave transparent ceramic samples with grain size between 10 and 50 μm. The most serious defects in the ceramics are closed pores which reduce their transparency.