Synthesis And Characterization Of Rare Earth Doped YAG Nanopowders

In this paper, We briefly illustrated the development and synthesis methods of Nd:YAG nanopowders and transparent ceramics. In addition, the development and application of supercritical drying technology were also introduced.In this paper, aluminum nitrate, yttrium nitrate, neodymium nitrate as raw materials, ammonium bicarbonate and urea as precipitation, respectively, a series of neodymium-doped yttrium aluminum garnet precursor powders were synthesized by chemical precipitation method combined with CO2 supercritical fluid drying, and calcined at different temperatures. The precursor and calcined products were characterized by XRD, FT-IR, TG/DTA, SEM, BET and fluorescence spectrophotometer test. The results showed that 1% Nd:YAG precursor powders were synthesized by ammonium bicarbonate co-precipitation combined with CO2 supercritical fluid drying, the specific surface area was 271.64m2·g-1. XRD results showed that the precursor powders were crystalline, YAG generated at 1100℃in air for 2h, including Y2O3 and YAM. When calcined temperature was 1400℃, pure YAG was not still obtained. The precursor powders which synthesized by urea homogeneous precipitation combined with conventional drying method composed of mixtures of amorphous hydroxide and carbonate, the specific surface area are small and serious agglomeration, after calcined at 1000℃in air for 2h, pure Nd:YAG were obtained, but the size distribution of particles was uneven, the dispersity were poor and agglomerate seriously. Compared with conventional drying method, CO2 supercritical fluid drying improved serious agglomeration that appeared in conventional drying method, so the precursor powders had good dispersion and high specific surface area and sintering activity. CO2 supercritical fluid drying samples which calcined at 800℃could be directly generated single YAG crystal phase, and intermediate phase did not appear. The powders which calcined at 1000℃still maintain a good dispersion, and particles were spherical shape, size distribution was between 35-45nm. In addition, the samples with different Nd doped were crystalline YAG phase, no intermediate phase. The cell parameters increased with the amount of Nd doping, but 20 decreased with the Nd increasing. The fluorescence spectra showed that the emission spectra and excitation spectra intensity increased with the rising of the sintering temperature, but it increased before the Nd-doped content 0.8%, and then descend with the increase of Nd-doped content.