Preparation and characterization of YAG materials doped with Nd, Yb or Er

YAG materials doped with Nd, Yb or Er have been prepared by reactive sintering using nanometric and submicrometric powders. The obtained results (density, transparency and microstructure) are related to the powder processing. The influence of the technique used to eliminate the solvent (spray drying in ethanol or evaporation by rotavapor & sieving) on the final microstructure is shown. Other processing features as the pressure during cold isostatic pressing, the use of a lubricant to ease the mutual sliding among particles during pressing, the calcination and sintering cycles are related to the microstructure evolution during sintering. Calcination is conducted in air at 800°C or 1100°C. Sintering is performed at 1700-1800°C for 8-16 h in a clean atmosphere furnace under high vacuum (10-6 millibar). Annealing cycle, when performed, is conducted at 1300°C x 1 h. The transmittance of samples is also reported (UV/VIS Lambda 35 Spectrometer, Perkin Elmer)