Investigation of YAP/YAG powder sintering behavior using advanced thermal techniques Sintering to transparency

The fabrication process of transparent YAG (Y3Al5O12) ceramics with an emphasis on examination of the sintering process and microstructural analysis is reported herein. Nanometric powder with an equivalent spherical diameter d(BET) = 60 nm consists mainly of hexagonal YAP phase (YAlO3). According to sintering analysis carried out using a dilatometer and high-temperature XRD analysis, the phase composition and phase transformation taking place at elevated temperatures accompany the sintering process and the fastest sintering rate was observed at temperatures of YAG formation. Based on the dilatometric and XRD analyses vs temperature, three temperatures were selected for pressureless sintering. Presintered samples were subjected to sintering under isostatic pressure using a hot isostatic pressing, after which transparent YAG was obtained. The best results were obtained for samples presintered at a relatively low temperature of 1600 degrees C, and for thus obtained sample, the in-line transmittance was 64% at lambda = 808 nm.