Highly-doped Nd:YAG ceramics fabricated by conventional and high pressure SPS

Spark plasma sintering (SPS) is an effective process for the fabrication of highly transparent oxide ceramics for photonic applications. In the present study, Nd-doped yttrium aluminum garnet (Nd:YAG) ceramics with various dopant concentrations (0.5-5 at.%) were fabricated at 1300-1400 degrees C using conventional SPS (60 MPa) and high pressure (300 MPa) conditions. The appearance, X-ray diffraction pattern, densification regime, microstructure, mechanical and optical properties were compared; the dependency on Nd concentration and sintering pressure is discussed. The pressure applied during the sintering process seemed to have only a minor effect on the luminescent properties, while the mechanical properties were superior for the samples sintered under high pressure conditions. The known concentration quenching phenomenon was observed and an equation for estimation of the Nd concentration, based on phosphorescence lifetime, is suggested.