Production of transparent yttrium oxide ceramics by the combination of low temperature spark plasma sintering and zinc cation-doping

Abstract

1mol% Zn2+-doped Y2O3 powder was consolidated utilizing spark plasma sintering (SPS) by systematically varying the heating schedule, sintering temperature, heating rate, holding time at the sintering temperature, and loading stress. Transparent, Zn2+-doped Y2O3 polycrystals were successfully produced at the heating rate of 2°C/min, sintering temperature of 890°C, holding time of 30min, and loading stress of 150 or 170MPa. The highest transmittance in the Zn2+-Y2O3 bodies at a wavelength of longer than 600nm was comparable to those in the undoped SPSed Y2O3 in the literature. Employing a sintering temperature and loading stress higher than the optimum values led to coarsened pore and grain sizes, resulting in a decreased transparency. Low heating rate at temperatures above 700°C was desirable for the attainment of high transparency. The grain boundary segregation of Zn2+ cations effectively contributed to the reduction of the sintering temperature required for attainment of transparency in the Y2O3 by SPS.