Densification and microstructural evolution of yttria transparent ceramics: The effect of ball milling conditions

Ho:Y2O3 ceramics were prepared by using solid-state reaction method with commercial oxide powders. The effect of ball milling condition, specifically slurry concentration (CS), on densification, microstructure evolution and transmittance of the Ho:Y2O3 ceramics was studied. Ho:Y2O3 powders were ball milled with slurry concentrations of 33.2–17.4 vol%. The samples were vacuum sintered between 1400 and 1850 °C. Over the CS range of 33.2–18.4 vol%, decreasing slurry concentration improved the densification, normal grain growth and optical transmittance of the Ho:Y2O3 ceramics. The 18.4 vol% Ho:Y2O3 powders showed the lowest agglomeration and highest densification rate, from which the ceramics prepared have the best transmittance. The grain growth exponents of the Ho:Y2O3 ceramics during final-stage of sintering were also studied.