Elastic moduli of transparent yttria

The elastic moduli of yttria (Y2O3) samples that were made from powders wit h various particle morphologies were studied by means of ultrasonic measure ments. The sound-wave velocities in the longitudinal and transverse modes w ere measured. The elastic moduli sere calculated from the sound velocities and density. For the high-purity, high-density (>5000 kg/m(3)) Y2O3 that wa s prepared in the present study, the average density and elastic moduli (an d their standard deviations) were as follows: density (rho) of 5020 +/- 18 kg/m(3), Young's modulus (E) of 179.8 +/- 4.8 GPa, shear modulus (G) of 69. 2 +/- 2.0 GPa, bulk modulus (B) of 148.9 +/- 3.0 GPa, and Poisson's ratio ( v) of 0.299 +/- 0.004. The average longitudinal and transverse soundwave ve locities (V-l and V-t, respectively) were 6931 +/- 65 and 3712 +/- 39 m/s, respectively. The elastic moduli of lanthana-strengthened yttria (LSY) were similar to 6% lower than those of high-purity Y2O3, and the v value for LS Y was similar to 0.304. It has been argued that soundwave velocity is bette r than density, in regard to predicting the elastic moduli of fully dense a nd slightly porous materials. A linear equation that describes the change o f the elastic moduli with soundwave velocity alone has been suggested. This equation was applicable to a relative elastic moduli range of 0.75-1.02.