The Single-Crystal Elasticity of Yttria (Y2O3) to High Temperature

The single-crystal elastic moduli of yttria have been measured by Brillouin spectroscopy up to 1200 C. The room temperature values obtained are C11 = 223.6 +/- 0.6 GPa, C44 = 74.6 +/- 0.5 GPa, and C12 = 112.4 +/- 1.0 GPa. The resulting bulk and (Voigt-Reuss-Hill) shear moduli are K = 149.5 +/- 1.0 GPa and G(sub VRH) = 66.3 +/- 0.8 GPa, respectively. These agree much more closely with experimental values reported for polycrystalline samples than do previous single-crystal measurements. Linear least squares regressions to the variation of bulk and shear moduli with temperature result in derivatives of dK/dT = -17 +/- 2 MPa/degC and dG(sub VRH)/dT = -8 +/- 2 MPa/degC. Elastic anisotropy was found to remain essentially constant over the temperature range studied.