Elastic constants of yttria (Y2O3) monocrystals to high temperatures

The single-crystal elastic moduli of yttria have been measured by Brillouin spectroscopy up to 1200 degreesC. The room temperature values obtained are C-11 = 223.7 +/-0.6 GPa, C-44 = 74.6 +/-0.7 GPa, and C-12 = 112.4 +/-1.1 G Pa. The resulting bulk and (Voigt-Reuss-Hill) shear moduli are K = 149.5 +/ -1.0 GPa and G(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 t o the variation of bulk and shear moduli with temperature result in derivat ives of dK/dT = -17 +/-2 MPa/degreesC and dG(VRH)/dT = -8 +/-2 MPa/degreesC . Elastic anisotropy was found to remain essentially constant over the temp erature range studied. (C) 2001 American Institute of Physics.