Elastic constants of single crystals of yttria-stabilized zirconia were determined through the temperature range 20" to 700°C. Crystals containing 8.1, 11.1, 12.1, 15.5, and 17.9 mol% YzO3 were measured. The elastic constant CI1 was found to decrease and CI2 and C, to increase with increasing YzO, content; this appears to be due to decreasing coulombic interaction as Y" replaces Zr"'. Except for the 8.1 mol% Y203 crystal, the conventional elastic constants all showed normal monotonic decreases with increasing temperature. In the case of the 8.1 mol% YzO, crystal, measurements as a function of temperature were not reproducible, and it is likely that this composition at room temperature is below the composition limit of thermodynamic stability of the cubic fluorite phase.
The elastic constants of a single crystal of pure thorium have been measured over the temperature range 4.2–300 K. Measurements were repeated on the same crystal after sufficient carbon had been added to bring the composition to ThC0.063. The results show that carbon addition strengthens thorium with respect to dilational deformation and with respect to torsional deformation along 〈110〉 directions, but weakens thorium with respect to torsional deformation along 〈100〉 directions. The changes with respect to torsional resistance result in a reduced anisotropy ratio, 2C44/(C11−C12). Carbon addition raises the Debye temperature by only ∼3%. Magnetic susceptibility measurements were made on the crystal both before and after carbon addition. The overall results are in qualitative accord with a directional covalent character for the Th-C bonding interactions.
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