Temperature coefficients of elastic constants of single crystal MgO between 80 and 1,300 K

Elastic constants of single crystal MgO have been measured by the rectangular parallelepiped resonance (RPR) method at temperatures between 80 and 1,300 K. Elastic constants C _ij (Mbar=10³ kbar) and their temperature coefficients (kbar/K) are: $$begin{gathered} {text{ }}C_{{text{11}}} {text{ }}C_{{text{12}}} {text{ }}C_{{text{44}}} {text{ }}K_s {text{ }}C_s hfill C_{ij} {text{ 300 K 2}}{text{.966 0}}{text{.959 1}}{text{.562 1}}{text{.628 1}}{text{.004}} hfill partial C_{ij} {text{/}}partial T{text{100 K }} - {text{0}}{text{.259 0}}{text{.013 }} - {text{0}}{text{.072 }} - {text{0}}{text{.078 }} - {text{0}}{text{.136}} hfill {text{ 300K }} - {text{0}}{text{.596 0}}{text{.068 }} - {text{0}}{text{.122 }} - {text{0}}{text{.153 }} - {text{0}}{text{.332}} hfill {text{ 800 K }} - {text{0}}{text{.619 0}}{text{.009 }} - {text{0}}{text{.152 }} - {text{0}}{text{.200 }} - {text{0}}{text{.314}} hfill {text{ 1,300 K }} - {text{0}}{text{.598 0}}{text{.036 }} - {text{0}}{text{.130 }} - {text{0}}{text{.223 }} - {text{0}}{text{.218}} hfill end{gathered} $$ By combining the present results with the previous data on the thermal expansivity and specific heat, the thermodynamic properties of magnesium oxide are presented and discussed. The elastic parameters of MgO at very high temperatures in the earth's lower mantle are also clarified.