Measured elastic moduli of single-crystal MgO up to 1800 K

Abstract

Using the rectangular parallelepiped resonance method we measured the temperature dependence of the adiabatic elastic moduli of single-crystal MgO over the temperature range 300–1800 K. The high temperature limit of our measurements extends by 500 K the upper limit over which elasticity data on MgO are now available. Although our measured temperature dependence of C ^s_ij are generally in good agreement with previous measurements over a more narrow range in temperature, we found that C ^s₄₄ decreases more rapidly with temperature, for T > 1000 K, than previous studies suggest. We also found that each of the slopes (ϱC ^s₁₁ /ϱT)_p, (ϱK_s/ϱT)_p, and (C ^s₄₄ /ϱT)_p become less negative with increasing temperature for T > 1400 K. From our measurements on elasticity we are able to confirm that the Grüneisen parameter at zero pressure is nearly constant with temperature up to 1800 K, with only a slight decrease above 1000 K. Utilizing our new data we present calculations showing the temperature dependence of thermodynamic parameters important in studies of earth's interior.