The elastic constants of single crystal Fe1-xO,MnO and CoO,and the elasticity of stoichiometric magnesiowuestite.

Abstract

Elastic constants of single-crystalline Fe1-xO (x=0.08), MnO and CoO have been measured by the rectangular parallelepiped resonance (RPR) method at temperatures between 30°C and Néel point TN (TN≅-87°C for Fe0.92O, ≅ -150°C for MnO and ≅16°C for CoO). In Fe0.92O and MnO, the shear constant C44 (or Cs for CoO) shows a drastic change at and around the Néel temperature, while the bulk modulus Ks and another shear constant Cs (or C44 for CoO) continue to show a linear temperature dependence even in the vicinity of the Néel point. The anomalous temperature variation of C44 in Fe0.92O persists above room temperatures. By using several empirical rules, the elastic properties of stoichiometric wüstite and magnesiowüstite are also evaluated. The elastic constants (Mbar) and their temperature coefficients (kbar/deg) at room temperature are: