Thermoelastic properties of magnesiowüstite, (Mg_1−xFe_x)O: determination of the Anderson–Grüneisen parameter by time-of-flight neutron powder diffraction at simultaneous high pressures and temperatures

The lattice parameters of Mg_1−xFe_xO (x = 0.2, 0.3, 0.4) in the range P < 10.3 GPa and 300 < T < 986 K have been determined by time-of-flight neutron powder diffraction. Fitting all data simultaneously to a P–V–T–x equation of state leads to values for the temperature derivative of the isothermal incompressibility, ∂K_T/∂T, and the isothermal Anderson–Grünseisen parameter, δ_T, of −0.024 (9) GPa K⁻¹ and 4.0 (16) at 300 K.