Properties of minerals at high temperatures and pressures: MgO as an example

734-736A simple theoretical method is investigated for the determination of the properties of minerals under the effect of high temperature and pressure. It is found that the formula for thermal expansivity derived in the present paper reduces to the relation derived earlier at P = 0. The superiority of the relation is discussed by investigating the variation of the coefficient of volume thermal expansion under the effect of temperature at P = 0. The results are also obtained under the effect of high pressures along different isotherms, viz. 1000, 1500, 2000 and 2500 K, and compared with the results based on ab initio method. A good agreement supports the validity of the relations reported in the present paper