Compression and Elastic Behavior of nc-MgO under High Pressure

In the present study, a theoretical model is developed by presenting the empirically modified extended form of the usual Tait equation of state to study the volume compression and elastic properties in nc-MgO under pressure. It is found that the extended form of usual Tait equation yields results very close to the experimental data. The validity of modified equation and usual Tait equation are tested according to Stacey criterion under infinite pressure and noted that the modified equation satisfies the Stacey criteria of stability while the usual Tait equation does not follow this criteria especially in high pressure range. Using modified form of Tait equation, we have thus determined the bulk modulus, shear modulus, Young's modulus and Poisson's ratio for MgO nanocrystal (7 nm) under pressure and the results so obtained are compared with the available experimental data. The pressure dependent elastic constants C11, C12, C44, shear velocity and compressional velocity are also determined with varying pressure. A good agreement with the available experimental data justifies the validity and applicability of the present model theory to explain the elastic behavior of nc-MgO under the effect of high pressure successfully.