Thermal expansivity and derivative properties of materials at extreme compression
We make use of some basic principles of calculus for an analysis of thermodynamic identities at extreme compression given by Stacey. The thermal expansivity of materials becomes zero at infinite pressure or extreme compression. The validity of this result originally due to Stacey has been proved in the present study in a simple manner. Higher order thermoelastic properties obtained from the derivatives of thermal expansivity have been investigated in the limit of infinite pressure. The most important results found in the present study reveal that temperature derivatives of bulk modulus become independent of pressure, and second pressure derivatives of bulk modulus become independent of temperature for materials at extreme compression.
Keywords: Thermal expansivity, Anderson-Grüneisen parameter, pressure derivatives and temperature derivatives, extreme compression behaviour