The 'Revolution in Materials' shows every sign of a continuation, probably with an increase in pace of development. The driving force into advanced engineering materials, perhaps better described as advanced engineering materials for engineering applications, is the requirement for their satisfactory performance under severe environment such high temperature T and/or high pressure p. From the knowledge of the structural and cohesive properties at ambient condition, one can determine the p-V relation or equation of state (EOS). The equations of state (EOS) (static as well as dynamic) provide us useful information about the structural stability of given material at a given thermodynamic state. It also gives information about the possible phase transitions in the specified material.