EOS Of Solid And Its Application In High Temperatures And High Pressures

Equation of state (EOS) is the relationship of every variable parameter, such as pressure, volume (or density) and temperature, for substance system under thermodynamic equilibrium. The study on the equation of state is a fundamental problem and an important content in physics. Making scientific researches on the EOS of compressed solids are the needs of producing, devising of weaponry and developing of other subjects. It is also the foundation that the solids can be extensively applied to practical producing and living. The investigations on the EOS of compressed solids are necessary in many basic sciences and interdisciplinary areas, e.g. geophysics, planetary science, astrophysics, physics of condensed matter, atomic and molecular physics, thermodynamics, statistical physics, etc.. They are also of important utilized values in the material science, explosive mechanics, energy engineering, aviation technicality and so on applied sciences. In this paper, we discourse upon the fundamental theory of EOS, mechanic and thermodynamic properties of solids. We also discussed some applicable semi-empirical ,semi-theoretical EOS of solids. An equation about the relation between volume thermal expansion coefficient and volume, temperature is presented. On the analysis of experimental values, we presented a new relationship for the product of volume thermal expansivity and bulk modulus with temperature. For the sake of validation, analysis and discussion,we put it into isobaric EOS and high temperature-high pressure EOS. The results show that it was valuable in application to some materials. We hope it can be applicable widely in other solids. In the introduction, we biefly describe the fundamental conceptions of EOS, review its development history, illustrate its typical applications in many fields, and recommend its predominant methods of investigating EOS at present. We mainly emphasize the EOS of solids in this paper, so we also recommended some properties of solids in this chapter-compression strain, elastic moduli, completeEOS, polynomial EOS, its principles of energy and pressure of crystals in static situation (when temperature T=0K), its thermal pressure and thermal energy contacting with the vibration of crystal lattice and electron. In chapter two, some thermodynamic parameters are being classified, summarized and analyzed. They are very important in studying the properties of solids and in deducing equation of state. Analyzing them systematically is significant. On the assumption that the product of volume thermal expansivity and bulk modulus based on the thermodynamic approximation theory, a new equation is presented for volume thermal expansion coefficient. On the analysis of some experimental values, a new equation between the product of and temperature is proposed. In the three chapter, the EOS used constantly at present by many investigators are elucidated and discussed according to theory foundation, phenomenological potential models, experimental bases, and the applied conditions of EOSs. We mainly discussed the isobaric EOSs, high temperature-high pressure EOSs and bulk modulus, shear modulus, second-order elastic moduli of solids. We analysed their validity and applicability. The equations proposed in this paper , being putted into isobaric EOSs and high temperature-high pressure EOSs, are used in MgO and other minerals for calculating the volume expansion(V/V0),bulk modulus from room temperature, respectively. The calculated results are being compared with the experimental values and the results obtained from other EOSs. From comparison we can conclude:For other EOSs if we calculate the corresponding values of minerals from room temperature, the error between the results obtained from other EOSs and the experimental values rises with the raising of temperatures, and the error can't being neglected at high temperature. But the results calculated using our equations haven't this trend. For every solid, they agree well with the experimental values at the whole temperature range we...