Pressure Dependence Of Expansivity Research Articles

A finite strain approach to thermal expansivity’s pressure dependence

The pressure dependence of thermal expansivity affects mineral density at pressure and is an extrapolator for calculating self-compression adiabats of a self-gravitating body. I review different models for the pressure dependence of expansivity and how to decide which performs best. A finite strain model, proposed here, performs better when used to calculate adiabatic temperature lapses in both the solid silicate and liquid metal parts of a planet than either an ad-hoc exponential dependence on pressure or a commonly used mineral physics model. Choosing a particular thermal expansivity pressure dependence leads to significantly different temperatures in planetary interiors, and to inferred subsolidus properties related to homologous melting temperature. In particular, thermal expansivity in liquid metal in planetary cores at pressures comparable to Earth’s core is significantly affected. The universality of the parameterization provides a simple way to model rocky planet interiors in our solar system and exoplanet interiors.

Pressure dependence of expansivity in the liquid hexane as a model for liquids

Along isothermal paths, the expansivity of liquid hexane is shown to follow a power law up to a few hundred MPa. The pole of this function is found to be close to the expected limits of thermodynamic stability (spinodal) of the liquid state. Analysis of argon and carbon dioxide data shows that the model may be extended to other liquids. A similar equation may be used to fit the isothermal compressibility data A temperature constante, variation du coefficient de dilatation suivant une loi de puissance de la pression jusqu'a plusieurs centaines de MPa. Observation de la presence du pole de cette fonction a proximite du lieu estime de la spinodale de l'etat liquide. Validite de cette propriete pour d'autres liquides. Relation similaire pour decrire la variation de la compressibilite isotherme avec la pression

Power Law Behavior of the Pressure Dependence of Expansivity in the Liquid Hexane as a Model for Liquids. Limit of Thermodynamic Stability

ABSTRACTIn this work a power lay is used to fit the isothermal pressure dependence of the expansivity α = V−1(∂V/∂T)p of liquid hexane. This functional form is also observed to fit the expansivity and the isothermal compressibility KT = −V−1(∂V/∂P)T data of the three liquids : hexane, argon, carbon dioxide.