Molar volume model for olivine solution

Abstract A new molar volume model for multicomponent olivine solid solutions, considering the linear summation of molar volumes of individual configurations weighted by their respective cation distribution fractions, is developed in this study. The model encompasses four possible configurations within olivine, each involving two distinct divalent ions occupying two different sites. Using available experimental data and employing the compound energy formalism to calculate cation distribution fractions, the study derives temperature‐dependent molar volume expressions for various olivine configurations. Strong correlations between the estimated molar volume and the effective ionic radii of constituent cations are established, allowing for the estimation of molar volume for olivine configurations without experimental data. The results provide a robust framework for accurately estimating the molar volume of olivine across diverse compositions and temperatures, enhancing our understanding of its thermal expansion characteristics. Moreover, these estimated molar volume expressions and observed correlations enable comprehensive insights into the thermal expansion behavior of multicomponent olivine solid solutions.