First-principles modelling of thermomechanical and thermodynamical properties of CaMnO3-delta-based perovskites

Abstract

This thesis investigates the material properties of perovskites, specifically focusing on potential applications in thermal energy storage. A comprehensive analysis of the thermophysical characteristics of the perovskites CaMnO3, CaFeO3 and SrFeO3 is conducted using firstprinciples calculations based on density functional theory. The study emphasizes the interrelation of thermodynamic and elastic properties. For this purpose, properties such as bulk modulus, Young’s modulus, shear modulus, heat capacity, thermal expansion, and thermal conductivity were calculated. The results reveal significant differences in the properties of the three perovskites, indicating that some materials are more suitable for thermal storage than others. Moreover, the findings demonstrate correlations between the elastic and thermodynamic properties of each perovskite, allowing for general conclusions on the extent to which computationally expensive material properties of perovskites like thermal expansion and thermal conductivity can be derived from more readily available metrics like the perovskites’ elastic constants or heat capacities. Furthermore, the results provide insights into correlations between the perovskite properties and the ones of their constituting binary metal oxides.