Materials Science and Engineering, Ames Laboratory
Journal or Book Title
Journal of Alloys and Compounds
Reversible, diffusionless, first-order solid-solid phase transitions accompanied by caloric effects are critical for applications in the solid-state cooling and heat-pumping devices. Accelerated discovery of caloric materials requires reliable but faster estimators for predictions and high-throughput screening of system-specific dominant caloric contributions. We assess reliability of the computational methods that provide thermodynamic properties in relevant solid phases at or near a phase transition. We test the methods using the well-studied B2 FeRh alloy as a “fruit fly” in such a materials genome discovery, as it exhibits a metamagnetic transition which generates multicaloric (magneto-, elasto-, and baro-caloric) responses. For lattice entropy contributions, we find that the commonly-used linear-response and small-displacement phonon methods are invalid near instabilities that arise from the anharmonicity of atomic potentials, and we offer a more reliable and precise method for calculating lattice entropy at a fixed temperature. Then, we apply a set of reliable methods and estimators to the metamagnetic transition in FeRh (predicted 346 +/- 12 K, observed 353 +/- 1 K) and calculate the associated caloric properties, such as isothermal entropy and isentropic temperature changes.
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Zarkevich, Nikolai A. and Johnson, Duane D., "Reliable thermodynamic estimators for screening caloric materials" (2019). Materials Science and Engineering Publications. 336.