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DOE OSTI · 2283839

Spin crossover transition driven by pressure: Barocaloric applications

Reis, Mario·Cheng, Yongqiang·dos Santos, Antonio M.
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Abstract

This article describes a mean-field theoretical model for Spin-Crossover (SCO) materials and explores its implications. It is based on a simple Hamiltonian that yields the high spin molar fraction as a function of temperature and pressure, as well as a temperature–pressure phase diagram for the SCO transition. In order to test the model, it was compared with the giant Barocaloric Effect (BCE) of the SCO material [FeL 2 ][B 4 ] 2 . Furthermore, we found that optical phonons are responsible for 92% of the total barocaloric entropy change. DFT calculations successively indicates that, as expected, the majority of this effect can be traced to low frequencies modes of vibration (400 cm -1 ), associated to the Fe coordination.

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75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITYBarocaloric EffectIron metalorganicMean Field ModelingSpin crossoverhighpressure

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Reis, Mario, Cheng, Yongqiang, dos Santos, Antonio M.. 2024-01-16. Spin crossover transition driven by pressure: Barocaloric applications. https://doi.org/10.1016/j.physb.2024.415689

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