Atomistic description of spin crossover under pressure and its giant barocaloric effect

Sergi Vela; Jordi Ribas-Arino; Steven P. Vallone; António M. dos Santos; Malcolm A. Halcrow; Karl G. Sandeman

doi:10.1039/d5tc02560e

Atomistic description of spin crossover under pressure and its giant barocaloric effect

Sergi Vela
, Jordi Ribas-Arino
, Steven P. Vallone
, António M. dos Santos
, Malcolm A. Halcrow
, Karl G. Sandeman

Materials Engineering

Research output: Contribution to journal › Article › peer-review

1 Scopus citations

Abstract

The pressure-dependent evolution of the Spin Crossover (SCO) transition has garnered significant interest due to its connection to the giant barocaloric effect (BCE) near room temperature. Pressure alters both the molecular and solid-state structures of SCO materials, affecting the relative stability of low- and high-spin states and, consequently, the transition temperature (T_1/2). Crucially, the shape of the T_1/2vs. pressure curve dictates the magnitude of the BCE, making its accurate characterization essential for identifying high-performance materials. In this work, we investigate the nonlinear T_1/2vs. pressure behavior of the prototypical SCO complex [FeL₂][BF₄]₂ [L = 2,6-di(pyrazol-1-yl)pyridine] using solid-state PBE+U computations. Our results unveil the mechanisms by which pressure influences its SCO transition, including the onset of a phase transition, as well as the key role of low-frequency phonons in the BCE. Furthermore, we establish a computational protocol for accurately modeling the BCE in SCO crystals, providing a powerful tool for the rapid and efficient discovery of new materials with enhanced barocaloric performance.

Original language	English
Pages (from-to)	19635-19641
Number of pages	7
Journal	Journal of Materials Chemistry C
Volume	13
Issue number	38
DOIs	https://doi.org/10.1039/d5tc02560e
State	Published - Oct 2 2025

Funding

S. V. acknowledges the Spanish Ministerio de Ciencia, Innovación y Universidades (MICIU) for projects PID2022-138265NA-I00 and CEX2021-001202-M. J. R.-A. acknowledges the MICIU for projects PID2023-149691NB-I00 and CEX2021-001202-M, and the Generalitat de Catalunya (Project 2021SGR00354). The CSUC, the IQCTUB, the University of Barcelona, and the Red Española de Supercomputación (RES, project QH-2023-2-0004) are also acknowledged for computational resources. S. P. V. and K. G. S. acknowledge support from 2 PSC-CUNY Awards, jointly funded by The Professional Staff Congress and The City University of New York (TRADA-48-433 and TRADB-51-383). S. P. V. received financial support from The Grace Spruch’47 Physics Fund at Brooklyn College. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory.

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10.1039/d5tc02560e

Cite this

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title = "Atomistic description of spin crossover under pressure and its giant barocaloric effect",

abstract = "The pressure-dependent evolution of the Spin Crossover (SCO) transition has garnered significant interest due to its connection to the giant barocaloric effect (BCE) near room temperature. Pressure alters both the molecular and solid-state structures of SCO materials, affecting the relative stability of low- and high-spin states and, consequently, the transition temperature (T1/2). Crucially, the shape of the T1/2vs. pressure curve dictates the magnitude of the BCE, making its accurate characterization essential for identifying high-performance materials. In this work, we investigate the nonlinear T1/2vs. pressure behavior of the prototypical SCO complex [FeL2][BF4]2 [L = 2,6-di(pyrazol-1-yl)pyridine] using solid-state PBE+U computations. Our results unveil the mechanisms by which pressure influences its SCO transition, including the onset of a phase transition, as well as the key role of low-frequency phonons in the BCE. Furthermore, we establish a computational protocol for accurately modeling the BCE in SCO crystals, providing a powerful tool for the rapid and efficient discovery of new materials with enhanced barocaloric performance.",

author = "Sergi Vela and Jordi Ribas-Arino and Vallone, \{Steven P.\} and \{dos Santos\}, \{Ant{\'o}nio M.\} and Halcrow, \{Malcolm A.\} and Sandeman, \{Karl G.\}",

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AU - Vela, Sergi

AU - Ribas-Arino, Jordi

AU - Vallone, Steven P.

AU - dos Santos, António M.

AU - Halcrow, Malcolm A.

AU - Sandeman, Karl G.

PY - 2025/10/2

Y1 - 2025/10/2

N2 - The pressure-dependent evolution of the Spin Crossover (SCO) transition has garnered significant interest due to its connection to the giant barocaloric effect (BCE) near room temperature. Pressure alters both the molecular and solid-state structures of SCO materials, affecting the relative stability of low- and high-spin states and, consequently, the transition temperature (T1/2). Crucially, the shape of the T1/2vs. pressure curve dictates the magnitude of the BCE, making its accurate characterization essential for identifying high-performance materials. In this work, we investigate the nonlinear T1/2vs. pressure behavior of the prototypical SCO complex [FeL2][BF4]2 [L = 2,6-di(pyrazol-1-yl)pyridine] using solid-state PBE+U computations. Our results unveil the mechanisms by which pressure influences its SCO transition, including the onset of a phase transition, as well as the key role of low-frequency phonons in the BCE. Furthermore, we establish a computational protocol for accurately modeling the BCE in SCO crystals, providing a powerful tool for the rapid and efficient discovery of new materials with enhanced barocaloric performance.

AB - The pressure-dependent evolution of the Spin Crossover (SCO) transition has garnered significant interest due to its connection to the giant barocaloric effect (BCE) near room temperature. Pressure alters both the molecular and solid-state structures of SCO materials, affecting the relative stability of low- and high-spin states and, consequently, the transition temperature (T1/2). Crucially, the shape of the T1/2vs. pressure curve dictates the magnitude of the BCE, making its accurate characterization essential for identifying high-performance materials. In this work, we investigate the nonlinear T1/2vs. pressure behavior of the prototypical SCO complex [FeL2][BF4]2 [L = 2,6-di(pyrazol-1-yl)pyridine] using solid-state PBE+U computations. Our results unveil the mechanisms by which pressure influences its SCO transition, including the onset of a phase transition, as well as the key role of low-frequency phonons in the BCE. Furthermore, we establish a computational protocol for accurately modeling the BCE in SCO crystals, providing a powerful tool for the rapid and efficient discovery of new materials with enhanced barocaloric performance.

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JO - Journal of Materials Chemistry C

JF - Journal of Materials Chemistry C

IS - 38

ER -

Atomistic description of spin crossover under pressure and its giant barocaloric effect

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