PRIVAULT, Gaël; MEVELLEC, Jean-Yves; LORENC, Maciej; HUMBERT, Bernard; JANOD, Etienne; DARO, Nathalie; CHASTANET, Guillaume; SUBEDI, Alaska; COLLET, Eric

doi:10.1021/acs.cgd.2c00659

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PRIVAULT, Gaël
Institut de Physique de Rennes [IPR]

MEVELLEC, Jean-Yves
Institut des Matériaux de Nantes Jean Rouxel [IMN]

LORENC, Maciej
Institut de Physique de Rennes [IPR]

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Article de revue

Ce document a été publié dans

Crystal Growth & Design. 2022, vol. 22, n° 8, p. 5100-5109

American Chemical Society

Résumé en anglais

In the family of spin-crossover materials, which undergo thermal conversion between low-spin (LS) and high-spin (HS) phases, it is of great interest to study vibrational modes. On the one hand, vibration modes are characteristic of the spin state, and vibrational spectroscopies are often used for monitoring spin-state switching driven by temperature, pressure, or light. On the other hand, spin-state thermal conversion is an entropy-driven process, and the vibrational entropy change represents the main contribution to the total entropy difference between LS and HS phases at solid state. However, the discussion of vibrations in spin-crossover materials is often limited at the molecular scale. Here we study vibration modes in the [Fe(phen)(2)(NCS)(2)] crystal, and we compare symmetry-resolved vibrational spectroscopy data performed on single crystal to density functional theory calculations performed in a periodic three-dimensional crystal. We discuss the complex nature of vibrational modes in crystals, including the vibration of molecules within the crystalline lattice, with different symmetries and frequencies. We also highlight the presence of many low-frequency libration modes of different symmetries. The contribution of vibrational entropy, added to the electronic entropy, provides a total entropy difference in the solid state, which is in very good agreement with calorimetric measurements.< Réduire

Mots clés en anglais

SPIN-CROSSOVER COMPLEX

RAMAN-SPECTROSCOPY

STRUCTURAL DYNAMICS

TRANSITION

STATE

FE(PHEN)2(NCS)2

DOI

http://dx.doi.org/10.1021/acs.cgd.2c00659

Project ANR

Transitions de phase ELECTROnique de matériaux moleculaires controllées par PHONONIQUE non-linéaire - ANR-19-CE30-0004

Origine

Importé de hal

Unités de recherche

Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB) - UMR 5026