Pressure‐induced spin‐crossover features at variable temperature revealed by in situ synchrotron powder x‐ray diffraction

Élodie Tailleur (1) , Mathieu Marchivie (1) , Jean-Paul Itié (2) , Patrick Rosa (1) , Nathalie Daro (1) , Phillippe Guionneau (1)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
2 SSOLEIL - Synchrotron SOLEIL

An accurate high‐pressure X‐ray diffraction investigation, at various temperatures, on a powder of a spin‐crossover (SCO) complex has allowed the rare deconvolution of the structural features of the high‐spin and low‐spin phases. As a result, the pressure dependence of the structural parameters of the high‐spin and low‐spin phases can be discussed independently in the pressure domain where both phases co‐exist within the powder. Consequently, crucial unprecedented information is given, such as the variation of bulk moduli with temperature, similar here in amplitude for both spin phases, the temperature‐dependence of the pressure‐induced SCO abruptness, the temperature dependence of the pressure at which SCO occurs, and arguments for a possible piezo‐hysteresis. Performed on the molecular complex [Fe(PM‐PeA)2(NCSe)2] (PM‐PeA=N‐(2′‐pyridylmethylene)‐4‐(phenylethynyl) aniline), this study reveals a pressure‐induced SCO at 0.16 GPa and demonstrates that, when increasing temperature, the pressure of transition increases linearly, the abruptness of the pressure‐induced SCO strongly increases, and the bulk moduli decrease.

Mots clés: bulk modulus; high pressure; powder diffraction; Rietveld refinement; spin-crossover

Domaines: Matériaux

Élodie Tailleur, Mathieu Marchivie, Jean-Paul Itié, Patrick Rosa, Nathalie Daro, et al.. Pressure‐induced spin‐crossover features at variable temperature revealed by in situ synchrotron powder x‐ray diffraction. Chemistry - A European Journal, 2018, 24 (54), pp.14495-14499. ⟨10.1002/chem.201802828⟩. ⟨hal-01880970⟩