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Re‐Appearance of Cooperativity in Ultra‐Small Spin‐Crossover [Fe(pz){Ni(CN) 4 }] Nanoparticles
Author(s) -
Peng Haonan,
Tricard Simon,
Félix Gautier,
Molnár Gábor,
Nicolazzi William,
Salmon Lionel,
Bousseksou Azzedine
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201406710
Subject(s) - nanoparticle , spin crossover , cooperativity , spin transition , hysteresis , mössbauer spectroscopy , materials science , nanocrystal , chemistry , analytical chemistry (journal) , crystallography , nanotechnology , condensed matter physics , chromatography , biochemistry , physics
A reverse nanoemulsion technique was used for the elaboration of [Fe(pz){Ni(CN) 4 }] nanoparticles. Low‐temperature micellar exchange made it possible to elaborate ultra‐small nanoparticles with sizes down to 2 nm. When decreasing the size of the particles from 110 to 12 nm the spin transition shifts to lower temperatures, becomes gradual, and the hysteresis shrinks. On the other hand, a re‐opening of the hysteresis was observed for smaller (2 nm) particles. A detailed 57 Fe Mössbauer spectroscopy analysis was used to correlate this unusual phenomenon to the modification of the stiffness of the nanoparticles thanks to the determination of their Debye temperature.