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Pressure and Temperature Spin Crossover Sensors with Optical Detection
GEMaC-CNRS, UMR 8635, Université de Versailles St Quentin en Yvelines, 45 Avenue des Etats Unis, Versailles Cedex 78035, France
Institute of Condensed Matter and Nanosciences, MOST–Inorganic Chemistry, Université Catholique de Louvain, Place L. Pasteur 1, Louvain-la-Neuve 1348, Belgium
* Author to whom correspondence should be addressed.
Received: 15 February 2012; in revised form: 17 March 2012 / Accepted: 20 March 2012 / Published: 10 April 2012
Abstract: Iron(II) spin crossover molecular materials are made of coordination centres switchable between two states by temperature, pressure or a visible light irradiation. The relevant macroscopic parameter which monitors the magnetic state of a given solid is the high-spin (HS) fraction denoted nHS, i.e., the relative population of HS molecules. Each spin crossover material is distinguished by a transition temperature T1/2 where 50% of active molecules have switched to the low-spin (LS) state. In strongly interacting systems, the thermal spin switching occurs abruptly at T1/2. Applying pressure induces a shift from HS to LS states, which is the direct consequence of the lower volume for the LS molecule. Each material has thus a well defined pressure value P1/2. In both cases the spin state change is easily detectable by optical means thanks to a thermo/piezochromic effect that is often encountered in these materials. In this contribution, we discuss potential use of spin crossover molecular materials as temperature and pressure sensors with optical detection. The ones presenting smooth transitions behaviour, which have not been seriously considered for any application, are spotlighted as potential sensors which should stimulate a large interest on this well investigated class of materials.
Keywords: spin crossover; pressure sensors; optical detection; smart materials; sensitive paints
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Linares, J.; Codjovi, E.; Garcia, Y. Pressure and Temperature Spin Crossover Sensors with Optical Detection. Sensors 2012, 12, 4479-4492.
Linares J, Codjovi E, Garcia Y. Pressure and Temperature Spin Crossover Sensors with Optical Detection. Sensors. 2012; 12(4):4479-4492.
Linares, Jorge; Codjovi, Epiphane; Garcia, Yann. 2012. "Pressure and Temperature Spin Crossover Sensors with Optical Detection." Sensors 12, no. 4: 4479-4492.