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Nouvelle publication de l’équipe CIEl : « Interplay between Crystal’s Shape and the Spatiotemporal Dynamics of the Spin Transition material »
H. Fourati, E. Milin, A. Slimani, G. Chastanet, Y. Abid, S. Triki, K. Boukheddaden
Phys. Chem. Chem. Phys., 2018, Accepted Manuscript , DOI: 10.1039/C8CP00868J
We investigated by means of optical microscopy (OM) the spatiotemporal features of the thermo-induced spin transition of the [Fe(2-pytrz)2{Pd(CN)4}].3H2O (1) (2-pytrz = 4-(2-pyridyl)-1,2,4,4H-triazole) single crystals having two different shapes (triangle and rectangle). While magnetic and calorimetric measurements, performed on a polycrystalline material, showed the respective average heating and cooling transition temperatures of (T½down ~152 K, T½up ~154 K) and (T½down ~160.0 K, T½up ~163.5 K); OM studies performed on a unique single crystal revealed significantly different switching temperatures (T½down ~152 K and T½up ~162 K). OM investigations showed an interface spreading over all crystals during the spin transition. Thanks to the color contrast between the low-spin (LS) and the high-spin (HS) states, we have been able to follow the real time dynamics of the spin transition between these two spin states, as well as to access to the thermal hysteresis loop of each single crystal. After an image processing, the HS-LS interface’s velocity was carefully estimated in the ranges [4.4 – 8.5] µm.s^(-1) and [2.5 – 5.5] µm.s^(-1) on cooling and heating, respectively. In addition, we found that the velocity of the interface is shape-dependent, and accelerates nearby the crystal’s borders. Interestingly, we remarked that, during the propagation process, the interface optimizes its shape so as to minimize the excess of elastic energy arising from the lattice parameter misfit between the LS and HS phases. All these original experimental results are well described using a spatiotemporal model based on the description of the spin-crossover problem as a reaction diffusion phenomenon.[:en]New publication of CIEl team : « Interplay between Crystal’s Shape and the Spatiotemporal Dynamics of the Spin Transition material »
H. Fourati, E. Milin, A. Slimani, G. Chastanet, Y. Abid, S. Triki, K. Boukheddaden
Phys. Chem. Chem. Phys., 2018, Accepted Manuscript , DOI: 10.1039/C8CP00868J
We investigated by means of optical microscopy (OM) the spatiotemporal features of the thermo-induced spin transition of the [Fe(2-pytrz)2{Pd(CN)4}].3H2O (1) (2-pytrz = 4-(2-pyridyl)-1,2,4,4H-triazole) single crystals having two different shapes (triangle and rectangle). While magnetic and calorimetric measurements, performed on a polycrystalline material, showed the respective average heating and cooling transition temperatures of (T½down ~152 K, T½up ~154 K) and (T½down ~160.0 K, T½up ~163.5 K); OM studies performed on a unique single crystal revealed significantly different switching temperatures (T½down ~152 K and T½up ~162 K). OM investigations showed an interface spreading over all crystals during the spin transition. Thanks to the color contrast between the low-spin (LS) and the high-spin (HS) states, we have been able to follow the real time dynamics of the spin transition between these two spin states, as well as to access to the thermal hysteresis loop of each single crystal. After an image processing, the HS-LS interface’s velocity was carefully estimated in the ranges [4.4 – 8.5] µm.s^(-1) and [2.5 – 5.5] µm.s^(-1) on cooling and heating, respectively. In addition, we found that the velocity of the interface is shape-dependent, and accelerates nearby the crystal’s borders. Interestingly, we remarked that, during the propagation process, the interface optimizes its shape so as to minimize the excess of elastic energy arising from the lattice parameter misfit between the LS and HS phases. All these original experimental results are well described using a spatiotemporal model based on the description of the spin-crossover problem as a reaction diffusion phenomenon.[:]