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The kinetics features of a thermal spin transition characterized by optical microscopy on the example of [Fe(bbtr)3](ClO4)2 single crystals: Size effect and mechanical instability
C. Chong, A. Slimani, F. Varret, K. Boukheddaden, E. Collet, J.-C. Ameline, R. Bronisz and
Chemical Physics Letters, 504 (1-3) (2011), p29-33
DOI:10.1016/j.cplett.2011.01.041 | unige:16831 | Abstract | Article HTML | Article PDF | Video1 | Video2 | Video3 | Video4 | Video5
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We investigated by optical microscopy the thermal spin transition in single crystals of [Fe(bbtr)3](ClO4)2 (bbtr = 1,4-di(1,2,3-triazol-1-yl) butane). The growth of the low-spin phase was observed for different crystal orientations and sizes. The process always started from a corner of the crystal but its further development depended on the size, shape and thermal history of the crystal. In crystals of smaller size, under isothermal conditions, the low-spin phase developed in a continuous way, through the propagation of a rather well defined transformation front, with a higher propagation velocity inside the planes perpendicular to the c axis. In larger crystals the spontaneous occurrence of inhomogeneous stresses led to a stepwise propagation process.