Heat capacities of the metal-assembled complex CuII2.97{CuII4[WV(CN)8]2.06[WIV(CN)8]1.94} · 4H2O were measured by adiabatic calorimetry and relaxation method under magnetic field. A heat capacity peak due to magnetic phase transition was observed at 38.7 K. Magnetic-field dependence of the magnetic phase transition revealed that this magnetic phase transition is ferromagnetic. Magnetic entropy was estimated to be 53.7 J K−1 mol−1, which agrees well with the expected value 9.03Rln2 (= 52.0 J K−1 mol−1). The ration of the magnetic entropy up to the magnetic transition temperature to the whole one suggests that this complex is regarded as a three-dimensional Heisenberg spin system with face-centered cubic lattice.
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Fig. 1. Three-dimensional network structure of CuII2+x{CuII4[WV(CN)8]4−2x[WIV(CN)8]2x} · yH2O. |
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Fig. 2. Heat capacity of CuII2.97{CuII4[WV(CN)8]2.06[WIV(CN)8]1.94} · 4H2O by adiabatic calorimetry. |
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Fig. 3. Heat capacities of CuII2.97{CuII4[WV(CN)8]2.06[WIV(CN)8]1.94} · 4H2O under magnetic fields by relaxation method. |