Heat capacity and phase transition of a five-coordinated antiferromagnet,IODOBIS (N,N-diethyldithiocarbamato) iron (III), in the temperature range from 0.4 TO 300 K |
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Authors: | Masanori Yoshikawa Michio Sorai Hiroshi Suga Syûzô Seki |
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Affiliation: | Department of Chemistry and Chemical Thermodynamics Laboratory, Faculty of Science, Osaka University, Toyonaka, Osaka 560, Japan |
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Abstract: | The heat capacity of iodobis (N,N-diethyldithiocarbamato) iron (III) has been measured between 0.4 and 300 K. A phase transition from an antiferromagnetic to a paramagnetic state was found at TN = (1.937 ± 0.010) K, and a Schottky-type anomaly arising from a zero-field single ion splitting was observed around 12 K. The total magnetic entropy and enthalpy, including the phase transition and the Schottky-type anomaly, are 11.36JK?1mol?1 and 134.5 J mol?1, respectively. The entropy is approximately equal to Rln 4 ( = 11.53 JK?1mol?1), confirming that the spin manifold is really a quartet. The entropy and enthalpy due to the phase transition are estimated to be (5.57±0.01)JK?1mol?1 and (13.2±0.05)Jmol?1, respectively. The entropy and enthalpy above tn are quite large, as in the case of the related compound chlorobis (N,N-diethyldithiocarbamato) iron (III). This fact suggests that the present complex may be considered to have a two-dimensional type of magnetic structure from a thermodynamic point of view. A correlation diagram between the transition entropy and energy is proposed, this being a diagnostic for the determination of the magnetic dimensionality. |
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