Phase Transition from Mott Insulating Phase into the Charge Ordering Phase with Molecular Deformation in Charge-Transfer Salts -(ET)
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- 作者：Akira Ota ; Lahcè ; ne Ouahab ; Sté ; phane Golhen ; Yukihiro Yoshida ; Mitsuhiko Maesato ; Gunzi Saito ; Roman
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- 刊名：Chemistry of Materials
- 出版年：2007
- 出版时间：May 15, 2007
- 年：2007
- 卷：19
- 期：10
- 页码：2455 - 2462
- 全文大小：370K
- 年卷期：v.19,no.10(May 15, 2007)
- ISSN：1520-5002
文摘
Two isostructural charge-transfer salts 
-(ET)4[M(CN)6][N(C2H5)4]·2H2O (ET = bis(ethylenedithio)tetrathiafulvalene and M = CoIII, FeIII) were synthesized, and their crystal structures, Raman spectra,electrical conductivities, electron spin resonance (ESR), and static magnetic susceptibilities as a functionof temperature were studied. At room temperature the salts contain two crystallographically independentET molecules with an average charge of +0.5. Temperature dependence of the Raman spectra revealedthat a charge disproportionation gradually occurs upon cooling, because new peaks originated from theET+ and ET0 grow gradually. ESR, static magnetic susceptibility, and conductivity data, supported byband structure calculation, give us firm evidence of the phase transition from the Mott insulating phasewith the fluctuation of charge order into the long-range charge ordered phase at around 150 K. Thecharge ordered ground state consists of (ET+)2 dimers and (ET0)2 dimers, where the neutral moleculesare found to be bent. The mechanism of this phase transition is discussed on the basis of crystallographic,spectroscopic, and magnetic features at various temperatures.
-(ET)4[M(CN)6][N(C2H5)4]·2H2O (ET = bis(ethylenedithio)tetrathiafulvalene and M = CoIII, FeIII) were synthesized, and their crystal structures, Raman spectra,electrical conductivities, electron spin resonance (ESR), and static magnetic susceptibilities as a functionof temperature were studied. At room temperature the salts contain two crystallographically independentET molecules with an average charge of +0.5. Temperature dependence of the Raman spectra revealedthat a charge disproportionation gradually occurs upon cooling, because new peaks originated from theET+ and ET0 grow gradually. ESR, static magnetic susceptibility, and conductivity data, supported byband structure calculation, give us firm evidence of the phase transition from the Mott insulating phasewith the fluctuation of charge order into the long-range charge ordered phase at around 150 K. Thecharge ordered ground state consists of (ET+)2 dimers and (ET0)2 dimers, where the neutral moleculesare found to be bent. The mechanism of this phase transition is discussed on the basis of crystallographic,spectroscopic, and magnetic features at various temperatures.