Interplay between the charge transport phenomena and the charge-transfer phase transition in RbxMn[Fe(CN)6]y.zH2O

Gábor Molnár, Saioa Cobo, Tarik Mahfoud, Esther J. M. Vertelman, Petra J. van Koningsbruggen, Philippe Demont, Azzedine Bousseksou

Research output: Contribution to journalArticle

Abstract

Charge transport and dielectric measurements were carried out on compacted powder and single-crystal samples of bistable RbxMn[Fe(CN)6]y·zH2O in the two valence-tautomeric forms (MnIIFeIII and MnIIIFeII) as a function of temperature (120-350 K) and frequency (10-2-106 Hz). The complex conductivity data reveal universal conductivity behavior and obey the Barton-Nakajima-Namikawa relationship. The charge transport is accompanied by dielectric relaxation that displays the same thermal activation energy as the conductivity. Surprisingly, the activation energy of the conductivity was found very similar in the two valence-tautomeric forms (0.55 eV), and the conductivity change between the two phases is governed mainly by the variation of the preexponential factor in each sample. The phase transition is accompanied by a large thermal hysteresis of the conductivity and the dielectric constant. In the hysteresis region, however, a crossover occurs in the charge transport mechanism at T < 220 K from an Arrhenius-type to a varying activation energy behavior, conferring an unusual “double-loop” shape to the hysteresis.
Original languageEnglish
Pages (from-to)2586-2593
Number of pages8
JournalJournal of Physical Chemistry: Part C
Volume113
Issue number6
DOIs
Publication statusPublished - 12 Feb 2009

Keywords

  • charge transport
  • dielectric measurements
  • compacted powder
  • single-crystal samples
  • bistable RbxMn[Fe(CN)6]y·zH2O
  • valence-tautomeric forms
  • MnIIFeIII and MnIIIFeII
  • conductivity behavior
  • Barton−Nakajima−Namikawa relationship
  • dielectric relaxation
  • valence-tautomeric form
  • 0.55 eV

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