Pressure and compositional dependence of electric conductivity in the (Mg1 - xFex)1 - δO (x = 0.01-0.40) solid-solution

Akira Yoshiasa, Osamu Ohtaka, Daisuke Sakamoto, Denis Andrault, Hiroshi Fukui, Maki Okube

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

(Mg1 - xFex)1 - δO (x = 0.01-0.43) single crystals (~ 8 mm in diameter) were made by a melt-growth method. Electrical conductivity measurements were carried out as functions of temperature and frequency by a complex impedance method under pressure (~ 43 GPa and ~ 673 K and at 0.1 MPa and ~ 1400 K). Our experimental results show a change in charge transport mechanism in the (Mg1 - xFex)1 - δO solid solution at high temperature. The temperature of inflection point of the slope in Arrhenius plots depend greatly on both composition and extrinsic factors of crystals. The low-temperature conduction mechanism in (Mg1 - xFex)1 - δO solid solution is small polaron. Pressure effect of the electric conductivity was observed and the conductivity increased to 0.5 at log scale of S/m with increasing pressure up to 43.4 GPa. The activation energy was decreased linearly with increasing pressure. Chemical composition and homogeneity of specimen rather than pressure greatly influence the electric conductivity. The activation energy of 2.37(4) eV for the (Mg0.99Fe0.01)1 - δO solid solution might correspond to a migration enthalpy of O ions through thermally formed defects. It is proposed that a possible dominant electrical conduction mechanism in ferropericlase under the lower mantle conditions, at least in the higher temperature region, is super ionic conduction.

Original languageEnglish
Pages (from-to)501-505
Number of pages5
JournalSolid State Ionics
Volume180
Issue number6-8
DOIs
Publication statusPublished - 2009 May 14

Keywords

  • (MgFe)O
  • Conduction mechanism in lower mantle
  • High pressure
  • Ionic conduction
  • Small polaron

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

Fingerprint Dive into the research topics of 'Pressure and compositional dependence of electric conductivity in the (Mg<sub>1 - x</sub>Fe<sub>x</sub>)<sub>1 - δ</sub>O (x = 0.01-0.40) solid-solution'. Together they form a unique fingerprint.

Cite this