Effect of dilution on the spin pairing transition in rhombohedral carbonates

Barbara Lavina, Przemyslaw Dera, Robert T. Downs, Oliver Tschauner, Wenge Yang, Olga Shebanova, Guoyin Shen

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

The compressibility of an iron-bearing magnesite (Mg0.87Fe 2+0.12Ca0.01)CO3 was determined by means of single crystal diffraction up to 64GPa. Up to 49 GPa the pressure-evolution of the unit cell volume of the solid solution with 12% of Fe2+ can be described by a third-order Birch-Murnaghan equation of state with parameters V0=281.0(5)Å3, K 0=102.8(3)GPa, K'0=5.44. The spin pairing of the Fe 2+ d-electrons occurs between 49 and 52 GPa, as evidenced by a discontinuous volume change. The transition pressure is increased by about 5GPa compared with the iron end-member; an effect consistent with a cooperative contribution of adjacent clusters to the spin transition. The trend is, however, opposite in the periclase-wüstite solid solution. Differences among the two structures, in particular in the Fe-Fe interactions, that might explain the different behavior are discussed.

Original languageEnglish (US)
Pages (from-to)224-229
Number of pages6
JournalHigh Pressure Research
Volume30
Issue number2
DOIs
StatePublished - Jun 2010

Keywords

  • Compressibility
  • Magnesite
  • Siderite
  • Single crystal diffraction
  • Spin transition

ASJC Scopus subject areas

  • Condensed Matter Physics

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