Structural characterization of temperature- and pressure-induced inverse{r_reversible}normal spinel transformation in magnetite

Journal Article · Mon Jan 01 04:00:00 EST 2007 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.75.020102· OSTI ID:20976645

Rozenberg, G Kh; Amiel, Y; Xu, W M; Pasternak, M P ^[1]; Jeanloz, R ^[2]; Hanfland, M ^[3]; Taylor, R D ^[4]

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1. School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv (Israel)
2. Department of Earth and Planetary Science, University of California, Berkeley, California 94720 (United States)
3. European Synchrotron Research Facility, Boite Postale 220, 38043 Grenoble (France)
4. MPA-10, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

High-precision powder x-ray diffraction and {sup 57}Fe Moessbauer studies up to 20 GPa show that magnetite (Fe{sub 3}O{sub 4}) undergoes a reversible normal{r_reversible}inverse transition with increasing pressure or decreasing temperature. There is no resolvable change in the spinel-type crystal structure or unit-cell volume at the phase transition. However, the volume of the tetrahedral (A) site increases (17%) and that of the octahedral (B) site decreases ({approx}7%) as electron charge density is transferred from the B to the A site. The corresponding valence changes cause the inverse {yields} normal transition with increasing pressure: Fe{sub A}{sup 3+}{yields}Fe{sub A}{sup 2+} and Fe{sub B}{sup 2.5+}{yields}Fe{sub B}{sup 3+}. There is an intermediate mixed configuration region at pressure-temperature (P-T) conditions lying between those at which magnetite is normal, T<T{sub norm}(P), or inverse, T>T{sub inv}(P)

• OSTI ID: 20976645
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 2 Vol. 75; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CHARGE DENSITY
CRYSTAL STRUCTURE
ELECTRONS
FERRITES
IRON 57
IRON OXIDES
MAGNETITE
MOESSBAUER EFFECT
PHASE TRANSFORMATIONS
PRESSURE RANGE GIGA PA
PRESSURE RANGE MEGA PA 10-100
SOLIDS
SPINELS
TEMPERATURE DEPENDENCE
VALENCE
X-RAY DIFFRACTION