CaTi2O4-type MgAl2O4
MgAl2O4
second-order Birch-Murnaghan · Original · 1998
V₀
240.3
ų
Unit cell
K₀
206
GPa
Isothermal
K′
4
dimensionless
Volume (V₀)
| Value | Unit | Basis | Z |
|---|---|---|---|
| 240.3 | ų | Unit cell | — |
Reported value and unit are preserved as extracted. Z (formula units per cell) is not stored yet, so molar ↔ ų/f.u. conversion is not applied automatically.
Composition
| Oxide | Molar |
|---|---|
| MgO | 1 |
| Al2O3 | 1 |
Formula: MgAl2O4
Conditions & method
- Tref
- —
- Pref
- —
- Structure
- post-perovskite (CaIrO3-type, Cmcm)
- Method
- experiment (XRD / DAC / multianvil compression)synchrotron X-ray diffraction in laser-heated diamond anvil cell (room temperature); TEM characterization
- Sample
- laser-heated diamond cell runs 3 and 4, polycrystalline MgAl2O4 spinel starting material + 5 wt% Pt
Source
- Paper
- High‐pressure transformations in MgAl2O4
- Authors
- Nobumasa Funamori; Raymond Jeanloz; Jeffrey Nguyen; A. Kavner; W. A. Caldwell; Kiyoshi Fujino; Nοbuyοshi Miyajima; Toru Shinmei; Naotaka Tomioka
- DOI
- 10.1029/98jb01575
- Year
- 1998
- Journal
- Journal of Geophysical Research Atmospheres
- Origin
- Original (measured or fitted in the source paper)
Evidence from the paper
"a = 2.778(2) Å, b = 9.211(11) Å, c = 9.394(3) Å, and V = 240.3(4) ų (Z = 4)... applying the Birch (second-order finite strain) equation of state, which amounts to assuming that both phases have a pressure derivative of the bulk modulus K0' = 4 at zero pressure... yielding 211 (±6) GPa and 206 (±3) GPa for the CaFe2O4 and CaTi2O4 phases, respectively."
Additional notes
lower mantle framing
Transformation from CaFe2O4 to CaTi2O4 phase expected in oceanic crust subducted deep into the lower mantle
unit cell parameters zero pressure
a = 2.778(2) Å, b = 9.211(11) Å, c = 9.394(3) Å
unit cell parameters high pressure
a = 2.598(3) Å, b = 8.591(14) Å, c = 8.761(4) Å at 64.3 GPa
shock wave consistency
EOS in good agreement with Hugoniot shock compression measurements [Marsh, 1980]; no evidence for higher-pressure phases to at least 110 GPa
summary statement
both CaFe2O4 and CaTi2O4 phases appear to have initial bulk moduli as small as K0 = 210 GPa (K0' = 4)