CaFe2O4-type MgAl2O4
MgAl2O4
second-order Birch-Murnaghan · Original · 1998
V₀
240.3
ų
Unit cell
K₀
211
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
- other / unspecified
- Method
- experiment (XRD / DAC / multianvil compression)synchrotron X-ray diffraction in laser-heated diamond anvil cell (room temperature)
- Sample
- laser-heated diamond cell run 2, 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
"The unit cell volume of the CaTi2O4 phase (240.3(4) ų) is the same, within our resolution, as that of the CaFe2O4 phase (240.3(2) ų) at zero pressure... 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... K0', which is now assumed to be 4."
Additional notes
lower mantle framing
Al-rich CaFe2O4-structured phase proposed as dominant mineral in subducted MORB at lower-mantle conditions
unit cell parameters zero pressure
a = 8.649(3) Å, b = 9.977(4) Å, c = 2.785(1) Å
unit cell parameters high pressure
a = 8.271(3) Å, b = 9.561(5) Å, c = 2.686(1) Å at 33.4 GPa
K0 uncertainty source
uncertainties calculated from differences between pressures determined by ruby fluorescence and Pt diffraction after heating
summary statement
both CaFe2O4 and CaTi2O4 phases appear to have initial bulk moduli as small as K0 = 210 GPa (K0' = 4)