Akimotoite

MgSiO3

third-order Birch-Murnaghan · Original · 1996

V₀

262.17

Å³

Unit cell

K₀

212

GPa

Unknown

K′

7.500

dimensionless

Volume (V₀)

Value	Unit	Basis	Z
262.17	Å³	Unit cell	—

Reported value and unit are preserved as extracted. Z (formula units per cell) is not stored yet, so molar ↔ Å³/f.u. conversion is not applied automatically.

Composition

Oxide	Molar
MgO	1
SiO2	1

Formula: MgSiO3

Conditions & method

T_ref: —
P_ref: —
Structure: ilmenite (akimotoite)
Method: experiment (XRD / DAC / multianvil compression)
energy-dispersive synchrotron X-ray powder diffraction in diamond-anvil cell (ruby-fluorescence pressure scale, H2O medium)
Sample: polycrystalline MgSiO3 ilmenite synthesized at 22.5 GPa, 1200 °C from MgSiO3 glass

Source

Paper: High-pressure X-ray diffraction study and equation of state of MgSiO 3 ilmenite
Authors: Bruno Reynard; G. Fiquet; J. P. Itié; D. C. Rubie
DOI: 10.2138/am-1996-1-206
Year: 1996
Journal: American Mineralogist
Origin: Original (measured or fitted in the source paper)

Evidence from the paper

The high-pressure volume data were fitted to a third-order Birch-Murnaghan equation of state and are consistent with the former determination of Ko = 212 GPa by Brillouin scattering; the data yield K~ = 7.5(10) if the ruby-fluorescence pressures are used ... Thus, we fixed the Ko value at 212 GPa to check the consistency of our data with the Brillouin-scattering determination by Weidner and Ito (1985). ... The ambient pressure volume was left to vary and never departed from our measurement in the cell by more than 0.01%. Table 1: P = 0.00 GPa, V = 262.17(49) Å³.

Additional notes

K0 source

fixed at Brillouin-scattering value of Weidner and Ito (1985)

pressure scale

ruby fluorescence

note

Ilmenite stability extends a few tens of kilometers into the lower mantle at low temperatures (paper's framing); K′ = 7.5 considered unrealistic due to nonhydrostatic overestimation of ruby pressures

second ambient volume after decompression

262.45(33) Å³