Bridgmanite

(Mg0.75,Al0.25)(Al0.25,Si0.75)O3 (x=0.25, pyrope composition)

fourth-order Birch-Murnaghan · Original · 2002

Why this differs from similar rows?

Model 2 (adjacent-pair coupled substitution, local charge balance) MD result; sibling row is Model 1 (random coupled substitution) for the same composition.

V₀

—

Unknown basis

K₀

179

GPa

Isothermal

K′

—

dimensionless

Volume (V₀)

Value	Unit	Basis	Z
—	—	Unknown basis	—

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	0.75
Al2O3	0.25
SiO2	0.75

Formula: (Mg0.75Al0.25)(Al0.25Si0.75)O3

Conditions & method

T_ref: 298 K
P_ref: —
Structure: orthorhombic perovskite (Pbnm/Pnma)
Method: molecular dynamics
molecular dynamics simulation (CMAS94 potential)
Sample: Model 2 (adjacent-pair coupled substitution, local charge balance) MD solid solution crystal

Source

Paper: Molecular dynamics simulation of MgSiO3-Al2O3 perovskite.
Authors: Tadashi Akamatsu; Ikumi KAMIOKA; Atsuhiro KIMURA; Katsuyuki Kawamura
DOI: 10.2465/jmps.97.13
Year: 2002
Journal: Journal of Mineralogical and Petrological Sciences
Origin: Original (measured or fitted in the source paper)

Evidence from the paper

By applying the 4th order Birch-Murnaghan equation, zero-pressure bulk modulus at 298 K is calculated to be 182(2) GPa (Model 1) - 179(2) GPa (Model 2) for the solid solution with x=0.25, and 247.5(1) GPa for the end member x=0.00.

Additional notes

bulk modulus at 50GPa 298K

500 GPa (Model 2)

note

MD simulation result, not experimental; no numerical V0 or K' reported