Phase Egg
AlSiO3(OH)
third-order Birch-Murnaghan · Original · 2018
Why this differs from similar rows?
DFT result for the low-pressure (LP) phase egg structure, below the ~15 GPa proton-transfer transition; sibling row is the high-pressure (HP) structure, a distinct polymorph.
V₀
210.21
ų
Unit cell
K₀
164.400
GPa
Isothermal
K′
7.140
dimensionless
Volume (V₀)
| Value | Unit | Basis | Z |
|---|---|---|---|
| 210.21 | 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 |
|---|---|
| Al2O3 | 0.5 |
| SiO2 | 1 |
| H2O | 0.5 |
Formula: AlSiO3(OH)
Conditions & method
- Tref
- —
- Pref
- —
- Structure
- other / unspecified
- Method
- first-principles DFT / ab initiofirst-principles DFT (GGA, PAW, VASP) static simulations
- Sample
- first-principles simulated ordered unit cell, low-pressure (asymmetric hydrogen bond) structure
Source
- Paper
- Anomalous elastic behavior of phase egg, AlSiO3(OH), at high pressures
- Authors
- Mainak Mookherjee; W. R. Panero; Bernd Wunder; Sandro Jahn
- DOI
- 10.2138/am-2019-6694
- Year
- 2018
- Journal
- American Mineralogist
- Origin
- Original (measured or fitted in the source paper)
Evidence from the paper
The bulk modulus at zero pressure (K0^LP), unit-cell volume at zero pressure (V0^LP), and the pressure derivative of zero-pressure bulk modulus (K0'^LP) for phase egg (LP), i.e., at pressures below the transfer of a proton, are 164.4 (±1.8) GPa, 210.21 (±0.14) ų, and 7.14 (±0.24), respectively.
Additional notes
linear moduli zero pressure
K_a^LP = 975.6 (±1.2) GPa, K_b^LP = 344.6 (±0.6) GPa, K_c*^LP = 531.1 (±0.8) GPa
lower mantle relevance
phase egg stable up to 20–30 GPa, transition zone to lower mantle depths; decomposes to δ-AlOOH + stishovite
static conditions
first-principles simulations are at static conditions (0 K)