Phase Egg
AlSiO3(OH)
third-order Birch-Murnaghan · Original · 2018
Why this differs from similar rows?
DFT result for the low-pressure (loP) phase Egg structure, below the ~15 GPa proton-transfer transition; sibling row is the high-pressure (hiP) structure, a distinct polymorph.
V₀
210.21
ų
Unit cell
K₀
164.400
GPa
Unknown
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)
- Sample
- first-principles simulated ordered unit cell
Source
- Paper
- Anomalous elastic behavior of phase Egg, AlSiO3(OH), at high pressures
- Authors
- —
- DOI
- 10.2138/am-2018-6694
- 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^loP), unit-cell volume at zero pressure (V0^loP) and the pressure derivative of zero-pressure bulk modulus (K'0^loP) for phase Egg (loP) i.e., at pressures below the transfer of proton are, 164.4 (±1.8) GPa, 210.21 (±0.14) ų, and 7.14 (±0.24) respectively.
Additional notes
static conditions
first principles simulations are at static conditions (0 K)
linear moduli GPa
Ka^loP = 975.6 (±1.2), Kb^loP = 344.6 (±0.6), Kc*^loP = 531.1 (±0.8)
framing
phase Egg stable up to 20-30 GPa, translating to transition zone to lower mantle depths; found as diamond inclusions from transition zone and upper part of lower mantle
proton transfer pressure
~15 GPa