Computer-Experimental Synthesis of Silica with the α-PbO2 Structure
- Murli H. Manghnani and
- Yasuhiko Syono
Published Online: 21 MAR 2013
Copyright © 1987 by Terra Scientific Publishing Company (TERRAPUB), Tokyo.
High-Pressure Research in Mineral Physics: A Volume in Honor of Syun-iti Akimoto
How to Cite
Matsui, Y. and Kawamura, K. (1987) Computer-Experimental Synthesis of Silica with the α-PbO2 Structure, in High-Pressure Research in Mineral Physics: A Volume in Honor of Syun-iti Akimoto (eds M. H. Manghnani and Y. Syono), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM039p0305
- Published Online: 21 MAR 2013
- Published Print: 1 JAN 1987
Print ISBN: 9780875900667
Online ISBN: 9781118664124
- Mineralogy and Crystal Chemistry;
- Phase transformations;
- High Pressure-High Temperature Research
A series of molecular dynamics (MD) calculations on model SiO2 systems with the fluorite configuration have been carried out over the pressure range of 0–300 GPa. A pressure-controlling, noncubic cell MD program (XDORTHO) was used, assuming two-body central potential functions. We observed a very rapid transformation from cubic to orthorhombic lattice structure below pressures of dynamic instability of SiO2-fluorite, and found the “product” to have the α-PbO2 structure.
The density (4.34 Mg/m3) and cohesive (lattice) energy (−13109 kJ/mol) of computer-synthesized SiO2 with the α-PbO2 structure are very close to the values for SiO2 with the futile structure (4.30 Mg/m3 and −13135 kJ / mol, respectively), with the IF-2 potential at 0 GPa and 300 K. In view of the absence of experimental evidence for existence of SiO2 with the α-PbO2 structure, we suppose that the polymorph, if it does exist, is metastable. However, if SiO2-fluorite exists at ultrahigh-pressure, we anticipate having only a reverted material in the α-PbO2structure.