dorsal/arxiv
View SchemaPrediction of Phase Transition in CaSiO$_3$ Perovskite and Implications for Lower Mantle Structure
| Authors | Lars Stixrude, Ronald E. Cohen, Rici Yu, Henry Krakauer |
|---|---|
| Categories | |
| ArXiv ID | physics/9610023 |
| URL | https://arxiv.org/abs/physics/9610023 |
| Journal | American Mineralogist, 81, 1293-1296 (1996) |
Abstract
First principles linear response calculations are used to investigate the lattice dynamics of what is thought to be the third most abundant phase in the lower mantle, CaSiO_3 perovskite. The commonly assumed cubic structure (Pm3m) is found to be dynamically unstable at all pressures, exhibiting unstable modes along the Brillouin zone edge from the M-point to the R-point. Based on these results, we predict that the ground state structure of CaSiO_3 perovskite is a distorted phase with lower than cubic symmetry. We predict that a phase transition occurs in CaSiO_3 perovskite within the earth's lower mantle from the low temperature distorted phase to the cubic phase at high temperature. The predicted phase transition provides a possible explanation of some of the seismological observations of reflective features within the lower mantle.
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"abstract": "First principles linear response calculations are used to investigate the\nlattice dynamics of what is thought to be the third most abundant phase in the\nlower mantle, CaSiO_3 perovskite. The commonly assumed cubic structure (Pm3m)\nis found to be dynamically unstable at all pressures, exhibiting unstable modes\nalong the Brillouin zone edge from the M-point to the R-point. Based on these\nresults, we predict that the ground state structure of CaSiO_3 perovskite is a\ndistorted phase with lower than cubic symmetry. We predict that a phase\ntransition occurs in CaSiO_3 perovskite within the earth\u0027s lower mantle from\nthe low temperature distorted phase to the cubic phase at high temperature. The\npredicted phase transition provides a possible explanation of some of the\nseismological observations of reflective features within the lower mantle.",
"arxiv_id": "physics/9610023",
"authors": [
"Lars Stixrude",
"Ronald E. Cohen",
"Rici Yu",
"Henry Krakauer"
],
"categories": [
"physics.geo-ph",
"cond-mat.mtrl-sci"
],
"journal_ref": "American Mineralogist, 81, 1293-1296 (1996)",
"title": "Prediction of Phase Transition in CaSiO$_3$ Perovskite and Implications for Lower Mantle Structure",
"url": "https://arxiv.org/abs/physics/9610023"
},
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