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Unusual Energy Balance Between Atoms in Postperovskite MgSiO 3
Author(s) -
Hirate Hiroshi,
Sawai Hiroshi,
Saito Yuki,
Yukawa Hiroshi,
Morinaga Masahiko,
Nakai Hiromi
Publication year - 2010
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2010.03822.x
Subject(s) - atom (system on chip) , perovskite (structure) , phase (matter) , stishovite , octahedron , chemistry , atomic physics , coordination number , crystallography , crystal structure , thermodynamics , ion , high pressure , physics , organic chemistry , computer science , embedded system
To understand the phase transition from perovskite to postperovskite MgSiO 3 , total energy is partitioned into atomic energy densities of constituent elements in the oxide, using the energy density analysis. The atomization energies, Δ E Mg for Mg atom, Δ E Si for Si atom, and Δ E O for O atom, are then evaluated by subtracting the atomic energy density from the energy of the isolated neutral atom, Mg, Si, and O, respectively. It is found that Δ E Si and Δ E Mg are much larger than Δ E O in the perovskite phase, but Δ E O is much larger than Δ E Si and Δ E Mg in the postperovskite phase. This means that most of the energies partitioned into Mg and Si atoms in the perovskite phase transfer to the O atoms in the postperovskite phase during the transition. Such an extremely stable O‐atom state is formed by the introduction of edge‐shared SiO 6 octahedra into the postperovskite structure. This is because the edge‐sharing makes the Si–O interatomic distances longer even in very high pressure conditions. The unusual energy balance between atoms is also seen in the other postperovskite, MgGeO 3 and NaMgF 3 .