TY - JOUR
T1 - Ab initio investigation of the high pressure elasticity of Mg2SiO4 forsterite and ringwoodite
AU - Stixrude, Lars
AU - Wentzcovitch, R. M.
AU - Da Silva, C.
AU - Kiefer, B.
PY - 1998/12/1
Y1 - 1998/12/1
N2 - We discuss the behavior of two minerals of the same composition, Mg2SiO4 but different structures: forsterite and ringwoodite. Ab initio plane-wave pseudopotential results are discussed in terms of the full elastic constant tensors of these phases and their elastic anisotropy. The structures of the two minerals, based on pseudo-hcp and pseudo-fcc packing of oxygens, respectively, show very different behavior at high pressure. While the elastic anisotropy of olivine depends weakly on pressure between 0 and 25 GPa, the anisotropy of ringwoodite decreases with pressure initially, vanishing at 17 GPa before increasing again at higher pressure. This unusual behavior is understood in terms of a change of sign of the combination of elastic constants c12+2c44-c11, and a resulting interchange of fast and slow directions of acoustic wave propagation. To gain insight into the origin of their elastic behavior, the ab initio results are compared with a simple model based on the O sub-lattice.
AB - We discuss the behavior of two minerals of the same composition, Mg2SiO4 but different structures: forsterite and ringwoodite. Ab initio plane-wave pseudopotential results are discussed in terms of the full elastic constant tensors of these phases and their elastic anisotropy. The structures of the two minerals, based on pseudo-hcp and pseudo-fcc packing of oxygens, respectively, show very different behavior at high pressure. While the elastic anisotropy of olivine depends weakly on pressure between 0 and 25 GPa, the anisotropy of ringwoodite decreases with pressure initially, vanishing at 17 GPa before increasing again at higher pressure. This unusual behavior is understood in terms of a change of sign of the combination of elastic constants c12+2c44-c11, and a resulting interchange of fast and slow directions of acoustic wave propagation. To gain insight into the origin of their elastic behavior, the ab initio results are compared with a simple model based on the O sub-lattice.
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M3 - Conference article
AN - SCOPUS:0032305781
VL - 499
SP - 15
EP - 25
JO - Materials Research Society Symposium - Proceedings
JF - Materials Research Society Symposium - Proceedings
SN - 0272-9172
T2 - Proceedings of the 1997 MRS Fall Symposium
Y2 - 2 December 1997 through 4 December 1997
ER -