The transformation of γ Fe2O3 to α Fe2O3:: thermal activation and the effect of elevated pressure

被引:14
作者
Adnan, J [1 ]
O'Reilly, W [1 ]
机构
[1] Univ Newcastle Upon Tyne, Dept Phys, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England
关键词
gamma Fe2O3; alpha Fe2O3; thermal activation; submarine crust;
D O I
10.1016/S0031-9201(98)00128-9
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
The transformation of acicular gamma Fe2O3 particles to a Fe2O3 has been monitored using magnetic properties as a proxy for gamma Fe2O3 concentration during the inversion process. The transformation is thermally activated, the height of the barrier opposing inversion being 3.7 eV at atmospheric pressure and 0.5 eV at a pressure of about 100 MPa. The barrier arises from the combination of a term representing the reduction in lattice energy in an inverted region, and the strain energy associated with the interface between the inverted and non-inverted phases. The sensitivity of the inversion process to pressure can be understood in terms of the dependence of these energy terms, and the energy barrier, on interatomic spacing. Extrapolation of these laboratory data to the conditions of the submarine crust at Site 504B of the Deep Sea Drilling Project is consistent with the inferred magnetic mineralogy of the recovered material. (C) 1999 Elsevier Science B.V. All rights reserved.
引用
收藏
页码:43 / 50
页数:8
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