Oxidation of nanometer-sized iron particles

2019-10-07 01:00:23

The layer Iron oxidation oxide

责任者: Linderoth, S.;Morup, S.;Bentzon, M.D. 单位: Dept. of Phys., Tech. Univ. Denmark, Lyngby, Denmark 来源出处: Journal of Materials Science(J. Mater. Sci. (UK)),1995/06/15,30(12):3142-8 摘要: The evolution of the oxidation of ultrafine (5 nm diameter) α-iron particles in ambient air has been studied using Mossbauer spectroscopy and electron microscopy. A 1-2 nm thick oxide layer was found to appear almost immediately, whereafter the oxidation proceeded rather slowly. The rate of oxidation can be understood from the Caberra-Mott model of oxidation of metal surfaces. The oxide formed consists of a mixture of Fe3O4 and γ-Fe2O3, but with the magnetic properties significantly modified due to the finite size of the oxide crystallites, e.g. the magnetic hyperfine fields are somewhat smaller than for the bulk Fe3O4 and γ-Fe2O3, and a very strong spin-canting was revealed. A Verwey transition was found to occur between 12 and 80 K. The Debye temperature of the oxide layer was found to be about 185 K for the thinnest observed oxide layer, increasing to about 215 K after exposure of the α-iron particles to air for one week 关键词: crystallites;Debye temperature;iron;metal-insulator transition;Mossbauer spectroscopy;oxidation;nanometer-sized Fe particles;oxidation;Verwey transition;oxide layer;crystallites;magnetic hyperfine fields;215 K;5 nm;12 to 80 K;Fe