论文信息 - Magnesium depletion in spinel during H.V.E.M. irradiations

Magnesium depletion in spinel during H.V.E.M. irradiations

Abstract The magnesium content of stoichiometric MgAl2O4 spinel is found to decrease progressively with electron dose during irradiation at elevated temperatures in a hgh voltage electron nucroscope (HVEM). The rate of decrease vanes with the electron beam energy. Diffraction patterns from the irradiated regions suggest that the end product is cubic γ-alumina rather than the equilibrium trigonal α-alumina. Additional reflections present in the patterns indicate a long-range ordering of the aluminium ions consistent with a true lattice parameter of 23.70 A, a three-fold increase over the tabulated value of 7.90 A for γ-alumina. A mechanism for the (spinel← γ-alumina) transformation is proposed. Microcracking is observed in some irradiated regions as a consequence of the 6.5% volume contraction associated with the transformation.

M. Jenkins | S. N. Buckley | S. Shaibani

[1] A. Stathopoulos,et al. Damage in the cation sublattice of α-Al2O3 irradiated in an HVEM , 1983 .

[2] G. P. Pells,et al. Radiation damage in pure and helium-doped α-Al2O3 in the HVEM Qualitative aspects of void and aluminium colloid formation , 1983 .

[3] G. P. Pells. The temperature dependence of the threshold displacement energy in MgO , 1982 .

[4] F. W. Clinard,et al. Neutron irradiation damage in MgO, Al2O3 and MgAl2O4 ceramics☆ , 1982 .

[5] T. Mitchell,et al. Electron irradiation damage in a-Al2O3 , 1981 .

[6] D. C. Phillips,et al. Radiation damage of α-Al2O3 in the HVEM: I. Temperature dependence of the displacement threshold , 1979 .

[7] D. C. Phillips,et al. Radiation damage of α-Al2O3 in the HVEM: II. Radiation damage at high temperature and high dose , 1979 .

[8] E. F. Osborn,et al. Fluoride Model Systems: III, The System NaF–BeF2 and the Polymorphism of Na2BeF4 and BeF2 , 1953 .

[9] A. Stathopoulos,et al. Radiation damage in the cation sublattice of alpha-Al2O3 , 1983 .