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MECHANISMS OF TRITIUM DIFFUSION IN LI2O - QUANTUM-CHEMICAL SIMULATION

SHLUGER, A; ITOH, N; NODA, K; (1991) MECHANISMS OF TRITIUM DIFFUSION IN LI2O - QUANTUM-CHEMICAL SIMULATION. J PHYS-CONDENS MAT , 3 (49) 9895 - 9906.

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Abstract

Using the intermediate neglect of differential overlap MO LCAO calculation procedure and the embedded molecular cluster model we have investigated atomic and electronic structure and key stages of diffusive transfer of T+ and T0 in Li2O, containing cation vacancies and F+ centres.The activation energy for the cation vacancy diffusion in Li2O is calculated to be 0.33 eV. Comparing different models of T+ and T0 atomic structures and the mechanisms of their diffusion, we have shown that the lowest activation energy (< 0.9 eV) requires the T+ ion in the cation site to transfer by a vacancy mechanism. However, the T0 diffusion activation energy is generally only slightly higher: if it occupies an interstitial position, it may jump via interstitial sites within an activation energy of about 1 eV; if it is trapped in the cation site, exchange with a nearest lattice cation will require an activation energy of about 1.1 eV. By analysing the driving forces for tritium diffusion we conclude that the isotopic effect cannot affect the results of our calculations.

Type:Article
Title:MECHANISMS OF TRITIUM DIFFUSION IN LI2O - QUANTUM-CHEMICAL SIMULATION
Keywords:NEUTRON-IRRADIATED LI2O, SOLID BREEDER MATERIALS, LITHIUM-OXIDE, ELECTRONIC-STRUCTURE, SINGLE-CRYSTAL, CONDUCTIVITY, DEFECTS, PARAMETRIZATION, RESONANCE, BEHAVIOR
UCL classification:UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Physics and Astronomy

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