| The tritium permeation barrier is one of the key scientific and technical problems in the field of tritium-based continuous supply and of tritium safety protection.Hydrogen and hydrogen isotope which have easy migration characteristics will remain in the surface and body phase of important parts of device.Retained tritium in the material will seriously affect the performance of materials and the tritium has huge pollution to the environment.Therefore,the study of tritium permeation barrier is necessary.Because of the poor working environment of the coating and a lot of affectly factors to the coating,the research of tritium permeation barrier are mostly concentrated in the making and testing,only a little research fouce on the diffusion mechanism of hydrogen and hydrogen isotopes.Based on the first-principles calculation method of density functional theory and the scheme of transition state search,this paper explores the stable location and diffusion way of hydrogen in the interface of?-Al2O3/?-AlPO4 coating,and then speculates the performance of resistant to tritium.The main contents include:?1?The diffraction pattern of coating was obtained by X-ray diffraction method.The crystal structures of alumina and aluminum phosphate were?-Al2O3 and?-AlPO4respectively,and then there are 13 possible supercavity models of-Al2O3 and?-AlPO4composite interface.The final interfacial crystal structure?-Al2O3?0001?/?-AlPO4?0001?was obtained by the first-principles method.?2?The two stable adsorption sites and one metastable adsorption sites of H in?-AlPO4 are calculated by using PW91-GGA of density functional theory.And the barrier energy of H diffusion in?-AlPO4 was calculated by transition state search.It was found that H was diffused in the?-AlPO4 in a rotating manner.?3?Nine stable adsorption sites of the interstitial H atoms of?-Al2O3?0001?/?-AlPO4?0001?were calculated by using the density functional theory.Then,through the transition state search,the 14 transition state energy of H atoms were obtained.And the two diffusion paths of H atoms at the interface were calculated.The diffusion mechanism of H atoms at?-Al2O3?0001?/?-AlPO4?0001?interface is explained,and the difficulty of H atom diffusion at the interface is predicted.In this paper,it is revealed that the diffusion of hydrogen at the?-Al2O3?0001?/?-AlPO4?0001?interface.The simulation results predict that the preformance of tritium barrier of?-Al2O3/?-AlPO4 composite is better than?-AlPO4 and?-Al2O3.Based on the understanding of the mechanism of blocking hydrogen permeation of tritium coating,it provides data support and theoretical guidance for the further evaluation of the tritium permeability of the coating,and also provides the theoretical basis for the future design and evaluation of tritium coating. |
PDF Full Text Request