TABLE OF CONTENTS ZHONGCHENG WU, SHUMING PENG, MAONIAN YANG, QIONG LIU
Institute of Nuclear and Chemistry, China Academy of Engineering Physics
The diffusion barriers for the single helium atom in Vanadium are studied by Effective Medium Theory. The relaxation of structure caused by the embedded atom is contained. The most possible diffusion path and diffusion barrier is determined from the results. Helium atom has the minimum energies in the interstitial site of tetrahedral in perfect structure of Vanadium. The value is about 4.37eV. The embedding energy of octahedral interstitial site is large than tetrahedral interstitial site. Helium diffuses out of the crystal along the (100). Keywords: Effective Medium Theory; Relaxation; Embedding energy; Diffusion barrier
Studies of helium in metals had attracted much attention in recent tens of years. Helium atoms produced by tritium decay will diffuse and agglomerate into bubbles in metals and they will affect the properties of fusion reactor materials and metal tritides. The many experiments and calculation of this problem had been studied and achieved some results. But there is no agreement to the existence and diffusion behavior for helium atom in metals. So theoretical study is very important. The direct calculation of total energies is very complicated, especially in situation where the symmetry is low. A simple way of determining the energies of a combined system from the propertied of the constituents has therefore been an important goal for the theoretical description of such systems. This is the main idea of Effective Medium Theory (EMT). In this...
