^3He的产生对钛氚化物性能的影响

Effect of Helium Production From Radioactive Decay of Tritium on Properties of Titanium Tritide

文章基于第一原理对T衰变成3He后钛氚化物体系的电子结构及弹性模量进行计算。计算结果表明:TiT2中衰变产生的3He将占据体积较小的四面体间隙,并非占据体积较大的八面体间隙;3He的产生加强了最近邻的T原子与Ti原子的成键作用,Ti—T总的平均成键作用增强,这是氚化物时效后平衡压降低的原因;3He产生后,体系Ti—T键的大量损耗是体系体模量急剧下降的原因。

Ab initio calculations based on plane-wave basis pseudopotential method were used to study the effects of helium production from the radioactive decay of tritium in case of TiTs. By investigating the electronic structure and elastic constant, it is found that the decay helium occupies the tetrahedron site, instead of the octahedron site though the volume of the octahedron interstice is much larger than that of the tetrahedron interstice. The presence of helium enhances the bonding interaction of the nearest T with Ti. This is the reason of the lowering of the tritium desorption plateau pressure. Accompaning T decay to helium, there is a much large depletion of Ti-T d-s σ bonding bond, and this decreases the bulk modulus largely.