• [1]

    B.Geffroy,C.Corbel.R.Triboulet,P.Hautojarvi and P.Moser,Matter Sci.Forumm,Vol.1012(Trans.Tech)(1986)1241.[2]R.Krause,A.Polity,A.Klimatow and M.Schenk,Positron Annihilation(Singapore:World Scientific,1988)684.[3]Y.J.He,x.F.Li,L.H.Li,w.z.Yu and J.R.Xiao,J.Phys:Condens.Matter(UK),1(1989)SA91.[4]R.Krause A.Klimakow,F.M.Kiessling,A.Polity,P.Gille and M.Schenk,J.Cryst,Grow.101(1990)512.[5]C.Gely,C,Corbel and R.Triboulet,J.Phys.:Condens,Matter(UK),2(1990)4763.