also show twelvefold rotational symmetry.The detailed results will be publi- shed elsewhere.The present research suggests that more accurate EDPs and HREMs be necessary for research. The authors would like to thank Ma Ruzhang,Chen Nanxian and Liu Qingsheng at the University of Science and Technology Beijing for their very helpful discussions.This work was supported by Science Development Founda- tion of U.S.T.B. Referenees 1 Chen H,Li X D and Kuo K H.Phys.Rev.Lett,.1988,60:1645 2 Kuo K H,Feng Y C and Chen H.Phys.Rev.Lett.,1988,61:1740 3 Pauling L.J.Nature,1985,317:512 4 Pauling L.Phys.Rev.Lett.,1987,58:365 5 Cahn J W,Gratias D and Shechtman D.J.Nature,1986,319:102 6 Min Lequan,Liu Qingsheng and Wu Yuzhen.J.University of Science and Technology Beijing,1989,11(4):388 295， 七 ， ， ，。 ， 。 ， · ， ， ， ， ， ， ， ， ， 。 ， ， 。 ， 是 ， ， ， 理