北京科技大学材料科学与工程学院,北京,100083;
清华大学材料系,北京电镜中心,北京,100084;
Department of Materials Science and Engineering, University of California, Berkeley, Colifornia 94720 and Department of Physics, University of California, Berkeley, California 94720;
Department of Materials Science and Engineering, University of California, Berkeley, Colifornia 94720 and Department of Physics, University of California, Berkeley, California 94720;
Department of Materials Science and Engineering, University of California, Berkeley, Colifornia 94720 and Department of Physics, University of California, Berkeley, California 94720;