[1] Shandong Univ, State Key Lab Crystal Mat, Jinan 250100, Shandong, Peoples R China
[2] Argonne Natl Lab, Ctr Nanoscale Mat, 9700 South Cass Ave, Argonne, IL 60439 USA
[3] Shandong Univ, Sch Phys, Jinan 250100, Shandong, Peoples R China
[4] Argonne Natl Lab, Chem Sci & Engn Div, 9700 South Cass Ave, Argonne, IL 60439 USA