%0 Journal Article %K Temperature %K Defects %K Electric fields %K Iron compounds %K Visualization %K Bismuth compounds %K Calcium compounds %K Activation barriers %K Collective dynamics %K Collective motions %K Crystalline solids %K Direct observations %K Electric field induced %K Future applications %K Oxide electrolytes %K Oxygen vacancies %A J.S Lim %A J.H Lee %A H.-S Park %A R Gao %A T.Y Koo %A L.W Martin %A Ramamoorthy Ramesh %A C.-H Yang %B NPG Asia Materials %D 2018 %G eng %I Nature Publishing Group %P 943-955 %R 10.1038/s41427-018-0087-5 %T Ultrafast collective oxygen-vacancy flow in Ca-doped BiFeO3 %V 10