1. Electronic Materials Research Laboratory, Key Laboratory of Ministry of Education & International Center for Dielectric Research, School of Electronic and Information Engineering, Xi’an Jiaotong University, Xi’an 710049, P. R. China
2. Laboratoire de Physico-Chimie de l’Etat Solide, ICMMO, CNRS-UMR 8182, Bâtiment 410, Université Paris-Sud XI, 15 rue Georges Clémenceau, 91405 Orsay Cedex, France
3. School of Photoelectric Engineering, Xi’an Technological University, Xi’an 710021, P. R. China
4. Institute for Superconducting and Electronic Materials (ISEM), University of Wollongong, Innovation Campus, Squires Way, North Wollongong, NSW 2500, Australia