1. Center for Dielectrics and Piezoelectrics, Materials Research Institute, Department of Material Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
2. Department of Electrical Engineering, National Cheng Kung University, Taiwan, No. 1, University Road, Tainan City 701, Taiwan
3. Laboratoire CIRIMAT, UMR CNRS5085, Université de Toulouse, 118 route de Narbonne 31062, Toulouse Cedex 9, France