1. Key Laboratory of Advanced Technologies of Materials, Ministry of Education China, Southwest Jiaotong University, Chengdu 610031, P. R. China
2. CRRC Qingdao Sifang Locomotive Co. Ltd, Qingdao 266550, P. R. China
3. Department of Chemical and Materials Engineering, The University of Auckland, PB 92019, Auckland 1142, New Zealand