1. State Key Lab of New Ceramics and Fine Processing School of Materials Science and Engineering Tsinghua University Beijing 100084 P. R. China
2. State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources School of New Energy North China Electric Power University Beijing 102206 P. R. China
3. Center for Advanced Mechanics and Materials Applied Mechanics Laboratory Department of Engineering Mechanics Tsinghua University Beijing 100084 P. R. China
4. Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 P. R. China