基金supported by the National Natural Science Foundation of China (NSFC) (21106178)the Scientific Research Foundation of Xuzhou (XJ11B009)+2 种基金the Polysilicon and Photovoltaic Energy Technology of Xuzhou (6AT102092)the Fundamental Research Funds for the Central Universities (2011QNA21)the State Key Laboratory of Advanced Technology for Materials Synthesis and Processing (Wuhan University of Technology) (2012-KF-13)~~