1. Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Straße 40, 01187 Dresden,
Germany
2. Key Laboratory
of Transparent Opto-Functional Inorganic Materials, Shanghai Institute
of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, China
3. Key Laboratory of Nonferrous Materials and New Processing
Technology, Ministry of Education, Guilin University of Technology, 12 Jiangan Road, Qixing, Guilin, Guangxi,
China