1. School of Metallurgy and Environment Central South University Changsha 410083 Hunan P.R. China
2. Hunan Joint International Research Center for Carbon Dioxide Resource Utilization State Key Laboratory of Powder Metallurgy School of Physics and Electronics Central South University Changsha 410083 Hunan P.R. China
3. Nanoinstitut München Fakultät für Physik Ludwig-Maximilians-Universität München 80539 München Germany
4. Hunan Provincial Key Laboratory of Nonferrous Value-added Metallurgy Changsha 410083 Hunan P.R. China
5. MOE Key Laboratory of Resource Chemistry and Shanghai Key Laboratory of Rare Earth Functional Materials Shanghai Normal University Shanghai 200234 P.R. China