1. Key Laboratory for Special Function Materials and Structural Design of Ministry of EducationNational and Local Joint Engineering Laboratory for Optical Conversion Materials and TechnologySchool of Physical Science and Technology Lanzhou University Lanzhou 730000 China
2. Institute for Solid State Physics (ISSP)The University of Tokyo Kashiwa Chiba 277‐8581 Japan
3. State Key Laboratory of Superhard MaterialsCollege of PhysicsJilin University Changchun 130012 China
4. State Key Laboratory of Inorganic Synthesis and Preparative ChemistryInstitute of ChemistryJilin University Changchun 130012 P. R. China