1. School of Materials Science and Engineering, Inner Mongolia Key Laboratory of Thin Film and Coatings, Inner Mongolia University of Technology, Hohhot 010051, PR China
2. School of Physical Science and Technology, Baotou Teachers’ College, Baotou 014030, PR China
3. College of Science, Inner Mongolia University of Technology, Hohhot 010051, PR China
4. School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021, PR China