[1] Ma M X, Zhu D C, Zhao C, et al. Mater. Sci., 2012, 57: 1728.

[2] Ma M X, Zhu D C, Zhao C. Opt. Commun., 2012, 285: 665.

[3] Aierken S, Rahman A Z M S, He J Y. J. Lumin., 2011, 131: 1840.

[4] Ma Y Y, He J Y, Rahman A Z M S. Spectrosc. Spectr. Anal., 2015, 35: 3241.

[5] Pawade V B, Dhoble N S, Dhoble S J. J. Rare Earth, 2014, 32: 593.

[6] Wang T, Xu X H, Zhou D C. J. Rare Earth, 2015, 33: 361.

[7] Fang H W, Huang S, Wei X T. J. Rare Earth, 2015, 33: 825.

[8] Xia Z G, Liang Y J, Yu D Y. Opt. Laser. Tech., 2014, 56: 387.

[9] Lei Z G, Chang T C, Cui J M. Chin. J. Lumin., 2013, 34: 1476.

[10] Dou X H, Zhao W R, Song E H. J. Rare Earth, 2012, 30: 739.

[11] Fu X Y, Fang L J, Niu S Y, et al. J. Lumin., 2013, 142: 163.

[12] Geng D L, Li G G, Shang M M, et al. Mater. Chem., 2012, 22: 14262.

[13] Huang C H, Chen T M. J. Phys. Chem. C, 2011, 115: 2349.