[1] [1] Pang Li-bin, Gao Shao-jie, Gao Zhan-jun, Li Hong-lian and Wang Zhi-jun, Optoelectronics Letters 9, 282 (2013).

[2] [2] Sun J., Zhang X., Xia Z. and Du H., Journal of Applied Physics 111, 013101 (2012).

[3] [3] Liu Hai-yan, Zhang Kun, Pang Li-bin, Gao Shao-jie, Gao Zhan-jun, Duan Ping-guang, Zhang Zi-cai and Wang Zhi-jun, Optoelectronics Letters 10, 451 (2014).

[4] [4] Zhou Q., Zhou Y., Liu Y., Luo L., Wang Z., Peng J., Yan J. and Wu M., Journal of Materials Cheistry C 3, 3055 (2015).

[5] [5] Zhou X. and Wang X., Luminescence 29, 143 (2014).

[6] [6] Zhang J., Liu Y., Li L., Zhang N., Zou L. and Gan S., RSC Advance 5, 29346 (2015).

[7] [7] Shi S., He L., Geng L., Jiang L., Wang S., Zhang J. and Zhou J., Ceramics International 41, 11960 (2015).

[8] [8] Ji H., Huang Z., Xia Z., Molokeev M. S., Jiang X., Lin Z. and Atuchin V. V., Dalton Transactions 44, 7679 (2015).

[9] [9] Wang Z., Liang H., Gong M. and Su Q., Optical Materials 29, 896 (2007).

[10] [10] Xu Z., Li C., Li G., Chai R., Peng C., Yang D. and Lin J., Journal of Physical Chemistry C, 114, 2573 (2010).

[11] [11] Li G., Li L., Li M., Bao W., Song Y., Gan S., Zou H. and Xu X., Journal of Alloys and Compounds 550, 1 (2013).

[12] [12] Wan L., Lü S., Sun L. and Qu X., Optical Materials 36, 628 (2014).

[13] [13] Wu L., Ji M., Wang H., Kong Y. and Zhang Y., Optical Materials Express 4, 1535 (2014).

[14] [14] Yang W. J., Luo L., Chen T. M. and Wang N. S., Chemistry of Materials 17, 3883 (2005).

[15] [15] Dorenbos P., Journal of Physics Condensed Mater 17, 8103 (2005).