[1] D. Ye, D. Li, W. Chen, Y. Shao, G. Xiao, M. Sun, and X. Fu, Res. Chem. Intermed. 35, 675 (2009).
[2] M. Guzik, E. Tomaszewicz, S. M. Kaczmarek, J. Cybinska, and H. Fuks, J. Non-Cryst. Solids 356, 1902 (2010).
[3] N. Y. Garces, M. M. Chirila, H. J. Murphy, J. W. Foise, E. A. Thomas, C. Wicks, K. Grencewicz, L. E. Halliburton, and N. C. Giles, J. Phys. Chem. Solids 64, 1195 (2003).
[4] H. Xia, H. Song, J. Wang, J. Zhang, T. Wang, J. Zhang, Y. Zhang, and Q. Nie, Cryst. Res. Technol. 40, 199 (2005).
[5] I. Nikolov, X. Mateos, F. Guell, J. Massons, V. Nikolov, P. Peshev, and F. Diaz, Opt. Mater. 25, 53 (2004).
[6] E. Cavalli, A. Belletti, and M. G. Brik, J. Phys. Chem. Solids 69, 29 (2008).
[7] I. Sokolska and S. Kuck, Spectrochim. Acta Part A 54, 1695 (1998).
[8] G. Wang, X. Long, L. Zhang, G. Wang, S. Polosan, and T. Tsuboi, J. Lumin. 128, 1556 (2008).
[9] H. Teng, S. Zhou, H. Lin, T. Jia, X. Hou, and J. Wang, Chin. Opt. Lett. 8, 414 (2010).
[10] Q. Fang, H. Chen, F. Xu, S. Wang, Z. Liang, and C. Jiang, Chin. Opt. Lett. 8, 1071 (2010).
[11] H. Xiao, H. Chen, F. Xu, C. Jiang, and P. Yang, J. Chin. Ceramic Soc. (in Chinese) 36, 617 (2008).
[12] A. Vedda, F. Moretti, and M. Fasoli, Phys. Rev. B 80, 045104 (2009).
[13] H. Xiao, H. Chen, F. Xu, C. Jiang, and P. Yang, J. Cryst. Growth 310, 521 (2008).
[14] H. Chen, H. Xiao, F. Xu, C. F. Xu, C. Jiang, and P. Yang, J. Inorganic Materials (in Chinese) 24, 1036 (2009).
[15] H. Chen, Q. Shen, Q. Fang, H. Xiao, S. Wang, Z. Liang, and C. Jiang, J. Synthetic Crystals (in Chinese) 39, 829 (2010).
[16] L. Luo and Y. Wang, J. Quantum Electronics (in Chinese) 25, 166 (2008).
[17] V. Yakovyna, A. Matkovskii, D. Sugak, I. Solskii, and S. Novosad, Radiat. Meas. 38, 403 (2004).
[18] Y. Abraham, N. A. W. Holzwarth, and R. T. Williams, Phys. Rev. B 62, 1733 (2000).
[19] K. Tanaka, K. Ohga, C.-K. Choo, and R. Nakata, J. Appl. Phys. 90, 5369 (2001).
[20] Y. Yang, J. Xu, and Y. Hang, Laser & Optoelectronics Progress (in Chinese) 144, 50 (2007).
[21] M.Y. Sharonov, A. B. Bykov, S. Owen, V. Petricevic, and R. R. Alfano, J. Appl. Phys. 93, 1044 (2003).
[22] H. Xia, J. Wang, H. Wang, J .Zhang, Y. Zhang, and H. Song, Rare Metals. (in Chinese) 29, 181 (2005).
[23] W. Kolbe, K. Petermann, and G. Huber, IEEE J. Quantum Electron. 21, 1596 (1985).
