Heine F, Heumann E, Danger T, et al. Green upconversion continuous wave Er3+:LiYF4 laser at room temperature [J]. Appl. Phys. Lett., 1994, 65(4):383-384.[2] Downing E, Hesselink L, Ralston J, et al. A three-color, solid-state, three-dimensional display [J]. Science, 1996, 273(5279):1185-1189.[3] Qin G, Yamashita T, Arai Y, et al. 22 dB all-fiber green amplifier using Er3+-doped fluoride fiber [J]. Opt. Commun., 2007, 279(2):298-302.[4] de Wild J, Rath J K, Meijerink A, et al. Enhanced near-infrared response of a-Si:H solar cells with β-NaYF4:Yb3+(18%), Er3+(2%) upconversion phosphors [J]. Sol. Energy Mater. Sol. Cells., 2010, 94(12):2395-2398.[5] Trupke T, Shalav A, Richards B S, et al. Efficiency enhancement of solar cells by luminescent up-conversion of sunlight [J]. Sol. Energy Mater. Sol. Cells, 2006, 90(18/19):3327-3338.[6] Liu C X, Wang P C, Luo Y S, et al. Tb3+-Er3+ couples as spectral converters in NaYF4 for GaAs solar cells [J]. Chin. J. Lumin. (发光学报),2011, 32(11):1120-1125 (in Chinese).[7] Menyuk N, Dwight K, Pierce J W. NaYF4:Yb,Er - an efficient upconversion phosphor [J]. Appl. Phys. Lett., 1972, 21(4):159-161.[8] Liu J, Shan H, Liu X M, et al. Effect of fluoride concentration on the phase of NaYF4:Yb3+, Er3+ synthesized in ionic liquid [J]. Chin. J. Lumin. (发光学报),2012, 33(2):135-138 (in Chinese).[9] Li C, Lin J. Rare earth fluoride nano-/microcrystals:synthesis, surface modification and application [J]. J. Mater. Chem., 2010, 20:6831-6847.[10] Mathews M D, Ambekar B R, Tyagi A K, et al. High temperature X-ray diffraction studies on sodium yttrium fluoride [J]. J Alloys Compd., 2004, 377(1/2):162-166.[11] Liu F, Ma E, Chen D, et al. Tunable red-green upconversion luminescence in novel transparent glass ceramics containing Er:NaYF4 nanocrystals [J]. J. Phys. Chem. B, 2006;110(42):20843-20846.[12] Zhao S, Xu S, Jia G, et al. Er3+/Yb3+ codoped oxyfluoride borosilicate glass ceramic containing NaYF4 nanocrystals for amorphous silicon solar cells [J]. Mater. Lett., 2011, 65(15/16):2407-2409.[13] Santana-Alonso A, Yanes A C, Méndez-Ramos J, et al. Sol-gel transparent nano-glass-ceramics containing Eu3+-doped NaYF4 nanocrystals [J]. J. Non-Cryst. Solids, 2010, 356(18/19):933-936.[14] Santana-Alonso A, Méndez-Ramos J, Yanes A C, et al. Up-conversion in sol-gel derived nano-glass-ceramics comprising NaYF4 nano-crystals doped with Yb3+, Ho3+ and Tm3+ [J]. Opt. Mater., 2010, 32(9):903-908.[15] Huang J W. MDI JADE Use Manual [M]. Changsha: Central South University (中南大学出版社), 2006:24-26 (in Chinese).[16] Lu Y F, Du Y G, Xiao J Y. et al. Quantitive analysis of crystal phases in glass-ceramics by X-ray diffraction method [J]. J. Chin. Ceram. Soc.(硅酸盐学报), 2005, 33(12):1488-1493 (in Chinese).[17] Guo S L, Jin Y P, Zhao H F. Determination of phase composition and mass fraction of bulk zinc-alanium based magnesium-lead alloy [J]. Mater. Rev.(材料导报), 2012, 23(2):64-74 (in Chinese).[18] Zhang X, Yang P, Li C, et al. Facile and mass production synthesis of β-NaYF4:Yb3+, Er3+/Tm3+ 1D microstructures with multicolor up-conversion luminescence [J]. Chem. Commun., 2011, 47(44):12143-12145.[19] Yang D, Dai Y, Ma Pa, et al. Synthesis of Li1-xNaxYF4:Yb3+/Ln3+(0≤x≤0.3, Ln=Er, Tm, Ho) nanocrystals with multicolor up-conversion luminescence properties for in vitro cell imaging [J]. J. Mater. Chem., 2012, 22(38):20618-20625.[20] Wang H Q, Nann T. Monodisperse upconverting nanocrystals by microwave-assisted synthesis [J]. ACS Nano, 200, 3(11):3804-3808.[21] Dou Q, Zhang Y. Tuning of the structure and emission spectra of upconversion nanocrystals by alkali ion doping [J]. Langmuir, 2011, 27(21):13236-13241.