Tm^(3+)掺杂的MFT玻璃材料的升频转换发光及光学性质的JO计算

本文报道了Ｔｍ３＋离子在ＭＦＴ玻璃材料中的光学性质．测量了吸收光谱，利用ＪＯ理论计算了不同能级的寿命、跃迁分支比及跃迁几率，计算了一些能级的辐射跃迁振子强度．测量了６５０ｎｍ激发下蓝色升频转换发光，讨论了升频转换发光强度与激发光功率的关系，计算了１Ｄ２→３Ｈ４和１Ｇ４→３Ｈ６两个蓝色跃迁的发射截面．

White luminescence of Ho^(3+)/Tm^(3+)/Yb^(3+)-codoped CaWO_4 synthesized via citrate complex route assisted by microwave irradiation

The nanocrystalline Ho3+/Tm3+/Yb3+ co-doped CaWO4 upconversion(UC) phosphors were successfully synthesized by a modified citrate complex method using microwave irradiation. The citrate complex precursors were heat-treated at temperature ranging from 300 to 700 °C for 3 h. Crystallization of the Ho3+/Tm3+/Yb3+ co-doped CaWO4 was detected at 400 °C, and entirely completed at 600 °C. The Ho3+/Tm3+/Yb3+ co-doped CaWO4 heat-treated at 600 °C showed primarily spherical and homogeneous morphology. Under the laser excitation of 980 nm, Ho3+/Tm3+/Yb3+ co-doped CaWO4 shows the bright white upconversion(UC) emission visible to the naked eye, which is composed of a blue emission at 475 nm from Tm3+, and green and red emissions at 543 and 651 nm respectively from Ho3+. The coordinates of Ho3+/Tm3+/Yb3+ co-doped CaWO4 in the Commission International De'eclairage(CIE) chromaticity diagram could be controlled from a cool to a warm white color depending on the Tm3+ and Ho3+ concentrations. The UC luminescent properties on Tm3+ and Ho3+ concentrations and related mechanism based on laser pump power were discussed in detail.