Quantum Cutting And Vacuum-ultraviolet Spectroscopy For GdMgB₅O₁₀: Ln(Eu～(3+), Er～(3+), Tb～(3+), Pr～(3+), Mn～(2+))

With the development of mercury-free fluorescent tubes and plasma display panels, research new system of quantum cutting phosphors becomes new means to promote the efficiency of VUV excited phosphors. Most of the quantum cutting systems hitherto is fluoride, which have no practical value due to their low stability, low absorbability and low energy conversion efficiency under VUV exciting. On the contrary, oxide have strong absorbability and easy to be synthesized. Furthermore, Gd³⁺ has rich energy level and can transfer energy to luminescent centers. So, the thesis selects GdMgB₅O₁₀ as host material to study its luminescent properties under VUV excitation and quantum cutting of Gd³⁺-Eu³⁺, Er³⁺-Gd³⁺-Tb³⁺ and Pr³⁺-Mn²⁺, in order to obtain useful quantum cutting phosphors.In this thesis, GdMgB₅O₁₀ : Re³⁺ phosphors were prepared by the thermal decomposition of the corresponding nitrates, their phase purity of phosphor is characterized by XRD, and the luminescent properties of these phosphors are measured in VUV/UV region by UV and VUV spectrophotometer system. The results indicate that:1. The main emission of Gd_1-xMgB₅O₁₀:xEu³⁺ peaked at about 610nm with the luminescence intensity 0.5 of that of commercial red phosphor (Y, Gd)BO₃:Eu³⁺ under 147nm excitation. And the optimal doping concentration were approximately x=0.005. In this system, the quantum cutting between Gd³⁺ and Eu³⁺ could not be discovered, the reason is that ⁸S_7/2�'⁶I_J transition of Gd³⁺ lain at about 200nm overlaps the CTS of Eu-O, which causes the exciting energy easy be transferred to the CTS, So, it is disadvantageous for the cross-relaxation energy transfer between Gd³⁺-Eu³⁺.2. Photon cascade emission of Pr³⁺ was observed in Gd_0.99MgB₅O₁₀:Pr_0.01 under 147nm excitation. There were two steps of radiative transition involved transitions ¹S₀�'¹D₂ (345nm) followed by ¹D₂�'³H₄ (585nm) or ¹D₂�'H₅ (695nm). The emission of GdMg_1-xB₅O₁₀: Mn_x under 147nm excitation is red band emission lied at630nm, which was attributed to transition 4Ti—>6A\ of Mn2+, and the optimal doping concentration were approximately x=0.05.The quantum cutting between Pr3+-Mn2+ could be discovered in Gdo.99Mgo.98 B5O10: Pro.oi> Mno.02, that caused the red emission of Mn2+ stronger.3. The main emission of Gdi.xMgB5Oi0: xTb3+peaked at about 543nm (5D4-^7F5) under 147nm excitation, and the optimal doping concentration were approximately x=0.15.The excitation spectrum indicates the energy transfer from Gd3+toTb3+ occurred. The emission of Er3+ could not be discovered in GdMgBsOio under 147nm excitation, but Er3+ increased the emission of Gd3+, which indicates the energy transfer from Er3+ to Gd3+ occurred. The quantum cutting within "Er3+-Gd3+-Tb3+" could not be discovered in Er3+, Tb3+ co-doped GdMgBsOio under VUV excitation.