Synthesis And Photoluminescence Properties Of Aluminosilicate Red Fhosphor

White light-emitting diodes are considered as new solid light source andhave the advantages of energy saving, environmental protection, long lifetime,small size and high efficiency, and so on, which have already been widelyused in lighting and display. A major way of producing white LEDs isphosphor conversion method, but the problems of low color rendering index,high color temperature exist due to the lack of red emission. With thedevelopment of white LEDs technology, seeking the stable red phosphors,which can be excited by n-UV and blue light, has become a hot research. Inmy work, Al₆Si₂O₁₃:Eu³⁺and MgAl₂O₄:Eu³⁺red phosphors are synthesized bysol-gel-microwave method and solid state-microwave method, respectively.The effects of microwave technology, activators, additives and matrixcomposition on red emitting properties have been investigated. The resultsshow that:1. The Al₆Si₂O₁₃:Eu³⁺red phosphors, which have the single Mullite phase,are prepared by sol-gel-microwave method using two-step sintering. First stepis at power of800W for45min, and second step is at power of680W for30min. In the excitation spectra of Al₆Si₂O₁₃:Eu³⁺phosphor, the transition of ⁷F₀â†'⁵L₆at395nm exhibits the strongest intensity, followed by the transitionof⁷F₀â†'⁵D₂at465nm. Upon395nm excitation, the electric-dipole⁵D₀â†'⁷F₂transition of Eu3+at612nm has the strongest intensity. The fluxes of Y₂O₃,NaF and the sensitizer of Bi₂O₃can improve the red luminescence intensity;the samples doped by15wt%Y₂O₃and5wt%Bi₂O₃exhibit the strongest redemission; the best doping concentration of NaF is8wt%. The Al₆Si₂O₁₃:Eu³⁺phosphors can be excited not only by n-UV but also by blue light and exhibitstable red emission, which are suitable for application in white LEDs.2. The MgAl₂O₄:Eu³⁺red phosphors are prepared by solidstate-microwave method using two-step sintering. First step is at power of680W for30min, and second step is at power of800W for30min. In theexcitation spectra of MgAl₂O₄:Eu³⁺phosphor, the main excitation peak is at395nm followed by the excitation peak at465nm. Upon395nm excitation,the electric-dipole⁵D₀â†'⁷F₂transition of Eu³⁺at612nm has the strongestintensity. The samples doped by4.5wt%B₂O₃show the strongest relativeluminescence intensity in mono-doped samples; the samples doped by4.5wt%B₂O₃and4mol%GeO2show the strongest relative luminescence intensity inco-doped samples; Mg_0.85Ca_0.15Al₂O₄phosphor exhibit the strongest relativeluminescence intensity in alkaline earth mental replacement samples. TheMgAl₂O₄:Eu3+phosphor can also be excited by n-UV and blue light,exhibitting stable red emission, which can also be a suitable candidate in thewhite light-emitting diodes to generate white light.