Preparation And Luminescent Properties Of MAlSiN₃: Eu²⁺(M=Ca, Sr) Phosphor And Its Multiphase System

InGaN-based white LED is widely applied in the lighting world for its excellent luminescent properties. The traditional white light consists of a high performance blue LED and yellow phosphor, but the white light spectrum produced by this way lacks red light and caused high color temperature and poor color performance. Therefore, in order to meet the LED needs of high CRI (color rendering index) and low color temperature, red phosphors are applied to white LED. Eu2+ activated nitride red phosphor can be effectively excited by ultraviolet or blue light and emit 590-680nm red light. This phosphor not only has excellent thermal stability and chemical stability, but also has wide emission wavelength range and high luminous efficiency, for which attracted more and more attention.In this thesis, the Eu2+ activated CaAlSiN3 red phosphor, Ca1-xSrxAlSiN3 solid solutions and (CaAlSiN3)(1-x)-(Si2N2O)x multiphase system were successfully prepared by high temperature solid state reaction at normal pressure. The crystal structure and the photoluminescence properties were investigated and the application was also studied. The main contents and conclusions of this thesis are as follows:(1) CaAlSiN3:Eu2+ red phosphor was successfully prepared by high temperature solid state reaction at normal pressure. The crystal structure of the phosphor was analyzed and the lattice parameters were calculated based on XRD measurement. The results show that the phosphor belongs to the orthorhombic phase, and the space group is Cmc21. The lattice parameters are a=0.9802 nm, b=0.5651 nm, c=0.5063 nm. The excitation spectrum of CaAlSiN3:0.01Eu2+ has two peaks, located at 300-350 nm and 400-500 nm, respectively. The emission spectrum presents as a broadband from 575nm to 775 nm, which is peaked at 650 nm.(2) The color adjustment function and thermal stability of CaAlSiN3:Eu2+ phosphor were studied. The results show that the CRI of white LED is improved when adding CaAlSiN3:Eu2+ phosphor into yellow phosphor, and the spectrum is more saturated. In addition, due to the special rigid structure of CaAlSiN3:Eu2+ phosphor, its thermal stability is better than that of Sr2Si5N8:Eu2+ phosphor.(3) The solid solutions of Eu2+ activated Ca1-xSrxAlSiN3 and (CaAlSiN3)(1-x)-(Si2N2O)x multiphase system were prepared, the photoluminescence was studied. The results show that both Ca1-xSrxAISiN3 solutions and (CaAlSiN3)(1-x)-(Si2N2O)x multiphase system can shorten the emission wavelength, which further expands the application of the MAlSiN3-based phosphors. In summary, the CaAlSiN3:Eu2+ red phosphors were prepared at normal pressure, and the thermal stability and photoluminescence of these phosphors are excellent. The preparation of Eu2+ activated Ca1-xSrxAlSiN3 solutions and (CaAlSiN3)(1-x)-(Si2N2O)x multiphase system successfully enlarge the application range of the phosphors for different LED chips and lighting requirement.