The Synthesis And Luminescence Properties Of Several Typical Silicates Phosphors

Long-lasting phosphorescence (LLP) materials have attracted considerable attention, due to their friendly environmental, energy economized and big market value. The traditional aluminates phosphors are not satisfied for the application, as their poor water resistance and bad compatibility with other materials. So we choose the silicates as the host materials, which show much more excellent performance compared with aluminates phosphors. And discuss their luminescence and afterglow properties.The main contents are listed as following:1. The improvements of the traditional silicates phosphors:For the first time through calculate and experiment data we confirm that, the454nm emission peak belongs to Eu2+in [CaO6] and the535nm emission peak belongs to Eu2+in [CaO8] in Ca2MgSi207. The Eu2+in [CaO6] can transfer its energy to Eu2+in [CaO8]. The duration of Ca1.998MgSi2O7:0.002Eu2+is12.5h, and only Eu2+in [CaO8] has contribution to the afterglow process. In Ca2MgSi2O7:Eu2+, Ce3=Ce3+can transfer its energy to Eu2+in [CaO8], and the energy-transfer efficiency from Ce3+to Eu2+is61%. After co-doping Ce3+, new traps are formed, the trap depth and frequency factors are improved markedly. The duration of Ca1.968MgSi207:Euo.oo2, Ce0.03can be prolonged to more than20h.2. The research of red and white light silicates long lasing phosphors:The energy transfer between Eu2+and Mn2+in Sr3MgSi2O8is systematically investigated. Through the persistent energy transfer of En2+→Mn2+, the duration of the red emission prolongs to more than2h. The role of Eu2+, Mn2+and Dy3+during the afterglow process is investigated carefully by the analysis of the thermoluminescence spectra. The energy transfer between Ce3+and Mn2+are testified in BaMg2Si2O7. Through the persistent energy transfer of Ce3+→Mn2+, the duration of the red emission of Mn2+prolongs to more than2h. After doping Dy3+doped into Sr2Al2SiO7, the phosphor shows a weak yellow emission. Through the energy transfer of Ce3+to Dy3+, the white emission can be obtained in Sr2Al2SiO7. The duration of Sr2Al2SiO7:Ce3+, Dy3+is50min. The finding suggests a promising approach to controlling the color of the photoluminescence and phosphorescence of long lasting silicates phosphors by persistent energy transfer. 3. The new type long lasting silicates phosphors:three kinds of island and frame-like silicates are synthesized by solid-state reaction. In the frame-like silicate Ba4(Si3O8)2, through co-doping Eu2+and Dy3+, we get a new kind of green long lasting silicate phosphor with excellent afterglow property. The lasting time of Ba4(Si3O8)2:Eu2+,Dy3+is more than24h. And Ba4(Si3O8)2:Eu2+can also be used as storage material as it has deep and stable traps which can immobilize the carriers permanently at room temperature. The island silicate Ca5MgSi3012is synthesized in different atmosphere. The host material has a self-trapped emission (STE) for which the oxygen vacancy deficiency is responsible. And the STE can transfer its energy to Eu2+. The duration of Ca5MgSi3012:Eu2+, Dy3+is more than5h; After doping Eu2+, Tb3+, Cr3+, and Cu+in island silicate Mg2SiO4. there is no afterglow phenomenon which means the island silicate Mg2SiO4can not be used as the host materials for long lasting phosphor.