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Synthesis And Luminescence Properties Of Non Rare-earth Mn Doped Red Phosphors

Posted on:2015-12-14Degree:MasterType:Thesis
Country:ChinaCandidate:S LiFull Text:PDF
GTID:2181330452964280Subject:Chemistry
Abstract/Summary:PDF Full Text Request
White LED has received wide attention and is considered as the nextgeneration lighting source due to its significant advantages of small powerconsumption, environmental-friendliness, long using lifetime and so on.Although the conversion efficiency of LED is high, the color deficiency inthe red region makes it exhibit low color rendering index (CRI). Therefore,it is important to develop red emitting phosphors of high efficiency. Rareearth Eu is the most common activator used in red phosphors. However,the limited supply leads to the high cost of Eu. Due to the relatively lowerprice, rich oxidation state variation and good optical properties of non-rareearth Mn, it is very promising for Mn to substitute for rare earth elementsin the fabrication of red phosphors.In this thesis, a serial of different contents of Mn2+ions dopedMgAl2O4red phosphors, exhibiting only red light centered at650nmunder290nm and435nm excitation, have been prepared by solid statereaction (SSR) and sol-gel method respectively. These phosphors havebeen characterized by X-ray diffraction (XRD), electron paramagneticresonance (EPR), fluorescence spectrophotometer (FS), scanning electronmicroscopy (SEM) measurements. The influence of Mn2+dopingconcentration on the luminescence properties of the phosphor was studied.The luminescence properties of the MgAl2O+4:Mn2synthesized from solidstate reaction have been compared with the sol-gel prepared sample. Theinfluence of flux MgF2on the luminescence properties of the samplesprepared from solid state reaction has also been studied.In addition, we used hydrothermal and sol-gel method to synthesize Mn4+doped SrGe4O9and Mg2TiO4red phosphors respectively. TheSrGe4O9:Mn4+phosphor emits red emission at656nm under290nm and423nm excitation and the Mg42TiO4:Mn+phosphor emits red emission at655nm under325nm or475nm excitation, which is due to the2E2â†'4A2transition of Mn4+. The influence of Mn4+doping concentration on theluminescence properties of the phosphor was studied and the luminescenceproperties of the SrGe4O9:Mn4+phosphors prepared from different methodswere compared.
Keywords/Search Tags:Manganese doping, red phosphor, solid state reaction, flux, hydrothermal method, sol-gel method
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