Synthesis And Property Tuning Of Several Kinds Of Typical Eu²⁺/Ce³⁺-doped Luminescence Materials

White light-emitting-diodes?WLEDs?have wide applications in the field of lighting.The combination of n-UV LED chip and multicolor phosphors shows great potential in the application.However,the luminescence materials for n-UV application suffer from many problems such as low efficiency,poor thermal stability or harsh preparation.In this thesis,we try to explore the synthesis and luminescence properties of several kinds of typical Ce³⁺/Eu²⁺-doped luminescence materials.On one hand,the thesis is aimed at obtaining luminescence materials with excellent properties and exploring their potential application;on the other hand,the thesis studies the relationship of composition-structure-property-luminescence performance in depth.This thesis is expected to be helpful for the improvement of luminescence mechanism and subsequent development of luminescence materials.The detailed research content is as follows:1.A series of quaternary nitride solid solutions with a general formula of Sr_1-xCa_xYSi₄N₇:0.01Eu²⁺ were synthesized by the carbothermal reduction and nitridation?CRN?method.The XRD patterns confirm the formation of a solid solution of Sr_1-xCa_xYSi₄N₇:Eu²⁺?0 ? x ? 0.5?.With the increase of Ca²⁺ content,the emission spectra shift from 540 nm to 564 nm under n-UV excitation.In addition,the thermal stability is comparable to that of the commercial?Sr,Ba?₂SiO₄:Eu²⁺ phosphor.2.A series of oxynitride phosphor SrSiAl₂O₃N₂: Eu²⁺?0.005 ? x ? 0.05?were successfully synthesized through a facile and efficient solid state route.The crystal structure,band structure and their photoluminescence properties were investigated.Under n-UV excitation,the emission spectra shift from 477 nm to 497 nm with an increase of Eu²⁺ concentration.The thermal stability is comparable to that of the commercial?Sr,Ba?₂SiO₄:Eu²⁺ phosphor.3.A kind of phosphate phosphor,Na₃Sc₂?PO₄?₃:Eu²⁺(NSP:Eu²⁺),was synthesized by solid-state reaction.The crystal structure,bandgap and photoluminescence properties were investigated.Under n-UV excitation,the NSP:Eu²⁺ phosphor exhibits a narrow blue emission peaking at 458 nm.The concentration quenching mechanism of the NSP:Eu²⁺ is dominated by the dipole-dipole interaction.Moreover,the NSP:Eu²⁺ shows better PL intensity,color purity and thermal quenching properties compared to commercial BAM phosphor.With temperature increasing,the emission intensity increases at first and then decreases,which could be induced by the defects caused by non-equivalent Eu²⁺ ions replacing Na⁺ ions.4.Two novel garnet phosphors,Ca₂YZr₂Al₃O₁₂:Ce³⁺(CYZA:Ce³⁺)and Ca2 Lu Hf2Al3O12:Ce³⁺(CLHA:Ce³⁺),have been successfully designed and synthesized using solid state method.The crystal structure,band structure,morphology and their photoluminescence properties were investigated.CYZA:Ce³⁺ and CLHA:Ce³⁺ can be efficiently excited by n-UV light and exhibit intense cyan emission.Their thermal stability are superior to that of the commercial?Sr,Ba?₂SiO₄:Eu²⁺ phosphor.A good white light has been obtained by combing the CLHA:Ce³⁺ phosphor with CaAlSiN₃:Eu²⁺ red phosphor.The CLHA:Ce³⁺ can be a promising candidate applied in white LEDs.