Synthesis And Photoluminescent Properties Of Samarium And Zirconium Ions Co-doped Stannate Phosphor Materials

Light-emitting diode(LED)light sources are widely used in production and life instead of conventional light sources.Phosphors play a vital role in LED lighting equipment,converting the ultraviolet or blue light generated by a chip to emit light of target color.Recent work on the development and application pf novel and efficient phosphor materials become popular in order to increase the light intensity of the LED light source.Rare-earth element doped phosphors have some superior characteristics of high luminous intensity,less doping amount and low production cost.Among them,samarium,as one of lanthanide rare-earth elements,has relatively a wide energy level and a high luminous efficiency.The emitted light color of samarium ions is mostly red,and the red phosphor is indispensable in the preparation of monochromatic or white LEDs.Calcium stannate-based(i.e.,CaSn O₃ and Ca₂Sn O₄)materials are an ideal matrix material because of their unique physical and chemical properties in terms of structure,dielectric,and catalysis.They are widely used in gas sensors,ceramic materials,catalysts,lithium-ion battery anode materials,etc.In this dissertation,samarium ion-doped calcium stannate phosphor materials were firstly synthesized by solid-phase method and co-precipitation method,respectively,and its photoluminescent properties were investigated,and explored.In addition,samarium/zirconium ions co-doped dicalcium stannate phosphor materials were also synthesized by solid-phase method and co-precipitation method,respectively,and their photoluminescent properties were analyzed.Studies on the preparation of calcium stannate-based phosphor materials co-doped with samarium/zirconium ions and the luminescent properties have a scientific significance and a promising application value.In chapter 1,luminescent materials type,luminescent mechanisms,and preparation methods were represented,and main research work on development and application of rare-earth element and/or metal element ion doping stannate-based fluorescent materials were summarized.The research purposes,contents,technical route and main innovation points of this dissertation were also given.In chapter 2,raw materials,synthesis equipment and characterization instruments used in the experiment were described,and the corresponding experimental conditions and operational principles of some instruments were introduced.In chapters 3 and 4,single-doped samarium ion and co-doped samarium/zirconium ions calcium stannate-based(i.e.,CaSn O₃ and Ca₂Sn O₄)phosphor materials were synthesized by solid-phase method and chemical co-precipitation method,respectively.The influences of doping samarium and/or zirconium ions,calcination temperature and time and ultrasound assistance on the crystal structure and photoluminescent properties of the product synthesized by co-precipitation method were investigated.The synthesized samples were characterized by laser particle size analyzer,X-ray diffraction spectrometer,scanning electron microscope(SEM),energy dispersive spectrometer(EDS),transient steady-state phosphor spectrometer,pyroluminescent spectrometer and inductively coupled plasma emission spectrometer.The results show that the doping of samarium and zirconium ions causes the lattice expansion and the crystal field environment to change,and the symmetry of the host lattice structure reduces and distorts,resulting in an increase in the luminous intensity of CaSn O₃:Sm³⁺,Zr⁴⁺and Ca₂Sn O₄:Sm³⁺,Zr⁴⁺phosphor materials,and increasing the trapping energy depth of the phosphor materials for prolonging the afterglow time.Ultrasound-assisted co-precipitation synthesis method reduces the precursor particle size and improves the size distribution,thereby increasing the luminous intensity of the synthesized product.The results also show that the particle size distribution of the product synthesized by co-precipitation method is more uniform,leading to a greater luminous intensity,compared to that by solid-phase method.In chapter 5,CaSnO₃:0.03Sm³⁺,0.04Zr⁴⁺phosphor material synthesized by co-precipitation method was selected to use as a phosphor material for the encapsulation of the corresponding LEDs based on the luminescent properties of all the products synthesized by solid-phase method and co-precipitation method,and the electroluminescent intensity and working stability of the LEDs were evaluated.Finally,this dissertation gave the main conclusions and prospects for future work based on the experimental results and the related discussion and analysis.