The Structural And Luminescent Properties Of Solid-solution Oxysalts Luminescent Materials

In recent years,luminescent materials have wide application in many fields such as fluorescent lighting,safety instructions,biological imaging and 3D display.As common solid-state luminescent materials,hosts doped with rare-earth ions have widely utilized as WLED materials,up-conversion materials,long-persistence materials and quantum-cutting materials.In addition,the emergence of solid-solution provides us more possibility to find new type of advanced functional materials.As all known,for solid-solution,the optical,electrical,magnetic,thermal and other properties are all highly dependent on their structural properties.Therefore,the research around the structure of solid-solutions and the attempt to build the link between their structural properties with other application performance has become one of the most important research projects in solid inorganic chemistry and material science,as it is instructive to the exploration and exploitation of new type of advanced functional materials.The structure of solid-solution luminescent materials have high effect on tunable luminescence,and doping such as rare-earth ions and transition metal ions play a more and more crucial role in luminous materials science.In our work,we studied the structural and luminescent properties of solid-solution luminescent materials and try to build proper theoretical model which is accordance with the experimental phenomena.The research results are generally presented as follows:The first chapter is the introduction part of this paper,which mainly introduces the research significance,the research background and the developing status to study solid-solution luminescent materials.Firstly,we introduces the basic knowledge of rare-earth elements,the fundamental spectroscopic principle,common characterization methods and the applications of rare-earth luminescent materials.At the same time,this paper introduces basic knowledge of solid-solution such as its definition,formation types,performance,function and research methods.The second chapter mainly introduces the structural and luminescent properties of self-activated solid-solution luminescent material Ba2xSr1-2xV2O7.All powder samples were synthesized via the conventional high-temperature solid-state reaction method and characterized through the X-ray diffraction spectrum.The XRD results showed that we successfully synthesized solid-solution samples.In addition,we measured the excitation and emission spectra of all samples.The experimental results showed that both the peak positions and bandwidths of excitation and emission witnessed a non-monotonic variation with increasing Ba:Sr ratio.The novel spectroscopic characteristics were linked to the disordered distribution of Ba2+ and Sr2+ in solid-solution,which not only strengthened the inhomogenous broadening of energy levels but also enlarged the energy difference between the excited singlets and triplets by enhancing the exchange interaction.Additionally,extreme points occurred at x = 0.25,which may meant the standard to measure disorder varied at this point.The third chapter mainly introduces the structural and luminescent properties of rare-earth doped solid-solution long-persistence luminescent materials BaxSr1-xAl2O4:Eu2+.Similar to Chapter 2,all powder samples were successfully synthesized via high-temperature solid-state reaction method,with the phase of the samples characterized by X-ray diffraction spectrum.The XRD results confirmed the formation of the solid-solutions and an obvious phase transition was observed.In addition,we evaluated the phase transition point with DFT calculation and found it accordance with the XRD result.For a certain solid-solution region,we observed that the peaks of emission bands was non-monotonously dependent on the composition.Different from the case in Chapter two,this work focused on the luminescent properties of doping centers rather than self-activated host,so we built a different theoretical model to explain the phenomena in this experiment.Through the analysis,we found that the abnormal spectral phenomenon is mainly due to different sites Eu2+prefer to occupy in different proportion of solid-solution samples.The fourth chapter mainly introduced the luminescence properties of Eu2+,Mn2+codoped halophosphate Ca5(PO4)3(F0.8Cl0.2)solid-solution samples.Unlike Chapter 2 and Chaper 3,this chapter discussed the anion-substitution solid-solution instead of the cation-substitution solid-solution.In this experiment,all the samples were synthesized by hydrothermal method.Through X-ray diffraction-spectrum characterization,we confirmed the formation of solid-solution.At the same time,the XRD results show that the introduction of certain proportion of Cl-will not make a big effect on Ca5(PO4)3F lattice.In this work,we studied the energy transfer from Eu2+ to Mn2+ and how to obtain white light via adjusting the doping concentrations of Eu2+ and Mn2+.The fifth chapter mainly introduced the luminescent properties of Tb3+,Ho3+codoped phosphate YPO4 and its feasibility for application in fluorescence temperature detection.We synthesized our powder sample by high-temperature solid-state reaction method.The X-ray diffraction result verified the successful synthesis of the crystal phase.In this chapter,we put forward a new mechanism which differed from traditional fluorescence temperature sensing scheme based on excited-state thermal coupling level and up-conversion fluorescence.In addition,we presented our mechanism with the sample YPO4:3.2%Tb3+,0.8%Ho3+.The temperature-detection mechanism was mainly based on the ground-state thermal-coupling levels of Tb3+ and the incorporation of Ho3+ was as a reference.The experimental results showed that the material has high temperature sensitivity,especially at room temperature.In the last chapter,we summarized the main content of this paper and make a prospect for the the application of solid-solution luminescent materials.