Synthesis And Optical Properties Of Several Single Matrix White Phosphors

White light emission has become a research hotspot in the field of materials in recent years.In practice,it is common to use a mixture of several fluorescent materials to achieve white light emission.However,this may cause problems of unstable white light and low luminous efficiency.The development of a new type of single matrix white luminescent material is an effective way to solve the above problems.The rare-earth ion Dy³⁺is an ideal dopant for single-matr ix white light emission while Bi³⁺can be used as a sensitizer to enhance the luminescence intensity of Dy³⁺.In addition,all-inorganic perovskite nanocrystal Cs PbX₃?X=Cl,Br,I?has been attracting much attention of researchers since its first report in 2015.CsPbX₃?X=Cl,Br,I?has unique optical properties and the potential to achieve white light emission of a single matrix.In our work,two kinds of Dy³⁺/Bi³⁺doped novel single-matrix phosphors were synthesized and studied,as well as the gowth mechanism of Cs PbBr₃ and its related nanocrystals under saturated recrystallization strategy.The main contents are as follows:Dy³⁺doped single-matr ix white phosphors Sr_2?1–y?Ca_2yY₈?SiO₄?₆O₂?0?y?1?were prepared by high temperature solid state reaction.The change of Sr/Ca ratio causes a significant change in the crystal field environment of the activated ions.All samples can exhibit strong white emission when excited by ultraviolet,vacuum ultraviolet and cathode-ray.With the increase of excitation energy,the peak intensity ratio of Dy³⁺emission?blue/yellow ratio?showed a significant change.Based on the optical properties,decay time and thermal quenching performance,this phenomenon is reasonably explained.The introduction of Bi³⁺resulted in a3.75-fold improvement in the emission intens ity of the best sample.The potential of this material as a single-matrix white phosphor has been investigated by LED packaging testing.Dy³⁺doped single-matrix white phosphor Ca₉Al?PO₄?₇ was prepared by high temperature solid state reaction.This phosphor can be characterized by emission of Dy³⁺when excited by ultraviolet,vacuum ultraviolet and cathode-ray.In addition,the thermal stability of the sample was investigated.Cs PbBr₃ and its related nanocrystals were synthesized by saturated recrystallization strategy and their gowth mechanism was studied.Based on the solubility difference between Cs⁺and other ions,we investigated the effects of PbBr₂/Cs Br ratio,concentration,precursor dosage and reaction time on the composition,morphology,size and optical properties of nanocrystals.This study has important guiding signif icance for the preparation of Cs PbBr₃ and its telated nanocrystals by saturation recrystallization at room temperature.