Research On Morphology And Luminescence Properties Of Rare Earth Fluoride Doped

Rare earth doped upconversion luminescent materials have been widely used in many fields due to their unique luminescent properties and good stability,which has relatively practical operational value.For example,they have been widely used in biological field and solar cell field.However,due to the defects of upconversion luminescent materials,they have high radiation-free transition and low luminescence efficiency,which limit their further application.Therefore,it is of practical significance to improve the luminescence efficiency of upconversion luminescent materials.Rare earth fluoride phonons have low energy and are the best matrix materials.The ionic radii of some metals are little different from those of rare earth ions,and they are often used as cations of rare earth fluoride matrix materials.In this paper,a series of research work has been carried out to improve the luminescence efficiency of rare earth doped luminescent materials,and the results are as follows:(1)Na Lu F₄(Lu=Y,Er)hexagonal prism crystal was synthesized by hydrothermal doping different amount of Co²⁺with EDTA as complexing agent,the study found that under the same other reaction conditions,doping different amount of Co²⁺can control the aspect ratio of nanocrystals.For NaYF₄crystal,with the increase of Co²⁺doping amount,the diameter of hexagonal prism increases gradually,and its length decreases gradually.For Na Er F₄crystal,with the increase of the amount of Co²⁺doping,the diameter and length of Na Er F₄crystal gradually decrease.Co²⁺doping has a great influence on the luminescence properties of crystal.With the increase of Co²⁺doping,the luminescence intensity of NaYF₄crystal increases first and then decreases.The emission intensity of NaYF₄crystal with 15%Co²⁺doping is nearly 6 times of that without Co²⁺doping.The luminescence intensity of Na Er F₄crystals continued to increase.Therefore,the luminescence properties of the samples can be controlled by controlling the amount of Co²⁺doping.(2)NaYF₄hexagonal prism crystal was synthesized by hydrothermal doping with different amounts of M²⁺(M=Ca,Mg and Ca,Mg,Co)using EDTA as the complexing agent.It was found that under the same other reaction conditions,the doping of different M²⁺could control the aspect ratio of the crystal.With the increase of the amount of hetero-metal doping,the diameter and length of NaYF₄crystal column doped with Ca²⁺gradually decrease,and when the Ca²⁺concentration reaches 25%,other phases are generated.The volume of NaYF₄crystal column doped with Mg²⁺expands slightly and its length increases slightly.NaYF₄crystal doped with Ca,Mg and Co ions has different phases.The luminescence intensity of NaYF₄crystal increases first and then decreases.When doped with 15%M,the emission intensity of the sample doped with Ca²⁺is nearly 9times that of the sample undoped with Co²⁺,and the emission intensity of the sample doped with Mg²⁺is nearly 3.5 times that of the sample undoped with Co²⁺.The luminescence intensity of the samples with more Ca,Mg and Co ions is much higher than that of other single-ion doped crystals.