Preparation And Characterization Of Rare-earth Luminescent Material CaWO₄: Eu³⁺

Luminescent materials doped with rare-earth ions have much excellent performance because of its'special electron configuration energy level of 4f and structure of charge transition zones, and the luminescent materials have the advantages of high luminous intensity, long after time, controllable emission wavelength, no radiation, no pollution, etc. Based on the situations of more and more attention to practical value of nanometer red rare-earth luminescent materials and immature researches on preparation technologies of the materials, we concentrated main efforts on lowing synthesis temperature, simplifying process flow, shortening reaction time and preparing products with pure phase and controllable particle form. In addition, we also concentrated efforts on finding a high-efficient, practical and low energy consumption preparation technology. The performance of luminescent materials is mainly determined by mean particle size, doping amount of Eu3+, crystallization degree etc. On one hand, a method of chemical precipitation has advantage of capability of preparing products with size-controllable and uniformly dispersed particles; on the other hand, high-energy ball milling method can lead power to carry out plastic deformation and phase transition, energy utilization rate is improved greatly, and solid solubility of activator in substrate is extended. Therefore, this subject fully utilized the advantages of the two methods and successfully synthesized luminescent material CaWO4:Eu3+ with proper particle size and superior luminescent properties.This article studied on preparing a series of luminescent material CaWO4:Eu3+ by the method of chemical precipitation through changing some factors, such as precipitation pH value, precipitation temperature, doping amount of Eu3+, calcining temperature, etc., and then, the prepared materials are characterized by some measures, such as XRD,SEM and FL. At the same time, the article studied on preparing a series of luminescent material CaWO4:Eu3+ by the method of high energy ball milling through changing some factors, such as ratio of milling media to material, ball milling temperature, ball milling time, doping amount of Eu3+ etc., and then, the prepared materials are characterized by some measures, such as XRD, SEM and FL. For this, we aim at obtaining the optimal preparing technology factors of the luminescent material CaWO4:Eu3+ with the strongest luminescent intensity.It is demonstrated by the experiments that:firstly, the strongest luminescent CaWO4:20% Eu3+ powder with proper and uniform particle size is prepared in a muffle at 950℃of calcining temperature for 2 hours from a precursor which is prepared at 7 of precipitation pH value and 40℃of precipitation temperature; secondly, the strongest luminescent CaWO4:30%Eu3+powder with proper and uniform particle size is prepared by a high energy ball milling method at 600℃for 1h from the precursor which is prepared at 7 of precipitation pH value and 40℃of precipitation temperature, and the ratio of milling media to material is 12:1; thirdly, compared with the chemical precipitation method, the high energy ball milling method can be used for lowing the synthesis temperature from 950℃to 600℃, lowing the reaction time from 2 h to 1 h, and rising the doping amount of Eu3+ from 20% to 30%. At the same time, the luminescent intensity and thermal stability are effectively improved, and uniformly dispersed luminescent powder particles without glomeration are obtained.