Combustion Synthesis And Luminescence Properties Of Vanadate Luminescence Materials

Vanadate luminescent materials have been attracting more and more attentions for the high-efficient sensitization from VO43- to rear earth ions as well as the self-activated emitting properties of VO43- group. The low synthesis temperature, good chemical and thermostability make vanadate phosphor a promising luminescent material. At present, YVO4:Eu3+ red phosphor has been a commercial product among the vanadate luminescent material. This famous phosphor was mainly obtained by high tempareture solid state reaction or oxalate precipitation process in industry. The high energy-intensive, time-consuming solid state reaction and complex, difficult-to-control oxalate precipitation process all have their drawbacks. While the combustion method as an easy and rapide, high efficient and energy saving procedure has great value in the synthesis of new materials. So it is very significant to research and practise combustion method to synthesis vanadate phosphor.In this study, a Eu3+ activated Ca3(VO4)2 red emitting phosphor and a self-activated emission vanadate garnet phosphor Ca2KMg2V3O12 were prepared by a high efficient citric acid-assisted sol combustion method. All the samples were characterized by X-ray diffraction (XRD),scanning eleerton microsopy (SEM) and fluorescence spectroscopy. The effects of process parameters on the phase composition, micor-structure and luminescence properties of as-synthesized smaples were investigated based on these measurements and analysises. The optimized procedure is Ca/V = 3:2.2,T = 900℃,n(CA):n(Ca2++V5+) = 0.8. Further, the influences of Eu3+ ion doping concentration, Na+ or Li+ co-doping with Eu3+ ion on the spectroscopic structure of Ca3(VO4)2:Eu3+ which prepared by the optimized processing were studied in the paper. It was found that Na+ or Li+ doping is beneficial for increasing of the f-f transition excitation of Eu3+ in Ca3(VO4)2.Ca2KMg2V3O12 phosphor was successfully synthesized by the similar process under 600 - 900℃. Its excitation spectrum distributed from 260nm to 425nm with a peak at about 320nm, and emission spectrum almost covers the whole visible light region with a main peak located between 520nm and 530nm. The CIE colour coordinate (x, y) = (0.323 - 0.339, 0.430 - 0.447) indicating that Ca2KMg2V3O12 can emitting bright, slightly yellowish green white light under the excitation of ultraviolet and near ultraviolet. The results of Rietveld refinement indicates that Ca2KMg2V3O12 have a cubic garnet crystal structure belonging to space group Ia3d with a = b = c = 12.50031±0.00041?, Z = 8. The deviation from Td symmetry of twisty [VO4] tetrahedra in the lattice may be the structure basis for the intense broad band emission of Ca2KMg2V3O12 phosphor.