Synthesis And Luminescent Properties Of Eu³⁺、 Tb³⁺Doped Bi-Based Oxyacid Salt Luminescent Materials

With the progress of science and technology, higher requirements on optical functional materials are putted forward, which makes the rare-earth luminescence materials play an important position in various application fields of rare earth. In numerous rare earth luminescent materials, materials with rare earth iron Eu3+、Tb3+as activator have become the main source of red light and green light and have been widely research. As the luminescence properties of Eu3+、Tb3+are close to the kinds, crystal phase and properties of the matching matrix materials, the studies of preparation the luminescent materials which have different matrix materials doped with Eu3+、Tb3+have received considerable interests. Bismuth based oxygen acid salts have stable crystal structure and high heat stability,which is a good matrix material and is favored by the researchers. In this paper, Bi2WO6、BiPO4and γ-Bi2MoO6are chosen as the matrix materials, the Eu3+、Tb3+doped Bi2WO6luminescent materials, the Eu3+、Tb3+doped BiPO4luminescent materials, as well as the Eu3+doped y-Bi2MoO6are prepared. DTA-TG、XRD and IR are used to characterize the crystal structure of the samples, and through the fluorescence spectrum its luminescent properties are studied.To start with, the Eu3+、Tb3+doped Bi2WO6red and green light emitting luminescent materials are prepared by a co-precipitation method with EDTA-2Na and the precipitant Na2WO4. The results show that a pure required sample Bi2WO6is formed when annealing temperature is increased to600℃and above. When annealing temperature is increased as high as1000℃, Bi2(WO4)3is appeared. Through the excitation and emission spectra of the Eu3+、Tb3+doped Bi2WO6luminescent material, we find that under465nm and488nm blue light excitation which is the highest excitation peak of the samples, the emission spectra show intense red-emission and green-emission, which corresponds to the5D0→7F2transitions on Eu3+and the5D4→7F5transitions on Tb3+. It indicates that the samples match the light-emitting wavelength of the common blue-emitting InGaN chips and are expected to be applicable to a new type of red-emission and green-emission light conversion materials which are applicable to the blue LED chips.Furthermore, the Eu3+、Tb3+doped BiPO4luminescent materials are prepared by a co-precipitation method and a hydrothermal method, respectively. The samples are prepared by a co-precipitation method, which has been used C2H6O2as a dispersant and (NH4)2HPO4as a precipitant. The XRD results show that hexagonal phase is prepared at room temperature. When annealing temperature reaches400℃, monoclinic phase is appeared. A pure monoclinic phase is formed when annealing temperature is increased to 600℃and above. Under395nm and377nm ultraviolet light which is as the highest excitation peak of the samples, the emission spectra show intense orange-emission and green-emission, and find that monoclinic phase have higher luminescent intensity. The Eu34+、Tb3+doped BiPO4are prepared by a hydrothermal method used C2H6O2as a dispersant. Hexagonal phase is transformed into monoclinic when the hydrothermal temperature and the hydrothermal time are increased. Through the excitation and emission spectra of the Eu3+、Tb3+doped BiPO4luminescent materials, the highest excitation peak of the samples is under395nm and377nm ultraviolet light as the same, it indicates that the monoclinic phase have higher luminescent intensity. However, the samples’emission intensity of orange-emission and green-emission is lower than the samples’prepared in a co-precipitation method.Eventually, the Eu3+doped γ-Bi2MoO6red light emitting luminescent materials are prepared by a co-precipitation method. When annealing temperature reaches800℃and the value of pH is5、7、9、11and13, orthorhombic phase γ-Bi2MoO6is formed. Under the monitoring of612nm wavelength light, in the excitation spectrum of y-Bi2MoO6:Eu3+, the width of absorption peak with charge transfer belt of Eu3+→O2-and Mo6+→O2-are not formed, only the strong linear transition peaks are formed in466nm and535nm, besides the intensity of them were similar. It indicates that the samples match the light-emitting wavelength of the common blue-emitting InGaN chips. Under466nm light excitation which is the highest excitation peak of the samples, the emission spectra shows intense red-emission, which corresponds to the5D0→7F2transitions on Eu3+, and the highest luminescent intensity when the value of pH is5.In this paper, Bi2WO6, BiPO4and y-Bi2MoO6are chosen as the matrix materials among bismuth based oxyacid salts, the most common characteristics of red and green light emitting Eu3+、Tb3+are chosen as an activator, we prepare the bismuth based oxyacid salt luminescent material with the good light performance through the simple and easily operate preparation method. It provides information for enriching the fields of luminescent materials and improving the application scopes of bismuth salts.