Synthesis And Characterization Of Europium-Doped Alkaline Earth Metal Borates Nanomaterials And Their Properties

Alkaline earth metal borates as host lattices for the luminescent material have triggered more and more research enthusiasm owing to their low cast, convenient fabrication, structural stability, low synthesis temperature, strong luminescence intensity and so on. That single functional materials are prepared into bifunctional or multifunctional composite materials has been a new trend to meet the needs of various fields. The investigationofthe alkaline earth metal borates which are as host lattices for luminescent material both as a single functional materials and bifunctional or multifunctional composite materials is significative both from scientific research and practical points of view.The series of europium-doped alkaline earth metal borates were successfully fabricated by the macrowave stratege and using poly(vinyl pyrrolidone)(PVP) as the template. And the bifunctional magnetic-luminescent Fe3O4/Mg3B2O6:Eu3+nanocomposites were successfully synthesized via a promising template-free microwave strategy. The as-prepared products were characterized by XRD, FT-IR, TG-DTA, SEM, TEM, PL, VSM, et al. The main points can be summarized as follows:(1) The series of europium-doped alkaline earth metal borates Mg3B2O6:Eu3+, CaB2O4:Eu3+, SrB2O4:Eu3+and BaB2O4:Eu3+were successfully fabricated by the macrowave stratege and using poly(vinyl pyrrolidone)(PVP) as the template using Mg(NO3)2-6H2O, Ca(NO3)2, Sr(NO3)2, Ba(NO3)2respectively and Na2B4O710H2O as the raw materials. SEM results showed that the Mg3B2O6:Eu3+, CaB2O4:Eu3+and BaB2O4:Eu3+are all irregular structure, and SrB2O4:Eu3+phosphors are hierarchical microspheres. PL results show that different host lattices have different fluorescence intensity, and the SrB2O4:Eu3+microspheres with regular structure have the highest fluorescence intensity.(2) The hierarchical SrB2O4:Eu3+microsphere phosphors have been successfully synthesized via PVP-assisted microwave strategy and a subsequent calcinations using Sr(NO3)2and Na2B4O7-10H2O as the raw materials. After calcinations at650℃, the precursor was converted to SrB2O4:Eu3+flower-like microsphere with diameters of-3μ m. And the microsphere is composed of large numbers of nanosheets with thicknesses of-50nm. The excitation spectra of the products monitored at613nm show a series of sharp bands. And the strongest one is at393nm. The products present the strong characteristic emission at613nm corresponding to5DO�'7F2of the Eu3+transition under393nm excitation. The microwave power and microwave reaction time、 the Eu3+concentration and the calcinations temperature have important effects on the morphology and luminescence properties of the products.(3) The flower-like Fe3O4/Mg3B2O6:Eu3+bifunctional nanocomposites were successfully synthesized via a promising template-free microwave strategy. The prepared Fe3O4/Mg3B2O6:Eu3+composites possessed flower-like structure composed of a large number of nanosheets with the thickness of about10nm. The Fe3O4nanospheres with diameters of-40nm are embedded with layers of the Mg3B2O6:Eu3+nanosheets. The N2adsorption-desorption measurement indicates the products have a relatively high surface area of133.5cm/g. Photoluminescence (PL) spectra presented that the composites displayed a strong red characteristic emission of Eu3+, and the intensity of emission at613nm is about1.36x106cd, Magnetic measurements showed that the obtained bifunctional nanocomposites exhibited superparamagnetic behavior at room temperature.