Preparation,structure And Eu-activated Fluorescence Properties Of Several New Phosphate Compounds

Luminescent materials have been extensively studied for their unique optical characteristics and their applications in different fields such as displays,lighting,lasers,scintillators and white light emitting diodes.In most cases,the luminescent material is composed of a rare earth activator and host matrix,and its performance depends largely on the elemental composition and microstructure of the host matrix.Inorganic phosphate is a promising host material,which has the advantages of low cost,good chemical and thermal stability,easy synthesis and environmental friendliness.In this paper,the single crystals of several new phosphate compounds were prepared by the molten salt method,then their structures were obtained by single crystal X-ray diffraction,and their related properties were studied.The luminescence characteristics of Eu ion activation were mainly studied.As follows:?1?A new phosphate crystal Cs Mg₂P₃O₁₀ was grown by molten salt method.The single-crystal X-ray diffraction analysis reveals that this compound crystallizes in orthorhombic space group Pbcn?No.60?with unit cell parameters a=7.8757?8??,b= three-dimensional framework.Based on its structural information,its electronic structure was calculated using first-principle.The results show that it is a direct band gap and the a wide blue band at 462 nm under the excitation of 340 nm.The optimal doping concentration x=0.01,and its CIE coordinate is?0.1382,0.0911?.?2?A new mixed-anion phosphate crystal Cs₂Bi₂Sr?P₂O₇??PO₄?₂ was obtained by molten salt method.The single-crystal X-ray diffraction analysis reveals that this compound crystallizes in monoclinic space group P2₁/c?No.14?with unit cell parameters a=17.708?10??,b=9.156?5??,c=9.221?5??,?=90.160?8?°,V=1495.04?³.Based on its structural information,the band gap was estimated by the combined density functional Cs₂Bi₂Sr?P₂O₇??PO₄?₂ were mainly studied.Under the excitation of 394 nm,the samples 612 nm.The temperature-dependent emission spectra suggest that the resultant products possess excellent thermal stability with activation energy of 0.226 e V.For the optimal photoluminescence lifetime under 394 nm excitation were determined to be about 92%and2.18 ms.The research results show that it has excellent light-emitting properties and has potential value as a red phosphor for white light-emitting diodes.In addition,related studies on its homologue A₂Bi₂M?P₂O₇??PO₄?₂?A=Rb,Cs;M=Ca,Sr?were also conducted.The single crystal X-ray diffraction data show that it belongs to the monoclinic space group P2₁/c?No.14?with Cs₂Bi₂Sr?P₂O₇??PO₄?₂,and the similarities and differences doping concentration is x=0.25,and the CIE coordinates are?0.625,0.3745?,which is orange-red.