Search

The lithium magnesium molybdate Li2-2xMg2+x (MoO4)3: xYb3+ (x= 0.01, 0.03, 0.05 and 0.07) phosphors were prepared by combustion synthesis method at 750 °C. The phases of prepared phosphors were confirmed by X-ray diffraction pattern and luminescent properties of phosphor materials were systematically studied. Li2Mg2(MoO4)3 has an orthorhombic symmetry and has discovered a three-dimensional framework consisting of metal-oxygen octahedra and trigonal prisms (where Li and Mg reside) that are interconnected by MoO4 tetrahedra. As a result of host absorption of Li2Mg2(MoO4)3, a broad excitation band ranging from 200 to 400 nm is recorded when Yb3+ emission was observed, photoluminescence spectra measured suggests the efficient energy transfer from host to Yb3+ ions. Upon ultraviolet excitation, an intense near-infrared emission of Yb3+ (²F5/2 → ²F7/2) around 986 nm is observed in Li2Mg2(MoO4)3: Yb3+. All the results indicate that Yb3+ doped Li2Mg2(MoO4)3 crystal can serve as UV excited phosphor that is a promising candidate as an associated application for the tunable laser. [ABSTRACT FROM AUTHOR]

Novel Li3Sr2La3-x(MoO4)8: xEu3+ phosphor (x=0.01, 0.03, 0.07 and 0.09 mole %) molybdate red phosphors had been synthesized by using a combustion Method at as temperature 750°C. The phase formation of the samples was investigated by X-ray diffraction measurements. The excitation and emission spectra indicated that this phosphor could be excited effectively by the visible light, and then emitted red light with the peaks located at 617nm. Upon 287 nm excitation, this phosphor show characteristic fluorescence 5D0 → 7FJ (J = 0, 1, 2, 3, 4) of the Eu3+ ions. The electronic transition located at 617 nm corresponding to 5D0 → 7F2 of Eu3+ ions, which is stronger than the magnetic dipole transition located at 593 nm corresponding to 5D0 →7F1 of Eu3+ ions. Different pathways involved in emission process have been studied. Concentration quenching has been observed for Eu3+ concentration 7%. Eu3+ doped Li3Sr2La3-x(MoO4)8: Eu3+ is a promising phosphor for applications in displays and optical devices. [ABSTRACT FROM AUTHOR]

In the present work Li4-xMoO5:xEu3+ (x=0.01, 0.03, 0.05 & 0.07) novel phosphors are prepared using Combustion synthesis method and their luminescent properties were investigated. The excitation spectra consist of broad charge transfer bands in the short-wave UV region of Mo6+→O2- and Eu3+→O²- with two sharp lines around 395nm and 465nm of the Eu3+ 4f excitation transitions. The results indicated that the characteristic emissions of MoO4 2- are quenched absolutely and phosphor exhibited intense red photoluminescence at 617 nm when excited by the light of 395nm, which was attributed to the electric dipole energy transition of 5D0→7F2 transition of Eu3+. The optimal doping concentration for Eu3+ ions is found to be 3 mol% and the quenching mechanism is attributed to the dipole-dipole interaction. [ABSTRACT FROM AUTHOR]