Luminescence properties of YTaO4 : Nb, Eu

A series of Y1-xEuxTa1-yNbyO4 (x=0-0.20, y=0-1.00) are synthesized by a mod ified solid state reaction method. When the concentration of NbO43- in yttr ium tantalate is low, the structure of these systems is M' type YTaO4, With increasing concentration of NbO43-, its structure completely changed from M' type YTaO4 to fergusonite YNbO4. Under UV excitation, the emission, spec tra of YTaO4 : Nb, Eu consist of two parts, the emission band between 300-4 50 nm is the charge transfer emission of NbO43-, and the sharp line emissio ns in the range of 500-720 nm originate from the transition of electrons in 4f shell of Eu3+. The main peak at 612.7 nm can be ascribed to the Eu3+5D0 -->F-7(2) transition and shows a strong red emission. Fixing the concentrat ion of Nb5+ and Eu3+ separately, and changing the concentration of another ions, the luminescent properties of Y1-xEuxTa1-yNbyO4 will change rapidly. The difference of luminescence is originated from different structures. The excitation spectra of NbO43- emission (lambda = 400 nm) in YTa0.98Nb0.02O4 is a strong excitation band peak at 235 nm. In fact, the band is composed of charge transfer excitation of TaO43- and charge transfer excitation of N bO43-. The excitation spectra of Eu3+5D0-->F-7(2) transition emission have two parts, the sharp lines between 300-600 nm and wide band between 200-300 nm. The sharp lines originate from Eu3+ f-f electron transitions, and the wide band includes both charge transfer excitation of TaO43- and NbO43-, an d charge transfer excitation of Eu3+. The excitation spectra of NbO43- emis sion (lambda = 400 nm) in Y0.99Eu0.01Ta0.98Nb0.02O4 is also a strong band, in which there also exists a charge transfer excitation of TaO43- and a cha rge transfer excitation of NbO43-. The strong evidence from excitation spec tra, emission spectra of this system show that there is a energy transfer f rom host lattice to activator in the process of luminescence.