Optical Excitation and Emission Spectra of YNbO4 : Eu3+

In the excitation spectra of YNbO4 : Eu3+, the charge transfer (CT) band around 270 nm due to [NbO4](3-) -Eu3+ interaction and sharp excitation peaks by f-f transition of Eu3+ strongly appeared simultaneously. CT band depended on the structural properties of powders, showing the red-shift with increasing the crystallinity, while the f-f transition peaks were independent of the crystallinity. For YNb1-xTaxO4 : Eu3+ (x = 0.05-0.2), [TaO4](3-) configuration was locally constructed, leading to the blue-shift in CT band and the decrease in the red emission intensity with increasing the Ta content.