Optical Excitation and Emission Spectra of YNbO₄: Eu³⁺

Abstract

In the excitation spectra of <TEX>$YNbO_4$</TEX> : <TEX>$Eu^{3+}$</TEX>, the charge transfer (CT) band around 270 nm due to <TEX>$[NbO_4]^{3-}$</TEX><TEX>$-Eu^{3+}$</TEX> interaction and sharp excitation peaks by f-f transition of <TEX>$Eu^{3+}$</TEX> 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 <TEX>$YNb_{1-x}Ta_xO_4$</TEX> : <TEX>$Eu^{3+}$</TEX> (x = 0.05.0.2), <TEX>$[TaO_4]^{3-}$</TEX>. 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.