Preparation of Eu3+-doped Ta2O5 phosphor particles by sol–gel method

Eu3+-doped Ta2O5 phosphor particles were prepared by a sol–gel method from tantalum (V) ethoxide (Ta(OC2H5)5), surfactant sorbitantrioleate (SPAN85®), mixed solvent of C2H5OH and n-C4H9OH, and H2O. Optical and structural properties of the particles were investigated by measuring luminescence and excitation spectra, luminescence quantum yield (QY), scanning electron microscope (SEM) images, and X-ray diffraction (XRD) patterns. The optimum conditions for preparing Eu3+-doped Ta2O5 spherical phosphor particles were determined by changing pH value of sol solutions and the molar ratios of SPAN85/Ta(OC2H5)5 and H2O/Ta(OC2H5)5. Under UV excitation, red luminescence mainly due to the 5D0 → 7FJ (J = 1, 2, 4) transitions of Eu3+ ions was observed. The strongest red luminescence with QY = 30% was obtained in 1Eu2O3-99Ta2O5 particles heat treated at 800 °C.