Conversion of green emission into white light in Gd2O3 nanophosphors

Gd2O3 nanophosphors were prepared by combustion synthesis with and without doping of Dy3+ ions. The X-ray powder diffraction patterns indicate that as-prepared Gd2O3 and 0.1 mol% Dy2O3 doped Gd2O3 nanophosphors have monoclinic structures. The transmission electron microscope (TEM) studies revealed that the as-prepared phosphors had an average crystallite sizes around 37 nm. The excitation and emission properties have been investigated for Dy3+ doped and undoped Gd2O3 nanophosphors. New emission bands were observed in the visible region for Gd2O3 nanophosphors without any rare earth ion doping under different excitations. A tentative mechanism for the origin of luminescence from Gd2O3 host was discussed. Emission properties also measured for 0.1 mol% Dy3+ doped Gd2O3 nanophosphors and found the characteristic Dy3+ visible emissions at 489 and 580 nm due to 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions, respectively. The chromaticity coordinates were calculated based on the emission spectra of Dy3+ doped and undoped Gd2O3 nanophosphors and analyzed with Commission Internationale de l'Eclairage (CIE) chromaticity diagram. These nanophosphors exhibit green color in undoped Gd2O3 and white color after adding 0.1 mol% Dy2O3 to Gd2O3 nanophosphors under UV excitation. These phosphors could be a promising phosphor for applications in flat panel displays.