Spectroscopic Study of Lu_2O_3:Yb~(3+),Ho~(3+)Nanopowders

A series of Lu_2O_3 nanopowders co-doped with Yb~(3+)and Ho~(3+)were synthesized by co- precipitation method.The Yb~(3+)concentration is 1mol% and the Ho~(3+)concentration ranges from 0.5mol% to 10mol%.The Stokes and Anti-Stokes spectroscopic properties of the prepared nanopowders were investigated,together with the relative intensities of Stokes and Anti-Stokes PL spectra dependence on the powders calcined at different temperatures.Strong green emissions were observed under the excitation of 447.5nm(Xenon Lamp)and 980nm(Laser Diode),respectively.Concentration quenching occurrs with the increase of Ho~(3+)concentration.Power studies reveal that a two-photon process is involved in the Anti-Stokes emissions and the possible upconversion mechanisms are energy transfer from Yb~(3+)to Ho_(3+).Concentration quenching and energy transfer process are confirmed by the decay time of the ~5F_4,~5S_2 level under the excitation of different pump wavelength.