Upconversion multicolor tuning in Er3+ and Yb3+ doped yttrium oxide prepared by precursor technique

The (Y0.9Er0.1-xYbx)2O3 (x = 0, 0.02, 0.05, 0.07, 0.08, 0.09) and Y1-(0.02+y)Er0.02YbyO3 (y = 0.05, 0.07, 0.09, 0.11) solid solutions have been synthesized by the precursor technique using mixed anhydrous formates. The crystal structure of ytterbium formate, Yb(HCOO)3, was established for the first time. The structural parameters and phase purity of the synthesized precursors and oxides were determined by X-ray phase analysis. The average sizes of crystallites are in the 60–80 nm range. The upconversion spectra of solid solutions exhibit a weak green and an intense red line attributed to 2H11/2,4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3+ ions. The green and red emissions of (Y0.9Er0.1-xYbx)2O3 and Y1-(0.02+y)Er0.02YbyO3 oxides are caused by two-photon conversion processes. The effect of dopant (erbium and ytterbium) concentration and Er3+/Yb3+ ratio on the intensity of upconversion emission were established, the contribution of upconversion green luminescence decreases with increasing the ytterbium concentration.