Observation of a Large Number of Upconversion Luminescence Peaks in the Range of 300–800 nm in Zr 0.85 O 2 /Eu 0.05 Yb 0.10 Nanoparticles: Blue and White Light Emitters

We prepared Eu 3+ - and Yb 3+ -doped ZrO 2 nanoparticles at two different annealing temperatures of 500 and 1300 °C. The structural analysis of the samples was performed using X-ray diffraction. A detailed analysis of the downconversion and upconversion spectra of the samples has been carried out. Emission peaks (green and red) of Eu 3+ ions, as well as host emission (blue light), are observed. The emission intensity increases with the excitation slit width, following the Beer–Lambert Law. Further, many peaks of Eu 3+ ions in the range of 300 to 800 nm have been observed through an upconversion process upon excitation with a 980 nm laser source. With an increase of the slit width (W) in the emission monochromator, the luminescence intensity (I) increases, following log (I) ∝ log (W). This is a nonlinear phenomenon. The emission peaks observed in the upconverted spectrum are assigned according to the literature. The cooperative energy transfer from 2Yb 3+ ions to Eu 3+ ions has been explained. The maximum number of Eu 3+ emission peaks (double to singlet) has been observed by varying the emission slit widths. Blue and white lights are obtained from the samples through downconversion and upconversion studies, respectively.