Effect of ytterbium substitution on LaEr(1−x)YbxO3 optical properties

A series of LaEr(1−x)YbxO3 (x=0, 0.01 and 0.05) samples were prepared with a combustion method and characterized by FTIR, Raman spectroscopy and X-ray diffraction. The optical properties of samples were studied upon laser excitations. The upconversion emission spectra registered under excitation at 980 nm show the presence of the typical erbium emission bands and that the higher intensity is given by sample with 5% of ytterbium concentration. The variation of upconversion intensity as a function of laser power of the LaEr0.95Yb0.05O3 sample reveals that two photons are implicated in the upconversion mechanism and that the lifetime of the 4S3/2→4I15/2 and 4F9/2→4I15/2 emissions of this sample is estimated to 12.3 and 97.7 µs, respectively. The calculated CIE chromaticity coordinates of the phosphor samples show that the green emission is dominant, and that its intensity increases by substituting erbium with 1% or 5% of ytterbium. The effect of ytterbium concentration on optical band gap shows that the gap energy value tends to decrease from 4.25 eV to 4.14 eV for 0% and 5% of ytterbium concentration, respectively. The increase in intensity of green emission by adding ytterbium to LaErO3 classifies these oxides as phosphor materials that could have applications in bioimaging of cells.