Solvent effect on the optimization of 1.54 μm emission in Er-doped Y2O3–Al2O3–SiO2 powders synthesized by a modified Pechini method

In order to find a new Er-doped host for near infrared (NIR) optical amplifiers, a study on the optimization of the erbium emission ions in the Y2O3–Al2O3–SiO2 system was performed. (100 − x) Y3Al5O12 − (x) SiO2 powders (x varies from 0 to 70, in mol%) with a fixed Er2O3 concentration of 1.0 mol% were synthesized by a modified Pechini method and heat-treated at 900 and 1000 °C. The photoluminescence (PL) spectra at 1540 nm of the 4I13/2 → 4I15/2 transition of Er3+ ions and the up-conversion spectra at visible region (2H11/2 + 4S3/2 + 4F9/2 → 4I15/2) upon 980 nm excitation were evaluated. Different techniques, such as thermogravimetry (TG), differential scanning calorimetry (DSC), X-ray powder diffractometry (XRD) and Fourier transform infrared spectroscopy (FT-IR) were considered to evaluate crystallization and phase-evolution of the powders as a function of the silica content (x) and annealing temperature. The analyses were based on the comparison between two different solvents used in the preparation of the polymeric resins: ethanol and water. The optimal conditions for ethanol are quite different than the conditions for water used as solvent, confirming that the PL properties at the NIR region are highly sensitive to the changes in the host stoichiometry and processing conditions. The highest emission intensity at 1540 nm was observed for x = 30 for ethanol and x = 70 for water, treated at 900 and 1000 °C, respectively. This result could be attributed to the combination of low symmetry and good dispersion of the Er3+ions in these hosts.