Facile planetary ball mill synthesis, structural, photoluminescence, linear, and nonlinear optical features of Erbium-doped TiO2 nanoparticles

Abstract

Pure TiO₂ and Er-doped TiO₂ nanoparticles were prepared via a high-energy planetary ball mill for photovoltaic applications. The doped sample was annealed at 350, 550 and 750 °C. The structural, linear, and nonlinear optical properties of Er-doped TiO₂ nanoparticles of Er³⁺ doping on TiO₂ nanoparticles were investigated using XRD, FTIR, HRTEM, photoluminescence, and UV–visible measurements. The crystal sizes of all samples, as determined by XRD, range from 24.55 nm for pure TiO₂ to 33.17–33.17 nm for Er-doped TiO₂ nanoparticles, that have been annealed at 350–750 °C. Thus, it was confirmed that there was high crystallinity and high phase stability up to 750 °C annealed temperature. The XRD results estimated using Scherrer's equation and the particle size observed in the TEM image are well agreed upon. The obtained spectra were used to investigate the linear and nonlinear optical properties via various optical parameters, including static refractive index, optical band gap energy, Urbach band tail energy, dispersion energy parameters using the Wemple and DiDomenico (WDD) single-oscillator model, nonlinear refractive index, and first and third optical susceptibilities. The calculated band gap is 3.68 eV, and doping results in a reduction to 3.62 eV. Photoluminescence produced a attractive result due to doping reduced its intensity, which indicates a decrease in the rate at which charge carriers recombine. These findings will contribute to the development of novel functional materials with potential applications in photonics and optoelectronics.