LAUSR

Er3+-doped (Bi1−xErx)2O3 (where x = 0.1, 0.13, 0.15, and 0.2) nanoparticles (NPs) with a single fluorite-type structure have been synthesized by the sol–gel method and sintered at 850°C for 3 h. Here E2O3-stabilized δ-Bi2O3 has been obtained at low erbium concentrations. Rietveld refinement confirms an Ln-O bond length increase by a crystallographic volume variation from 166.51(1) to 168.54(1) Å3, as a consequence of enhanced ionic conductivity, which proved to be inversely proportional to the increase in Er3+ concentration. A reduction in the small cation (Er3+) concentration (x = 0.1) induces a grain boundary resistance decrease in the intermediate temperature (IT) range. A marked compressive stress tensor at high temperature was also observed, even at lower Er3+ cation concentrations, where the tetragonal structure takes place. The β-(Bi1−xErx)2O3 solid-state oxide ion conductor proved to have potential as a solid oxide electrolyte at ITs due to its conductivity and high compressive residuals stress (− 370 MPa).