High angle annular dark field-scanning transmission electron microscopy and high-resolution transmission electron microscopy studies in the Er2O3–ZrO2 system

ZrO2:Er3+ nanocrystals synthesized by the sol-gel method using a non-ionic (PLURONIC P-127) surfactant in order to produce single nanocrystals were characterized. High angle annular dark field-scanning transmission electron microscopy (HAADF-STEM), energy dispersive X-ray spectroscopy and high resolution transmission electron microscopy were used to characterize the ZrO2:Er3+ nanoparticles annealed at 1000 °C for 5 h. Single nanocrystals of monoclinic zirconia phase well-dispersed with a faceted morphology were obtained after the calcination. Er atoms were randomly integrated in the zirconia lattice as a subtitutional solid solution. Segregation of Er2O3 phase at the annealing temperature was not observed. Substitution of some Zr by Er atoms in the monoclinic zirconia lattice was directly observed by HAADF-STEM analysis.