Structural, optical, and magnetic characterization of Er-doped In2O3 nanoparticles.

(In 1-x Er x) 2 O 3 nanoparticles were synthesized by lyophilization of an aqueous solution of indium and erbium acetates and then applying heat treatments. These nanoparticles were characterized regarding their structural, optical, and magnetic properties over a temperature range of 2–300 K. For x ≤ 0.04, all samples were monophasic, crystallized with cubic structure (Ia-3 space group), and characterized by oxygen vacancies. Er doping reduced the crystallite size and increased the lattice strain. However, no change in energy bandgap was observed after erbium dilution in the oxide matrix. The doped samples were paramagnetic over the entire temperature range, but at low temperatures paramagnetism coexisted with a ferromagnetic phase. The ferromagnetism was attributed to the presence of magnetic polarons acting as mediators of the coupling between the Er3+ ions. The low-temperature segments of the magnetization curves, i.e., M(T< 20 K), were successfully fitted based on the Bound Magnetic Polaron model. [Display omitted] • In2-xErxO3 monophasic NPs were successfully synthesized by lyophilization and heat treatments. • The semiconductor In2O3 was for the first doped with a HRE and the solubility limit for Er was 4%at. • Er doping decreased particle size, increased strain, and did not change the semiconductor bandgap. • In2-xErxO3 is PM at and below RT but a FM phase appears at T < 20 K. • The FM phase is due to bound magnetic polarons formed by Er3+ cations. [ABSTRACT FROM AUTHOR]