Functional properties of LaxCe1−xO2−δ nanocrystals and their bulk ceramics.

Structure-property correlations were investigated for La_xCe_1−xO_2−δ (x = 0.05, 0.15) system (for both nanoparticles and ceramic). The nanoparticles were synthesized by the co-precipitation route and characterized for their structural, catalytic and visible light driven photocatalytic properties. Synthesised La_xCe_1−xO_2−δ nanopowders depicted phase purity with excellent compositional control as confirmed by various structural characterisation tools. The 15% La³⁺-doped ceria nanoparticles portrayed superior photocatalytic properties; complete degradation (99%) of the methylene blue dye was observed within 60 min of visible light irradiation under an alkaline medium. High density (> 96%) of the ceramics (sintered at 1580 °C for 2 h) confirmed promising sinterability of the synthesised powders. The ionic conductivities of the La_xCe_1−xO_2−δ ceramics increased with temperature and frequency owing to enhanced oxygen vacancies in the ceria matrix as a result of doping (of La³⁺-ions); a maximum conductivity of ~ 8.4 × 10⁻² S cm⁻¹ was obtained at 900 °C for the 15% La³⁺-doped ceria ceramics at 1 MHz frequency. [ABSTRACT FROM AUTHOR]