Defects and Phase Formation in Non-Stoichiometric LaFeO₃: a Combined Theoretical and Experimental Study

The defect chemistry of perovskite compounds is directly related to the stoichiometry and valence states transition-metal ions. Defect engineering has become increasingly popular as it offers possibility influence catalytic properties perovskites for applications in energy storage conversion devices such solid-oxide fuel electrolyzer cells. LaFeO3 (LFO) can be regarded a base compound family catalytically active La1–xAxFe1–yByO3??, which well electronic ionic conductivity tuned by substitution on cationic sites. Combining theoretical experimental approaches, we explore suitability A-site vacancy engineering, namely, feasibility actively manipulating state Fe concentration point defects synthesizing La-deficient LFO. In part, formation energies concentrations were determined function processing conditions first-principles density functional theory calculations with Hubbard-U correction (DFT + U). Based DFT U results, significant compositional deviations from stoichiometric LFO cannot expected providing rich or poor oxidic precursor (Fe2O3 La2O3) solid-state route. was synthesized targeted La-site deficiency. We analyze resulting phases detail X-ray diffraction dedicated microscopy methods, scanning electron (scanning) transmission combination energy-dispersive spectroscopy energy-loss spectrometry. Instead variation La/Fe ratio, mixture two Fe2O3 observed, an invariant charge Fe, line results. discuss our findings respect partly differing assumptions made previously published studies this material system.