Single-phased Ru3+-doped LaFeO3 nanocrystalline particles (6-70 nm), with nominal compositions of LaFe1-xRuxO3 (x = 0.00, 0.015, 0.03, 0.05 and 0.08), were prepared using mechano-synthesis at temperatures that are ca. 400 °C- 700 °C lower than those used to synthesize cation-doped LaFeO3 conventionally. The Ru3+ ions are found to substitute exclusively for the Fe3+ ones at the octahedral sites of the perovskite-related structure. The lattice parameters of all samples are suggestive of a weak Jahn-Teller-like distortion as opposed to the normal distortion of orthorhombic perovskites. 57Fe Mössbauer measurements for all samples show the Fe3+ ions to be in high-spin state implying that the observed lattice distortion is due to particle-size surface-induced disorder rather than the electronic degeneracy associated with the normal Jahn-Teller distortion. The decrease in the Mössbauer hyperfine magnetic fields with increasing Ru3+ content is attributed mainly to particle size reduction rather than the cationic substitution of Fe3+ by the Ru3+. A monotonic decrease of the optical band gap from 2.17 eV (x = 0.00) to 1.79 eV (x = 0.08) was observed, revealing how doping with Ru3+ affects the optical absorption of the LaFeO3 nanoparticles.
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