A series of (Lu1 - xInx)(2)O-3 (x = 0-1) powders have been synthesized by a facile co-precipitation route using ammonium hydrogen carbonate (AHC) as the precipitant. The effects of In3+ substitution for Lu3+ on the particle properties, structure features and optical performances of the materials were systematically investigated. The results show that (1) the (Lu1 - xInx)(2)O-3 precursor samples with x = 0-0.5 possess a chemical composition of basic carbonate, however, the precursor specimen with x = 1 is hydrated oxyhydroxide; (2) In3+ addition significantly affects the nucleation kinetics of the binary Lu-In system, leading to the empty interiors inside the precursors; (3) calcining the resultant precursors directly yields well-dispersed (Lu1 - xInx)(2)O-3 oxide particles with ultrafine sizes of similar to 65 nm; (4) both the lattice parameters and theoretical densities of the solid solutions linearly decrease along with increasing In3+ incorporation; (5) In3+ doping apparently red-shifts the absorption edge of UV-vis absorption spectroscopy and the bandgap energies of the (Lu1 - xInx)(2)O-3 oxide powders generally decrease at a higher In3+ content. (C) 2017 Elsevier B.V. All rights reserved.