Synthesis and electrical conductivity of La2NiO4 + δ derived from a polyaminocarboxylate complex precursor

La2NiO4 + δ with a pure K2NiF4 phase was synthesized from a polyaminocarboxylate complex precursor with diethylenetriaminepentaacetic acid (H5DTPA) as ligand, and the electrical conducting properties of sintered La2NiO4 + δ were investigated. The thermal decomposition of the complex precursor was investigated by thermogravimetry (TG) and differential scanning calorimetry (DSC). Homogeneous and fine powder (100–200 nm) with a pure K2NiF4 phase was produced by calcining the complex precursor at 900 °C for 2 h in air. It was found that La2NiO4 + δ ceramic sintered at 1300 °C for 4 h shows a dense microstructure with average grain size of about 1 μm. The La2NiO4 + δ ceramic exhibits an electrical conductivity of 76 Ω− 1 cm− 1 at 800 °C. This research demonstrates the advantage of the polyaminocarboxylate complex method in preparing La2NiO4 + δ with respect to the simplicity of synthesis process, fine and uniform morphology of synthesized powder and superior electrical conducting properties of sintered specimen.