LAUSR

Abstract The starting sample T-La1.8Nd0.2CuO4 (SG: Bmab) has been synthesized by the conventional solid-state reaction at 900 °C. The T′-La1.8Nd0.2CuO4 (SG: I4/mmm) sample has been obtained via a topotactic reduction reaction of T-La1.8Nd0.2CuO4 (SG: Bmab) using CaH2 (as reductor) followed by an oxidation at 400 °C in air. The temperature of the phase transition (T-T′) has been determined using the differential thermal analysis (DTA) and the temperature-dependent powder X-ray diffraction (TDXD). The crystal structures of the title compounds have been refined by using the Rietveld method and confirmed by the means of the charge distribution model (CHARDI). The electrical properties of the title compounds have been studied by impedance complex spectroscopy between 200 °C and 650 °C. This study shows two slopes in the Arrhenius plot with experimental activation energies 1.033 eV and 1.657 eV which correspond to the reduced phase and the T′ phase respectively. The simulation of oxygen diffusion in structures by using the Bond Valence Site Energy (BVSE) method shows three-dimensional pathways of oxygen diffusion. The calculated activation energies of the T′ and T structure are 1.619 and 2.369 eV, respectively.