Enhancement of Bi-based niobate pyrochlores conductivity with Ru-doping. Structural, optical, and electrical properties

New Ru-doped bismuth-based pyrochlores were synthesized. The effects of Ru-doping in Bi1.5Mg0.375Cu0.375Nb1.5-xRuxO7-d on the formation of the crystal structure, stability, optical, and electrical properties of the compositions were studied. For compositions up to x = 0.1, only a phase of the pyrochlore type was detected by X-ray diffraction method (XRD) and energy dispersive X-ray analysis (EDX). Small impurities of Bi2Ru2O7, RuO2 and CuO were found for samples with x > 0.25. The lattice parameters of pyrochlores decrease upon doping with Ru. X-ray diffraction modeling revealed the structural stability of the doped compositions and the distribution of Ru4} cations in the B sites of the A2B2O6O' pyrochlore structure. A decrease in the band gap energy Eg was observed upon doping with Ru: 2.40 (x = 0) - 2.10 eV (x = 0.5) for the direct transition and 1.52 (x = 0) - 0.16 eV (x = 0.5) for indirect transition as a result of optical spectra analysis and DFT-HSE03 calculation. The chemical compatibility of the obtained pyrochlores with the manganite perovskite La0.7-Sr0.3MnO3 was studied. The pyrochlores can be considered as a component of cathode composite material for using in intermediate temperature solid oxide fuel cells (IT-SOFC).& COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.