Thermodynamic and transport properties of triple ionic-electronic conducting pure and molybdenum-doped lanthanum tungstate

Total electrical conductivity measurements were performed on molybdenum-doped lanthanum tungstate, La 28- x (W 1- y Mo y ) 4+ x O 56- δ with a La/(W + Mo) molar ratio of 5.6 and different Mo concentrations ( y = 0.0, 0.1, 0.2, 0.3), under reducing conditions in various H 2 /H 2 O gas mixtures across temperatures ranging from 600 °C to 900 °C. By fitting the experimental data to appropriate model equations, the equilibrium constant of the hydrogenation reaction as well as the mobilities and concentrations of the mobile charge carriers were obtained. The results demonstrate that the partial substitution of W by Mo within the experimental range can enhance its electronic conductivity by more than one and a half orders of magnitude, while the protonic and oxide ionic conductivities remain essentially unaffected. This work introduces a systematic approach to evaluate transport and thermodynamic parameters of triple ionic-electronic conducting oxides using total conductivity data. • Revealing conductivity trends in pure and Mo-doped lanthanum tungstates. • Model fitting uncovers key equilibrium and transport parameters. • Protonation shows consistent behavior across all studied compositions. • Mo doping may boost electronic conductivity by over 1.5 orders of magnitude. • Protonic and oxide ionic conductivities stay stable under Mo substitution.