In recent years, multi-phase materials capable of multi-ion transport have emerged as attractive candidates for a variety of electrochemical devices. Here, we provide experimental results for fabricating a composite electrolyte made up of a one-dimensional fast sodium-ion conductor, sodium zirconogallate, and an oxygen-ion conductor, yttria-stabilized zirconia. The composite is synthesized through a vapor phase conversion mechanism, and the kinetics of this process are discussed in detail. The samples are characterized using diffraction, electron microscopy, and electrochemical impedance spectroscopy techniques. Samples with a finer grain structure exhibit higher kinetic rates due to larger three-phase boundaries (TPBs) per unit area. The total conductivity is fitted to an Arrhenius type equation with activation energies ranging from 0.23 eV at temperatures below 550 °C to 1.07 eV above 550 °C. The electrochemical performance of multi-phase multi-species, mixed sodium- and oxygen-ion conductors, is tested under both oxygen chemical potential gradient as well as sodium chemical potential gradient, before and after reaching equilibrium, are discussed using the Goldman-Hodgkin-Kats (GHK) and the Nernst equation. The total conductivity of the degraded cathode and anode terminals is investigated using electrochemical impedance spectroscopy. The degradation investigation of samples indicates a decrease in conductivity adjacent to the anode terminal, the loss of sodium content, and the formation of β-gallia adjacent to the fuel electrode after ~396h at 1463 K.

In recent years, multi-phase materials capable of multi-ion transport have emerged as attractive candidates for a variety of electrochemical devices. Here, we provide experimental results for fabricating a composite electrolyte made up of a one-dimensional fast sodium-ion conductor, sodium zirconogallate, and an oxygen-ion conductor, yttria-stabilized zirconia. The composite is synthesized through a vapor phase conversion mechanism, and the kinetics of this process are discussed in detail. The samples are characterized using diffraction, electron microscopy, and electrochemical impedance spectroscopy techniques. Samples with a finer grain structure exhibit higher kinetic rates due to larger three-phase boundaries (TPBs) per unit area. The total conductivity is fitted to an Arrhenius type equation with activation energies ranging from 0.23 eV at temperatures below 550 °C to 1.07 eV above 550 °C. The electrochemical performance of multi-phase multi-species, mixed sodium- and oxygen-ion conductors, is tested under both oxygen chemical potential gradient as well as sodium chemical potential gradient, before and after reaching equilibrium, are discussed using the Goldman-Hodgkin-Kats (GHK) and the Nernst equation. The total conductivity of the degraded cathode and anode terminals is investigated using electrochemical impedance spectroscopy. The degradation investigation of samples indicates a decrease in conductivity adjacent to the anode terminal, the loss of sodium content, and the formation of β-gallia adjacent to the fuel electrode after ~396h at 1463 K.

In recent years, multi-phase materials capable of multi-ion transport have emerged as attractive candidates for a variety of electrochemical devices. Here, we provide experimental results for fabricating a composite electrolyte made up of a one-dimensional fast sodium-ion conductor, sodium zirconogallate, and an oxygen-ion conductor, yttria-stabilized zirconia. The composite is synthesized through a vapor phase conversion mechanism, and the kinetics of this process are discussed in detail. The samples are characterized using diffraction, electron microscopy, and electrochemical impedance spectroscopy techniques. Samples with a finer grain structure exhibit higher kinetic rates due to larger three-phase boundaries per unit area. The total conductivity is fitted to an Arrhenius type equation with activation energies ranging from 0.23 eV at temperatures below 550°C to 1.07 eV above 550°C. The electrochemical performance of multi-phase multi-species, mixed Na+, and O2- conductor, is tested under both oxygen chemical potential gradient as well as sodium chemical potential gradient are discussed using the Goldman-Hodgkin-Kats and the Nernst equation.

Samples of 6 mol%Sc2O3 ? 1 mol% CeO2 co ? doped ZrO2 were fabricated by conventional ceramic processing methods and sintered at various temperatures from 1000?C to 1650?C in air. The sintering conditions on microstructure and phase content are investigated using various characterization methods, including pycnometry, diffraction, and spectroscopy. The electrical conductivity of samples was investigated using electrochemical impedance spectroscopy (EIS). The effect of inductive load (measured from room temperature to 800?C) is discussed in low to high temperature regimes. At T < 400?C since the arc is not a complete semicircle, the high-frequency arc could be fit using a constant phase element (CPE), while by subtraction of inductive load, a good fit is achieved using a capacitor element instead of CPE. The Arrhenius conductivity plot of samples reveals that the specimen sintered at 1600?C for 6 hours exhibits the highest conductivity. The activation energy (Ea) and conductivity pre-exponential (??0) factor are calculated from a linear fit to data that decreases by the increase in sintering temperature.