Modeling of electrical conductivity in the proton conductor Ba0.85K0.15ZrO3-δ (original) (raw)
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Proton diffusivity in the BaZr 0.9 Y 0.1 O 3− δ proton conductor
Journal of Applied …, 2009
The thermally activated proton diffusion in BaZr0.9Y0.1O3-d was studied with electrochemical imped-ance spectroscopy (IS) and quasi-elastic neutron scattering (QENS) in the temperature range 300900 K. The diffu-sivities for the bulk material and the grain boundaries as ...
Hydrostatic pressure decreases the proton mobility in the hydrated BaZr0.9Y0.1O3 proton conductor
Applied Physics Letters, 2010
Yttrium substituted BaZrO3, with nominal composition BaZr0.9Y0.1O3, a ceramic proton conductor, was subject to impedance spectroscopy for temperatures 300 K < T < 715 K at mechanical pressures 1 GPa < p < 2 GPa. The activation energies Ea of bulk and grain boundary conductivity from two perovskites synthesized by solid-state reaction and sol-gel method were determined under high pressures. At high temperature, the bulk activation energy increases with pressure by 5% for sol-gel derived sample and by 40% for solid-state derived sample. For the sample prepared by solid-state reaction, there is a large gap of 0.17 eV between the activation energy at 1.0 GPa and > 1.2 GPa. The grain boundary activation energy is around a factor two times as that of the bulk, and it reaches a maximum at 1.25 - 1.5 GPa, and then decrease as the pressure increases, indicating higher proton mobility in the grain boundaries at higher pressure. Since this effect is not reversible, it is suggested that the grain boundary resistance decreases as a result of pressure induced sintering. The steady increase of the bulk resistivity upon pressurizing suggests that the proton mobility depends on the space available in the lattice. In return, an expanded lattice with a/a0 > 1 should thus have a lower activation energy, suggesting that thin films expansive tensile strain could have a larger proton conductivity with desirable properties for applications.
The high temperature proton conductor BaZr 0.4Ce 0.4In 0.2O 3-a
J Power Sources, 2004
The oxygen ion conductor yttria-stabilized zirconia (YSZ), which is usually used as the electrolyte of SOFC, operates at high temperatures of about 1000 • C. The recent trend in developing SOFC is to reduce the operating temperature. Proton conducting cerates may allow the intermediate temperature operation for SOFC applications. Rare-earth-doped BaCeO 3 electrolytes with the perovskite structure present good protonic conductivities at moderate temperatures but rather poor chemical stability and endurance for moisture. Barium zirconate, in contrast, is a rather stable material but exhibits low protonic conductivity. We then focused on a practical protonic conductor of BaZr 0.4 Ce 0.4 In 0.2 O 3 (BZCI) that has a relatively high durability against moisture and good protonic conductivity. However, little is known about its stability and electrochemical properties in reducing hydrogen. In this work, the electrochemical properties of BZCI as SOFC electrolytes were investigated in concentration cell and fuel cell operations. From the results of concentration cell measurements, it was revealed that BZCI has good proton conductivities in hydrogen-rich atmospheres and behaves as a protonic and oxide ionic conductor in oxygen-rich atmospheres, with some extent of electronic conductivity, which lowers its ionic transport number. Open circuit voltage (OCV) measurements in Fuel cell operations showed that OCV value of a Pt| BZCI| Pt cell is about 870 mV at 800 • C and 1020 mV at 600 • C.
Applied Physics Letters, 2010
Yttrium substituted BaZrO 3 , with nominal composition BaZr0.9Y0.1O3, a ceramic proton conductor, was subject to impedance spectroscopy for temperatures 300 K < T < 715 K at mechanical pressures 1 GPa < p < 2 GPa. The activation energies E a of bulk and grain boundary conductivity from two perovskites synthesized by solid-state reaction and sol-gel method were determined under high pressures. At high temperature, the bulk activation energy increases with pressure by 5% for sol-gel derived sample and by 40% for solid-state derived sample. For the sample prepared by solid-state reaction, there is a large gap of 0.17 eV between the activation energy at 1.0 GPa and > 1.2 GPa. The grain boundary activation energy is around a factor two times as that of the bulk, and it reaches a maximum at 1.25 -1.5 GPa, and then decrease as the pressure increases, indicating higher proton mobility in the grain boundaries at higher pressure. Since this effect is not reversible, it is suggested that the grain boundary resistance decreases as a result of pressure induced sintering. The steady increase of the bulk resistivtiy upon pressurising suggests that the proton mobility depends on the space available in the lattice. In return, an expanded lattice with a/a0 > 1 should thus have a lower activaqtion energy, suggesting that thin films expansive tensile strain could have a larger proton conductivity with desirable properties for applications.