Temperature dependence of partial conductivities of the BaZr0.7Ce0.2Y0.1O3-δ proton conductor
[EN] Partial conductivities are presented for BaZrCeYO, an important proton conductor for protonic-ceramic fuel cells and membrane reactors. Atmospheric dependencies of impedance performed in humidified and dry O, air, N and H(10%)/N(90%) in the temperature range 300–900 °C, supported by the modifie...
| Autores: | , , |
|---|---|
| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2017 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/200985 |
| Acceso en línea: | http://hdl.handle.net/10261/200985 |
| Access Level: | acceso abierto |
| Palabra clave: | BZCY72 Transport numbers Proton conductivity Defect chemistry EMF method |
| Sumario: | [EN] Partial conductivities are presented for BaZrCeYO, an important proton conductor for protonic-ceramic fuel cells and membrane reactors. Atmospheric dependencies of impedance performed in humidified and dry O, air, N and H(10%)/N(90%) in the temperature range 300–900 °C, supported by the modified emf method, confirm significant electron-hole and protonic contributions to transport. For very reducing and wet atmospheres, the conductivity is predominantly ionic, with a higher participation of protons with decreasing temperature and increasing water-vapour partial pressure (pHO). From moderately reducing conditions of wet N to wet O, however, the conductivity is considerably influenced by electron holes as revealed by a significant dependence of total conductivity on oxygen partial pressure (pO). With higher pHO, proton transport increases, with a concomitant decrease of holes and oxygen vacancies. However, the effect of pHO is also influenced by temperature, with a greater protonic contribution at both lower temperature and pO. Values of proton transport number t ≈ 0.63 and electronic transport number t ≈ 0.37 are obtained at 600 °C for pHO = 0.022 atm and pO = 0.2 atm, whereas t ≈ 0.95 and t ≈ 0.05 for pO = 10 atm. A hydration enthalpy of −109 kJ mol is obtained in the range 600–900 °C. |
|---|