Eutectic ceramics of the CeO2 – ZrO2 – MgO system produced by laser-assisted directional solidification
Oxide eutectics have great potentiality as structural or functional materials, owing to the outstanding properties derived from the eutectic microstructure. Among them, the eutectic of the ZrO2 – MgO system is particularly noteworthy because of the unusual combination of thermomechanical, optical an...
| Autores: | , , , |
|---|---|
| Tipo de documento: | artigo |
| Estado: | Versão publicada |
| Data de publicação: | 2022 |
| País: | España |
| Recursos: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositório: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/280284 |
| Acesso em linha: | http://hdl.handle.net/10261/280284 |
| Access Level: | Acceso aberto |
| Palavra-chave: | Eutectic ceramics CeO2–ZrO2–MgO Directional solidification CO2 separation membranes |
| Resumo: | Oxide eutectics have great potentiality as structural or functional materials, owing to the outstanding properties derived from the eutectic microstructure. Among them, the eutectic of the ZrO2 – MgO system is particularly noteworthy because of the unusual combination of thermomechanical, optical and electrical properties. In a recent application, Zr1-δMgδO2-δ – MgO eutectic oxides have been used to produce porous supports for molten-carbonate based CO2 separation membranes. Here we explore composite ceramic oxides of the CexZr1-xO2 – MgO (x ≤ 0.5) system with eutectic microstructure, with the motivation that incorporating cerium may enhance the CO2 permeation properties. Eutectic composites with different cerium content are produced by a laser-assisted directional solidification technique at variable solidification rate, v. In all cases the composite bicrystal consists of two phases, MgO and a fluorite-like (CexZr1-x)1-yMgyO2-y phase. A purely fibrilar microstructure is found for x ≥ 0.3 at v = 25 mm/h, with MgO fibres embedded within the fluorite-like matrix. The MgO mol% in the eutectic composites decreases from ∼53% for x = 0 to ∼48% for x = 0.5. X-ray and Raman results evidence long-range ordering in a quasi-tetragonal monoclinic symmetry for x = 0.5. Impedance spectroscopy results are consistent with a change from ionic to mainly electronic conductivity when the atmosphere is changed from air or Ar to 5%H2–Ar. |
|---|