Densification and enhancement of the grain boundary conductivity of gadolinium-doped barium cerate by ultra fast flash grain welding

Author(s)

Muccillo, R. ^[1] ; Muccillo, E. N. S. ^[1] ; Kleitz, M. ^[2]

Affiliation

^[1] Univ Sao Paulo, Ctr Sci & Technol, Mat Energy & Nucl Res Inst, BR-05508900 Sao Paulo - Brazil

^[2] Polytech Inst Grenoble INPG, LEPMI, F-38402 St Martin Dheres - France

• Document type: Journal article
• Source: Journal of the European Ceramic Society; v. 32, n. 10, p. 2311-2316, AUG 2012.
• Web of Science Citations: 46

Abstract

Doped barium cerate is a promising solid electrolyte for intermediate temperature fuel cells as a protonic conductor. However, it is difficult to sinter it to high density at a reasonable temperature. Moreover, it presents a high grain boundary resistivity at intermediate temperatures. Flash grain welding was applied to compacted samples, starting from a temperature of 910 degrees C and applying, for a short time, an ac electric polarization of 40 V, 1000 Hz. At that frequency, the resulting current flows through the grain boundaries promoting a welding via a local Joule heating. A large decrease of the grain boundary resistivity was observed by impedance spectroscopy. Scanning electron microscopy observations of polished and etched surfaces revealed highly sintered regions. Attempts were also made to combine flash grain welding with conventional sintering. (C) 2012 Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 05/53241-9 - Study of intergranular phenomena in ceramic materials
• Grantee: Reginaldo Muccillo
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 10/51293-0 - Michel Kleitz | Conseil National de la Recherche Scientifique - France
• Grantee: Eliana Navarro dos Santos Muccillo
• Support Opportunities: Research Grants - Visiting Researcher Grant - International