Zn as sintering aid for ceria-based electrolytes

• Published in: Solid state ionics Vol. 262; pp. 522 - 525
• Main Authors: Villas-Boas, Lúcia A., Figueiredo, Filipe M.L., de Souza, Dulcina P.F., Marques, Fernando M.B.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2014
• Subjects: Ceria; Densification; Dopants; Electrolytes; Electronic conductivity; Electronics; Grain boundaries; Ionic conductivity; Nanopowders; Nitrates; Sintering; Sintering aid; Zinc; Nanopowders; Electronic conductivity; Sintering aid; Ceria; Ionic conductivity
• ISSN: 0167-2738; 1872-7689
• DOI: 10.1016/j.ssi.2013.11.002

Gd-doped ceria (CGO) nanopowders were mixed with up to 1mol% of Zn (as nitrate) to exploit the role of this dopant on sintering and electrical performance. All samples were prepared by two-step sintering schedules to try to combine the advantages of both effects on low-temperature densification. Structural and microstructural analyses were complemented with impedance spectroscopy (wide range of temperatures and oxygen partial pressures) and ion-blocking measurements. The combination of all data suggests that Zn is preferentially located in the grain boundary region, playing a significant role on sintering. Zn additions (1mol%) allowed for a 100°C lower sintering temperature with respect to pure CGO. A marginal effect on the oxide-ion conductivity and a small enhancement (less than 20%) in n-type electronic conductivity was found between Zn-free and 1mol% Zn-doped CGO. The removal of Zn from CGO after sintering is discussed. •The densification of CGO to 96.6% at 1200°C with only 1mol% Zn as sintering aid was studied.•Zn has modest effect on the ionic and electronic conductivity of CGO.•Electrical properties deviate from classical bulk behavior models.•Grain boundaries play a relevant role on sintering and electrical performance.•The post-sintering removal of Zn from CGO was discussed.