Tailoring phase stability and electrical conductivity of Sr 0.02La 0.98Nb 1-xTa xO 4 for intermediate temperature fuel cell proton conducting electrolytes

Alma B. Santibáñez-Mendieta, Emiliana Fabbri, Silvia Licoccia, Enrico Traversa*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Sr 0.02La 0.98Nb 1 - xTa xO 4 (SLNT, with x = 0.1, 0.2, and 0.4) proton conducting oxides were synthesized by solid state reaction for application as electrolyte in solid oxide fuel cells operating below 600 °C. Dense pellets were obtained after sintering at 1600 °C for 5 h achieving a larger average grain size with increasing the tantalum content. Dilatometric measurements were used to obtain the SLNT expansion coefficient as a function of tantalum content (x), and it was found that the phase transition temperature increased with increasing the tantalum content, being T = 561, 634, and 802 °C for x = 0.1, 0.2, and 0.4, respectively. The electrical conductivity of SLNT was measured by electrochemical impedance spectroscopy as a function of temperature and tantalum concentration under wet (p H2O of about 0.03 atm) Ar atmosphere. At each temperature, the conductivity decreased with increasing the tantalum content, at 600 °C being 2.68 × 10 -4, 3.14 × 10 -5, and 5.41 × 10 -6 Scm -1 for the x = 0.1, 0.2, and 0.4 compositions, respectively. SLNT with x = 0.2 shows a good compromise between proton conductivity and the requirement of avoiding detrimental phase transitions for application as a thin-film electrolyte below 600 °C.

Original languageEnglish (US)
Pages (from-to)6-10
Number of pages5
JournalSolid State Ionics
Volume216
DOIs
StatePublished - May 28 2012

Keywords

  • Electrolyte
  • Niobate
  • Proton conductivity
  • SOFC
  • Tantalate

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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