3 research outputs found
Tailoring phase stability and electrical conductivity of Sr0.02La0.98Nb1–xTaxO4 for intermediate temperature fuel cell proton conducting electrolytes
Sr0.02La0.98Nb1–-xTaxO4 (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 (pH2O 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