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Enhanced reducibility and conductivity of Na/K-doped SrTi0.8Nb0.2O3.

Authors :: Xiao, Guoliang
Nuansaeng, Sirikanda
Zhang, Lei
Suthirakun, Suwit
Heyden, Andreas
Loye, Hans-Conrad zur
Chen, Fanglin
Source :: Journal of Materials Chemistry A; 2013, Vol. 1 Issue 35, p10546-10552, 7p
Publication Year :: 2013
Abstract: Donor and acceptor co-doped SrTiO<subscript>3</subscript> materials have shown interesting features in their conductivity and reducibility. In this work, 10 mol% Na<superscript>+</superscript> or K<superscript>+</superscript> as acceptor dopants have been introduced into the A-site of donor-doped strontium titanate, SrTi<subscript>0.8</subscript>Nb<subscript>0.2</subscript>O<subscript>3</subscript>, and the doping impact on their properties has been studied. By doping with Na or K, the sinterability of SrTi<subscript>0.8</subscript>Nb<subscript>0.2</subscript>O<subscript>3</subscript> in reducing atmospheres has been improved. Na<subscript>0.1</subscript>Sr<subscript>0.9</subscript>Ti<subscript>0.8</subscript>Nb<subscript>0.2</subscript>O<subscript>3</subscript> and K<subscript>0.1</subscript>Sr<subscript>0.9</subscript>Ti<subscript>0.8</subscript>Nb<subscript>0.2</subscript>O<subscript>3</subscript> show metallic conduction behavior after being sintered at 1400 °C in 5% H<subscript>2</subscript>/N<subscript>2</subscript>. Electrical conductivity reaches 1180 S cm<superscript>−1</superscript> at 400 °C and 272 S cm<superscript>−1</superscript> at 800 °C for K<subscript>0.1</subscript>Sr<subscript>0.9</subscript>Ti<subscript>0.8</subscript>Nb<subscript>0.2</subscript>O<subscript>3</subscript>, which is higher than that of Sr<subscript>0.99</subscript>Ti<subscript>0.8</subscript>Nb<subscript>0.2</subscript>O<subscript>3</subscript> prepared under similar conditions, indicating the improved reducibility of acceptor doped SrTi<subscript>0.8</subscript>Nb<subscript>0.2</subscript>O<subscript>3</subscript>. Such improvement may be attributed to the improved oxide ionic conductivity and cation mobility at high temperatures. Reduced polarization resistance is also observed using Na<subscript>0.1</subscript>Sr<subscript>0.9</subscript>Ti<subscript>0.8</subscript>Nb<subscript>0.2</subscript>O<subscript>3</subscript> and K<subscript>0.1</subscript>Sr<subscript>0.9</subscript>Ti<subscript>0.8</subscript>Nb<subscript>0.2</subscript>O<subscript>3</subscript> as anodes on YSZ electrolytes, suggesting improved catalytic activity by Na/K-doping. [ABSTRACT FROM AUTHOR]