Electronic conductivity enhancement of (La,Sr)TiO3 with Nb-doping on B-Site

Authors

E Kazakevicius, Vilnius University
George Tsekouras, University of WollongongFollow
K A. Michalow-Mauke, Paul Scherrer Institute
S Kazlauskas, Paul Scherrer Institute
T Graule, Swiss Federal Laboratories for Materials Science and Technology

RIS ID

100702

Publication Details

Kazakevicius, E., Tsekouras, G., Michalow-Mauke, K. A., Kazlauskas, S. & Graule, T. (2014). Electronic conductivity enhancement of (La,Sr)TiO₃ with Nb-doping on B-Site. Fuel Cells: from fundamentals to systems, 14 (6), 954-960.

Abstract

B-site doped, A-site deficient strontium titanates with general formula La_xSr_1-3x/2+γxNb_yTi_1-yO_3-δ (x = 0.2, 0.25, 0.3, 0.35, 0.4; y = 0, 0.02, 0.03; γ = 0.03) were produced by flame spray synthesis and the electrical conductivity of dense ceramic bars sintered under reducing conditions measured over broad temperature and oxygen concentration ranges. As-synthesized powders were nano-scale and slightly reduced, while it was observed that sinterability was promoted by both La substitution and Nb doping. Electrical conductivity measurements on dense bars under reducing conditions revealed that stoichiometric substitution of Ti⁴⁺ by Nb⁵⁺ raised conductivity by approx. 40%, with a maximum value of 226 S cm⁻¹ observed at 900 °C. This was attributed to a higher concentration of Ti'_Ti defects, due to concurrent and enhanced oxygen vacancy (V_O) formation under reducing conditions. The electronic properties of a slightly porous bar sample of the La_0.3Sr_0.559Nb_0.02Ti_0.98O_3-δ composition were found to be stable over one redox cycle.