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Electronic Conductivity Enhancement of (La,Sr)TiO 3 with Nb‐Doping on B‐Site
Author(s) -
Kazakevičius E.,
Tsekouras G.,
MichalowMauke K. A.,
Kazlauskas S.,
Graule T.
Publication year - 2014
Publication title -
fuel cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.485
H-Index - 69
eISSN - 1615-6854
pISSN - 1615-6846
DOI - 10.1002/fuce.201400015
Subject(s) - materials science , analytical chemistry (journal) , conductivity , stoichiometry , electrical resistivity and conductivity , doping , ceramic , sintering , oxygen , vacancy defect , bar (unit) , mineralogy , crystallography , chemistry , metallurgy , optoelectronics , organic chemistry , chromatography , electrical engineering , engineering , physics , meteorology
B‐site doped, A‐site deficient strontium titanates with general formula La x Sr 1–3 x /2+ γx Nb y Ti 1– y O 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 Ti 4+ by Nb 5+ raised conductivity by ∼ 40%, with a maximum value of 226 S cm −1 observed at 900 °C. This was attributed to a higher concentration of $ {\rm{Ti}}_{{\rm{Ti}}}^{\prime} $ defects, due to concurrent and enhanced oxygen vacancy ( $ {\rm{V}}_{\rm{o}}^{\bullet \bullet} $ ) formation under reducing conditions. The electronic properties of a slightly porous bar sample of the La 0.3 Sr 0.559 Nb 0.02 Ti 0.98 O 3– δ composition were found to be stable over one redox cycle.