Defect formation and transport in La0.95Ni0.5Ti0.5O3-delta
authors Yakovlev, SO; Kharton, VV; Naumovich, EN; Zekonyte, J; Zaporojtchenko, V; Kovalevsky, AV; Yaremchenko, AA; Frade, JR
nationality International
journal SOLID STATE SCIENCES
author keywords lanthanum; nickelate-titanate; A-site deficiency; defect association; oxygen ionic conductivity; hole transport; atomistic modelling; thermal expansion
keywords ELECTRICAL-PROPERTIES; MIXED CONDUCTIVITY; PARTIAL OXIDATION; PEROVSKITE-TYPE; SYNTHESIS GAS; METHANE; STABILITY; OXIDES; CONDUCTORS; CONVERSION
abstract Deficiency in the A sublattice of orthorhombic perovskite-type La1-xNi0.5Ti0.5O3-delta, with maximum at x =0.07-0.08, is compensated by the formation of trivalent nickel and oxygen vacancies. The atomistic computer simulations showed that these defects are trapped near the A-site cation vacancies, resulting in the stabilization of Ni3+ cations and low electronic and oxygen-ionic transport. The average thermal expansion coefficient of La0.95M0.5Ti0.5O3-delta ceramics, calculated from dilatometric data in air, increases from 8.6 x 10(-6) K-1 at 300-800 K to 12.0 x 10(-6) K-1 at 1300-1500 K. The data on Seebeck coefficient and total conductivity, predominantly p-type electronic, suggest a broadband mechanism of hole transport. The activation energies for the hole and ionic conductivities are 89 and 430 U/mol, respectively. The oxygen ion transference numbers determined by the faradaic efficiency measurements in air, vary in the range 9.5 x 10(-5)-8.1 x 10(-4) at 1173-1248 K, increasing with temperature. Reducing oxygen partial pressure leads to a moderate decrease of the conductivity, followed by phase decomposition in the p(O-2) range 9 x 10(-11) to 8 x 10(-9) atm at 1073-1223 K. The low-p(O-2) stability limit of La0.95M0.5Ti0.5O3-delta perovskite was found between that of La3Ni2O7 and Ni/NiO boundary. (c) 2006 Elsevier Masson SAS. All rights reserved.
publisher ELSEVIER SCIENCE BV
issn 1293-2558
year published 2006
volume 8
issue 11
beginning page 1302
ending page 1311
digital object identifier (doi) 10.1016/j.solidstatesciences.2006.07.010
web of science category Chemistry, Inorganic & Nuclear; Chemistry, Physical; Physics, Condensed Matter
subject category Chemistry; Physics
unique article identifier WOS:000242535700005
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journal impact factor 2.434
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