|
authors |
Marozau, IP; Shaula, AL; Kharton, VV; Vyshatko, NP; Viskup, AP; Frade, JR; Marques, FMB |
|
nationality |
International |
|
journal |
MATERIALS RESEARCH BULLETIN |
|
author keywords |
oxides; ceramics; electrical properties; ionic conductivity; thermal expansion |
|
keywords |
OXIDE-ION CONDUCTORS; FORMER SOVIET-UNION; TECHNOLOGY; ELECTROCHEMISTRY; CONDUCTIVITY; DIFFUSION |
|
abstract |
The oxygen ion transference numbers of La1.7Bi0.3Mo2O9, La2Mo1.7W0.3O9 and La2Mo1.95V0.05O9 ceramics, determined by modified faradaic efficiency and e.m.f. methods at 973-1173 K, vary in the range 0.995-0.977 in air, decreasing when temperature increases. The activation energies for the ionic and electronic transport are 61-71 kJ/ mol and 123-141 kJ/mol, respectively. Reducing oxygen chemical potential leads to increasing n-type electronic contribution to the total conductivity, which remains, however, essentially p(O-2)-independent down to oxygen pressures of 10(-4)-10(-3) atm and exhibits reversible drop on further reduction, probably due to phase decomposition. Doping La2Mo2O9 with calcium results in segregation of a CaMoO4-based phase, accompanied with increasing electronic transport. The average thermal expansion coefficients of La2Mo2O9-based materials, calculated from dilatometric data in air, are (14.4-14.8) x 10(-6) K-1 at 300-700 K and (16.4-22.5) x 10(-6) K-1 at 700-1070 K. (C) 2004 Elsevier Ltd. All rights reserved. |
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publisher |
PERGAMON-ELSEVIER SCIENCE LTD |
|
issn |
0025-5408 |
|
year published |
2005 |
|
volume |
40 |
|
issue |
2 |
|
beginning page |
361 |
|
ending page |
371 |
|
digital object identifier (doi) |
10.1016/j.materresbull.2004.10.003 |
|
web of science category |
Materials Science, Multidisciplinary |
|
subject category |
Materials Science |
|
unique article identifier |
WOS:000226906400018
|
