resumo
The present work explores mechanosynthesis of lanthanum aluminate-based perovskite ceramics and corresponding effects on ionic-electronic transport properties. La1-xCaxAlO3-delta (x = 0.05-0.20) nanopowders were prepared via one-step high-energy mechanochemical processing. Sintering at 1450 degrees C yielded dense ceramics with submicron grains. As-prepared powders and sintered ceramics were characterized by XRPD, XPS and SEM. Electrochemical studies showed that partial oxygen-ionic conductivity in prepared La1-xCaxAlO3-delta increases with calcium content up to 10 at.% in the lanthanum sublattice and then levels off at similar to 6 x 10(-3) S/cm at 900 degrees C. La1-xCaxAlO3-delta ceramics are mixed conductors under oxidizing conditions and ionic conductors with negligible contribution of electronic transport in reducing atmospheres. Oxygen-ionic contribution to the total conductivity is 20-68% at 900 degrees C in air and increases with Ca content, with temperature and with reducing p(O-2). Impedance spectroscopy results showed however that electrical properties of mechanosynthesized La1-xCaxAlO3-delta ceramics below similar to 800 degrees C are determined by prevailing grain boundary contribution to the total resistivity.
palavras-chave
ELECTRICAL-CONDUCTIVITY; COMBUSTION SYNTHESIS; LANTHANUM ALUMINATE; OXIDE; SR; BEHAVIOR; POWDER; LA0.95SR0.05ALO3-DELTA; LA0.95SR0.05GAO3-DELTA; LAGAO3
categoria
Materials Science
autores
Fabian, M; Arias-Serrano, BI; Yaremchenko, AA; Kolev, H; Kanuchova, M; Briancin, J
nossos autores
Aleksey Yaremchenko
Investigador Principal
Blanca Isabel Arias Serrano
Bolseiro de pós-Doutoramentoagradecimentos
This work was supported by the Slovak Research and Development Agency APVV (contracts SK-PT-18-0039 and 15-0438) and the Slovak Grant Agency (contract No. 2/0055/19). BIAS and AAY would like to acknowledge financial support by the FCT, Portugal (bilateral project Portugal-Slovakia 2019-2020, project CARBOSTEAM (POCI-01-0145-FEDER-032295) and project CICECO-Aveiro Institute of Materials (FCT ref. UID/CTM/50011/2019), financed by national funds through the FCT/MCTES and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. HK thanks to SAIA, n.o. for financial support within National Scholarship Programme of the Slovak republic (NSP).