Strontium and cobalt doped-lanthanum chromite
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2015
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Ceramics International
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Perovskite powders prepared by combustion synthesis with a nominal composition of La0.800Sr0.200Cr0.920Co0.080O3.000 δ were obtained from
the corresponding metal nitrates, and characterised in terms of in-situ phase development (crystalline structure and thermal behaviour).
Synchrotron X-ray powder diffraction (SXRPD) and Rietveld analyses demonstrated that the as-prepared powder showed an orthorhombic
perovskite structure with an estimated composition of La0.803Sr0.197Cr0.966Co0.034O3.000 δ. Second phases present in the as-prepared powder
were m-LaCrO4, CoLa1.250Sr0.750O4.000, c-CoCr2.000O4.000 and m-SrCrO4.000. Sintering processes, including phase transition (from orthorhombic
to rhombohedral) of the main phase and, melting/evaporation of second phases have been studied by DTA/TGA and dilatometric studies; the
results were in full agreement with those detected by High-Temperature Synchrotron X-ray powder diffraction (HT-SXRPD). The transition
temperature was determined to be 1380 1C by dilatometric studies, and between 1240 and 1405 1C by HT-SXRPD.
Dye-pressed samples sintered at 1600 1C/4 h showed a density of 98.9 dth%. The phase transition is an irreversible process since the sintered
perovskite, measured at room temperature after cooling, only showed the rhombohedral phase as main phase. The evaluation of the linearity of
the conductivity versus the inverse of temperature and the activation energy values of the sintered material indicated that the electrical conduction
occurs via the non-adiabatic small-polaron mechanism in either air or hydrogen atmosphere. In the reducing environment, the perovskite shows
significantly reduced electrical conductivity compared with that in air, as it is expected for a p-type conductor.
& 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
Como referenciar
SETZ, L.F.G.; SANTACRUZ, I.; LEON-REINA, L.; TORRE, A.G. De la; ARANDA, M.A.G.; MELLO CASTANHO, S.R.H.; MORENO, R.; COLOMER, M.T. Strontium and cobalt doped-lanthanum chromite: characterisation of synthesised powders and sintered materials. Ceramics International, v. 41, p. 1177-1187, 2015. Disponível em: http://repositorio.ipen.br/handle/123456789/23269. Acesso em: 10 May 2024.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.