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Structural and magnetic properties of pure and Ca-doped LaCoO3 nanopowders obtained by a sol-gel route (Articolo in rivista)

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Structural and magnetic properties of pure and Ca-doped LaCoO3 nanopowders obtained by a sol-gel route (Articolo in rivista) (literal)

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L. Armelao, D. Barreca, G. Bottaro, C. Maragno, E. Tondello, A. Caneschi, C. Sangregorio, S. Gialanella (2006)
Structural and magnetic properties of pure and Ca-doped LaCoO3 nanopowders obtained by a sol-gel route
in Journal of nanoscience and nanotechnology (Print)
(literal)

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L. Armelao, D. Barreca, G. Bottaro, C. Maragno, E. Tondello, A. Caneschi, C. Sangregorio, S. Gialanella (literal)

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1,2,3: ISTM-CNR and INSTM - Department of Chemistry - University of Padova - Italy 4,5: Department of Chemistry and INSTM - University of Padova - Italy 6,7: Department of Chemistry and INSTM - University of Firenze - Italy 8: Department of Materials Engineering and Industrial Technologies - University of Trento - Italy (literal)

Titolo

Structural and magnetic properties of pure and Ca-doped LaCoO3 nanopowders obtained by a sol-gel route (literal)

Abstract

Pure and Ca-doped LaCoO3 nanopowders were prepared by a non-alkoxidic sol-gel route using cobalt(II) acetate, lanthanum(III) nitrate and calcium(II) acetate as oxide precursors. The structural evolution and magnetic properties of the samples were studied as a function of thermal treatments in air up to 1273 K. In particular, the microstructure and composition of the systems were analyzed by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). For both pure and calcium-doped samples annealing at 973 K resulted in the formation of cubic LaCoO3 (average crystallite size < 30 nm). This phase was fully retained in the calcium-doped materials even after annealing at higher temperatures, whereas a transition to the rhomboedral polymorph was detected in the pure samples at 1073 K. The magnetic behavior of the nanopowders was investigated as a function of temperature and applied field using both dynamic and static susceptibility measurements. Pure lanthanum cobaltite samples underwent a transition to an ordered state at 88 K, and their magnetic properties changed as a function of thermal treatments. As concerns calcium-doped samples, they ordered ferromagnetically at 171 and 185 K, depending on the annealing temperature, and displayed open hysteresis loops with coercive field as large as 1.75 T at low temperatures. (literal)

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