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Author Franco, D.G.; Fuertes, V.C.; Blanco, M.C.; Fernández-Díaz, M.T.; Sánchez, R.D.; Carbonio, R.E.
Title Synthesis, structure and magnetic properties of La3Co2SbO9: A double perovskite with competing antiferromagnetic and ferromagnetic interactions Type Journal Article
Year 2012 Publication Journal of Solid State Chemistry Abbreviated Journal J. Solid State Chem.
Volume 194 Issue Pages 385-391
Keywords La3Co2SbO9; Double perovskite; Powder neutron diffraction; Rietveld refinement; Ferromagnetic; Magnetic frustration
Abstract The synthesis, structural characterization, and magnetic properties of La3Co2SbO9 double perovskite are reported. The crystal structure has been refined by X-ray and neutron powder diffraction data in the monoclinic space group P21/n. Co2+ and Sb5+ have the maximum order allowed for the La3Co2SbO9 stoichiometry. Rietveld refinements of powder neutron diffraction data show that at room temperature the cell parameters are a=5.6274(2) Å, b=5.6842(2) Å, c=7.9748(2) Å and β=89.999(3)°. Magnetization measurements indicate the presence of ferromagnetic correlations with TC=55 K attributed to the exchange interactions for non-linear Co2+–O–Sb5+–O–Co2+ paths. The effective magnetic moment obtained experimentally is μexp=4.38 μB (per mol Co2+), between the theoretical one for spin only (3.87 μB) and spin-orbit value (6.63 μB), indicating partially unquenched contribution. The low magnetization value at high magnetic field and low temperature (1 μB/f.u., 5 T and 5 K) and the difference between ZFC and FC magnetization curves (at 5 kOe) indicate that the ferromagnetism do not reach a long range order and that the material has an important magnetic frustration.
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Language Summary Language (up) Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-4596 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 671
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Author Franco, D.G.; Carbonio, R.E.; Nieva, G.
Title Synthesis and structural and magnetic characterization of the frustrated magnetic system La2Ni4/3−xCoxSb2/3O6 Type Journal Article
Year 2013 Publication Journal of Solid State Chemistry Abbreviated Journal J. Solid State Chem.
Volume 207 Issue Pages 69-79
Keywords Double perovskites; Neutron diffraction; Rietveld refinement; Ferrimagnetism; Magnetic frustration
Abstract We report the synthesis of double perovskites La2Ni4/3−xCoxSb2/3O6 with x=0, 1/3, 2/3 and 1 by a solid state method. Rietveld refinements of X-ray and neutron powder diffraction data show that all samples crystallize in space group P21/n, with almost perfect occupation of the 2d octahedral site with the transition metals, while all Sb5+ are randomly distributed in a 2c octahedral site. The saturation magnetization in hysteresis loops indicates that the samples are ferrimagnetic throughout all the series. Virgin magnetization curves lie outside hysteresis loops at low temperatures and thermal evolution of Hm – defined as the inflection point of these curves – follows the de Almeida–Thouless dependence for x ≠ 0 . This spin glass like behavior below 30 K is also supported by thermal evolution of the coercivity, which follows an exponential law typical of magnetic clusters, not found in the pure Ni2+ perovskite, x=0 extreme.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language (up) Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-4596 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number BT @ pedrazp @ Serial 670
Permanent link to this record