Structure, crystal chemistry and magnetism of rare earth calcium-doped cobaltates: Ln2−xCaxCoO4+δ (Ln = Pr, Nd, Sm, Eu and Gd)
Single-phase samples of Ln2−xCaxCoO4+δ (Ln = Pr3+ − Gd3+) around x∼1 have been prepared. For the first time, the phase field for these compounds has been defined using powder X-ray diffraction and a very narrow solid solution was observed. Under our synthetic conditions, the K2NiF4 structure was not formed for the large La3+ ion, or for compositions containing the smaller rare earths ions (<Gd3+) and Y3+. Thermogravimetric analysis indicates average cobalt oxidation states ranging between ∼3.2+ and ∼3.3+. Rietveld refinement of structures using synchrotron powder X-ray diffraction data indicates that the larger rare earth ions LnCaCoO4+δ (Ln = Pr3+ − Sm3+) form tetragonal (I4/mmm) structures at room temperature, while (Ln = Eu3+, Gd3+) crystallised with orthorhombic (Bmab) structures. The evolution of structure between the low temperature orthorhombic form and the high temperature tetragonal form was investigated between 80 K and 575 K using high-resolution synchrotron X-ray powder diffraction. Orthorhombic to tetragonal transitions were observed for SmCaCoO4.17 (T∼230 K), EuCaCoO4.13 (T∼320 K) and GdCaCoO4.11 (T∼465 K). Magnetic measurements for LnCaCoO4+δ (Ln = Pr3+ − Gd3+) indicate paramagnetic behaviour along with weak antiferromagnetic interactions and Co3+ in a 6t2g low-spin state. PrCaCoO4.17 was found to order antiferromagnetically below 15 K.
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dig-cirad-fr-5779092022-04-15T12:56:09Z http://agritrop.cirad.fr/577909/ http://agritrop.cirad.fr/577909/ Structure, crystal chemistry and magnetism of rare earth calcium-doped cobaltates: Ln2−xCaxCoO4+δ (Ln = Pr, Nd, Sm, Eu and Gd). Thorogood Gordon J., Orain Pierre-Yves, Ouvry Mickael, Piriou Bruno, Tedesco Tony, Wallwork Kia S., Herrmann Jan, James Michael. 2011. Solid State Sciences, 13 (12) : 2113-2123.https://doi.org/10.1016/j.solidstatesciences.2011.08.008 <https://doi.org/10.1016/j.solidstatesciences.2011.08.008> Researchers Structure, crystal chemistry and magnetism of rare earth calcium-doped cobaltates: Ln2−xCaxCoO4+δ (Ln = Pr, Nd, Sm, Eu and Gd) Thorogood, Gordon J. Orain, Pierre-Yves Ouvry, Mickael Piriou, Bruno Tedesco, Tony Wallwork, Kia S. Herrmann, Jan James, Michael eng 2011 Solid State Sciences 000 - Autres thèmes Single-phase samples of Ln2−xCaxCoO4+δ (Ln = Pr3+ − Gd3+) around x∼1 have been prepared. For the first time, the phase field for these compounds has been defined using powder X-ray diffraction and a very narrow solid solution was observed. Under our synthetic conditions, the K2NiF4 structure was not formed for the large La3+ ion, or for compositions containing the smaller rare earths ions (<Gd3+) and Y3+. Thermogravimetric analysis indicates average cobalt oxidation states ranging between ∼3.2+ and ∼3.3+. Rietveld refinement of structures using synchrotron powder X-ray diffraction data indicates that the larger rare earth ions LnCaCoO4+δ (Ln = Pr3+ − Sm3+) form tetragonal (I4/mmm) structures at room temperature, while (Ln = Eu3+, Gd3+) crystallised with orthorhombic (Bmab) structures. The evolution of structure between the low temperature orthorhombic form and the high temperature tetragonal form was investigated between 80 K and 575 K using high-resolution synchrotron X-ray powder diffraction. Orthorhombic to tetragonal transitions were observed for SmCaCoO4.17 (T∼230 K), EuCaCoO4.13 (T∼320 K) and GdCaCoO4.11 (T∼465 K). Magnetic measurements for LnCaCoO4+δ (Ln = Pr3+ − Gd3+) indicate paramagnetic behaviour along with weak antiferromagnetic interactions and Co3+ in a 6t2g low-spin state. PrCaCoO4.17 was found to order antiferromagnetically below 15 K. article info:eu-repo/semantics/article Journal Article info:eu-repo/semantics/publishedVersion http://agritrop.cirad.fr/577909/1/James.2011.pdf text Cirad license info:eu-repo/semantics/restrictedAccess https://agritrop.cirad.fr/mention_legale.html https://doi.org/10.1016/j.solidstatesciences.2011.08.008 10.1016/j.solidstatesciences.2011.08.008 info:eu-repo/semantics/altIdentifier/doi/10.1016/j.solidstatesciences.2011.08.008 info:eu-repo/semantics/altIdentifier/purl/https://doi.org/10.1016/j.solidstatesciences.2011.08.008 |
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000 - Autres thèmes 000 - Autres thèmes Thorogood, Gordon J. Orain, Pierre-Yves Ouvry, Mickael Piriou, Bruno Tedesco, Tony Wallwork, Kia S. Herrmann, Jan James, Michael Structure, crystal chemistry and magnetism of rare earth calcium-doped cobaltates: Ln2−xCaxCoO4+δ (Ln = Pr, Nd, Sm, Eu and Gd) |
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Single-phase samples of Ln2−xCaxCoO4+δ (Ln = Pr3+ − Gd3+) around x∼1 have been prepared. For the first time, the phase field for these compounds has been defined using powder X-ray diffraction and a very narrow solid solution was observed. Under our synthetic conditions, the K2NiF4 structure was not formed for the large La3+ ion, or for compositions containing the smaller rare earths ions (<Gd3+) and Y3+. Thermogravimetric analysis indicates average cobalt oxidation states ranging between ∼3.2+ and ∼3.3+. Rietveld refinement of structures using synchrotron powder X-ray diffraction data indicates that the larger rare earth ions LnCaCoO4+δ (Ln = Pr3+ − Sm3+) form tetragonal (I4/mmm) structures at room temperature, while (Ln = Eu3+, Gd3+) crystallised with orthorhombic (Bmab) structures. The evolution of structure between the low temperature orthorhombic form and the high temperature tetragonal form was investigated between 80 K and 575 K using high-resolution synchrotron X-ray powder diffraction. Orthorhombic to tetragonal transitions were observed for SmCaCoO4.17 (T∼230 K), EuCaCoO4.13 (T∼320 K) and GdCaCoO4.11 (T∼465 K). Magnetic measurements for LnCaCoO4+δ (Ln = Pr3+ − Gd3+) indicate paramagnetic behaviour along with weak antiferromagnetic interactions and Co3+ in a 6t2g low-spin state. PrCaCoO4.17 was found to order antiferromagnetically below 15 K. |
format |
article |
topic_facet |
000 - Autres thèmes |
author |
Thorogood, Gordon J. Orain, Pierre-Yves Ouvry, Mickael Piriou, Bruno Tedesco, Tony Wallwork, Kia S. Herrmann, Jan James, Michael |
author_facet |
Thorogood, Gordon J. Orain, Pierre-Yves Ouvry, Mickael Piriou, Bruno Tedesco, Tony Wallwork, Kia S. Herrmann, Jan James, Michael |
author_sort |
Thorogood, Gordon J. |
title |
Structure, crystal chemistry and magnetism of rare earth calcium-doped cobaltates: Ln2−xCaxCoO4+δ (Ln = Pr, Nd, Sm, Eu and Gd) |
title_short |
Structure, crystal chemistry and magnetism of rare earth calcium-doped cobaltates: Ln2−xCaxCoO4+δ (Ln = Pr, Nd, Sm, Eu and Gd) |
title_full |
Structure, crystal chemistry and magnetism of rare earth calcium-doped cobaltates: Ln2−xCaxCoO4+δ (Ln = Pr, Nd, Sm, Eu and Gd) |
title_fullStr |
Structure, crystal chemistry and magnetism of rare earth calcium-doped cobaltates: Ln2−xCaxCoO4+δ (Ln = Pr, Nd, Sm, Eu and Gd) |
title_full_unstemmed |
Structure, crystal chemistry and magnetism of rare earth calcium-doped cobaltates: Ln2−xCaxCoO4+δ (Ln = Pr, Nd, Sm, Eu and Gd) |
title_sort |
structure, crystal chemistry and magnetism of rare earth calcium-doped cobaltates: ln2−xcaxcoo4+δ (ln = pr, nd, sm, eu and gd) |
url |
http://agritrop.cirad.fr/577909/ http://agritrop.cirad.fr/577909/1/James.2011.pdf |
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