Structural and magnetic characterization of ordered Sr2LnSbO6 (Ln=rare earth) perosvkite

Fernández Martínez, Francisco; Montero de Juan, José Luis; Cascales, C.; Romero, J. y Sáez Puche, R. (2009). Structural and magnetic characterization of ordered Sr2LnSbO6 (Ln=rare earth) perosvkite. En: "7th International Conference on f Elements, ICfE 7", 23/08/2009 - 27/08/2009, Cologne, Germany.

Descripción

Título: Structural and magnetic characterization of ordered Sr2LnSbO6 (Ln=rare earth) perosvkite
Autor/es:
  • Fernández Martínez, Francisco
  • Montero de Juan, José Luis
  • Cascales, C.
  • Romero, J.
  • Sáez Puche, R.
Tipo de Documento: Ponencia en Congreso o Jornada (Artículo)
Título del Evento: 7th International Conference on f Elements, ICfE 7
Fechas del Evento: 23/08/2009 - 27/08/2009
Lugar del Evento: Cologne, Germany
Título del Libro: Proceedings of the 7th International Conference on f Elements, ICfE 7
Fecha: 2009
Materias:
Escuela: E.U.I.T. Industrial (UPM) [antigua denominación]
Departamento: Química Industrial y Polímeros [hasta 2014]
Licencias Creative Commons: Reconocimiento - Sin obra derivada - No comercial

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Resumen

The double perovskites A2LnMO6 (A = Sr2+ and Ba2+; Ln = trivalent lanthanide cation; M = pentavalent 4d or 5d transition elements) have been widely studied concerning their structure and properties [1]. If the Ln and M cations are ordered within the B-perosvkite sites the symmetry and size of the unit cell change when are compared to the ideal cubic aristotype. Woodward predicted 15 possible space groups for the ordered A2BB’O6 perovskites when the cation ordering and the octahedral tilting around the pseudo-cubic axes take place simultaneously [2]. The ordered double perovskites A2LnMO6 with only one of the two B-sites carrying magnetic moment, namely Ln, show a magnetic sublattice consisting of edge-sharing tetrahedral, which represents a frustrating magnetic geometry in three dimensions. More recently, the structure of double perovskites Sr2LnSbO6 (Ln= Dy, Ho, Gd, Y and In) has been investigated, and the monoclinic symmetry of the space group P21/n, with Ln and Sb elements ordered in the B-sites, was reported [3, 4]. We report the preparation of the whole family of double perovskites Sr2LnSbO6 (Ln = La-Lu), which crystallize with the P21/n space group, with lattice parameters p= a2a , p= a2b and p= a2c(β∼90 º), being the lattice parameter of the cubic aristotype. A progressive decreasing was observed in lattice parameters with the increasing of the atomic number of the Ln cation, according with the wellknown lanthanide contraction. pa Magnetic susceptibility measurements for this family of compounds reveal a paramagnetic behaviour in a very wide temperature range. From experimental spectroscopic data as well as from a semi-empirical estimation (Simple Overlap Model SOM [5]) of the crystal-field parameters corresponding to the point site symmetry of the magnetically active Ln, Oh, and using the wavefunctions associated with the energy levels obtained, the paramagnetic susceptibility and its evolution vstemperature is simulated according to the van Vleck formalism. The observed deviation from the Curie–Weiss behaviour at low temperature, very well reproduced in each case, reflects the splitting of the ground state of the corresponding Ln cation under the influence of the crystal field. Thus, magnetic frustration or cooperative interactions do not need to be considered to explain the mentioned low temperature deviation from the linearity of Curie-Weiss plots.

Más información

ID de Registro: 5590
Identificador DC: http://oa.upm.es/5590/
Identificador OAI: oai:oa.upm.es:5590
URL Oficial: http://www.icfe.de/
Depositado por: Memoria Investigacion
Depositado el: 23 Dic 2010 08:59
Ultima Modificación: 20 Abr 2016 14:21
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