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Synthesis and characterisation of the novel double perovskites La2CrB2/3Nb1/3O6, B = Mg, Ni, Cu

G. Svensson ; J. Grins ; S. Shafeie ; D. Masson ; Stefan T. Norberg (Institutionen för kemi- och bioteknik, Oorganisk miljökemi) ; Sten G. Eriksson (Institutionen för kemi- och bioteknik, Oorganisk miljökemi) ; S. Hull ; K. V. Zakharov ; O. S. Volkova ; A. N. Vasil'ev ; S. Y. Istomin
Materials Research Bulletin (0025-5408). Vol. 47 (2012), 9, p. 2449-2454.
[Artikel, refereegranskad vetenskaplig]

The novel perovskites La2CrB2/3Nb1/3O6, B = Mg, Ni, and Cu have been synthesised at 1350 degrees C in air via the citrate route. Rietveld refinements using neutron powder diffraction (NPD) data showed that the compounds adopt the GdFeO3 type structure with space group Pbnm, and unit cell parameters a approximate to b approximate to root 2 x a(p) and c approximate to 2 x a(p), where a(p) approximate to 3.8 angstrom. Selected area electron diffraction (SAED) of B = Ni and Cu samples confirmed space group Pbnm. However, distinct reflections forbidden in Pbnm symmetry, but allowed in the monoclinic sub-group P2(1)/n and unit cell parameters a approximate to b approximate to root 2 x a(p) and c approximate to 2 x a(p), beta approximate to 90 degrees were present in SAED patterns of B = Mg sample. This indicates an ordering of the B-cations within the crystal structure of La2CrMg2/3Nb1/3O6. High-resolution electron microscopy (HREM) study indicating uniform, without formation of clusters, ordering of B-cations in the crystallites of La2CrMg2/3Nb1/3O6. Magnetic susceptibility measurements show that the compounds are antiferromagnetic (with some glass or spin clustering effects due to additional ferromagnetic interactions between the B-cations) with T-N for La2CrB2/3Nb1/3O6, B = Mg, Ni, Cu being 90, 125 and 140K, respectively.

Nyckelord: Inorganic compounds, Oxides, X-ray diffraction, Neutron scattering, Crystal structure, Magnetic, neutron-diffraction, lanthanum chromite, crystal-structure, phase-transition, lacro3, lacr1-xnixo3, catalysts



Denna post skapades 2012-10-30. Senast ändrad 2016-07-01.
CPL Pubid: 165259

 

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Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Oorganisk miljökemi (2005-2014)

Ämnesområden

Kemi

Chalmers infrastruktur