Synthesis and characterisation of the novel double perovskites La2CrB2/3Nb1/3O6, B = Mg, Ni, Cu
Artikel i vetenskaplig tidskrift, 2012

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.

lanthanum chromite

catalysts

Oxides

X-ray diffraction

lacr1-xnixo3

Neutron scattering

Magnetic

Crystal structure

lacro3

neutron-diffraction

Inorganic compounds

phase-transition

crystal-structure

Författare

G. Svensson

Stockholms universitet

J. Grins

Stockholms universitet

Samrand Shafeie

Stockholms universitet

D. Masson

Stockholms universitet

Stefan Norberg

Chalmers, Kemi- och bioteknik, Oorganisk miljökemi

Sten Eriksson

Chalmers, Kemi- och bioteknik, Oorganisk miljökemi

S. Hull

Rutherford Appleton Laboratory

K. V. Zakharov

Moscow State University

O. S. Volkova

Moscow State University

A. N. Vasil'ev

Moscow State University

S. Y. Istomin

Moscow State University

Materials Research Bulletin

0025-5408 (ISSN)

Vol. 47 9 2449-2454

Ämneskategorier

Kemi

DOI

10.1016/j.materresbull.2012.05.019