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

Oxides

lanthanum chromite

crystal-structure

Neutron scattering

catalysts

X-ray diffraction

lacr1-xnixo3

phase-transition

lacro3

neutron-diffraction

Magnetic

Inorganic compounds

Crystal structure

Author

G. Svensson

Stockholm University

J. Grins

Stockholm University

Samrand Shafeie

Stockholm University

D. Masson

Stockholm University

Stefan Norberg

Chalmers, Chemical and Biological Engineering, Environmental Inorganic Chemistry

Sten Eriksson

Chalmers, Chemical and Biological Engineering, Environmental Inorganic Chemistry

S. Hull

STFC 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

Subject Categories

Chemical Sciences

DOI

10.1016/j.materresbull.2012.05.019

More information

Latest update

5/20/2021