Synthesis and characterisation of the novel double perovskites La2CrB2/3Nb1/3O6, B = Mg, Ni, Cu
2012 (English)In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 47, no 9, 2449-2454 p.Article in journal (Refereed) Published
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.
Place, publisher, year, edition, pages
2012. Vol. 47, no 9, 2449-2454 p.
Inorganic compounds, Oxides, X-ray diffraction, Neutron scattering, Crystal structure, Magnetic properties
Research subject Materials Chemistry
IdentifiersURN: urn:nbn:se:su:diva-81827DOI: 10.1016/j.materresbull.2012.05.019ISI: 000309081400052OAI: oai:DiVA.org:su-81827DiVA: diva2:565439