Synthesis and characterisation of the novel double perovskites La{sub 2}CrB{sub 2/3}Nb{sub 1/3}O{sub 6}, B = Mg, Ni, Cu

Journal Article · Sat Sep 15 00:00:00 EDT 2012 · Materials Research Bulletin

DOI:https://doi.org/10.1016/J.MATERRESBULL.2012.05.019· OSTI ID:22215738

Grins, J.; Shafeie, S.; Masson, D. ^[1]; Norberg, S. T.; Eriksson, S. ^[2]; Hull, S. ^[3]; Zakharov, K. V.; Volkova, O. S.; Vasil’ev, A. N.; Istomin, S. Ya. ^[4]

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1. Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm (Sweden)
2. Department of Chemical and Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg (Sweden)
3. ISIS, Rutherford Appleton Laboratory, Didcot OX11 OQX (United Kingdom)
4. M.V. Lomonosov Moscow State University, 119991 Moscow (Russian Federation)

Highlights: ► La{sub 2}CrB{sub 2/3}Nb{sub 1/3}O{sub 6}, B = Mg, Ni, Cu perovskites adopt the GdFeO{sub 3} type structure. ► HREM and ED study indicating week ordering of B-cations for B = Mg. ► Antiferromagnetics with T{sub N} 90 (Mg), 125 (Ni) and 140 K (Ni). -- Abstract: The novel perovskites La{sub 2}CrB{sub 2/3}Nb{sub 1/3}O{sub 6}, B = Mg, Ni, and Cu have been synthesised at 1350 °C in air via the citrate route. Rietveld refinements using neutron powder diffraction (NPD) data showed that the compounds adopt the GdFeO{sub 3} type structure with space group Pbnm, and unit cell parameters a≈b≈√(2)×a{sub p} and c ≈ 2 × a{sub p}, where a{sub p} ≈ 3.8 Å. 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{sub 1}/n and unit cell parameters a≈b≈√(2)×a{sub p} and c ≈ 2 × a{sub p}, β ≈ 90° were present in SAED patterns of B = Mg sample. This indicates an ordering of the B-cations within the crystal structure of La{sub 2}CrMg{sub 2/3}Nb{sub 1/3}O{sub 6}. High-resolution electron microscopy (HREM) study indicating uniform, without formation of clusters, ordering of B-cations in the crystallites of La{sub 2}CrMg{sub 2/3}Nb{sub 1/3}O{sub 6}. 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{sub N} for La{sub 2}CrB{sub 2/3}Nb{sub 1/3}O{sub 6}, B = Mg, Ni, Cu being 90, 125 and 140 K, respectively.

• OSTI ID: 22215738
• Journal Information: Materials Research Bulletin, Vol. 47, Issue 9; Other Information: Copyright (c) 2012 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0025-5408
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
36 MATERIALS SCIENCE
ANTIFERROMAGNETISM
ELECTRON DIFFRACTION
INORGANIC COMPOUNDS
INTERACTIONS
MAGNETIC SUSCEPTIBILITY
MONOCLINIC LATTICES
NEUTRON DIFFRACTION
ORTHORHOMBIC LATTICES
PEROVSKITES
SPACE GROUPS
SYNTHESIS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION