Evidence of low-dimensional antiferromagnetic ordering and crystal structure in the R sub 2 BaNiO sub 5 ( R =Y,Er) oxides

Journal Article · Thu Nov 01 00:00:00 EST 1990 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.42.7918· OSTI ID:6259435

Amador, J; Gutierrez-Puebla, E; Monge, M A; Rasines, I; Ruriaaz-Valero, C ^[1]; Fernandez, F; Saez-Puche, R ^[2]; Campa, J A ^[3]

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1. Instituto de Ciencia de Materiales, Consejo Superior de Investigaciones Cientificas, Serrano 113, Madrid (Spain)
2. Departamento de Quimica Inorganica, Facultad de Ciencias Quimicas, Universidad Complutense, Madrid (Spain)
3. Departamento de Cristalografia y Mineralogia, Facultad de Ciencias Geologicas, Universidad Complutense, Madrid (Spain)

Crystals of {ital R}{sub 2}BaNiO{sub 5} ({ital R}=Y,Er) have been grown, and their structures have been established by single-crystal x-ray diffraction. Both compounds crystallize in the Nd{sub 2}BaNiO{sub 5} structure type, with one-dimensional chains of vertex-sharing NiO{sub 6} octahedra in the direction of the {bold a} axis. These octahedra show an unusual twofold distortion: The Ni-O distances to the two axial oxygen atoms are considerably shorter, 0.3 A, than those to the four equatorial oxygens, and these oxygens are distorted from the right angles of a regular octahedron to 79.0(2){degree} or 77.7(6){degree}, respectively. As a result of this, Ni-O(axial)-Ni distances are very short, 3.76 and 3.75 A for {ital R}=Y and Er, respectively. X-ray powder diffraction data and the results of magnetic measurements for both oxides are given. The structural features mentioned elucidate why Ni{sup 2+} ions in polycrystalline Y{sub 2}BaNiO{sub 5} behave as a monodimensional system in which they become antiferromagnetically ordered below 300 K. Besides that, the ferromagnetic interactions that operate below 40 K can be due to tridimensional interchain interactions and/or the presence of ferromagnetic impurities. The estimated Neel temperature for Y{sub 2}BaNiO{sub 5}, higher than that reported for Y{sub 2}BaCuO{sub 5}, is explained by the promotion of the superexchange Ni-O-Ni interactions along the chains of flattened NiO{sub 6} octahedra sharing corners. In Er{sub 2}BaNiO{sub 5} both effects are masked by the strong paramagnetic signal of Er{sup 3+}, and a maximum observed at 15.6 K for the susceptibility is attributed to tridimensional ordering of the Er{sup 3+} cations.

• OSTI ID: 6259435
• Journal Information: Physical Review, B: Condensed Matter; (USA), Vol. 42:13; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
ANTIFERROMAGNETISM
CRYSTAL STRUCTURE
ERBIUM OXIDES
NICKEL OXIDES
YTTRIUM OXIDES
BOND LENGTHS
COORDINATION NUMBER
HIGH-TC SUPERCONDUCTORS
LOW TEMPERATURE
MEDIUM TEMPERATURE
TEMPERATURE DEPENDENCE
VERY LOW TEMPERATURE
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
DIMENSIONS
ERBIUM COMPOUNDS
LENGTH
MAGNETISM
NICKEL COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
RARE EARTH COMPOUNDS
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies