Chemical bonding topology superconductors: III. Layered quaternary lanthanide nickel borocarbides and boronitrides

Journal Article · Mon Jul 01 04:00:00 EDT 1996 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1006/jssc.1996.0245· OSTI ID:494455

King, R B ^[1]

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1. Univ. of Georgia, Athens, GA (United States)

The concept of porous delocalization has been extended to the conducting skeletons of quaternary lanthanide nickel borocarbide and boronitride superconductors and related nonsuperconducting materials. Such materials exhibit layered structures of the general type (LnX){sub n}(Ni{sub 2}B{sub 2})(Ln = lanthanide, particularly the nonmagnetic La{sup III} or Lu{sup III}; X = C or N; n 1, 2, or 3) containing planar square Ni nets bonded to BCB{sup 2-} ligands in the superconducting LnNi{sub 2}B{sub 2}C, BC{sup 3-} ligands in the nonsuperconducting LnNiBC and Ln{sub 2}NiBC{sub 2}, and BN{sup 2-} ligands in the superconducting La{sub 3}Ni{sub 2}B{sub 2}N{sub 3}. The linear BCB{sup 2-} bridges linking adjacent Ni layers in LnNi{sub 2}B{sub 2}C lead to a porous conducting skeleton in LnNi{sub 2}B{sub 2}C. The BC{sup 3-} ligands in the nonsuperconducting LuNiBC and the closely related Ln{sub 2}NiBC{sub 2} = Ln{sub 2}C{sub 2}{center_dot}2LnNiBC do not link adjacent Ni layers in LuNiBC so that LuNiBC has only a two-dimensional conducting skeleton, which is not necessarily porous in these two dimensions. The superconducting La{sub 3}Ni{sub 2}B{sub 2}N{sub 3} = LaN{center_dot}2LaNiBN has a similar local Ni environment as LuNiBC but with BN{sup 2-} rather than the isolelectronic BC{sup 3-} ligands above and below each Ni layer. However, in La{sub 3}Ni{sub 2}B{sub 2}N{sub 3} unlike LuNiBC the LaNiBN units are linked electronically by the La atoms in the intermediate LaN layer leading to a three-dimensional conducting skeleton in La{sub 3}Ni{sub 2}B{sub 2}N{sub 3} rather than the two-dimensional conducting skeleton of LuNiBC. The linear BNLaNB units linking the Ni layers in La{sub 3}Ni{sub 2}N{sub 3} lead to a porous conducting skeleton similar to that in the LnNi{sub 2}B{sub 2}C superconductors.

• OSTI ID: 494455
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 2 Vol. 124; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
40 CHEMISTRY
BORIDES
CARBIDES
ELECTRONIC STRUCTURE
MATHEMATICAL MODELS
NICKEL COMPOUNDS
NITRIDES
RARE EARTH COMPOUNDS