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Full Record Details
Persistent URL
http://purl.org/net/epubs/work/52819
Record Status
Checked
Record Id
52819
Title
Topotactic Nitrogen Transfer: Structural Transformation in Cobalt Molybdenum Nitrides
Contributors
SM Hunter
,
D McKay
,
RI Smith (STFC Rutherford Appleton Lab.)
,
JSJ Hargreaves
,
DH Gregory
Abstract
The temperature-programmed reaction of Co3Mo3N under H2/Ar results in a new nitride with composition Co6Mo6N. Powder neutron diffraction (PND) studies have confirmed unequivocally that the compound possesses the eta-12 carbide structure, in which N atoms are exclusively located at 8a crystallographic sites, as opposed to the 16c sites exclusively occupied in the Co3Mo3N phase. On this basis, it possible to rationalize the observation that 50% nitrogen loss occurs under the high-temperature reduction conditions employed. Reaction of the reduced eta-12 phase under N2/H2 results in the regeneration of the eta-6 Co3Mo3N nitride and return of nitrogen to the 16c sites (only). Although established for corresponding ternary carbide structures, the eta-12 carbide structure is unprecedented in nitrides and a topotactic cycling between eta-carbide structures is hitherto unknown. The ammonia synthesis activity of the eta-6 nitride at ambient pressure and 400 °C is 167 micromol /g /h, whereas the eta-12 structure is unstable and reverts back to the eta-6 structure under reaction conditions. Studies of the magnetic properties of the cobalt molybdenum nitrides demonstrate that both the eta-6 and eta-12 nitrides exhibit no long-range magnetic ordering and are superparamagnetic, although the coercive field (Hc) observed in magnetization measurements is diminished in the reduced nitride.
Organisation
ISIS
,
ISIS-POLARIS
,
STFC
Keywords
Materials
,
Chemistry
Funding Information
Related Research Object(s):
Licence Information:
Language
English (EN)
Type
Details
URI(s)
Local file(s)
Year
Journal Article
Chem Mater
22, no. 9 (2010): 2898-2907.
doi:10.1021/cm100208a
2010
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