Journal ArticleDOI
The manganese nitrides η-Mn3N2 and θ-Mn6N5+x : nuclear and magnetic structures
TLDR
In this paper, high temperature neutron powder diffraction measurements reveal a simultaneous decay of the sublattice magnetisations and the tetragonal distortion of the unit cell dimensions, and a close inspection of the data reveals some systematic ambiguities of the magnetic structure which are analysed in detail.Abstract:
Neutron powder diffraction measurements on η-Mn3N2
and θ-Mn6N5 + x (x = 0.26)
revealed the nuclear and magnetic structures of these metallic interstitial
compounds. At ambient temperatures the crystal structures of both materials
derive from an fcc arrangement of Mn with N occupying octahedral sites. The
unit cells are face-centred tetragonal, η-Mn3N2: a = 4.2046(1) A, c = 12.131(1) A ≈ 3 × 4.041 A; θ-Mn6N5.26: a = 4.2193(1) A, c = 4.1287(1) A.
Both phases show an antiferromagnetic ordering of the first kind with magnetic
moments between 3.3 and 3.8 µB.The
data for η-Mn3N2 confirm a previously reported
ordered arrangement of N on 2/3 of the octahedral sites and the collinear
antiferromagnetic superstructure with the magnetic moments oriented perpendicular
to the tetragonal c axis. However, a close inspection of the data
reveals some systematic ambiguities of the magnetic structure which are analysed
in detail. In θ-Mn6N5 + x
(x = 0.26) the N atoms show no long-range occupational
order on the octahedral sites. At ambient temperatures the collinear magnetic
moments are tilted by 23° relative to the tetragonal c axis.
High temperature neutron powder diffraction measurements reveal a simultaneous
decay of the sublattice magnetisations and the tetragonal distortion of the
cell dimensions. At about 550 K the magnetic moments align parallel
to the c axis, and up to the critical temperature of 660 K
they decrease continuously to zero. Parallel to this, the tetragonal distortion
of the unit cell reduces and finally approaches a face-centred cubic structure.The
consequences of the results with respect to the Mn/N phase diagram are discussed.read more
Citations
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Journal ArticleDOI
Chemistry of Ammonothermal Synthesis
TL;DR: Ammonothermal synthesis is a method for synthesis and crystal growth suitable for a large range of chemically different materials, such as nitrides, amides, and polychalcogenides as mentioned in this paper.
Journal ArticleDOI
Crystalline phase and orientation control of manganese nitride grown on MgO(001) by molecular beam epitaxy
TL;DR: In this paper, the phase and orientation of manganese nitride grown on MgO(001) using molecular beam epitaxy are shown to be controllable by the Mn/N flux ratio as well as the substrate temperature.
Journal ArticleDOI
Nonprecious transition metal nitrides as efficient oxygen reduction electrocatalysts for alkaline fuel cells
TL;DR: In this article , a family of nonprecious transition metal nitrides (TMNs) as ORR electrocatalysts in alkaline medium was reported. And the most active catalyst, carbon-supported cobalt nitride (Co3N/C), exhibited a half-wave potential of 0.862 V and achieved a record-high peak power density among reported nitride cathode catalysts of 700 mW cm−2 in alkaline membrane electrode assemblies.
Patent
Synthesis of metal nanoparticle compositions from metallic and ethynyl compounds
Teddy M. Keller,Syed B. Qadri +1 more
TL;DR: A process of making metal nanoparticles comprising the steps of: providing a precursor composition comprising at least one metallic compound and at least 1 organic compound; wherein the organic compound is selected from the group consisting of an ethynyl compound, a metal-ethynyl complex, and combinations thereof; and heating the precursor composition under conditions effective to produce metal nanoparticle as discussed by the authors.
Journal ArticleDOI
Electronic structure and magnetic interactions in MnN and Mn 3 N 2
TL;DR: In this paper, the magnetic moments were found to be about $3.5 g/a$ in both the FM and non-magnetic MnN, and the mean field approximation predicted a slightly lower N 2eel temperature in the FM than in the nonmagnetic NMN in contrast with experiment.
References
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Journal ArticleDOI
A note on the magnetic intensities of powder neutron diffraction
TL;DR: In this paper, general intensity formulas of powder neutron diffraction lines are given for magnetic structures with a single spin-axis as a function of the spin direction with respect to the crystallographic axes.
Journal ArticleDOI
Crystal structure and magnetic properties of the compound MnN
TL;DR: The compound MnN was prepared as a single phase by DC reactive sputtering and its crystal structure was determined to be face-centered tetragonal one with the NaCl type by X-ray diffraction measurements.
Journal ArticleDOI
Structure determination of ζ-Fe2N by neutron and synchrotron powder diffraction
D. Rechenbach,Herbert Jacobs +1 more
TL;DR: In this paper, the crystal structure of ζ-Fe 2 N was studied by neutron and high resolution synchrotron powder diffraction at room temperature, and the results showed that the structure was orthorhombic.
Journal ArticleDOI
Hochdrucksynthese der η-phase im System Mn-N: Mn3N2
Herbert Jacobs,C. Stüve +1 more
TL;DR: In this article, the Umsetzung von Mangan mit ammoniak bei 6 kbar und Temperaturen von 400 bis 600°C fuhrt zu Mn3N2.