Structures of New Nitrides Prepared using Solid Oxide Precursors

1995 ◽  
Vol 410 ◽  
Author(s):  
Joel D. Houmes ◽  
David S. Bem ◽  
Hans-Conrad Zur Loye
Keyword(s):  
Solid State ◽  
Transition Metal ◽  
Transition Metal Dichalcogenides ◽  
Reaction Times ◽  
Solid Oxide ◽  
Metal Nitrides ◽  
Transition Metal Nitrides ◽  
X Ray Diffraction ◽  
X Ray ◽  
Metal Dichalcogenides

ABSTRACTSeveral novel transition metal nitrides and oxynitrides were synthesized via ammonolysis of solid state oxide precursors at temperatures ranging from 700°C-900°C and reaction times ranging from 12 hours to 4 days. The products were characterized by powder X-ray diffraction and their structures were determined by powder X-ray Rietveld refinement. The relationships between the structures of these nitrides and oxynitrides, and their similarity to the structures of the transition metal dichalcogenides, is discussed.

Triethanolamine Molybdate, a New Polymeric Precursor for Molybdenum Nitride

2007 ◽  
Vol 29-30 ◽  
pp. 195-198
Author(s):  
S. Mondal ◽  
A.K. Banthia
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Transition Metal ◽  
Niobium Nitride ◽  
Metal Nitrides ◽  
Molybdenum Nitride ◽  
Transition Metal Nitrides ◽  
Polymeric Precursor ◽  
X Ray Diffraction ◽  
X Ray

Nitrides remain a relatively unexplored class of materials primarily due to the difficulties associated with their synthesis and characterization. Several synthetic routes, including high temperature reactions, microwave assisted synthesis, and the use of plasmas, to prepare binary and ternary nitrides have been explored. Transition metal nitrides form a class of materials with unique physical properties, which give them varied applications, as high temperature ceramics, magnetic materials, superconductors or catalysts. They are commonly prepared by high temperature conventional processes, but alternative synthetic approaches have also been explored, more recently, which utilize moderate temperature condition. Transition metal nitrides particularly, molybdenum nitride, niobium nitride, and tungsten nitride have important applications as catalyst in hydrodenitridation reactions. These nitrides have been traditionally synthesized using high temperature nitridation treatments of the oxides. The nitridation temperatures are very high (> 800- 1000 oC). The aim of our work is to synthesize molybdenum nitride by a simple, low-temperature route. The method involves pyrolysis of a polymeric precursor, which was prepared from the condensation reaction between triethanolamine and molybdic acid. The melting point of the product is 180oC. The polymeric precursor and its pyrolyzed products are characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). X-ray diffraction shows that molybdenum nitride (MoN) obtained from this method has hexagonal crystal structure. MoN is obtained by this method at very low temperature (~ 400 oC).

Synthesis of New Nitrides Using Solid State Oxide Precursors

1993 ◽  
Vol 327 ◽  
Author(s):  
Joel D. Houmes ◽  
David S. Bem ◽  
Hans-Conrad Zur Loye
Keyword(s):  
Solid State ◽  
Magnetic Measurements ◽  
Reaction Times ◽  
Magnetic Ordering ◽  
Beta Phase ◽  
Alpha Phase ◽  
Transition Metal Nitrides ◽  
X Ray Diffraction ◽  
X Ray ◽  
Trigonal Prismatic Coordination

AbstractSeveral novel transition metal nitrides were synthesized via ammonolysis of solid state oxide precursors at temperatures ranging from 700°C-900°C and reaction times ranging from 12 hours to 4 days. Both intermetallic nitrides, Fe3Mo3N and Co3Mo3N, and ionic/covalent nitrides, FeWN2, MnWN2, Ta5N6 and Nb5N6, were prepared by this method. The products were characterized by powder X-ray diffraction and their structures were determined by powder X-ray Rietveld refinement. The intermetallic nitrides were found to be isostructural with the eta-carbide structure, Fe3W3C, while the ionic/covalent nitrides have layered structures, with metals in octahedral and trigonal prismatic coordination environments. Two polymorphs of the MnWN2 composition, α-MnWN2 and β-MnWN2, were isolated after ammonolysis at 700°C and 800°C, respectively. While the alpha phase can be converted into the beta phase by heating to 800°C under ammonia, annealing the beta phase at 700°C did not result in a structural transformation. Magnetic measurements show that FeWN2 orders antiferromagnetically at 45K. The magnetic ordering temperature was confirmed by M6ssbauer spectroscopy. All the other nitrides were paramagnetic down to 5K. Conductivity measurements show that FeWN2 and MnWN2 are metallic.

scholarly journals Stress-controlled decomposition routes in cubic AlCrN films assessed by in-situ high-temperature high-energy grazing incidence transmission X-ray diffraction

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
M. Meindlhumer ◽  
S. Klima ◽  
N. Jäger ◽  
A. Stark ◽  
H. Hruby ◽  
...  
Keyword(s):  
High Temperature ◽  
Transition Metal ◽  
Stress Level ◽  
Grazing Incidence ◽  
High Energy ◽  
Metal Nitrides ◽  
Transition Metal Nitrides ◽  
X Ray Diffraction ◽  
X Ray

AbstractThe dependence of decomposition routes on intrinsic microstructure and stress in nanocrystalline transition metal nitrides is not yet fully understood. In this contribution, three Al0.7Cr0.3N thin films with residual stress magnitudes of −3510, −4660 and −5930 MPa in the as-deposited state were in-situ characterized in the range of 25–1100 °C using in-situ synchrotron high-temperature high-energy grazing-incidence-transmission X-ray diffraction and temperature evolutions of phases, coefficients of thermal expansion, structural defects, texture as well as residual, thermal and intrinsic stresses were evaluated. The multi-parameter experimental data indicate a complex intrinsic stress and phase changes governed by a microstructure recovery and phase transformations taking place above the deposition temperature. Though the decomposition temperatures of metastable cubic Al0.7Cr0.3N phase in the range of 698–914 °C are inversely proportional to the magnitudes of deposition temperatures, the decomposition process itself starts at the same stress level of ~−4300 MPa in all three films. This phenomenon indicates that the particular compressive stress level functions as an energy threshold at which the diffusion driven formation of hexagonal Al(Cr)N phase is initiated, provided sufficient temperature is applied. In summary, the unique synchrotron experimental setup indicated that residual stresses play a decisive role in the decomposition routes of nanocrystalline transition metal nitrides.

Broadband 1T-titanium selenide-based saturable absorbers for solid-state bulk lasers

Nanoscale ◽  
2018 ◽  
Vol 10 (43) ◽  
pp. 20171-20177 ◽  
Author(s):  
Bingzheng Yan ◽  
Baitao Zhang ◽  
Hongkun Nie ◽  
Guoru Li ◽  
Xiaoli Sun ◽  
...  
Keyword(s):  
Phase Transition ◽  
Solid State ◽  
Transition Metal ◽  
Transition Metal Dichalcogenides ◽  
Saturable Absorbers ◽  
Metal Dichalcogenides

1T-titanium selenide (1T-TiSe2), a representative of 1T phase transition metal dichalcogenides (TMDs), exhibits semimetallic behaviour with a nearly zero bandgap structure, which makes it a promising photoelectric material.

scholarly journals Bis(dicarbollide) Complexes of Transition Metals as a Platform for Molecular Switches. Study of Complexation of 8,8′-Bis(methylsulfanyl) Derivatives of Cobalt and Iron Bis(dicarbollides)

Molecules ◽  
2020 ◽  
Vol 25 (23) ◽  
pp. 5745
Author(s):  
Sergey A. Anufriev ◽  
Sergey V. Timofeev ◽  
Alexei A. Anisimov ◽  
Kyrill Yu. Suponitsky ◽  
Igor B. Sivaev
Keyword(s):  
Solid State ◽  
Transition Metal ◽  
Molecular Switches ◽  
X Ray Diffraction ◽  
Chelate Complexes ◽  
X Ray ◽  
Complexes Of Transition Metals ◽  
Silver Palladium ◽  
Solid State Structures ◽  
Derivatives Of

Complexation of the 8,8′-bis(methylsulfanyl) derivatives of cobalt and iron bis(dicarbollides) [8,8′-(MeS)2-3,3′-M(1,2-C2B9H10)2]− (M = Co, Fe) with copper, silver, palladium and rhodium leads to the formation of the corresponding chelate complexes, which is accompanied by a transition from the transoid to the cisoid conformation of the bis(dicarbollide) complex. This transition is reversible and can be used in design of coordination-driven molecular switches based on transition metal bis(dicarbollide) complexes. The solid-state structures of {(Ph3P)ClPd[8,8′- (MeS)2-3,3′-Co(1,2-C2B9H10)2-κ2-S,S′]} and {(COD)Rh[8,8′-(MeS)2-3,3′-Co(1,2-C2B9H10)2-κ2-S,S′]} were determined by single crystal X-ray diffraction.

Lattice modulation in the hexagonal-type antiphase domain structure of Au–33at.%Cd alloy

1982 ◽  
Vol 15 (2) ◽  
pp. 174-181 ◽  
Author(s):  
Y. Watanbe ◽  
H. Iwasaki
Keyword(s):  
Crystal Structure ◽  
Transition Metal Dichalcogenides ◽  
Antiphase Domain ◽  
Charge Density Waves ◽  
Physical Significance ◽  
Intensity Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Metal Dichalcogenides ◽  
Antiphase Domains

The crystal structure of an ordered Au–33at.%Cd alloy has been reinvestigated by X-ray diffraction. Least-squares refinement using single-crystal intensity data collected by photographic methods has shown that mixed occupation by the two kinds of atoms preferentially occurs in the atomic sites located near the boundaries of the hexagonal antiphase domains, confirming the results obtained by electron diffraction [Hirabayashi, Yamaguchi, Hiraga, Ino, Sato & Toth (1970). d. Phys. Chem. Solids, 31, 77–94]. The refinement has also shown that many of the atoms are periodically displaced from the normal positions of the fundamental h.c.p. lattice. The physical significance of the occupancy and displacement modulations is discussed. The latter bears a resemblance to the motion of cations in the transition-metal dichalcogenides and the direction of the displacements in the alloy can be explained if charge-density waves synchronizing with the occupancy waves are assumed to exist.

scholarly journals High-Pressure Annealing of a Prestructured Nanocrystalline Precursor to Obtain Tetragonal and Orthorhombic Polymorphs of Hf3N4

2014 ◽  
Vol 1655 ◽  
Author(s):  
Ashkan Salamat ◽  
Pierre Bouvier ◽  
Benjamin M. Gray ◽  
Andrew L. Hector ◽  
Simon A. J. Kimber ◽  
...  
Keyword(s):  
High Pressure ◽  
Transition Metal ◽  
Fluorite Structure ◽  
Metal Nitrides ◽  
Transition Metal Nitrides ◽  
X Ray Diffraction ◽  
Semiconducting Materials ◽  
Composition And Structure ◽  
Metal Organic ◽  
Diamond Anvil

ABSTRACTTransition metal nitrides containing metal ions in high oxidation states are a significant goal for the discovery of new families of semiconducting materials. Most metal nitride compounds prepared at high temperature and high pressure from the elements have metallic bonding. However amorphous or nanocrystalline compounds can be prepared via metal-organic chemistry routes giving rise to precursors with a high nitrogen:metal ratio. Using X-ray diffraction in parallel with high pressure laser heating in the diamond anvil cell this work highlights the possibility of retaining the composition and structure of a metastable nanocrystalline precursor under high pressure-temperature conditions. Specifically, a nanocrystalline Hf3N4 with a tetragonal defect-fluorite structure can be crystallized under high-P,T conditions. Increasing the pressure and temperature of crystallization leads to the formation of a fully recoverable orthorhombic (defect cottunite-structured) polymorph. This approach identifies a novel class of pathways to the synthesis of new crystalline nitrogen-rich transition metal nitrides.

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