Investigation of tetragonal ReN2 and WN2 with high shear moduli from first-principles calculations

Du, Xiang Po; Wang, Yuanxu; Lo, Veng Cheong

doi:10.1016/j.physleta.2010.04.020

Cited by 42 publications

(24 citation statements)

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“…They also computed a bulk modulus for this structure to 331 GPa and estimated a hardness of 17 GPa. Du et al studied a structure derived from the CsCltype (Pm-3m), with pernitride dumbbells occupying the anion positions [138]. They found remarkably high bulk and shear moduli for this structure, and estimated its hardness to be 46 GPa.…”

Section: Figurementioning

confidence: 99%

Nitrogen-rich transition metal nitrides

Salamat

Hector

Kroll

et al. 2013

Coordination Chemistry Reviews

124

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The solid state chemistry leading to the synthesis and characterization of metal nitrides with N:M ratios > 1 is summarized. Studies of these compounds represent an emerging area of research. Most transition metal nitrides have much lower nitrogen contents, and they often form with nonor sub-stoichiometric compositions. These materials are typically metallic with often superconducting properties, and they provide highly refractory, high hardness materials with many technological applications. The higher metal nitrides should achieve formal oxidation states (OS) attaining those found among corresponding oxides, and they are expected to have useful semiconducting properties. Only a very few examples of such high OS nitrogen-rich compounds are known at present. The main group elements typically form covalently bonded nitride ceramics such as Si 3 N 4 , Ge 3 N 4 and Sn 3 N 4 , and the early transition metals Zr and Hf produce Zr 3 N 4 and Hf 3 N 4 . However, the only main example of a highly nitrided transition metal compound known to date is Ta 3 N 5 , that has a formal oxidation state +5 and is a semiconductor with visible light absorption leading to applications as a pigment and in photocatalysis. New synthesis routes are being explored to study the possible formation of other N-rich materials that are predicted to exist by ab initio calculations. There is a useful interplay between theoretical predictions and experimental synthesis studies at ambient and high pressure conditions, as we explore and establish the existence and structure-property relations of these new nitride compounds and polymorphs. Here we review the state of current investigations and indicate possible new directions for further work.[a] European Synchrotron Radiation Facility,

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Section: Figurementioning

confidence: 99%

Nitrogen-rich transition metal nitrides

Salamat

Hector

Kroll

et al. 2013

Coordination Chemistry Reviews

124

View full text Add to dashboard Cite

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“…The peculiar feature of these nitrides is that nitrogen atoms are dimerized as pseudomolecules, which are considered to enhance their hardness. Though ReN 2 has been theoretically investigated by several groups, [11][12][13] experimental investigation on stoichiometric rhenium nitrides is still unavailable until very recently after Friedrich et al synthesized bulk hexagonal Re 2 N and Re 3 N. [14] Under 20 GPa/2000 K and 10.5-16 GPa/2200 K thermomechanical treatment, Re 2 N and Re 3 N, respectively, can be synthesized in the laser-heated diamond anvil cell. These novel rhenium nitrides are claimed to have very high bulk moduli of 400 GPa, categorized as ultraincompressible materials.…”

Section: Introductionmentioning

confidence: 99%

The effect of structure and phase transformation on the mechanical properties of Re₂N and the stability of Mn₂N

Wang

2011

J Comput Chem

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First-principles calculations were carried out on recently synthesized Re₂N and Re₃N as well as hypothetical Tc and Mn nitrides. It is found that structure and covalent bonds play an important role in determining mechanical properties. Under a large strain along (0001)<1010> direction, Re₂N undergoes a phase transformation with a slight increase in ideal shear strength. On the other hand, it is transformed into a phase with weaker mechanical properties, if the strain is along Re₂ <1210> direction. Mn₂N can be synthesized under moderate conditions due to its more negative formation energy. Re₂N, Re₃N, and Mn₂ N show structure-related mechanical property under larger strains to ReB₂ but exhibit much lower ideal strengths, which is attributed to the larger ionicity of cation-anion bond. Three-dimensional framework of strong covalent bonds is thus highly recommended to design superhard materials.

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“…proposed that Re mononitride forms in wurtzite-type, NbO-type, and NiAs-type structures, respectively. Besides, orthorhombic (SG Pbcn ) and tetragonal (SG P 4 /mmm ) Re dinitrides (denoted as orth-ReN 2 and tetr-ReN 2 ) with high bulk and shear modulus has been predicted theoretically232425. Recently, Kawamura et al 26.…”

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confidence: 99%

Nitrogen concentration driving the hardness of rhenium nitrides

Zhao

Bao

et al. 2014

Sci Rep

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The structures and properties of rhenium nitrides are studied with density function based first principle method. New candidate ground states or high-pressure phases at Re:N ratios of 3:2, 1:3, and 1:4 are identified via a series of evolutionary structure searches. We find that the 3D polyhedral stacking with strong covalent N-N and Re-N bonding could stabilize Re nitrides to form nitrogen rich phases, meanwhile, remarkably improve the mechanical performance than that of sub-nitrides, as Re3N, Re2N, and Re3N2. By evaluating the trends of the crystal configuration, electronic structure, elastic properties, and hardness as a function of the N concentration, we proves that the N content is the key factor affecting the metallicity and hardness of Re nitrides.

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Investigation of tetragonal ReN2 and WN2 with high shear moduli from first-principles calculations

Cited by 42 publications

References 44 publications

Nitrogen-rich transition metal nitrides

Nitrogen-rich transition metal nitrides

The effect of structure and phase transformation on the mechanical properties of Re₂N and the stability of Mn₂N

Nitrogen concentration driving the hardness of rhenium nitrides

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Investigation of tetragonal ReN2 and WN2 with high shear moduli from first-principles calculations

Cited by 42 publications

References 44 publications

Nitrogen-rich transition metal nitrides

Nitrogen-rich transition metal nitrides

The effect of structure and phase transformation on the mechanical properties of Re2N and the stability of Mn2N

Nitrogen concentration driving the hardness of rhenium nitrides

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The effect of structure and phase transformation on the mechanical properties of Re₂N and the stability of Mn₂N