Etude aux rayons X de la solution solide cobalt-carbone

Cadeville, M.C.; Lapierre, M.F.

doi:10.1016/0036-9748(72)90211-6

“…Some findings have been examined in[1] using the GGA Approximation, where stable phases are labeled as "S" and unstable ones as "U".Tables 1-3 display the values of the DFT-calculated equilibrium lattice constant (a), three separate elastic constants (𝐶 11 , 𝐶 12 , 𝐶 44 ), and cohesive energy per formula unit (𝐸 𝑐𝑜ℎ ) for three distinct structures . From the table 1, we can observe that the calculated results of the equilibrium lattice constant (a) of 3d transitional metal carbides in rs-structure are in reasonable agreement with experimental and theoretical values[51,52,53,54,55,57,19,56,17,58] except CoC. The reason that the CoC deviated from the experimental value may be due to the presence of the low amount of interstitial carbons to stabilize the cobalt metal in the experiment[59], whereas in the computational method, CoC is used with a stoichiometry of 1:1.…”

supporting

confidence: 73%

Ab initio study of structural, mechanical and electronic properties of 3d transitional metal carbide in cubic rocksalt (rs), zincblende (zb), and cesium chloride (cc) structures by using LDA and GGA Approximation

Sabbar,

Al-Zubaidi,

Kurdi

et al. 2023

J Mol Model

2

0

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“…Some findings have been examined in[1] using the GGA Approximation, where stable phases are labeled as "S" and unstable ones as "U".Tables 1-3 display the values of the DFT-calculated equilibrium lattice constant (a), three separate elastic constants (𝐶 11 , 𝐶 12 , 𝐶 44 ), and cohesive energy per formula unit (𝐸 𝑐𝑜ℎ ) for three distinct structures . From the table 1, we can observe that the calculated results of the equilibrium lattice constant (a) of 3d transitional metal carbides in rs-structure are in reasonable agreement with experimental and theoretical values[51,52,53,54,55,57,19,56,17,58] except CoC. The reason that the CoC deviated from the experimental value may be due to the presence of the low amount of interstitial carbons to stabilize the cobalt metal in the experiment[59], whereas in the computational method, CoC is used with a stoichiometry of 1:1.…”

supporting

confidence: 73%

Ab initio study of structural, mechanical and electronic properties of 3d transitional metal carbide in cubic rocksalt (rs) , zincblende (zb) , and cesium chloride (cc)

Sabbar,

Al-Zubaidi,

Kurdi

et al. 2023

Preprint

0

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We have studied three structures of 3d transition metal carbides (TMCs) using LDA and GGA approximations. Interestingly, we found that the 3d TMCs (except ScC in rs, zb structures) have higher cohesive energy (Ecoh) than their nitrides indicating carbides are thermodynamically more stable. The computed values of Vickers hardness (Hv) of rs-TiC is about 25.66 GPa and are compatible with the experimental value, rs-TiC and rs-VC are the hardest carbides and even more complicated than their nitrides; this study can reduce the high cost and the time used in experimental discoveries which do not have promising properties. In addition, theoretical calculations can assist the discovery of new super-hard TMCs and grab experimental attention to possible material choices for obtaining desired physical properties; surprisingly, only two carbides in GGA approximation (CrC and MnC) and in addition to this CrC in LDA approximation in cesium chloride (cc) structure are mechanically stable.In contrast, all the 3d TMCs in rocksalt (rs) and seven in zincblende (zb) structures are mechanically stable. The general trend of charge transfer from 3d transitional metal to carbon indicates decreased ionicity and increased covalency along the series. The hybridization of p orbitals of carbon with d orbitals of metal plays a crucial role in determining the mechanical stability and hardness of 3d TMCs. The computation of the total density of states indicates that all the 3d TMCs except zb-TiC and zb-FeC in all phases are metallic. We observed that the elastic constant C44 is anti-correlated with the number of electronic states around EF.

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“…Reference XRD patterns can be downloaded from AtomWork () provided by the National Institute of Materials Science. 24 Patterns were simulated with the data published in refs (25) (hcp-Co, CoO (space group Fm 3̅ m )), (26) (in French, fcc-Co), (27) (Co 3 O 4 ( Fd 3̅ m )), (28) (L2 1 -Co 2 TiSn), and (29) (Co 3 Sn 2 ( Pnma )).…”

Section: Results and Discussionmentioning

confidence: 99%

Heusler Alloys: A Group of Novel Catalysts

Kojima

¹

,

Kameoka

²

,

Tsai

³

2017

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In this study, we investigated the catalytic properties of various Heusler alloys for the hydrogenation of propyne and the oxidation of carbon monoxide. For propyne hydrogenation, Co 2 FeGe alloy showed a higher activity than that of elemental Co, where neither Fe nor Ge showed any activity. This clearly indicates an alloying effect. For the oxidation of carbon monoxide, although most alloys showed a significant change in catalytic activity during measurement due to an irreversible oxidation of the alloy, Co 2 TiSn alloy showed a very small change. The results indicate that the catalytic activity and stability of a Heusler alloy can be tuned by employing an appropriate set of elements.

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Etude aux rayons X de la solution solide cobalt-carbone

Cited by 25 publications

References 3 publications

Ab initio study of structural, mechanical and electronic properties of 3d transitional metal carbide in cubic rocksalt (rs), zincblende (zb), and cesium chloride (cc) structures by using LDA and GGA Approximation

Ab initio study of structural, mechanical and electronic properties of 3d transitional metal carbide in cubic rocksalt (rs), zincblende (zb), and cesium chloride (cc) structures by using LDA and GGA Approximation

Ab initio study of structural, mechanical and electronic properties of 3d transitional metal carbide in cubic rocksalt (rs) , zincblende (zb) , and cesium chloride (cc)

Heusler Alloys: A Group of Novel Catalysts

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