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Electronic structure, stability, and strength of Cu-NiAl alloys : experiment and DFT investigation

Zarhri Zakaryaa

Opto-Electronics Review

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2022

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Vol. 30, No. 2

art. no. e141707

EN

In this study, the copper doping effect on the NiAl structural stability, strength, and electronic structure was investigated. The samples were prepared using induction melting at 2073 K. This material presents good mechanical and physical properties such as high-temperature strength, fatigue or impact, and corrosion resistance which meet technical requirements of many applications. The microstructure of the Cu-doped nickel aluminide was studied using a metallurgical microscope and its lattice parameter was also studied and characterized using an X-ray diffractometer for different concentrations of Cu. The lattice constant of the existing phases was calculated, and it was found that the lattice distortion and gamma prime phase energy have high values allowing the increase of the entropy term of the alloy and subsequently increasing its hardness. From the ab-initio calculation, it was determined that the Cu atoms have the Al sites as a preferred site and prefer to bond with Ni atoms which leads to the improvement of the material hardness. Ab-initio density functional theory was applied to study the formation energy that revealed increasing with Cu amount.

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1H NMR, 13C NMR and Computational Study of the Structure of Salicylaldehyde Anion in Solution

Horbaczewski M., Szczeciński P., Gryff-Keller A., Molchanov S.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 12

2089-2096

EN

1H NMR and 13C NMR spectra of salicylaldehyde potassium salt in DMF-d7 solution with addition of kryptofix 222 were mea sured. Quantitative comparison of car bon chemical shifts with shielding constants calculated for syn and anti con form ers of salicyl aldehyde an ion [GIAO DFT B3LYP/6-311G(2d,p) PCM] re vealed that in the applied conditions the anti form prevailed. Similar correla tion performed for salicylaldehyde lith ium salt indicated that in this case the syn conformer dominated. Analysis of experimental and calculated J(1H,13C) and J(1H,1H) values supported above conclusions.

3

1H NMR, 13C NMR and Computational DFT Study of the Structure of 2-Acylcycloalkane-1,3-diones in Solution

Szczeciński P., Gryff-Keller A., Molchanov S.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 8

1449-1455

EN

1H and13C NMR spectra of 2-acylcyclopentane-1,3-dione [acyl = formyl (1); acetyl (2)] and 2,6-dioxocyclohexanecarboxylic acid (3) have beenmeasured. The optimummolecular structures of endo- and exo-enolic forms of investigated objects in solution have been found using DFT method with B3LYP functional and 6-311G(2d,p) basis set. The theoretical values of the NMR parameters have been then calculated using GIAO-DFT method with the same functional and basis set. The theoretical data obtained for compounds 1–3 have been used to interpret their experimental NMR spectra in terms of the equilibrium between different tautomers. It has been found that for investigated triketones an endo-tautomer overwhelmingly prevails.