Novel superconducting niobium beryllide Nb3Be with A15 structure

Tuleushev, A. Zh.; Володин, В. Н.; Tuleushev, Yu. Zh.

doi:10.1134/1.1633313

Cited by 20 publications

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“…A-15 structured superconductor Nb 3 Be possesses cubic crystal structure with PM-3N (223) space group [15] whereas Nb 3 Be 2 phase possesses tetragonal crystal structure with space group P4/MBM (127) [16]. Nb 3 Be has eight atoms per unit cell with two formula units whereas Nb 3 Be 2 phase has ten atoms per unit cell with two formula units.…”

Section: A Structural Propertiesmentioning

confidence: 99%

Insight into the physical properties of two niobium based compounds, Nb3Be and Nb3Be2, via a first principles calculation

Rahaman

Ali

2018

Chinese Journal of Physics

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We investigate the structural, electronic, mechanical and elastic properties of two niobium based intermetallic compounds Nb 3 Be and Nb 3 Be 2 by using the DFT based theoretical method. A good agreement is found among the structural parameters of both the phases with experimentally evaluated parameters. For both the phases metallic conductivity is observed while Nb 3 Be phase is more conducting than that of Nb 3 Be 2 phase. Evaluated DOS at Fermi level indicates that Nb 3 Be 2 phase is electrically more stable than Nb 3 Be phase. For both phases Nb-4d states is mostly responsible for metallic conductivity. The study of total charge density and Mulliken atomic population reveal the existence of covalent, metallic and ionic bonds in both intermetallics. Both the phases are mechanically stable in nature while Nb 3 Be phase is more ductile than Nb 3 Be 2 phase. The study of Vickers hardness exhibits that Nb 3 Be 2 phase is harder than that of Nb 3 Be. Both compounds are anisotropic in nature while Nb 3 Be phase possesses large anisotropic characteristics than that of Nb 3 Be 2 phase. The Debye temperature of both the compounds are also calculated and discussed.

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Section: A Structural Propertiesmentioning

confidence: 99%

Insight into the physical properties of two niobium based compounds, Nb3Be and Nb3Be2, via a first principles calculation

Rahaman

Ali

2018

Chinese Journal of Physics

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“…We have carried out our investigation by using the density functional theory based CASTEP computer program together with the generalized gradient approximation (GGA) with the PBESOL exchangecorrelation function [5][6][7][8][9]. The pseudo atomic calculation is performed for Nb-4s 2 4p 6 4d 4 5s 1 and Be-2s 2 . The k-point sampling of the Brillouin zone was constructed using Monkhorst-Pack scheme [10] with 4×4×4 grids in primitive cells of NbBe 2 .…”

Section: Computational Detailsmentioning

confidence: 99%

“…In 1974 O. Rapp investigated the superconductivity in different Laves phase compounds and reported the superconducting temperature of ZrW 2 , HfW 2 and ZrMo 2 Lave phases are 0.12 K [1]. New niobium beryllide Nb 3 Be with the A15 type structure has been synthesized by Tuleushev et al using thermal treatment of the amorphous film system [2]. He reported the superconductivity in Nb 3 Be is 10 K which is quite large.…”

Section: Introductionmentioning

confidence: 99%

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Novel Laves phase superconductor NbBe 2 : A theoretical investigation

Rahaman

Rahman

2016

Computational Condensed Matter

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A new Laves phase superconductor NbBe 2 , prototype with MgCu 2 , having maximum T c ~2.6 K has been reported very recently. Based on first-principle calculations, we systematically study the structural, elastic, mechanical, electronic, thermal and superconducting properties of the newly reported superconducting intermetallic compound NbBe 2 . The study of Cauchy pressure and Pugh's ratio reveal the brittle manner of NbBe 2 . This compound exhibits metallic conductivity and the Nb-Be bonds have a covalent feature in which the contribution of Nb-4d state is dominant near Fermi level. The Debye temperature of NbBe 2 is 664.54 K calculated using our elastic constants data. We obtain the heat capacity (C v ) of NbBe 2 at ambient condition is 20.75 cal/cell K using quasi-harmonic model. Finally, we investigate the electronphonon coupling constant, phonon dispersion curve and density of states which indicates that the compound under study is a weakly coupled BCS superconductor.

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“…Existem outros usos de BeT e como semicondutores, isolantes elétricos e em células solares [42,43], bem como outras variedades de compostos utilizados em LEDs como [44] e uma liga de N b 3 Be que apresenta supercondutividade [45].…”

Section: Compostos De Berílio: Pesquisas E Aplicaçõesunclassified

Investigação de sistemas moleculares contendo berílio: caracterização espectroscópica e termoquímica

Lima¹

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This work has mainly focused on the spectroscopic characterization of the beryllium halides, BeCl, BeBr and BeI. Knowledge about these species was substantially increased through the calculation of parameters that are difficult to access in an experimental characterization. As the few experimental works carried out for these halides presented inconclusive results for the C 2 Σ + − X 2 Σ + transition, we carried out accurate calculations of transition probabilities, thus offering a new interpretation about the existing data, including also results for other electronic transitions as yet unknown. Calculations using the method Multireference Configuration Interaction (MRCI) along with correlation-consistent basis set functions of quintuple-zeta quality were used to obtain the potential energy curves associated with the first and second dissociation channels for the doublet and quartet states of these species. Spectroscopic parameters such as vibrational constants w e , w e x e , the rotational constant B e and the equilibrium distance were determined for the low-lying states. Furthermore, we also calculated the excitation energy (T e) and the dissociation energy (D e) with and without the inclusion of spin-orbit effects. The obtained results significantly expanded our knowledge about the electronic states of this species. For states already investigated experimentally, there was good consistency between the calculated and the experimental parameters. The energy differences between the two channels in the dissociation limit for BeCl, BeBr and BeI molecules obtained in this work were: 21835, 21889 and 21998 cm −1 , in agreement with the corresponding experimental results of the three species (21 980 cm −1). The theoretical determination of the dissociation energy D 0 was very satisfactory. We obtained 92.24, 72.77, and 51.75 kcal • mol −1 , respectively, for the BeCl, BeBr and BeI molecules including spin-orbit effects, compared to 91.78, 71 and 57 kcal • mol −1. For a more complete analysis of the potential energy curves, they also were obtained considering relativistic effects. The calculated spin-orbit coupling constants in the equilibrium region of BeCl, BeBr and BeI molecules were respectively 41, 207 and 324 cm −1 , in good agreement with the experimental results: 52.8, 198, and 361.1 cm −1 , respectively. The calculated spin-orbit splitting in the dissociation limit was 823, 3446 and 6975 cm −1 (BeCl, BeBr and BeI) also consistent with the experimental results: 882, 3685.24 and 7603.15 cm −1 , respectively. Additionally, a detailed analysis of the dissociation channels of HBeP and BePH molecules was performed. The construction of a relative energies diagram allowed us to derive a set of important data for all the possible dissociation channels. In particular, it is shown the relative stability and the energy in the dissociation limit. For the energy in the dissociation limit, we obtained results consistent with the experimental values. Our calculations for the first three dissociation channels HBeP = H + Be res...

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Novel superconducting niobium beryllide Nb3Be with A15 structure

Cited by 20 publications

References 0 publications

Insight into the physical properties of two niobium based compounds, Nb3Be and Nb3Be2, via a first principles calculation

Insight into the physical properties of two niobium based compounds, Nb3Be and Nb3Be2, via a first principles calculation

Novel Laves phase superconductor NbBe 2 : A theoretical investigation

Investigação de sistemas moleculares contendo berílio: caracterização espectroscópica e termoquímica

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