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1.
Phys Chem Chem Phys ; 2024 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-38835236

RESUMO

The unique attributes of hydrophilicity, expansive surface groups, remarkable flexibility, and superior conductivity converge in MXene, a pioneering 2D material. Owing to MXene's exceptional properties, diverse strategies have been explored to enhance its characteristics. Janus MXene and stress-strain response considerations represent the primary avenues of interest today. In this study, we investigated the Janus MXene structure under biaxial stress using first-principles calculations. The most stable configuration of Janus MoWC MXene identified in our analysis exhibits an atomic arrangement known as the hexagonal (2H) phase. Subsequently, we examined the mechanical and electronic properties of 2H-MoWC when subjected to biaxial strain. Our findings indicate that the 2H phase of Janus MoWC MXene demonstrates superior strength compared to the tetragonal (1T) phase. Analysis of the ELF of the 2H-MoWC structure unveiled that the robust C-C bond within the material is the underlying factor enabling the 2H phase to withstand a maximum of 9% tensile strain. Furthermore, we demonstrate that 2H-MoWC is a superconductor with the superconducting temperature (Tc) of 1.6 K, and the superconductivity of 2H phase can be enhanced by biaxial strain with the Tc reaching 7 K. This study offers comprehensive insights into the properties of Janus MoWC monolayer under biaxial stress, positioning it as a promising candidate for 2D straintronic applications.

2.
Inorg Chem ; 63(18): 8142-8154, 2024 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-38640445

RESUMO

The covalent bonding framework of crystalline single-bonded cubic AsN, recently synthesized under high pressure and high temperature conditions in a laser-heated diamond anvil cell, is here studied by means of density functional theory calculations and compared to single crystal X-ray diffraction data. The precise localization of the nonbonding electron lone pairs and the determination of their distances and orientations are related to the presence of characteristic structural motifs and space regions of the unit cell dominated by repulsive electronic interactions, with the relative orientation of the electron lone pairs playing a key role in minimizing the energy of the structure. We find that the vibrational modes associated with the expression of the lone pairs are strongly localized, an observation that may have implications for the thermal conductivity of the compound. The results indicate the thermodynamic stability of the experimentally observed structure of AsN above ∼17 GPa, provide a detailed insight into the nature of the chemical bonding network underlying the formation of this compound, and open new perspectives to the design and high pressure synthesis of new pnictogen-based advanced materials for potential applications of energetic and technological relevance.

3.
Sci Rep ; 14(1): 4545, 2024 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-38402274

RESUMO

High-quality VO[Formula: see text] films were fabricated on top of c-Al[Formula: see text]O[Formula: see text] substrates using Reactive Bias Target Ion Beam Deposition (RBTIBD) and the studies of graphene/VO[Formula: see text] heterostructure were conducted. Graphene layers were placed on top of [Formula: see text] 50 and [Formula: see text] 100 nm VO[Formula: see text]. The graphene layers were introduced using mechanical exfoliate and CVD graphene wet-transfer method to prevent the worsening crystallinity of VO[Formula: see text], to avoid the strain effect from lattice mismatch and to study how VO[Formula: see text] can affect the graphene layer. Slight increases in graphene/VO[Formula: see text] T[Formula: see text] compared to pure VO[Formula: see text] by [Formula: see text] 1.9 [Formula: see text]C and [Formula: see text] 3.8 [Formula: see text]C for CVD graphene on 100 and 50 nm VO[Formula: see text], respectively, were observed in temperature-dependent resistivity measurements. As the strain effect from lattice mismatch was minimized in our samples, the increase in T[Formula: see text] may originate from a large difference in the thermal conductivity between graphene and VO[Formula: see text]. Temperature-dependent Raman spectroscopy measurements were also performed on all samples, and the G-peak splitting into two peaks, G[Formula: see text] and G[Formula: see text], were observed on graphene/VO[Formula: see text] (100 nm) samples. The G-peak splitting is a reversible process and may originates from in-plane asymmetric tensile strain applied under the graphene layer due to the VO[Formula: see text] phase transition mechanism. The 2D-peak measurements also show large blue-shifts around 13 cm[Formula: see text] at room temperature and slightly red-shifts trend as temperature increases for 100 nm VO[Formula: see text] samples. Other electronic interactions between graphene and VO[Formula: see text] are expected as evidenced by 2D-peak characteristic observed in Raman measurements. These findings may provide a better understanding of graphene/VO[Formula: see text] and introduce some new applications that utilize the controllable structural properties of graphene via the VO[Formula: see text] phase transition.

4.
Sci Rep ; 14(1): 731, 2024 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-38184703

RESUMO

A double-layered hydrophobic-coated stainless steel mesh (CSSM) was successfully prepared by vapor deposition of polydimethylsiloxane (PDMS) to form aerosol silica (SiO2) particles on SSM followed by coating with the in situ modified SiO2 generated in the natural rubber (NR) latex for use in oil/seawater separation. The in situ SiO2 particles were modified with octyltriethoxysilane (OTES) or hexadecyltrimethoxysilane (HDTMS). Transmission electron microscopy, 29Si solid-state nuclear magnetic resonance, and Fourier transform infrared spectroscopy were used to determine the structure of the in situ modified SiO2 generated in the NR latex. Scanning electron microscopy and water contact angle analyses were applied to characterize the morphology and hydrophobicity of the CSSM, respectively. The presence of aerosol SiO2 particles from PDMS and in situ modified SiO2 by OTES (MSi-O) or HDTMS (MSi-H) generated in the NR could enhance the surface roughness and hydrophobicity of the CSSM. The hydrophobic CSSM was then applied for the separation of chloroform/seawater and crude oil/seawater mixtures. A high separation efficiency (up to 99.3%) with the PDMS/NR/MSi-H CSSM was obtained and the mesh was reusable for up to 20 cycles.

5.
Sci Rep ; 14(1): 1275, 2024 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-38218957

RESUMO

The crystal diffusion variational autoencoder (CDVAE) is a machine learning model that leverages score matching to generate realistic crystal structures that preserve crystal symmetry. In this study, we leverage novel diffusion probabilistic (DP) models to denoise atomic coordinates rather than adopting the standard score matching approach in CDVAE. Our proposed DP-CDVAE model can reconstruct and generate crystal structures whose qualities are statistically comparable to those of the original CDVAE. Furthermore, notably, when comparing the carbon structures generated by the DP-CDVAE model with relaxed structures obtained from density functional theory calculations, we find that the DP-CDVAE generated structures are remarkably closer to their respective ground states. The energy differences between these structures and the true ground states are, on average, 68.1 meV/atom lower than those generated by the original CDVAE. This significant improvement in the energy accuracy highlights the effectiveness of the DP-CDVAE model in generating crystal structures that better represent their ground-state configurations.

6.
Sci Rep ; 13(1): 20295, 2023 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-37985841

RESUMO

Investigating superconductivity represents one of the most significant phenomena in the field of condensed matter physics. Our simulations aim to elucidate the structures in the metallic state of Mg1-xMoxB2, which is essential for predicting their superconducting properties. By employing a first-principle cluster expansion and particle-swarm optimization, we have predicted the structures of Mg1-xMoxB2 ternary alloys, including Mg0.667Mo0.333B2, Mg0.5Mo0.5B2, and Mg0.333Mo0.667B2, and have determined their thermodynamically stable configurations under both atmospheric and high-pressure conditions. To investigate the potential for superconductivity in these structures, we have conducted a detailed examination of electronic properties that are pertinent to determining the superconducting state. Regarding superconducting properties, Mg0.333Mo0.667B2 exhibits superconductivity with a critical temperature (Tc) of 7.4 K at ambient pressure. These findings suggest that the theoretically predicted structures in Mg/Mo-substituted metal borides could play a significant role in synthesis and offer valuable insights into superconducting materials.

7.
Sci Rep ; 13(1): 16854, 2023 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-37803050

RESUMO

The structural stability and internal properties of hybrid organic-inorganic perovskites (HOIPs) have been widely investigated over the past few years. The interplay between organic cations and inorganic framework is one of the prominent features. Herein we report the evolution of Raman modes under pressure in the hybrid organic-inorganic perovskite MAPbI[Formula: see text] by combining the experimental approach with the first-principles calculations. A bulk MAPbI[Formula: see text] single crystal was synthesized via inverse temperature crystallization (ITC) technique and characterized by Raman spectroscopy, while the diamond anvil cells (DACs) was employed to compress the sample. The classification and behaviours of their Raman modes are presented. At ambient pressure, the vibrations of inorganic PbI[Formula: see text] octahedra and organic MA dominate at a low-frequency range (60-760 cm[Formula: see text]) and a fingerprint range (900-1500 cm[Formula: see text]), respectively. The applied pressure exhibits two significant changes in the Raman spectrum and indicates of phase transition. The results obtained from both experiment and calculations of the second phase at 3.26 GPa reveal that the internal vibration intensity of the PbI[Formula: see text] octahedra (< 110 cm[Formula: see text]) reduces as absences of MA libration (150-270 cm[Formula: see text]) and internal vibration of MA (450-750 cm[Formula: see text]). Furthermore, the hydrogen interactions around 1300 cm[Formula: see text] remain strong high pressure up to 5.34 GPa.

8.
Chemosphere ; 341: 139982, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37648169

RESUMO

Carbon nanotubes (CNTs) composed of bimetallic nickel-palladium (NiPd) nanoparticles encapsulated in graphitic carbon shells (NdPd@CNT) are prepared by the chemical vapour deposition method using waste polyethylene terephthalate (PET) plastic carbon sources and NiPd-decorated carbon sheets (NiPd@C) catalyst. The characterization results reveal that the face-centered cubic crystalline (fcc)-structured NiPd bimetallic alloy nanoparticles are encased by thin carbon nanotubes. The bimetallic synergism of NiPd nanoparticles actuates the outer CNT layers and accelerates the electrical conductivity, stimulating the electrochemical activity toward an effective hydrogen evolution reaction (HER). By virtue of the collective individualities of highly conductive aligned carbon walls and bimetallic active sites, the NiPd@CNT-equipped HER delivers a minimum overpotential of 87 mV and a Tafel slope value of 95 mV dec-1. The existing intact contact between NiPd and CNT facilitates continuous electron and ion transportation and firm stability toward long-term hydrogen production in HER. Notably, the NiPd@CNT reported here produces excellent electrochemical activity with minimal charge transference resistance, substantiating the efficacy of NiPd@CNT for futuristic green hydrogen production.


Assuntos
Hidrogênio , Nanotubos de Carbono , Níquel , Paládio , Gases
9.
Sci Rep ; 13(1): 10504, 2023 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-37380870

RESUMO

Mixtures of different metal diborides in the form of solid solutions are promising materials for hard-coating applications. Herein, we study the mixing thermodynamics and the mechanical properties of AlB[Formula: see text]-structured Sc[Formula: see text]Ta[Formula: see text]B[Formula: see text] solid solutions using the first-principles method, based on the density functional theory, and the cluster-expansion formalism. Our thermodynamic investigation reveals that the two diborides readily mix with one another to form a continuous series of stable solid solutions in the pseudo-binary TaB[Formula: see text] [Formula: see text]ScB[Formula: see text] system even at absolute zero. Interestingly, the elastic moduli as well as the hardness of the solid solutions show significant positive deviations from the linear Vegard's rule evaluated between those of ScB[Formula: see text] and TaB[Formula: see text]. In case of Sc[Formula: see text]Ta[Formula: see text]B[Formula: see text], the degrees of deviation from such linear trends can be as large as 25, 20, and 40% for the shear modulus, the Young's modulus, and the hardness, respectively. The improvement in the stability as well as the mechanical properties of Sc[Formula: see text]Ta[Formula: see text]B[Formula: see text] solid solutions relative to their constituent compounds is found to be related to the effect of electronic band filling, induced upon mixing TaB[Formula: see text] with ScB[Formula: see text]. These findings not only demonstrate the prominent role of band filling in enhancing the stability and the mechanical properties of Sc[Formula: see text]Ta[Formula: see text]B[Formula: see text], but also it can potentially open up a possibility for designing stable/metastable metal diboride-based solid solutions with superior and widely tunable mechanical properties for hard-coating applications.

10.
Food Res Int ; 162(Pt A): 111961, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36461286

RESUMO

Starch modification utilizes a substantial amount of water. This research aimed to investigate the effect of nonthermal dielectric barrier discharge (DBD) argon and helium plasma on tapioca starch's physicochemical properties and techno-functionality. Dry starch samples were treated with plasma generated from argon and helium gases at different voltage levels (10 and 15 kV) for 5, 10, and 15 min. The treatment did not destroy the starch's crystalline structure, as evidenced by the birefringence under polarized light. Scanning electron micrographs showed dented starch granules. A marginal decrease in pH value of all treated samples was noted. A reduction in amylose and amylopectin molecular weight and increased reducing sugars were observed in the treated samples. Fourier transform infrared spectroscopy analysis showed a slight change in the 1047/1022 cm-1 absorbance ratio, indicating a change in short-range ordered degree of starch, while X-ray diffractometry showed a decrease in crystallinity. A significant reduction in peak viscosity, breakdown, and setback was observed. The gelatinized plasma-treated starch dispersion showed less shear-thinning and less thixotropic with increasing voltage and treatment times. This research proved that modification of starch in the solid-state using nonthermal plasma is feasible.


Assuntos
Manihot , Gases em Plasma , Argônio , Hélio , Amido
11.
RSC Adv ; 12(41): 26808-26814, 2022 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-36320850

RESUMO

Lanthanum hydride compounds LaH3 become stabilized by yttrium substitution under the influence of moderate pressure. Novel materials with a wide range of changes in the structural properties as a function of hydrogen are investigated by means of the first-principles cluster expansion technique. Herein, the new compounds La1-x Y x H3, where 0 ≤ x ≤ 1, are determined to adopt tetragonal structures under high-pressure with the compositions La0.8Y0.2H3, La0.75Y0.25H3, and La0.5Y0.5H3. The corresponding thermodynamic and dynamical stabilities of the predicted phases are confirmed by a series of calculations including, for example, phonon dispersion, electronic band structure, and other electronic characteristics. According to the band characteristics, all hydrides except that of I41/amd symmetry are semiconductors. The tetragonal La0.5Y0.5H3 phase is found to become semi-metallic, as confirmed by adopting the modified Becke-Johnson exchange potential. The physical origins of the semiconductor properties in these stable hydrides are discussed in detail. Our findings provide a deeper insight into this class of rare-earth ternary hydrides.

12.
ACS Omega ; 7(32): 28190-28197, 2022 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-35990471

RESUMO

Motivated by Matthias' sixth rule for finding new superconducting materials in a cubic symmetry, we report the cluster expansion calculations, based on the density functional theory, of the superconducting properties of Al0.5Zr0.5H3. The Al0.5Zr0.5H3 structure is thermodynamically and dynamically stable up to at least 200 GPa. The structural properties suggest that the Al0.5Zr0.5H3 structure is a metallic. We calculate a superconducting transition temperature using the Allen-Dynes modified McMillan equation and anisotropic Migdal-Eliashberg equation. As result of this, the anisotropic Migdal-Eliashberg equation demonstrated that it exhibits superconductivity under high pressure with relatively high-T c of 55.3 K at a pressure of 100 GPa among a family of simple cubic structures. Therefore, these findings suggest that superconductivity could be observed experimentally in Al0.5Zr0.5H3.

13.
Phys Chem Chem Phys ; 24(29): 17862-17869, 2022 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-35851907

RESUMO

MXenes are a family of novel two-dimensional (2D) materials attracting intensive interest because of the rich chemistry rooted from the highly diversified surface functional groups. This enables the chemical optimization suitable for versatile applications, including energy conversion and storage, sensors, and catalysis. This work reports the ab initio study of the crystal energetics, electronic properties, and mechanical properties, and the impacts of strain on the electronic properties of tetragonal (1T) and hexagonal (2H) phases of Mo2C as well as the surface-terminated Mo2CT2 (T = O, F, and Cl). Our findings indicate that 2H-Mo2C is energetically more stabilized than the 1T counterpart, and the 1T-to-2H transition requires a substantial energy of 210 meV per atom. The presence of surface termination T atoms on Mo2C intrinsically induces variations in the atomic structure. The calculated structures were selected based on the energetic and thermodynamic stabilities (400 K). The O atom prefers to be terminated on 2H-Mo2C, whereas the Cl atom energetically stabilizes on 1T-Mo2C. Meanwhile, with certain configurations, 2H-Mo2CF2 and 1T-Mo2CF2 with slightly different energies could exist simultaneously. The Mo2CO2 possesses the highest mechanical strength and elastic modulus (σmax = 52 GPa at εb = 20% and E = 507 GPa). The nature of the ordered centrosymmetric layer and the strong bonding between 4 d-Mo and 2 p-O of 2H-Mo2CO2 are responsible for its promising mechanical properties. Interestingly, the topological properties of 2H-Mo2CO2 at a wide range of strains (-10% to 12%) are reported. Moreover, 2H-Mo2CF2 is metallic through the range of calculation. Meanwhile, originally semiconducting 1T-Mo2CF2 and 1T-Mo2CCl2 preserve their features under the ranges of the strain of -2% to 10% and -1% to 5%, respectively, beyond which they undergo the semiconductor-to-metal transitions. These findings would guide the potential applications in modern 2D straintronic devices.

14.
Nanomaterials (Basel) ; 12(11)2022 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-35683728

RESUMO

In this work, Ni−W/B nanocomposite coatings were successfully fabricated on low carbon steel by using pulse current (PC) electrodeposition. The effects of the frequency and duty cycle on the microstructure, wear resistance, and microhardness of the coatings were studied. The results obtained show that the distribution and content of boron particles (>4 wt.%) in the PC electrodeposition coatings are significantly better than those of direct current (DC) electrodeposition coatings (less than 4 wt.%). The hardness results reveal that the highest microhardness of 1122 HV can be obtained at a frequency of 100 Hz and duty cycle of 30%. Furthermore, the relationship between the microstructure and mechanical properties was discussed.

15.
Sci Rep ; 12(1): 6700, 2022 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-35468975

RESUMO

We explored the phase stability of ternary pentahydride [Formula: see text] based on the first principles evolutionary algorithm. Here, we successfully search for a candidate structure up to 500 GPa. As a consequence, the possible stable structure of [Formula: see text] is found be to a monoclinic structure with space group Pm at a pressure of 50 GPa. Moreover, the orthorhombic structure with a space group of Cmcm is found to be thermodynamically stable above 316 GPa. With this, the Kohn-Sham equation plays a crucial role in determining the structural stability and the electronic structure. Therefore, its structural stability is discussed in term of electronic band structure, Fermi surface topology, and dynamic stability. With these results, we propose that the superconducting transition temperature ([Formula: see text]) of Cmcm structure is estimated to be 50 K at 450 GPa. This could be implied that the proposed Cmcm structure may be emerging as a new class of superconductive ternary metal pentahydride. Our findings pave the way for further studies on an experimental observation that can be synthesized at high pressure.

16.
ACS Appl Mater Interfaces ; 14(6): 7909-7916, 2022 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-35103464

RESUMO

Aqueous zinc ion batteries (ZIBs) are emerging as a promising candidate in the post-lithium ion battery era, while the limited choice of cathode materials plagues their further development, especially the tunnel-type cathode materials with high electrochemical performance. Here, a tunnel-type vanadium-based compound based on hydrogen vanadium bronze (HxV2O5) microspheres has been fabricated and employed as the cathode for fast Zn2+ ions' intercalation/deintercalation, which delivers an excellent capacity (425 mAh g-1 at 0.1 A g-1), a remarkable cyclability (91.3% after 5000 cycles at 20 A g-1), and a sufficient energy density (311.5 Wh kg-1). As revealed by the experimental and theoretical results, such excellent electrochemical performance is confirmed to result from the fast ions/electrons diffusion kinetics promoted by the unique tunnel structure (3.7 × 4.22 Å2, along the c direction), which accomplishes a low Zn2+ ion diffusion barrier and the superior electron-transfer capability of HxV2O5. These results shed light on designing tunnel-type vanadium-based compounds to boost the prosperous development of Zn2+ ion storage cathodes.

17.
Sci Rep ; 12(1): 2343, 2022 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-35149743

RESUMO

We use the first principle calculation to investigate the intrinsic magnetism of graphitic carbon nitrides (GCNs). By preserving three-fold symmetry, the GCN building blocks have been built out of different combinations between 6 components which are C atom, N atom, s-triazine, heptazine, heptazine with C atom at the center, and benzimidazole-like component. That results in 20 phases where 11 phases have been previously reported, and 9 phases are newly derived. The partial density of states and charge density have been analyzed through 20 phases to understand the origin of the presence and absence of intrinsic magnetism in GCNs. The intrinsic magnetism will be present not only because the GCNs comprising of radical components but also the [Formula: see text]-conjugated states are not the valence maximum to break the delocalization of unpaired electrons. The building blocks are also employed to study alloys between g-[Formula: see text] and g-[Formula: see text]. The magnetization of the alloys has been found to be linearly dependent on a number of C atoms in the unit cell and some magnetic alloys are energetically favorable. Moreover, the intrinsic magnetism in GCNs can be promoted or demoted by passivating with a H atom depending on the passivated positions.

18.
ACS Appl Mater Interfaces ; 13(32): 38416-38424, 2021 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-34342444

RESUMO

Aqueous zinc-ion batteries (ZIBs) with cost-effective and safe features are highly competitive in grid energy storage applications, but plagued by the sluggish Zn2+ diffusion kinetics and poor cyclability of cathodes. Herein, a one-stone-two-birds strategy of La3+ incorporation (La-V2O5) is developed to motivate Zn2+ insertion/extraction kinetics and stabilize vanadium species for V2O5. Theoretical and experimental studies reveal the incorporated La3+ ions in V2O5 can not only serve as pillars to expand the interlayer distance (11.77 Å) and lower the Zn2+ migration energy barrier (0.82 eV) but also offer intermediated level and narrower band gap (0.54 eV), thus accelerating the electron/ion diffusion kinetics. Importantly, the steadily doped La3+ ions effectively stabilize the V-O bonds by shortening the bond length, thereby inhibiting vanadium species dissolution. Therefore, the resulting La-V2O5-ZIBs deliver an exceptional rate capacity of 405 mA h g-1 (0.1 A g-1), long-term stability with 93.8% retention after 5000 cycles (10 A g-1), and extraordinary energy density of 289.3 W h kg-1, outperforming various metal-ions-doped V2O5 cathodes. Moreover, the La-V2O5 pouch cell presents excellent electrochemical performance and impressive flexibility and integration ability. The strategies of incorporating rare-earth-metal ions provide guidance to other well-established aqueous ZIBs cathodes and other advanced electrochemical devices.

19.
Sci Rep ; 11(1): 16403, 2021 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-34385486

RESUMO

Hafnium hydrogen compounds have recently become the vibrant materials for structural prediction at high pressure, from their high potential candidate for high-temperature superconductors. In this work, we predict [Formula: see text] by exploiting the evolutionary searching. A high-pressure phase adopts a sodalite-like clathrate structure, showing the body-centered cubic structure with a space group of [Formula: see text]. The first-principles calculations have been used, including the zero-point energy, to investigate the probable structures up to 600 GPa, and find that the [Formula: see text] structure is thermodynamically and dynamically stable. This remarkable result of the [Formula: see text] structure shows the van Hove singularity at the Fermi level by determining the density of states. We calculate a superconducting transition temperature ([Formula: see text]) using Allen-Dynes equation and demonstrated that it exhibits superconductivity under high pressure with relatively high-[Formula: see text] of 132 K.

20.
Sci Rep ; 11(1): 15215, 2021 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-34312409

RESUMO

By means of first-principles cluster expansion, anisotropic superconductivity in the transition metal dichalcogenide Nb(Se[Formula: see text]S[Formula: see text])[Formula: see text] forming a van der Waals (vdW) layered structure is observed theoretically. We show that the Nb(Se[Formula: see text]S[Formula: see text])[Formula: see text] vdW-layered structure exhibits minimum ground-state energy. The Pnnm structure is more thermodynamically stable when compared to the 2H-NbSe[Formula: see text] and 2H-NbS[Formula: see text] structures. The characteristics of its phonon dispersions confirm its dynamical stability. According to electronic properties, i.e., electronic band structure, density of states, and Fermi surface indicate metallicity of Nb(Se[Formula: see text]S[Formula: see text])[Formula: see text]. The corresponding superconductivity is then investigated through the Eliashberg spectral function, which gives rise to a superconducting transition temperature of 14.5 K. This proposes a remarkable improvement of superconductivity in this transition metal dichalcogenide.

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