| 1. |
- Borman, V. D., et al.
(författare)
-
Observation of electron localization in rough gold nanoclusters on the graphite surface
- 2007
-
Ingår i: JETP Letters. - 0021-3640 .- 1090-6487. ; 86:6, s. 393-397
-
Tidskriftsartikel (refereegranskat)abstract
- The results of scanning tunneling spectroscopy of the electronic states of Au nanoclusters on the graphite surface are presented. The tunneling current is found to be different at different points of a rough-surface nano-cluster. The measured differential current-voltage curve of the clusters is nonmonotonic near the Fermi energy, and the tunneling conductance decreases by almost a factor of two as the cluster volume changes from I to 0.1 mm(3). This decrease can be associated with the change in the density of the electronic states near the Fermi energy. The observed features are qualitatively described within the framework of the mechanism of electron localization in disordered systems.
|
|
| 2. |
- Borman, V. D., et al.
(författare)
-
Formation of high- and low-density clusters in a 1D system
- 2008
-
Ingår i: Physica. E, Low-Dimensional systems and nanostructures. - : Elsevier BV. - 1386-9477 .- 1873-1759. ; 40:3, s. 643-648
-
Tidskriftsartikel (refereegranskat)abstract
- The properties of monoatomic chains have been studied theoretically by means of statistical mechanics methods. The applied approach can be used to evaluate the interatomic distances and lifetimes of one-dimensional (1D) and quasi-1D systems. In particular, we show that the 1D clusters of gold atoms can exist in two states with different lattice parameters (similar to 3.6 and similar to 2.8 angstrom) that can explain the whole variety of experimental observations on monoatomic gold chains without assuming any wire contamination.
|
|
| 3. |
|
|
| 4. |
- Krivosheeva, A. V., et al.
(författare)
-
Band gap modifications of two-dimensional defected MoS2
- 2015
-
Ingår i: International Journal of Nanotechnology. - 1475-7435 .- 1741-8151. ; 12:8-9, s. 654-662
-
Tidskriftsartikel (refereegranskat)abstract
- The changes in structural and electronic properties, occurring in one monolayer of MoS2 at different concentrations of oxygen atoms doping and vacancies are investigated by means of ab initio computer simulation. The substitution of sulphur atoms by oxygen ones reduces the band gap for high concentrations only, transforming direct-gap semiconductor into an indirect one, whereas a smaller concentration of oxygen practically does not influence the gap. The presence of sulphur vacancies strongly reduces the band gap, leading to bands overlapping at high concentration and appearance of new bands at the gap region, which are determined by Mo 4d states with the mixture of S 3p states, at low concentrations.
|
|
| 5. |
|
|
| 6. |
- Troyan, V., et al.
(författare)
-
Density of electronic states in gold nanoclusters pulsed laser deposited on HOPG
- 2008
-
Ingår i: Superlattices and Microstructures. - : Elsevier BV. - 0749-6036 .- 1096-3677. ; 44:4-5, s. 650-656
-
Tidskriftsartikel (refereegranskat)abstract
- The results of the experimental investigation of tunneling current-voltage characteristics of Au nanoclusters pulsed laser deposited on highly oriented pyrolytic graphite are presented. It is demonstrated that the observed size dependence of the tunneling conductance of Au nanoclusters can be caused by the change of the density of electronic states at the Fermi energy due to the interaction of conduction electrons with non-regular boundary of a cluster under investigation.
|
|
| 7. |
- Migas, Dmitry B., et al.
(författare)
-
Temperature induced structural and polarization features in BaFe12O19
- 2023
-
Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry (RSC). - 2050-7526 .- 2050-7534. ; 11:36, s. 12406-12414
-
Tidskriftsartikel (refereegranskat)abstract
- We report the observation of a peculiar polarization behavior of BaFe12O19 in electric field where the linear polarization is detected at temperatures below 150 K whereas at higher temperatures a hysteresis-like polarization response is observed. At the same time, the performed neutron diffraction analysis shows no variations in crystal or magnetic structures with temperature. Based on the results of ab initio calculations we suggest the mechanism able to explain the experimentally observed behavior. We show that specific Fe atoms do not occupy the positions formally assigned to them by the conventional centrosymmetric P6(3)/mmc (#194) space group (z = 0.25; 0.75) as these positions correspond to local energy maxima. Instead, these Fe atoms are shifted along the z-axis to positions z = 0.259 (0.241) and z = 0.759 (0.741), which correspond to local energy minima. To an inversion center move between these minima Fe atoms need to overcome an energy barrier. This barrier is rather insignificant for smaller volumes but it becomes larger for expanded volumes due to coupling between the displacements of these Fe atoms. Additionally, our analysis suggests that the non-centrosymmetric and polar P6(3)mc (#186) space group could be appropriate for the description of the BaFe12O19 structure.
|
|
| 8. |
- Migas, D. B., et al.
(författare)
-
The Surface Energy and Band Structure of gamma-WO3 Thin Films
- 2017
-
Ingår i: Science of Advanced Materials. - : AMER SCIENTIFIC PUBLISHERS. - 1947-2935 .- 1947-2943. ; 9:3-4, s. 469-474
-
Tidskriftsartikel (refereegranskat)abstract
- By means of ab initio calculations we demonstrate sizable anisotropy in surface energy of the gamma-WO3 (001), (010) and (100) surfaces. The (001) surface has the smallest surface energy followed by the (010) and (100) surfaces. Their surface band structures are characterized by dispersion of bands near the gap region and by band-gap values similar to the ones of the bulk. The role of surface atoms in stabilizing the band gap is revealed. Variations in the position of the Fermi level are traced with respect to the different surface reconstructions.
|
|
| 9. |
- Diklic, Natasa P., et al.
(författare)
-
Sodium storage via single epoxy group on graphene - The role of surface doping
- 2019
-
Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 297, s. 523-528
-
Tidskriftsartikel (refereegranskat)abstract
- Due to its unique physical and chemical properties, graphene is being considered as a promising material for energy conversion and storage applications. Introduction of functional groups and dopants on/in graphene is a useful strategy for tuning its properties. In order to fully exploit its potential, atomic-level understanding of its interaction with species of importance for such applications is required. We present a DFT study of the interaction of sodium atoms with epoxy-graphene and analyze how this interaction is affected upon doping with boron and nitrogen. We demonstrate how the dopants, combined with oxygen-containing groups alter the reactivity of graphene towards Na. Dopants act as attractors of epoxy groups, enhancing the sodium adsorption on doped oxygen-functionalized graphene when compared to the case of non-doped epoxy-graphene. Furthermore, by considering thermodynamics of the Na interaction with doped epoxy-graphene it has been concluded that such materials are good candidates for Na storage applications. Therefore, we suggest that controlled oxidation of doped carbon materials could lead to the development of advanced anode materials for rechargeable Na-ion batteries.
|
|
| 10. |
- Dobrota, Ana S., et al.
(författare)
-
A DFT study of the interplay between dopants and oxygen functional groups over the graphene basal plane - implications in energy-related applications
- 2017
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : ROYAL SOC CHEMISTRY. - 1463-9076 .- 1463-9084. ; 19:12, s. 8530-8540
-
Tidskriftsartikel (refereegranskat)abstract
- Understanding the ways graphene can be functionalized is of great importance for many contemporary technologies. Using density functional theory calculations we investigate how vacancy formation and substitutional doping by B, N, P and S affect the oxidizability and reactivity of the graphene basal plane. We find that the presence of these defects enhances the reactivity of graphene. In particular, these sites act as strong attractors for OH groups, suggesting that the oxidation of graphene could start at these sites or that these sites are the most difficult to reduce. Scaling between the OH and H adsorption energies is found on both reduced and oxidized doped graphene surfaces. Using the O-2 molecule as a probe we show that a proper modelling of doped graphene materials has to take into account the presence of oxygen functional groups.
|
|
