| 1. |
- Li, Hu, 1986-, et al.
(author)
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Fabrication of BP2T functionalized graphene via non-covalent π-π stacking interactions for enhanced ammonia detection
- 2021
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In: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 11:57, s. 35982-35987
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Journal article (peer-reviewed)abstract
- Graphene has stimulated great enthusiasm in a variety of fields, while its chemically inert surface still remains challenging for functionalization towards various applications. Herein, we report an approach to fabricate non-covalently functionalized graphene by employing pi-pi stacking interactions, which has potentialities for enhanced ammonia detection. 5,5 '-Di(4-biphenylyl)-2,2 '-bithiophene (BP2T) molecules are used in our work for the non-covalent functionalization through strong pi-pi interactions of aromatic structures with graphene, and systematic investigations by employing various spectroscopic and microscopic characterization methods confirm the successful non-covalent attachment of the BP2T on the top of graphene. From our gas sensing experiments, the BP2T functionalized graphene is promising for ammonia sensing with a 3-fold higher sensitivity comparing to that of the pristine graphene, which is mainly attributed to the enhanced binding energy between the ammonia and BP2T molecules derived by employing the Langmuir isotherm model. This work provides essential evidence of the pi-pi stacking interactions between graphene and aromatic molecules, and the reported approach also has the potential to be widely employed in a variety of graphene functionalizations for chemical detection.
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| 2. |
- Murugesan, Chinnasamy, et al.
(author)
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Cobalt tetraphosphate as an efficient bifunctional electrocatalyst for hybrid sodium-air batteries
- 2021
-
In: Nano Energy. - : Elsevier BV. - 2211-2855 .- 2211-3282. ; 89
-
Journal article (peer-reviewed)abstract
- Economic and efficient bifunctional electrocatalysts are pivotal in realization of rechargeable (hybrid) metal-air batteries. It is ideal to employ noble-metal free bifunctional electrocatalysts that are not selective towards oxygen evolution and reduction (OER and ORR) activities. This work unveils cobalt-based tetraphosphate K2Co(PO3)(4) as an economic bifunctional electrocatalyst acting as cathode for rechargeable hybrid sodium-air batteries. Auto combustion route led to the development of homogeneous, carbon-coated, spherical K2Co(PO3)(4) nanoparticles enabling active site exposure to incoming guest molecules (O-2, OH-). This monoclinic compound exhibited superior oxygen evolution activity with low overpotential (ca. 0.32 V) surpassing the commercial RuO2 catalyst. Tetraphosphate K2Co(PO3)(4) was successfully implemented in hybrid Na-air batteries delivering reversible cycling with roundtrip efficiency over 70%. DFT study revealed this catalytic activity stem from the most active and stable surface (001) and half-metallic nature of Co in K2Co(PO3)(4). Cobalt tetraphosphates can be harnessed to design low cost electrocatalysts for hybrid sodium-air batteries.
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| 3. |
- Wani, Ishtiaq Hassan, 1985-, et al.
(author)
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A sub 20 nm metal-conjugated molecule junction acting as a nitrogen dioxide sensor
- 2019
-
In: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 11:14, s. 6571-6575
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Journal article (peer-reviewed)abstract
- The interaction of a gas molecule with a sensing material causes the highest change in the electronic structure of the latter, when this material consists of only a few atoms. If the sensing material consists of a short, conductive molecule, the sensing action can be furthermore probed by connecting such molecules to nanoelectrodes. Here, we report that NO2 molecules that adhere to 4,4'-biphenyldithiol (BPDT) bound to Au surfaces lead to a change of the electrical transmission of the BPDT. The related device shows reproducible, stable measurements and is so far the smallest (<20 nm) gas sensor. It demonstrates modulation of charge transport through molecules upon exposure to nitrogen dioxide down to concentrations of 55 ppb. We have evaluated several devices and exposure conditions and obtained a close to linear dependence of the sensor response on the gas concentration.
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| 4. |
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| 5. |
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| 6. |
- Abdel-Hafiez, Mahmoud, et al.
(author)
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Pressure-induced reentrant transition in NbS3 phases : Combined Raman scattering and x-ray diffraction study
- 2019
-
In: Physical Review B. - : AMER PHYSICAL SOC. - 2469-9950 .- 2469-9969. ; 99:23
-
Journal article (peer-reviewed)abstract
- We report the evolution of charge density wave states under pressure for two NbS3 phases: triclinic (phase I) and monoclinic (phase II) at room temperature. Raman and x-ray diffraction (XRD) techniques are applied. The x-ray studies on the monoclinic phase under pressure show a compression of the lattice at different rates below and above similar to 7 GPa but without a change in space group symmetry. The Raman spectra of the two phases evolve similarly with pressure; all peaks almost disappear in the similar to 6-8 GPa range, indicating a transition from an insulating to a metallic state, and peaks at new positions appear above 8 GPa. The results suggest suppression of the ambient charge-density waves and their subsequent recovery with new orderings above 8 GPa.
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| 7. |
- Ahmadivand, Arash, et al.
(author)
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Terahertz plasmonics : The rise of toroidal metadevices towards immunobiosensings
- 2020
-
In: Materials Today. - : ELSEVIER SCI LTD. - 1369-7021 .- 1873-4103. ; 32, s. 108-130
-
Research review (peer-reviewed)abstract
- This work reviews fundamentals and the recent state-of-art achievements in the field of plasmonic biosensing based terahertz (THz) spectroscopy. Being nonpoisonous and nondestructive to the human tissues, THz signals offer promising, cost-effective, and real-time biodevices for practical pharmaco-logical applications such as enzyme reaction analysis. Rapid developments in the field of THz plasmonics biosensors and immunosensors have brought many methodologies to employ the resonant subwavelength structures operating based on the fundamental physics of multipoles and asymmetric lineshape resonances. In the ongoing hunt for new and advanced THz plasmonic biosensors, the toroidal metasensors have emerged as excellent alternates and are introduced to be a very promising technology for THz immunosensing applications. Here, we provide examples of recently proposed THz plasmonic metasensors for the detection of thin films, chemical and biological substances. This review allows to compare the performance of various biosensing tools based on THz plasmonic approach and to understand the strategic role of toroidal metasensors in highly accurate and sensitive biosensors instrumentation. The possibility of using THz plasmonic biosensors based on toroidal technology in modern medical and clinical practices has been briefly discussed.
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| 8. |
- Ahmadivand, Arash, et al.
(author)
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Toroidal Metaphotonics and Metadevices
- 2020
-
In: Laser & Photonics reviews. - : WILEY-V C H VERLAG GMBH. - 1863-8880 .- 1863-8899. ; 14:11
-
Research review (peer-reviewed)abstract
- Toroidal moments in artificial media have received growing attention and considered as a promising framework for initiating novel approaches to manage intrinsic radiative losses in nanophotonic and plasmonic systems. In the past decade, there has been substantial attention on the characteristics and excitation methods of toroidal multipoles-in particular, toroidal dipole-in 3D bulk and planar metaplatforms. The remarkable advantages of toroidal resonances have thrust the toroidal metasurface technology from relative anonymity into the limelight, in which researchers have recently centered on developing applied optical and optoelectronic subwavelength devices based on toroidal metaphotonics and metaplasmonics. In this focused contribution, the key principles of 3D and flatland toroidal metastructures are described, and the revolutionary tools that have been implemented based on this topology are briefly highlighted. Infrared photodetectors, immunobiosensors, ultraviolet beam sources, waveguides, and functional modulators are some of the fundamental and latest examples of toroidal metadevices that have been introduced and studied experimentally so far. The possibility of the realization of strong plexciton dynamics and pronounced vacuum Rabi oscillations in toroidal plasmonic metasurfaces are also presented in this review. Ultimate efficient extreme-subwavelength scale devices, such as low-threshold lasers and ultrafast switches, are thus in prospect.
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| 9. |
- Allal, Adel, et al.
(author)
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A comparative theoretical investigation of optoelectronic and mechanical properties of KYS2 and KLaS2
- 2020
-
In: Materials Science in Semiconductor Processing. - : Elsevier BV. - 1369-8001 .- 1873-4081. ; 113
-
Journal article (peer-reviewed)abstract
- The ternary sulfides KYS2 and KLaS2 are two promising candidates for numerous applications, as much as white LED, X-ray phosphor and transparent conductor materials. However, theoretical studies on these materials are lacking, and many of their physical properties are still unknown. The aim of this work is to investigate the physical properties of the ternary sulfides KYS2 and KLaS2 namely, structural, elastic, optoelectronic, thermodynamic analysis, and set the substitution effect of Y and La elements in the two compounds. The fundamental properties calculations are based on ab-initio pseudopotential framework, with both local density approximation (LDA) and generalized gradient approximations (GGA) along with an expanded set of plane waves. The Becke, 3-parameter, Lee–Yang–Parr (B3LYP) hybrid functional is also employed to describe the electronic structures and optical properties. The optimized crystal parameters are correlated very well with the existing experimental data. The predicted values of the elastic constants demonstrate that the two compounds are mechanically stable and can be classified as brittle materials. The band structure analysis reveals that both KYS2 and KLaS2 have indirect band gap. The optical properties, like the refractive index, extinction, absorption and reflectivity coefficients, are determined for various polarizations of incident light, while both compounds present optical anisotropy. The obtained optical properties indicate the high transparency of KYS2 and KLaS2 in the infrared and visible regions, which makes them promising candidates for many of transparent applications. The thermodynamic properties are investigated with the help of quasiharmonic Debye model approximation. KYS2 has a larger bulk modulus value, which make it more beneficial in engineering applications. Calculations of thermodynamical properties indicate that KYS2 compound has better thermal conductivity, stronger chemical bonds and bigger hardness.
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| 10. |
- Allal, Adel, et al.
(author)
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Phase stability, phonon, electronic, and optical properties of not-yet-synthesized CsScS2, CsYS2, and APmS(2) (A= Li, Na, K, Rb, Cs) materials : Insights from first-principles calculations
- 2022
-
In: Materials Science in Semiconductor Processing. - : Elsevier. - 1369-8001 .- 1873-4081. ; 150
-
Journal article (peer-reviewed)abstract
- Transparent conducting materials (TCMs) combine two exclusive properties, electrical conductivity and visible light transparency; which make them a unique class of materials. They are required in a wide range of applications in modern life ranging from touchscreen-based devices, flat panel displays, light-emitting diodes (LED), and solar cells. Most of the commercially and widely used TCMs are n-type, whereas the development of highperformance p-type TCMs remains an outstanding challenge in the actual time. Herein, using the newly developed SCAN meta-GGA and the hybrid HSE06 functionals, we have explored the structural stability and physical properties of not-yet-synthesized ternary materials CsScS2, CsYS2, and APmS(2) (A = Li, Na, K, Rb, Cs) to identify promising p-type TCMs. As result, the calculated formation energy, phase diagram and phonon dispersion curves confirm that these materials are thermodynamically stable and feasible to synthesize experimentally. All these materials, have large optical band gaps (larger than 3.4 eV), small hole effective masses (except for LiPmS2), and have no absorption and weak reflectivity of the visible light. Our work demonstrates that these compounds have suitable properties for p-type TCMs applications.
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| 11. |
- Allal, Adel, et al.
(author)
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Structural stability, mechanical, electronic and optical behaviour of RbXS2 (X = Y and La) under high pressure : A first-principle study
- 2020
-
In: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 848
-
Journal article (peer-reviewed)abstract
- The high-pressure behaviour of the ternary sulphides, RbXS2 (X = Y and La), has been investigated by using first-principle calculations based on density functional theory. Upon applying hydrostatic pressure, the unit-cell parameters (a, c) decrease with different rates, indicating an anisotropic axial compression. The most of RbYS2 and RbLaS2 crystals compressibility comes from Rb+1-S-2 bonds. Elastic constants and their dependence on pressure and related mechanical properties have been reported and analysed. From Pugh's criterion, RbYS2 and RbLaS2 turn from brittle to ductile material for applied pressures beyond 3.1 GPa and 2.9 GPa, respectively. Stability criteria show that RbYS2 and RbLaS2 are not mechanically stable in ci-NaFeO2 crystal structure above 20.63 GPa and 16.24 GPa, respectively. Both RbYS2 and RbLaS2 have indirect band gap, which decreases with increasing pressure. However, no indirectdirect band gap transition is observed for both materials. Finally, the calculated optical spectrum of both compounds exhibits an anisotropy and a broadening at high pressures.
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| 12. |
- Alluri, Nagamalleswara Rao, et al.
(author)
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Crystallinity modulation originates ferroelectricity like nature in piezoelectric selenium
- 2022
-
In: Nano Energy. - : Elsevier. - 2211-2855 .- 2211-3282. ; 95
-
Journal article (peer-reviewed)abstract
- Modern room temperature ferroelectrics/piezoelectrics significantly impact advanced nanoelectronics than conventional chemical compounds. Changes in crystallinity modulation, long-range order of atoms in metalloids permits the design of novel materials. The ferroelectric like nature of a single element (selenium, Se) is demonstrated via in-plane (E perpendicular to(ar) to the Se helical chains in micro-rod (MR)) and out-of-plane (E parallel to(el) to the Se helical chains in MR) polarization. Atomic electron microscopy shows large stacks of covalently bound Se atoms in a c-axis orientation for tip bias voltage-dependent switchable domains with a 180 degrees phase and butterfly displacement curves. The single crystalline Se MR has a high in-plane piezoelectric coefficient of 30 pm/V relative to polycrystalline samples due to larger grains, crystal imperfections in MR, and tuned helical chains. The energy conversion of a single Se-MR demonstrated via d(13), d(12) (or d(15)) piezoelectric modes.
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| 13. |
- Anikina, Ekaterina, et al.
(author)
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Elucidating hydrogen storage properties of two-dimensional siligraphene (SiC8) monolayers upon selected metal decoration
- 2020
-
In: Sustainable Energy & Fuels. - : Royal Society of Chemistry (RSC). - 2398-4902. ; 4:11, s. 5578-5587
-
Journal article (peer-reviewed)abstract
- Density functional theory calculations with dispersion corrections were employed to investigate the hydrogen (H-2) adsorptive properties of siligraphene (SiC8), pristine and decorated with selected alkali (Li, Na, and K) and alkaline-earth (Be, Mg, and Ca) metals. We found that all the considered metals (Me), except Mg and Be, bind strongly to SiC8 even at high doping concentrations (SiC8Me2) by donating a major portion of their valence electrons to SiC8. Ab initio molecular dynamics (AIMD) simulations confirmed the thermal stabilities of SiC8Me2 (Me = Li, Na, K, Ca) at 300 K. We showed that Li, Na, and Ca-doped SiC8 adsorbed multiple H-2 molecules with binding energies (E-bind) at least two times stronger than that of the pristine SiC8 (Epristinebind = -70 meV per H-2). Overall, both SiC8Li2 and SiC8Ca2 adsorbed two and four H-2 molecules per metal adatom, respectively, having E-bind within the desirable range for an effective adsorption/desorption process. The resulting gravimetric densities of SiC8Li2 and SiC8Ca2 were 5.5 wt% and 7.3 wt%, respectively, surpassing the U.S. Department of Energy's 2025 goal of 5.5 wt%. The estimated H-2 desorption temperatures exceed substantially the boiling point of liquid nitrogen, confirming the potential of light metal decorated SiC8 as a promising material for H-2 storage.
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| 14. |
- Anikina, Ekaterina, et al.
(author)
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High-capacity reversible hydrogen storage properties of metal-decorated nitrogenated holey graphenes
- 2022
-
In: International journal of hydrogen energy. - : Elsevier. - 0360-3199 .- 1879-3487. ; 47:19, s. 10654-10664
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Journal article (peer-reviewed)abstract
- Motivated by the need for an effective way of storing hydrogen (H-2), a promising energy carrier, we have performed density functional theory (DFT) calculations with different van der Waals corrections coupled with the statistical thermodynamic analysis and ab initio molecular dynamics (AIMD) on the light-metal decorated nitrogenated holey graphene (C2N) monolayers. We have found that the decoration by selected light metals (Na, Mg, Ca) improves the H2 adsorption on the C2N to the desired levels (> 150 meV/H-2). Moreover, the metal dopants strongly bonded with C2N even at higher doping concentrations, which invalidates the metal clusters formation. Among considered metals, Na and Mg resulted in H-2 storage capacities of 5.5 and 6.9 wt%, respectively, which exceed the target set by the U.S. Department of Energy's for 2025. Thermodynamic analysis and the AIMD simulations were employed to investigate the H-2 sorption at varied conditions of temperature and pressure for practical applications.
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| 15. |
- Anikina, Ekaterina, et al.
(author)
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Li-decorated carbyne for hydrogen storage : charge induced polarization and van't Hoff hydrogen desorption temperature
- 2020
-
In: Sustainable Energy & Fuels. - : ROYAL SOC CHEMISTRY. - 2398-4902. ; 4:2, s. 691-699
-
Journal article (peer-reviewed)abstract
- We have studied carbyne as a promising hydrogen storage material. Density functional theory simulations with vdW corrections have been used to investigate lithium sorption on carbyne and the interaction of pristine and Li-functionalized carbon chains with molecular hydrogen. We showed that Li adatoms at small concentrations stay atomically dispersed on carbyne, donating 0.9e to the chain. Moreover, in the presence of Li, hydrogen adsorption energy increases by more than 5 times in comparison with pristine carbyne. Overall, up to three hydrogen molecules per Li adatom have an adsorption energy close to the range of 200-600 meV per H-2, which is necessary for effective sorption/desorption cycles. The resulting theoretical uptake (7.1 wt%) is higher than the U.S. Department of Energy's ultimate goal (6.5 wt%). The calculated van't Hoff desorption temperatures exceed considerably the boiling point of liquid nitrogen. Our results confirm the potential of Li-decorated carbyne for hydrogen storage.
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| 16. |
- Anikina, Ekaterina, et al.
(author)
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Tunning Hydrogen Storage Properties of Carbon Ene-Yne Nanosheets through Selected Foreign Metal Functionalization
- 2020
-
In: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 124:31, s. 16827-16837
-
Journal article (peer-reviewed)abstract
- In this study, we have employed density functional theory with a range of van der Waals corrections to study geometries, electronic structures, and hydrogen (H-2) storage properties of carbon ene-yne (CEY) decorated with selected alkali (Na, K) and alkaline-earth metals (Mg, Ca). We found that all metals, except Mg, bind strongly by donating a major portion of their valence electrons to the CEY monolayers. Thermal stabilities of representative systems, Ca-decorated CEY monolayers, have been confirmed through ab initio molecular dynamics simulations (AIMD). We showed that each metal cation adsorbs multiple H-2 with binding energies (E-bind) considerably stronger than on pristine CEY. Among various metal dopants, Ca stands out with the adsorption of five H-2 per each Ca having E-bind values within the desirable range for effective adsorption/desorption process. The resulting gravimetric density for CEY@Ca has been found around 6.0 wt % (DFT-D3) and 8.0 wt % (LDA), surpassing the U.S. Department of Energy's 2025 goal of 5.5 wt %. The estimated H-2 desorption temperature in CEY@Ca exceeds substantially the boiling point of liquid nitrogen, which confirms its potential as a practical H-2 storage medium. We have also employed thermodynamic analysis to explore the H-2 adsorption/desorption mechanism at varied conditions of temperature and pressure for real-world applications.
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| 17. |
- Anikina, E. V., et al.
(author)
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Influence of Kubas-type interaction of B–Ni codoped graphdiyne with hydrogen molecules on desorption temperature and storage efficiency
- 2020
-
In: Materials Today Energy. - : Elsevier. - 2468-6069. ; 16
-
Journal article (peer-reviewed)abstract
- We have investigated functionalized 2D carbon allotrope, graphdiyne (GDY), as a promising hydrogen storage media. Density functional theory with a range of vdW corrections was employed to study Ni decoration of pristine and boron-doped GDY and the interaction of resulting structures with molecular hydrogen. We showed that boron-doped GDY is thermally stable at 300 K, though, its synthesis requires an endothermic reaction. Also, boron doping enhances Ni binding with the graphdiyne by increasing the charge transfer from Ni to GDY. Ni doping drastically influenced hydrogen adsorption energies: they rise from ~70 meV per H2 molecule on pristine GDY to a maximum of 1.29 eV per H2 becoming too high in value for room temperature reversible applications. Boron doping improves the situations: in this case, after Ni decoration desorption temperature estimation is ~300–500 K. Overall, each Ni adatom on B-doped GDY can bind only one H2 molecule within the needed energy range, which gives low hydrogen uptake (~1.2 wt%). However, doping with boron led to the decrease in the value of hydrogen adsorption energy and good desorption temperature estimations, therefore, codoping of metal atoms and boron could be an effective strategy for other transition metals.
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| 18. |
- Araujo, Rafael B., et al.
(author)
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Assessing Electrochemical Properties of Polypyridine and Polythiophene for Prospective Application in Sustainable Organic Batteries
- 2017
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In: Physical Chemistry, Chemical Physics - PCCP. - 1463-9076 .- 1463-9084. ; 19:4, s. 3307-3314
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Journal article (peer-reviewed)abstract
- Conducting polymers are being considered promising candidates for sustainable organic batteries mainly due to their fast electron transport properties and high recyclability. In this work, key properties of polythiophene and polypyridine have been assessed through a combined theoretical and experimental study focusing on such applications. A theoretical protocol has been developed to calculate redox potentials in solution within the framework of the density functional theory and using continuous solvation models. Here, the evolution of the electrochemical properties of solvated oligomers as a function of the length of the chain is analyzed and then the polymer properties are estimated via linear regressions using ordinary least square. The predicted values were verified against our electrochemical experiments. This protocol can now be employed to screen a large database of compounds in order to identify organic electrodes with superior properties.
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| 19. |
- Araujo, Rafael B., et al.
(author)
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Designing strategies to tune reduction potential of organic molecules for sustainable high capacity batteries application
- 2017
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In: Journal of Materials Chemistry A. - 2050-7488 .- 2050-7496. ; 5:9, s. 4430-4454
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Journal article (peer-reviewed)abstract
- Organic compounds evolve as a promising alternative to the currently used inorganic materials in rechargeable batteries due to their low-cost, environmentally friendliness and flexibility. One of the strategies to reach acceptable energy densities and to deal with the high solubility of known organic compounds is to combine small redox active molecules, acting as capacity carrying centres, with conducting polymers. Following this strategy, it is important to achieve redox matching between the chosen molecule and the polymer backbone. Here, a synergetic approach combining theory and experiment has been employed to investigate this strategy. The framework of density functional theory connected with the reaction field method has been applied to predict the formal potential of 137 molecules and identify promising candidates for the referent application. The effects of including different ring types, e.g. fused rings or bonded rings, heteroatoms, [small pi] bonds, as well as carboxyl groups on the formal potential, has been rationalized. Finally, we have identified a number of molecules with acceptable theoretical capacities that show redox matching with thiophene-based conducting polymers which, hence, are suggested as pendent groups for the development of conducting redox polymer based electrode materials.
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| 20. |
- Araujo, Rafael Barros Neves de, et al.
(author)
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Divulging the Hidden Capacity and Sodiation Kinetics of NaxC6Cl4O2 : A High Voltage Organic Cathode for Sodium Rechargeable Batteries
- 2017
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In: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 121:26, s. 14027-14036
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Journal article (peer-reviewed)abstract
- In the current emerging sustainable organic battery field, quinones are seen as one of the prime candidates for application in rechargeable battery electrodes. Recently, C6Cl4O2, a modified quinone, has been proposed as a high voltage organic cathode. However, the sodium insertion mechanism behind the cell reaction remained unclear due to the nescience of the right crystal structure. Here, the framework of the density functional theory (DFT) together with an evolutionary algorithm was employed to elucidate the crystal structures of the compounds NaxC6Cl4O2 (x = 0.5, 1.0, 1.5 and 2). Along with the usefulness of PBE functional to reflect the experimental potential, also the importance of the hybrid functional to divulge the hidden theoretical capacity is evaluated. We showed that the experimentally observed lower specific capacity is a result of the great stabilization of the intermediate phase Na1.5C6Cl4O2. The calculated activation barriers for the ionic hops are 0.68, 0.40, and 0.31 eV, respectively, for NaC6Cl4O2, Na1.5C6Cl4O2, and Na2C6Cl4O2. These results indicate that the kinetic process must not be a limiting factor upon Na insertion. Finally, the correct prediction of the specific capacity has confirmed that the theoretical strategy used, employing evolutionary simulations together with the hybrid functional framework, can rightly model the thermodynamic process in organic electrode compounds.
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| 21. |
- Arslanov, T. R., et al.
(author)
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Large pressure-induced magnetoresistance in a hybrid ferromagnet-semiconductor system : Effect of matrix modification on the spin-dependent scattering
- 2020
-
In: Journal of Applied Physics. - : AMER INST PHYSICS. - 0021-8979 .- 1089-7550. ; 128:21
-
Journal article (peer-reviewed)abstract
- Magnetic nanocomposites based on MnAs clusters embedded in a chalcopyrite host usually do not exhibit large magnetoresistance (MR) at room temperature, while pronounced effects are localized at very low temperatures. In the present work, we observed an appearance of large pressure-induced negative and positive MR at room temperature in the Zn0.1Cd0.9GeAs2 hybrid system containing 10% MnAs inclusions. With the applied pressure, a substantial modification of the electron transport from semimetallic to semiconducting type occurs, followed by a subsequent structural transition at P approximate to 3.5GPa into almost metallic high-pressure phase. This picture is simultaneously supported by temperature-dependent and room temperature high-pressure transport measurements. Using a semiempirical expression, taking into account a spin-dependent scattering of charge carriers due to MnAs nanoclusters, as well as a two-band conductivity model, we have been able to partially describe the observed MR effects. The predominantly weak positive contribution at P=1GPa, which is well described in the framework of the proposed approach indicates the presence of spin-polarized charge carriers. Based on the two-band model calculations, a negative spin polarization was found at P >= 3GPa that ascribed to a structural change of the matrix. As our results indicate, an emerging MR in the structural transition region is characterized by a complex behavior. In particular, the negative part of MR demonstrates a magnetic field dependence different than Delta rho/rho (0)similar to H-2, suggesting the presence of unusual scattering mechanisms in magnetotransport.
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| 22. |
- Arslanov, T. R., et al.
(author)
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Low energy band gap state in compressed needlelike structure of CdSb:Ni
- 2019
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 115:25
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Journal article (peer-reviewed)abstract
- We studied the effect of high pressure on the border of intrinsic conductivity in CdSb doped with 0.5%Ni, the structure of which is needlelike due to spherical extended NiSb inclusions. The bandgap state has been found to be strongly governed by a structural transition in the composite structure. A pressure-induced phase exhibits an activation behavior only upon heating with a very low energy gap by 0.05 eV at 5.32 GPa, while metallic conductivity appears upon subsequent cooling, which is attributed to the instability of the cadmium antimonide structure. Room-temperature Hall effect measurements confirm that the high-pressure phase is not fully metallized, yielding a hole concentration of 4.08 x 10(18) cm(-3) at the onset of structural transition and a reduced magnitude by order in this phase.
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| 23. |
- Aslam, Muhammad Kashif, et al.
(author)
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How to avoid dendrite formation in metal batteries : Innovative strategies for dendrite suppression
- 2021
-
In: Nano Energy. - : Elsevier. - 2211-2855 .- 2211-3282. ; 86
-
Research review (peer-reviewed)abstract
- With increasing the diversity of electronic/electric appliances and large-scale energy storage systems, highenergy-density based device technology has been in great demand. Meanwhile, for developing of high-voltage and high-capacity cathode, the use of metals including lithium (Li), sodium (Na), potassium (K), or zinc (Zn) is quite impressive to replace the traditional anodes with low capacity upper limit such as graphite, silicon carbon, and hard carbon which is considered as "holy grail" strategy to explore high-energy density systems. However, these so-called metal batteries (MBs) also face many thorny issues including high anode reactivity, dendritic growth, and high safety risks. Among all these muddle, the dendrite growth is quite sever issue and has attracted much attention of many recognized materials scientist and battery researchers. The formation of dendrite increase the surface area of metal anodes, induce the rupture and reconstruction of solid electrolyte interphase (SEI) film, which is likely to accelerate the excessive consumption of electrolyte and the formation of dead metals. Consequently, battery lose its capability and short circuit produced which causes serious safety issues. Therefore, it is badly needed to inhibit or even eliminate the formation of dendrites during the repeated charge and discharge process to find advanced and fast battery technology. In this review, we summarize the basic mechanistic theoretical models about dendrites formation and their effects on the battery performance. Moreover, we recapitulate the reported literature about dendrites concept and their solution from battery invention to its modernism for smart electric appliances and zero emission electric vehicles. Besides, perspective of interface energy/volume stress, several innovative strategies for restraining, regulating and eliminating dendrites are also part of this review. Finally, perspectives conclusions for the development of MBs about dendrite level are given for the progress of future battery science.
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| 24. |
- Bahti, Soukaina, et al.
(author)
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Structures, stabilities, optoelectronic and photocatalytic properties of Janus aluminium mono-chalcogenides Al(Ga, In)STe monolayers
- 2022
-
In: Physica. E, Low-Dimensional systems and nanostructures. - : Elsevier. - 1386-9477 .- 1873-1759. ; 142
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Journal article (peer-reviewed)abstract
- Computational design of new two-dimensional materials constitutes an effective and promising approach in the development and exploration of a wide range of emerging applications such as optoelectronics, photocatalysis, energy storage, and conversion. Within the framework of this work, we systematically investigated for the first time, the structural, stability, optoelectronic, and pho-tocatalytic properties of new predicted Al(Ga, In)STe monolayers derived from Janus Aluminium mono-chalcogenides through Density Functional Theory and Ab-Initio molecular dynamic simulations. After a full optimization of both struc-tures, their dynamics and thermal stability was confirmed through the calculations of phonon spectrum and ab-initio molecular dynamics at a chosen temperature, respectively. Subsequently, the electronic and optical properties were explored and findings revealed that both monolayers exhibit a semiconducting characteristic with a direct and indirect electronic band gap of about 2.23 and 2.69 eV using HSE06 hybrid functional for AlGaSTe and AlInSTe monolayers, re-spectively. Furthermore, the optical absorption indicates a strong absorption of light in the range between 3 and 18 eV. More noticeably, Both Janus monolayers considered exhibiting a promising optical absorption in the visible wavelength region with an absorption coefficient greater than 105 cm−1. In addition, the photocatalytic properties of these structures were investigated by plotting the band edge positions straddle the reduction potential of H2 and the oxidation potential H2O. Based on our results, we conclude that both monolayers offer good thermodynamic stability allowing them to be processed experimentally and can be used as very appropriate candidates for optoelectronics and photocatalytic applications.
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| 25. |
- Bandyopadhyay, Arka, et al.
(author)
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8-16-4 graphyne : Square-lattice two-dimensional nodal line semimetal with a nontrivial topological Zak index
- 2021
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In: Physical Review B. - : American Physical Society (APS). - 2469-9950 .- 2469-9969. ; 103:7
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Journal article (peer-reviewed)abstract
- An unprecedented graphyne allotrope with square symmetry and nodal line semimetallic behavior has been proposed in the two-dimensional (2D) realm. The emergence of the Dirac loop around the high-symmetry points in the presence of both the inversion and time-reversal symmetries is a predominant feature of the electronic band structure of this system. Besides, the structural stability in terms of the dynamic, thermal, and mechanical properties has been critically established for the system. Following the exact analytical model based on the realspace renormalization group scheme and tight-binding approach, we have inferred that the family of 2D nodal line semimetals with square symmetry can be reduced to a universal four-level system in the low-energy limit. This renormalized lattice indeed explains the underlying mechanism responsible for the fascinating emergence of 2D square nodal line semimetals. Besides, the analytical form of the generic dispersion relation of these systems is well supported by our density-functional theory results. Finally, the nontrivial topological properties have been explored for the predicted system without breaking the inversion and time-reversal symmetry of the lattice. We have obtained that the edge states are protected by the nonvanishing topological index, i.e., Zak phase.
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