KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Search Results

Now showing 1 - 7 of 7

Some of the metrics are blocked by your
consent settings
Thermodynamic and dynamic stability of NaLiC4: Exploring superconductivity in a layered hexagonal compound through first-principles calculations
(2024-06-01)
Pluengphon, Prayoonsak
;
Sukmas, Wiwittawin
;
Tsuppayakorn-aek, Prutthipong
;
Kotmool, Komsilp
;
Sakulkalavek, Aparporn
The layered hexagonal compound NaLiC<inf>4</inf> has been thoroughly investigated to assess its thermodynamic and dynamic stability in comparison to its parent compounds NaC<inf>2</inf> and LiC<inf>2</inf>. Utilizing first-principles calculations and phonon analyzes, NaLiC<inf>4</inf> has demonstrated remarkable stability within a pressure range of 10 to 100 GPa, surpassing the thermodynamic stability of NaC<inf>2</inf> and LiC<inf>2</inf>. It exhibits metallic behavior with distinctive electronic bands along high symmetry paths, suggesting a conducive environment for superconductivity. The superconducting transition temperature (T<inf>c</inf>) of NaLiC<inf>4</inf> under different pressures was estimated using the Allen–Dynes equation, with a maximum T<inf>c</inf> of 79 K observed at 10 GPa. However, as pressure increases, T<inf>c</inf> gradually decreases, indicating the significant impact of external pressure conditions on the superconducting properties. Notably, the in-plane E<inf>2g</inf> phonon mode originating from the layered hexagonal structure of carbon atoms plays a crucial role in facilitating electron–phonon coupling and influencing the superconducting behavior and T<inf>c</inf> of NaLiC<inf>4</inf>. These findings highlight the thermodynamic and dynamic stability of NaLiC<inf>4</inf> as a promising candidate for exploring superconductivity, offering insights into its electronic properties, pressure-dependent T<inf>c</inf> behavior, and the influence of specific phonon modes. Further theoretical investigations and experimental studies are necessary to fully unlock the potential of NaLiC<inf>4</inf> and its contribution to the development of high-performance superconductors.
Some of the metrics are blocked by your
consent settings
Role of anharmonicity in phonon-mediated superconductivity of quasi- van der Waals layered XP2 (X = As, Sb, Bi) structures: Insight from first-principles calculations
(2023-10-10)
Tsuppayakorn-aek, Prutthipong
;
Pluengphon, Prayoonsak
;
Sukmas, Wiwittawin
;
Sakulkalavek, Aparporn
;
Inceesungvorn, Burapat
It is of utmost importance to prioritize the undertaking of investigating superconductivity, as it represents one of the most intriguing and significant phenomena in the field of condensed matter physics. Our research endeavors to shed light on the metallic state of van der Waals layered XP<inf>2</inf> (X = As, Sb, Bi) structures, which is crucial in predicting their superconducting properties. Employing a first-principle evolutionary algorithm, we predicted the structures of phosphides, including AsP<inf>2</inf>, SbP<inf>2</inf>, and BiP<inf>2</inf>, and determined their energetically stable configurations under atmospheric pressure. To investigate the potential for superconductivity in these structures, we conducted a thorough examination of relevant electronic properties. One of the crucial factors we addressed was the role of anharmonic phonon properties in determining the superconducting state in van der Waals layered structures. Our findings suggest that the introduction of anharmonicity can significantly suppress the superconducting abilities of such structures. Hence, the anharmonicity present in AsP<inf>2</inf>, SbP<inf>2</inf>, and BiP<inf>2</inf> could be held accountable for the lower observed superconducting critical temperature in these van der Waals layered structures.
Some of the metrics are blocked by your
consent settings
Influence of pressure on elasticity, mechanical properties, and Li diffusion in battery electrode material LiCoO2: First-principles calculations
(2023-09-01)
Sailuam, Wutthigrai
;
Fongkaew, Ittipon
;
Busayaporn, Wutthikrai
;
Klinkla, Rakchat
;
Phacheerak, Kanoknan
This study used first-principles calculations based on density functional theory with generalized gradient approximation (GGA) of the Perdew Burke and Ernzerhof (PBE) parameterized form to investigate the influence of pressure on the structural, elastic, and mechanical properties of rhombohedral LiCoO<inf>2</inf>. The results indicate that rhombohedral LiCoO<inf>2</inf> remains stable up to 10 GPa. The calculated ground state properties agree well with experimental and other calculation data, validating the approach. Additionally, the calculated elastic constants, bulk modulus, Young's modulus, shear modulus, and Poisson's ratio at 0 GPa agree with previous results. The study found that all elastic constants continuously increase with increasing pressure. The deformation resistances along the axial direction are stronger than those in shape. The relationship between elasticity and length is such that C<inf>11</inf> > C<inf>33</inf>, indicating that the incompressibility along the a axis is stronger than that along the c axis. The analysis of Poisson's ratio (ν) and Pugh's criterion B/G strongly suggests that rhombohedral LiCoO<inf>2</inf> exhibits ductile behavior under pressure up to 10 GPa. The material is clearly anisotropic behavior, but the material exhibits improved isotropic behavior as pressure increases. Regarding Li ion diffusion in rhombohedral LiCoO<inf>2</inf>, the study found that the migration pathway for Li ions in rhombohedral LiCoO<inf>2</inf> is a direct route that extends from the V<inf>Li</inf> site to the closest Li site. The diffusion process is hindered by a diffusion energy barrier of 0.87 eV, which is in good agreement with available theoretical data. Furthermore, the Li ion diffusion energy barrier increases with pressure because the decrease in d<inf>mean</inf> and polyhedral volume, along with changes in angle and torsional distortion factors of CoO<inf>6</inf> octahedra, which can reduce the charging and discharging speeds of Li-ion batteries that use rhombohedral LiCoO<inf>2</inf> as the cathode material.
Some of the metrics are blocked by your
consent settings
Role of Lifshitz transition stabilized carbon hexagon structure from biaxial strain: A case of sodium carbide with superconducting condition
(2023-06-15)
Tsuppayakorn-aek, Prutthipong
;
Pluengphon, Prayoonsak
;
Sukmas, Wiwittawin
;
Sukserm, Akkarach
;
Kotmool, Komsilp
We theoretically report on an investigation of sodium carbide system by means of first-principles calculations based on density functional theory. Herein, the diverse sodium–carbon structures are predicted by taking carbon-rich compositions of NaC<inf>2</inf> with a carbon hexagon structure as a starting point. Metallic phases of NaC<inf>2</inf> at a pressure of 100 GPa are predicted to be stabilized by biaxial strain, culminating in the strain-induced electronic topological transitions, also known as the Lifshitz transitions. We found that the flat band accommodates localized electrons around the Fermi level, originating from the effect of biaxial strain, which results in low-velocity electrons forming up to at least 20% of Cooper pairs. According to the respective phonon-mediated superconductivity, NaC<inf>2</inf> is dynamically stable not only without the influence of biaxial strain but also with that of the biaxial tensile strain, indicating possible enhancement of the critical temperature superconductor (T<inf>c</inf>). Furthermore, the estimated T<inf>c</inf> reaches 29.5 K, slightly higher than 24.7 K for the case without biaxial strain. These findings suggest that the possibility of superconductivity is promoted by the applied biaxial tensile strain. Our findings pave the way for future investigation of high superconductivity in carbon-based materials and suggest the possibility of metal-carbides being synthesisable and exhibiting quite a high T<inf>c</inf> superconductivity.
Some of the metrics are blocked by your
consent settings
The pressure effect on the structural, elastic, and mechanical properties of orthorhombic MgSiN2 from first-principles calculations
(2021-10-01)
Bootchanont, Atipong
;
Phacheerak, Kanoknan
;
Fongkaew, Ittipon
;
Limpijumnong, Sukit
;
Sailuam, Wutthigrai
Pressure effect on lattice parameters, elastic moduli, Poisson's ratio, Cauchy pressure, elastic anisotropy, and Vickers hardness of orthorhombic MgSiN<inf>2</inf> by means of first-principles calculations based on density functional theory (DFT) by generalized gradient approximation (GGA) in the functional form by Perdew, Bruke, and Ernzerhof (PBE) of the exchange-correlation were presented. The structural properties, elastic moduli, B<inf>0</inf>/G, Poisson's ratio (ν) and Cauchy pressure under pressure up to 10 GPa were calculated. The optimized structural and ground state properties under ambient pressure were in agreement with the available experiments and other calculations. The orthorhombic MgSiN<inf>2</inf> was mechanically stable under pressure up to 10 GPa by the elastic stability criteria investigation. Under pressure, the relationship of elasticity in length was C<inf>33</inf> > C<inf>11</inf> > C<inf>22</inf>, indicating that it is easier to compress along the b-axis than along the a-axis and c-axis, respectively. The calculated bulk modulus, shear modulus, Young's modulus and Poison's ratio index all increased with an increase in the pressure. The B<inf>0</inf>/G, Poisson's ratio (ν) and Cauchy pressure analyses implied that orthorhombic MgSiN<inf>2</inf> was single crystal, and a critical pressure for brittle-to-ductile transition was found to be 2 GPa. The Cauchy pressure of {100} plane, {010} plane and {001} plane, Vickers hardness (H<inf>v</inf>) and the shear anisotropy as a function of pressure were investigated from the calculation.
Some of the metrics are blocked by your
consent settings
First-principles study of Bi and Al in orthorhombic PbZrO3
(2016-04-01)
Chotsawat, Maneerat
;
Sarasamak, Kanoknan
;
Thanomngam, Pitiporn
;
Limpijumnong, Sukit
;
T-Thienprasert, Jiraroj
Lead zirconate PbZrO<inf>3</inf> (PZO) is one of the most important ceramic materials due to its antiferroelectric property, which can be used in many technological applications. Due to the toxicity of Pb, there is an attempt to replace Pb with other non-toxic elements. It has been reported that doping orthorhombic-PZO with Bi and Al atoms could stabilize the antiferroelectric property in a wide temperature range and reduce the lead content in the material. In this work, we used first-principles calculations based on density functional theory to investigate the microscopic and electronic structures of Bi and Al defects in orthorhombic-PZO. Our calculated defect formation energies revealed that Bi atom can substitute on either Pb site (A-site) or Zr site (B-site); depending on the Fermi-level as well as the crystal growth condition. On the other hand, Al atom is likely to substitute only on the Zr site. In addition, our calculations revealed that there is only a small binding between Bi<inf>Pb</inf> and adjacent Al<inf>Zr</inf> or Bi<inf>Zr</inf> with the binding energies of ∼0.2 eV. This indicates that Bi<inf>Pb</inf> and Al<inf>Zr</inf> (or Bi<inf>Zr</inf>) are unlikely to form complexes.
Some of the metrics are blocked by your
consent settings
X-ray absorption spectroscopy of indium nitride, indium oxide, and their alloys
(2010-04-16)
T-Thienprasert, Jiraroj
;
Rujirawat, Saroj
;
Nukeaw, Jiti
;
Limpijumnong, Sukit
To investigate the local structure of InN, In<inf>2</inf>O<inf>3</inf> and their alloys, synchrotron (In L<inf>3</inf>-edge) X-ray absorption near edge structures (XANES) of indium oxynitride samples with varied O contents are used in conjunction with first-principles calculations. A good agreement between the measured and simulated spectra is obtained. It is found that the spectra are sensitive to the coordination number of the In atoms, i.e., fourfold for InN-like structures and sixfold for In<inf>2</inf>O<inf>3</inf>-like structures. Moreover, the spectra are quite insensitive to the species (N or O) around In. The calculated band structures and density of states are also presented and discussed. © 2010 Elsevier B.V. All rights reserved.

KMITL

Browse

Filters

Settings

Sort By

Results per page

Search Results