KMITL

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

Browse

Search Results

Now showing 1 - 10 of 18

Some of the metrics are blocked by your
consent settings
Possible high-temperature superconductivity in LiCuH at ambient pressure
(2026-12-01)
Tsuppayakorn-aek, Prutthipong
;
Thasitha, Sirinee
;
Udomkijmongkol, Anan
;
Sukmas, Wiwittawin
;
Hussain, Tanveer
We theoretically investigate the structural stability, electronic property, and superconductivity of the hydrogen-rich compound LiCuH in its face-centered cubic phase. First-principles calculations show that LiCuH is thermodynamically metastable at ambient pressure but dynamically stable. Moreover, ab initio molecular dynamics (AIMD) simulation at 300 K further confirms that LiCuH remains structurally intact without decomposition. These results suggest that the material may be synthesized under high pressure and retained after decompression. Although thermodynamically metastable at ambient conditions, its dynamic stability supports its persistence after pressure release. Moreover, LiCuH exhibits metallic behavior with a flat band and van Hove singularity (vHS) near the Fermi level and Fermi-surface states dominated by Cu–d and H–s orbitals. Phonon calculations further indicate that hydrogen vibrations dominate the phonon contribution, while the electronic states near the Fermi level govern the coupling strength, resulting in a large electron–phonon coupling constant. Insights into the superconducting temperature () are obtained using various theoretical approaches, which estimate to be in the range of 93–152 K. Bonding analysis further indicates mixed covalent–ionic character within Cu–H octahedra. These results highlight LiCuH as a promising hydrogen-based metastable superconductor for future experimental exploration.
Some of the metrics are blocked by your
consent settings
Structural stabilities, elastic property, and robust topological phases in Janus MoWCO2MXene from first-principles investigation
(2026-02-25)
Thasitha, Sirinee
;
Tsuppayakorn-aek, Prutthipong
;
Kaewmaraya, Thanayut
;
Hussain, Tanveer
;
Bovornratanaraks, Thiti
Two-dimensional (2D) topological materials have attracted considerable interest because of their potential applications in next-generation quantum and spintronic devices. In this work, we systematically investigate the structural, mechanical, and electronic properties of Janus MoWCO<inf>2</inf> MXene using first-principles density functional theory (DFT) calculations, both with and without spin–orbit coupling (SOC). The energetically favored O-terminated configurations are examined in detail, revealing that the 2H phase exhibits higher thermodynamic, mechanical, and dynamical stability than the 1T phase. In the absence of SOC, both phases display metallic behavior. Upon inclusion of SOC, a band inversion emerges at the Γ point. In particular, SOC opens a narrow band gap of approximately 0.10 eV in the 2H phase, whereas the 1T phase remains gapless and exhibits semimetallic characteristics. Topological analysis based on helical edge states and Z<inf>2</inf> invariants indicates that 2H-MoWCO<inf>2</inf> is a strong topological insulator candidate, while 1T-MoWCO<inf>2</inf> can be classified as a topological semimetal candidate. These findings suggest that Janus MoWCO<inf>2</inf> MXene represents a promising two-dimensional platform for exploring SOC-driven topological phases and related quantum phenomena.
Some of the metrics are blocked by your
consent settings
Exploring phonon mediated superconductivity of and under high pressure insight from first-principles calculations
(2025-12-01)
Tsuppayakorn-aek, Prutthipong
;
Bovornratanaraks, Thiti
;
Kotmool, Komsilp
Investigating novel materials under high pressure presents a challenge in condensed matter physics. In this study, we examine and, materials identified through an evolutionary algorithm, which exhibit thermodynamic stability up to at least 100 GPa. Our findings reveal that exhibits a rhombohedral structure () at pressures ranging from 0 GPa to 25 GPa, transitioning to a hexagonal structure () between 50 GPa and 100 GPa. In contrast, is predicted to have a monoclinic structure (C2/m) at low pressures and a hexagonal structure () at higher pressures. Notably, both materials are dynamically stable within the harmonic approximation at pressures beyond 15 GPa for and beyond 25 GPa for. Furthermore, accurately capturing the thermal lattice vibrations of these materials under strong quantum anharmonicity requires advanced methods. Using a stochastic approach to self-consistent harmonic approximation (SSCHA), we introduce anharmonic corrections to further explore lattice dynamics. For superconducting properties, shows a remarkable critical temperature () of 44.5 K at a pressure of 25 GPa, as predicted within the harmonic approximation. In comparison, achieves a of approximately 13 K at a pressure of 50 GPa when anharmonic corrections are applied using the Allen-Dynes modified McMillan equation. Our findings bridge a gap in understanding electronic band structure, phonon linewidth impacts, and vibrational modes under pressure, offering key insights into phase stability and superconducting mechanisms. These findings introduce a promising new class of materials, emphasizing their potential to enrich superconductivity research by advancing previously overlooked substances.
Some of the metrics are blocked by your
consent settings
Exploring Hydrogen-Bearing Metallic Alloys: Phonon-Mediated Superconductivity in (Zr,Hf)H3 under High Pressure
(2025-01-09)
Tsuppayakorn-Aek, Prutthipong
;
Sukmas, Wiwittawin
;
Kotmool, Komsilp
;
Luo, Wei
;
Bovornratanaraks, Thiti
Advanced structural forecasting of alloy hydrides, particularly through cluster expansion combined with first-principles calculations, opens up new possibilities for discovering novel phases in transition metal alloy hydrides like (Zr,Hf)H<inf>3</inf>. Within this framework, significant findings have been made for compounds Zr<inf>7</inf>HfH<inf>24</inf>, Zr<inf>4</inf>Hf<inf>2</inf>H<inf>18</inf>, Zr<inf>2</inf>Hf<inf>2</inf>H<inf>12</inf>, and Zr<inf>2</inf>Hf<inf>4</inf>H<inf>18</inf>, which demonstrate thermodynamic stability at 100 GPa. All identified structures exhibit metallic properties, suggesting a promising pathway to superconductivity. In terms of superconducting properties, Zr<inf>7</inf>HfH<inf>24</inf>, Zr<inf>4</inf>Hf<inf>2</inf>H<inf>18</inf>, Zr<inf>2</inf>Hf<inf>2</inf>H<inf>12</inf>, and Zr<inf>2</inf>Hf<inf>4</inf>H<inf>18</inf> show critical temperatures (T<inf>c</inf>) of 15.9, 14.6, 8.2, and 12.8 K, respectively, at 100 GPa. Notably, Zr<inf>4</inf>Hf<inf>2</inf>H<inf>18</inf> achieves the highest T<inf>c</inf> within the (Zr,Hf)H<inf>3</inf> series, reaching approximately 17 K at 150 GPa. Our analysis of the superconducting state is based on H-rich criteria under specific conditions, revealing that hydrogen’s contribution to the partial density of states is lower than that of hafnium and zirconium. The investigation also finds that these structures lack H clathrate configurations or H<inf>2</inf>-like molecular units, suggesting they are unlikely to reach near-room-temperature T<inf>c</inf>. These results highlight how structural frameworks supported by H or H<inf>2</inf>-like molecules could potentially enhance superconductivity. Additionally, the alignment of the vibrational modes of the alloy with those observed in hafnium suggests that Hf-substituted Zr alloys support superconductivity and offer theoretical feasibility for achieving higher critical temperatures across a broader range of alloying combinations.
Some of the metrics are blocked by your
consent settings
Strong electron–phonon coupling and predicted high superconducting transition temperature of MXenes revealed in 2H-Mo2N under biaxial stress
(2024-12-15)
Kotmool, Komsilp
;
Tsuppayakorn-aek, Prutthipong
;
Bovornratanaraks, Thiti
;
Kaewmaraya, Thanayut
;
Sakdanuphab, Rachsak
Extensive investigations have been conducted on Mo-based MXenes due to their high superconducting temperatures (T<inf>c</inf>). This work theoretically reports strong electron–phonon coupling (EPC) and high T<inf>c</inf> (≈38 K) of 2H-Mo<inf>2</inf>N under biaxial stress, with excellent mechanical properties. EPC and T<inf>c</inf> are elucidated upon dynamically stable strain range. At 0% strain, EPC constant (λ) and T<inf>c</inf> are 1.32 and 22.7 K, respectively. They are improved when subjected to biaxial stresses. Strong EPC with λ over 2.0 occurs at −4%, −2.5%, and 5% strains, yielding enhanced T<inf>c</inf>. The finding suggests that the energy levels of electronic bands at the Fermi level are enhanced by strain, which enhances EPC. Moreover, the impact of functional groups on superconductivity has been investigated. The λ’s of Mo<inf>2</inf>NH<inf>2</inf> and Mo<inf>2</inf>NO<inf>2</inf> are reduced, and T<inf>c</inf> drops nearly to 20.0 and 0.9 K, respectively. This work provides an example of designing 2D superconductors by tuning atomic recipes and strain-dependent engineering.
Some of the metrics are blocked by your
consent settings
Hydrogenation-induced superconducting properties of MgB2 investigated using Migdal–Eliashberg formalism: Insights from a first-principles study
(2024-09-01)
Tsuppayakorn-aek, Prutthipong
;
Sukmas, Wiwittawin
;
Pluengphon, Prayoonsak
;
Petchsirivej, Sukanya
;
Sakulkalavek, Aparporn
Theoretical investigation of hydrogenation processes has applied to magnesium diborides under ambient conditions, which identified two structurally stable phases, i.e, Mg<inf>4</inf>B<inf>6</inf>H<inf>2</inf> and Mg<inf>4</inf>B<inf>4</inf>H<inf>4</inf>. These identifications were evaluated through assessments of their lattice dynamics stability using density functional perturbation theory. Both phases exhibit metallic behavior within their electronic band structures. Our findings showcase the significant impact of anisotropic Migdal–Eliashberg calculations, enhancing the superconducting properties within this system and resulting in a notably higher T<inf>c</inf> of 34 K. Mg<inf>4</inf>B<inf>4</inf>H<inf>4</inf> exhibits superconductivity with a T<inf>c</inf> of 17 K under atmospheric conditions, as determined by anisotropic Migdal–Eliashberg calculations. Our study underscores the wide range of structural variations achievable through the hydrogenation of MgB<inf>2</inf> and highlights the crucial importance of hydrogen atom placement within these structures. In addition, the calculation result indicates the influence of band dispersion characteristics on Fermi velocity, a factor attributed to both anharmonicity and harmonicity, which plays a pivotal role in determining the superconducting properties of these materials.
Some of the metrics are blocked by your
consent settings
Novel hard and unusual superconducting monoclinic phase of FeB2C2: An ab initio evolutionary study
(2024-06-14)
Kotmool, Komsilp
;
Pinsook, Udomsilp
;
Luo, Wei
;
Ahuja, Rajeev
;
Bovornratanaraks, Thiti
This study focuses on conducting an ab initio evolutionary investigation to search for stable polymorphs of iron diborocarbides with the formula FeB 2 C 2 . We also examined other forms of C contents, including FeB 3 C and FeBC 3 . Our findings reveal that the lowest energetic structure of FeB 2 C 2 is a semimetallic monoclinic phase with a space group (s.g.) of C2/m and a metastable metallic phase of FeB 2 C 2 is an orthorhombic structure with s.g. of Pmmm. In addition, structural and relative properties of FeB 3 C and FeBC 3 are performed and discussed to compare with FeB 2 C 2 . All predicted structures are dynamically and elastically stable, verified without negative phonon frequency and Born criteria, respectively. We also analyzed the energetic stability through calculated cohesive and formation energies, which showed that C2/m- FeB 2 C 2 is stable at low pressure. Interestingly, the C2/m and Pmmm phases of FeB 2 C 2 are hard materials with Vickers hardness ( H v ) of 22.40 and 27.52 GPa, respectively. Additionally, we examined the electron-phonon coupling of both FeB 2 C 2 phases. Unexpectedly, we found that the semimetallic C2/m- FeB 2 C 2 phase is a superconductor with a significant superconducting temperature ( T c ) exceeding 6 K. These findings provide some novel results for the Fe-B-C system and pave the way for investigating other metal borocarbides and related ternary compounds.
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
Stability, thermodynamic, electronic, and thermoelectric properties of triclinic Cu2Se structure
(2024-06-01)
Kotmool, Komsilp
;
Khammuang, Satchakorn
;
Rudradawong, Chalermpol
;
Thatsami, Niphat
;
Kaewmaraya, Thanayut
The conversion of heat into electricity using the thermoelectric effect is a crucial issue to tackle the ever-increasing global energy consumption. Cu<inf>2</inf>Se is one of the high-performance thermoelectric materials due to its liquid-like atomic structure, which minimizes the phonon-derived thermal conductivity. Nevertheless, the unambiguous atomic structure of the low-temperature phase, α-Cu<inf>2</inf>Se, remains controversial. By employing a combination of theoretical approaches including an evolutionary algorithm for structural searching, density functional theory, and lattice dynamics, the α-Cu<inf>2</inf>Se phase is proposed to crystalize in the dynamically stable triclinic Cu<inf>2</inf>Se structure (s.g. P1) which can be regarded as a monoclinic polymorph (s.g. P2<inf>1</inf>/c<sup>†</sup>) through slight distortion. The corresponding heat capacity (C<inf>V</inf>) and Debye temperature (Θ<inf>D</inf>) are 0.37 J/g K and 276 K, respectively, indicating low thermal conductivity in the material. The semiconducting P1 phase possesses an indirect gap of 1.0 eV. Additionally, based on the Boltzmann transportation theory, fundamental thermoelectric parameters around the transition temperature (300–500 K) are investigated. Beyond the semiconducting phase, a novel metallic phase identified as the triclinic P1̄ phase is also discovered, exhibiting a two-dimensional (2D) crystal geometry.
Some of the metrics are blocked by your
consent settings
First-principles study on structural stabilities, mechanical properties, and biaxial strain-induced superconductivity in Janus MoWC monolayer
(2024-05-27)
Thasitha, Sirinee
;
Tsuppayakorn-Aek, Prutthipong
;
Udomkijmongkol, Anan
;
Khammuang, Satchakorn
;
Kaewmaraya, Thanayut
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 (T<inf>c</inf>) of 1.6 K, and the superconductivity of 2H phase can be enhanced by biaxial strain with the T<inf>c</inf> 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.

KMITL

Browse

Filters

Settings

Sort By

Results per page

Search Results