International Journal of Physics | Vol. 13, No. 6, June 2022 | pp. 41–48
DOI: 10.46882/2022/IJP/000146
Research Article
Title: Thermal Dispersion Metrics and Phonon Scattering at Silicon-Carbide Superlattice Interfaces
Names of Authors: M. G. Richter¹, D. W. Meyer²
Authors’ Affiliations:
¹ Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany
² Institute of Physics, Karlsruher Institut für Technologie, Karlsruhe, Germany
Abstract: Effectively dissipating heavy thermal loads across mismatched semiconductor boundaries is a major technical hurdle in developing next-generation wide-bandgap high-power electronics and electric vehicle control modules. This paper uses molecular dynamics simulations to quantify thermal dispersion metrics and track phonon wavepacket scattering at defective silicon-carbide (Si-SiC) superlattice interfaces. We constructed atomistic models using the optimized Tersoff empirical potentials, incorporating varying concentrations of interfacial dislocation networks and chemical grading steps. Longitudinal and transverse acoustic phonon wavepackets were generated with narrow frequency spreads centered between 2.0 THz and 10.0 THz. The computational data demonstrate that high-frequency acoustic phonons (f greater than 5.5 THz) undergo strong diffuse scattering at the rough interface, dropping the calculated transmission coefficient from 0.82 down to 0.18. This transport degradation is driven by severe acoustic impedance mismatch and localized interface vibrational modes. The overall interfacial thermal conductance was calculated to decrease by 46.0% when the interface roughness parameter scaled from 0.1 nm to 0.6 nm at 300.0 K. These molecular dynamics calculations clarify the atomic-scale paths limiting heat carrier propagation, helping engineers design targeted thermal management interfaces.
Keywords: Thermal conductance; phonon wavepacket; molecular dynamics; superlattice interfaces; silicon carbide; electronics cooling
Manuscript Timeline: Received: March 02, 2022; Revised: April 14, 2022; Accepted: May 02, 2022; Published: June 15, 2022
Citation: Richter, M. G., & Meyer, D. W. (2022). Thermal Dispersion Metrics and Phonon Scattering at Silicon-Carbide Superlattice Interfaces. International Journal of Physics, 13(6), 41–48.
International Journal of Physics | Vol. 13, No. 5, May 2022 | pp. 33–40
DOI: 10.46882/2022/IJP/000145
Research Article
Title: Relativistic Hydrodynamic Modeling of Particle Production Cascades in Asymmetric Sulfur-Gold Collisions
Names of Authors: H. L. Mueller¹, S. C. O’Brien²
Authors’ Affiliations:
¹ Institut für Kernphysik, Karlsruher Institut für Technologie, Karlsruhe, Germany
² School of Physics, University College Dublin, Dublin, Ireland
Abstract: High-energy asymmetric heavy-ion collisions provide a unique experimental baseline to map out the spatial geometry boundaries and core transport conditions required to produce a collective quark-gluon plasma droplet. This study presents a relativistic hydrodynamic modeling framework to simulate particle production cascades in asymmetric sulfur-gold (S-Au) collisions at a center-of-mass energy of 200.0 GeV per nucleon pair. We utilized a 3+1 dimensional viscous hydrodynamic code coupled with a statistical hadronization module to compute transverse momentum spectra and azimuthal anisotropy coefficients. The initial energy density profiles were generated using a Monte Carlo Glauber model to capture sub-nucleon scale configurations. The numerical simulations show that expanding systems build a substantial radial flow profile, which shifts the mean transverse momentum of protons up to 1.32 GeV/c in high-multiplicity events. The calculated elliptic flow coefficient (v²) displays a strong mass-ordering effect, which matches experimental measurements gathered by modern tracking spectrometers within a tight ±5.8% margin. This close agreement suggests that intermediate asymmetric systems can achieve brief hydrodynamic collective expansion. These findings help clarify the boundaries of fluid-like behavior in subatomic interactions.
Keywords: Relativistic hydrodynamics; particle production; sulfur-gold collisions; elliptic flow; Glauber model; statistical hadronization
Manuscript Timeline: Received: February 11, 2022; Revised: March 24, 2022; Accepted: April 10, 2022; Published: May 16, 2022
Citation: Mueller, H. L., & O’Brien, S. C. (2022). Relativistic Hydrodynamic Modeling of Particle Production Cascades in Asymmetric Sulfur-Gold Collisions. International Journal of Physics, 13(5), 33–40.
International Journal of Physics | Vol. 13, No. 4, April 2022 | pp. 25–32
DOI: 10.46882/2022/IJP/000144
Research Article
Title: Kinetic Simulation of Electron Transport Properties and Ionization Coefficients in Low-Pressure Carbon Dioxide-Argon Plasmas
Names of Authors: A. M. El-Chemali¹, S. H. Zhang²
Authors’ Affiliations:
¹ Department of Physics, Faculty of Science, Lebanese University, Beirut, Lebanon
² Department of Physics, Tsinghua University, Beijing, China
Abstract: Carbon dioxide gas discharges enriched with noble gas buffers are widely deployed across green engineering sectors for greenhouse gas recycling, plasma etching, and waste processing. This study develops a self-consistent kinetic simulation model to evaluate electron transport properties and compute ionization coefficients in low-pressure CO₂-Ar mixtures. We solved the electron Boltzmann equation using a multi-term spherical harmonic expansion engine over a reduced electric field range (E/N) spanning 5.0 Td to 500.0 Td. The model incorporates comprehensive cross-section sets detailing elastic scattering, rotational excitation, vibrational thresholds, dissociative attachment, and electron-impact ionization tracks. Our calculations demonstrate that introducing argon carriers (from 20.0% to 80.0% by volume) significantly elevates the high-energy tail of the electron energy distribution function. At E/N = 50.0 Td, the total CO₂ dissociation rate coefficient scales up by an order of magnitude due to Penning ionization actions mediated by metastable argon configurations. The calculated electron drift velocity constants match independent swarm experimental tracks within a tight ±4.5% variance, providing fundamental target vectors for reactor optimization.
Keywords: Carbon dioxide plasmas; Boltzmann equation; electron transport; plasma kinetics; cross-section; Penning ionization
Manuscript Timeline: Received: January 08, 2022; Revised: February 17, 2022; Accepted: March 09, 2022; Published: April 12, 2022
Citation: El-Chemali, A. M., & Zhang, S. H. (2022). Kinetic Simulation of Electron Transport Properties and Ionization Coefficients in Low-Pressure Carbon Dioxide-Argon Plasmas. International Journal of Physics, 13(4), 25–32.
International Journal of Physics | Vol. 13, No. 3, March 2022 | pp. 17–24
DOI: 10.46882/2022/IJP/000143
Research Article
Title: High-Pressure Elastic Moduli and Structural Transitions in Ultra-Incompressible Tantalum Diboride
Names of Authors: V. I. Morozov¹, D. L. Santos²
Authors’ Affiliations:
¹ Institute of High Pressure Physics, Russian Academy of Sciences, Troitsk, Russia
² Department of Physics, University of Coimbra, Coimbra, Portugal
Abstract: Synthesizing ultra-incompressible refractory materials capable of retaining structural integrity under extreme mechanical stress and shear paths is vital for aerospace components and industrial drill systems. This paper examines the high-pressure elastic moduli and evaluates structural transitions in hexagonal tantalum diboride (TaB₂) up to hydrostatic pressures of 140.0 GPa. We performed first-principles density functional theory computations within the generalized gradient approximation framework across compressed lattice profiles. At zero pressure, the calculated bulk modulus is B0 = 291.0 GPa, with an elastic derivative value of B0' = 4.10, matching experimental diamond anvil cell measurements within a 1.2% margin. The single-crystal elastic constants (C11, C33, C44, C12, and C13) climb linearly under volumetric compression, matching all Born mechanical stability criteria across the tested pressure limits. The directional compressibility curves show that the crystal c-axis displays exceptional rigidity due to short, highly covalent tantalum-boron networks interlocking the basal atomic planes. Electronic density of states charts verify a large population at the Fermi edge, proving that TaB₂ retains its metallic profile under ultra-high structural strain.
Keywords: Tantalum diboride; density functional theory; elastic constants; high pressure; mechanical stability; directional compressibility
Manuscript Timeline: Received: December 14, 2021; Revised: January 20, 2022; Accepted: February 08, 2022; Published: March 11, 2022
Citation: Morozov, V. I., & Santos, D. L. (2022). High-Pressure Elastic Moduli and Structural Transitions in Ultra-Incompressible Tantalum Diboride. International Journal of Physics, 13(3), 17–24.
International Journal of Physics | Vol. 13, No. 2, February 2022 | pp. 9–16
DOI: 10.46882/2022/IJP/000142
Research Article
Title: Resonant Energy Transfer Dynamics between Colloidal InP Quantum Dots and Monolayer Molybdenum Disulfide
Names of Authors: T. H. Nguyen¹, M. G. Richter²
Authors’ Affiliations:
¹ Department of Physics, Vietnam National University, Hanoi, Vietnam
² Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany
Abstract: Hybrid zero-dimensional and two-dimensional semiconductor assemblies provide new pathways for designing light-harvesting architectures, field-effect transistors, and highly sensitive photodetectors. This paper evaluates the non-radiative Förster resonant energy transfer (FRET) dynamics between colloidal indium phosphide (InP) core-shell quantum dots and monolayer molybdenum disulfide (MoS₂). The hybrid thin-film interfaces were prepared via sequential spin-coating routines onto quartz substrates. We carried out steady-state photoluminescence and time-resolved single-photon counting tracks at an operating room temperature of 300 K. The experimental measurements reveal a strong 80.0% quenching of the quantum dot photoluminescence yield when layered onto the MoS₂ sheet. Concurrently, the average exciton lifetime of the InP quantum dots decreased from 5.8 ns down to 1.15 ns. This lifetime shortening yields a calculated FRET efficiency of 80.1% with an energy transfer rate of 0.70 ns⁻¹. The donor-acceptor separation thickness was estimated to be 4.0 nm using the standard Förster model. Spectral overlap maps verify that energy migration is governed by the crossover between quantum dot emission and the MoS₂ exciton absorption profiles, facilitating near-field sensitization.
Keywords: Quantum dots; molybdenum disulfide; resonant energy transfer; fluorescence lifetime; hybrid nanostructures; optoelectronics
Manuscript Timeline: Received: November 02, 2021; Revised: December 18, 2021; Accepted: January 11, 2022; Published: February 15, 2022
Citation: Nguyen, T. H., & Richter, M. G. (2022). Resonant Energy Transfer Dynamics between Colloidal InP Quantum Dots and Monolayer Molybdenum Disulfide. International Journal of Physics, 13(2), 9–16.
International Journal of Physics | Vol. 13, No. 1, January 2022 | pp. 1–8
DOI: 10.46882/2022/IJP/000141
Research Article
Title: Density Functional Theory Analysis of Catalytic Carbon Dioxide Reduction on Boron-Doped Graphene Nanoribbons
Names of Authors: A. L. Silva¹, H. L. Mueller²
Authors’ Affiliations:
¹ Institute of Physics, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
² Institut für Kernphysik, Karlsruher Institut für Technologie, Karlsruhe, Germany
Abstract: Electrochemical reduction of carbon dioxide (CO₂) into chemical feedstocks provides a promising strategy for carbon capture operations and synthetic fuel manufacturing. This investigation uses density functional theory calculations to analyze the catalytic performance and reaction pathways of CO₂ reduction on metal-free boron-doped graphene nanoribbons. We modeled three distinct layouts: edge boron substitution, central boron cluster networks, and boron-doped single vacancy sites. Free energy profiles for intermediate steps leading to molecular formic acid (HCOOH) and carbon monoxide (CO) were computed using the computational hydrogen electrode framework. The quantum calculations demonstrate that edge boron substitution sites lower the activation barrier for the initial rate-determining protonation step (*CO₂ + H⁺ + e⁻ -> *COOH) to 0.46 eV. This value is significantly lower than the 1.18 eV barrier calculated for pristine graphene structures. The overpotential required to trigger selective formic acid production on boron configurations was estimated at -0.40 V versus the standard hydrogen electrode. Charge density mappings show that boron doping induces localized electron deficiency and spin polarization on adjacent carbon atoms, stabilizing the intermediates.
Keywords: Carbon dioxide reduction; density functional theory; boron-doped graphene; electrocatalysis; reaction mechanism; overpotential
Manuscript Timeline: Received: October 12, 2021; Revised: November 24, 2021; Accepted: December 15, 2021; Published: January 14, 2022
Citation: Silva, A. L., & Mueller, H. L. (2022). Density Functional Theory Analysis of Catalytic Carbon Dioxide Reduction on Boron-Doped Graphene Nanoribbons. International Journal of Physics, 13(1), 1–8.