International Journal of Physics | Vol. 1, No. 3, March 2010 | pp. 17–24
Research Article
Title: Dielectric Relaxation and AC Conductivity in Polyaniline-Titanium Dioxide Nanocomposites
Names of Authors: G. H. Nair¹, H. I. Rao², I. J. Kumar¹
Authors’ Affiliations: ¹Department of Physics, Cochin University of Science and Technology, Kochi, India; ²Department of Materials Science, National Institute of Technology, Warangal, India
Abstract: Polyaniline-TiO₂ nanocomposites with varying weight percentages (10 wt% to 40 wt%) of titanium dioxide nanoparticles were synthesized via an in-situ chemical oxidative polymerization technique. The frequency-dependent AC conductivity sigma_ac(omega) and dielectric permittivity epsilon' were measured in the frequency range of 10² Hz to 10⁶ Hz at room temperature (298 K). Analysis of the dielectric data reveals a Maxwell-Wagner-Sillars type interfacial polarization contributing to a large dielectric constant value exceeding epsilon' = 4.5 × 10³ at low frequencies. The AC conductivity follows the universal power law sigma_ac(omega) = A0 × omega^s, where the exponent s decreases from 0.94 to 0.62 with increasing temperature and filler concentration, supporting a correlated barrier hopping (CBH) charge transport model. X-ray diffraction and FTIR spectroscopy validate the homogeneous incorporation of anatase TiO₂ phases within the amorphous polyaniline matrix, showing peak crystallite sizes d = 18.4 nm.
Keywords: Nanocomposites, Polyaniline, Titanium dioxide, Dielectric relaxation, AC conductivity
Manuscript Timeline: Received 05 December 2009, Revised 10 January 2010, Accepted 18 January 2010, Published 01 March 2010
Citation: Nair, G. H., Rao, H. I., & Kumar, I. J. (2010). Dielectric Relaxation and AC Conductivity in Polyaniline-Titanium Dioxide Nanocomposites. International Journal of Physics, 1(3), 17–24. DOI: 10.46882/2010/IJP/000003
International Journal of Physics | Vol. 1, No. 9, September 2010 | pp. 65–72
Research Article
Title: Probing Neutrino Mass Hierarchies with Atmospheric Muon Decay Signatures at Deep-Core Detectors
Names of Authors: W. X. Yang¹, X. Y. Zhao²
Authors’ Affiliations: ¹Department of Physics, University of Wisconsin-Madison, Madison, USA; ²Kavli Institute for the Physics and Mathematics of the Universe, Kashiwa, Japan
Abstract: Atmospheric neutrino oscillations traversing Earth's matter core undergo resonant flavor conversions governed by the Mikheyev-Smirnov-Wolfenstein effect. We evaluate the sensitivity of multi-megaton ice/water Cherenkov detectors to resolve normal versus inverted neutrino mass hierarchies using multi-GeV muon neutrino event rates. Incorporating three-flavor mixing parameters including sin²(theta_13) = 0.025 and delta_cp phases, simulated cascade energy resolutions delta_E / E = 0.15 allow distinction of matter-induced asymmetries in the energy window E_v = 2 to 12 GeV. Baseline traversal path analysis reveals an enhanced electron appearance probability P(mu -> e) variance up to 14.5% near the zenith angle cos(theta_z) = -0.62. Systematic uncertainties related to the atmospheric flux ratio phi(nubar_mu) / phi(v_mu) are modeled using nuisance parameters, indicating a 3-sigma discovery potential for the mass hierarchy after 5 years of full detector exposure.
Keywords: Neutrino oscillation, Mass hierarchy, Atmospheric muons, Cherenkov detector, Matter effects
Manuscript Timeline: Received 01 June 2010, Revised 08 July 2010, Accepted 19 July 2010, Published 01 September 2010
Citation: Yang, W. X., & Zhao, X. Y. (2010). Probing Neutrino Mass Hierarchies with Atmospheric Muon Decay Signatures at Deep-Core Detectors. International Journal of Physics, 1(9), 65–72. DOI: 10.46882/2010/IJP/000009
International Journal of Physics | Vol. 1, No. 12, December 2010 | pp. 95–102
DOI: 10.46882/2010/IJP/000012
Article Type: Original Research Paper
Title: Experimental Evaluation of Plasma Parameter Profiles in a Low-Pressure Inductively Coupled Argon Discharge
Names of Authors: M. I. Garba¹, A. L. Nielsen²
Authors’ Affiliations: ¹Department of Physics, Bayero University, Kano, Nigeria; ²Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
Abstract: Inductively coupled plasma (ICP) sources are widely utilized in semiconductor manufacturing for precision etching and thin-film deposition due to their ability to generate high ion densities at low operating pressures. This study presents an experimental investigation of the spatial profiles of electron density, electron temperature, and plasma potential in a cylindrical ICP reactor operating with pure argon gas. The measurements were conducted using a computer-controlled, RF-compensated Langmuir probe across a radiofrequency (RF) power range of 100 W to 500 W at gas pressures between 1.33 Pa and 6.67 Pa. The experimental results show a distinct transition from the low-density capacitive mode (E-mode) to the high-density inductive mode (H-mode) when the RF power exceeds a threshold of 180 W at 2.67 Pa. In the H-mode, the peak electron density reaches 4.2 x 10¹¹ cm⁻³ near the reactor center, while the electron temperature remains stable between 2.8 eV and 3.5 eV. Spatial profiles reveal that the electron energy distribution function (EEDF) deviates significantly from a Maxwellian distribution at lower pressures, exhibiting a bi-Maxwellian structure due to nonlocal electron kinetics. These spatial metrics provide essential baseline data for validating two-dimensional fluid models of industrial plasma processing chambers.
Keywords: Inductively coupled plasma; Argon discharge; Langmuir probe; Electron density; Electron temperature; E-H mode transition; Electron energy distribution function; Semiconductor processing.
Manuscript Timeline: Received: September 05, 2010; Revised: October 20, 2010; Accepted: November 12, 2010; Published: December 02, 2010.
Citation: Garba, M. I., & Nielsen, A. L. (2010). Experimental Evaluation of Plasma Parameter Profiles in a Low-Pressure Inductively Coupled Argon Discharge. International Journal of Physics, 1(12), 95–102.
International Journal of Physics | Vol. 1, No. 7, July 2010 | pp. 49–56
Research Article
Title: Anomalous Thermal Transport in Single-Layer Graphene Ribbons with Isotopic Defects
Names of Authors: R. S. Tan¹, S. T. Wu²
Authors’ Affiliations: ¹Department of Physics, National University of Singapore, Singapore; ²School of Physics, Peking University, Beijing, China
Abstract: Nonequilibrium molecular dynamics simulations were conducted to examine thermal conductivity kappa in rectangular graphene ribbons possessing random carbon-13 isotope substitutions. Concentration fractions c of isotopic impurities varied from 0.01 to 0.50. The room-temperature thermal conductivity decreases from a pristine baseline value of kappa = 3100 W/mK down to 850 W/mK at c = 0.50 due to enhanced mass-difference phonon scattering. Spectral energy analysis indicates that low-frequency acoustic phonons retain long mean free paths, whereas high-frequency optical modes experience substantial localization. By applying the Allen-Feldman theory alongside Green-Kubo formalisms, we establish that boundary scattering combined with isotopic point-defect disorder yields a temperature scaling of kappa proportional to T^(-1.2) in the 200 K to 400 K regime. These findings outline design limitations for thermal management in carbon-based nanoelectronic devices.
Keywords: Graphene, Thermal conductivity, Isotopic defects, Molecular dynamics, Phonon scattering
Manuscript Timeline: Received 02 April 2010, Revised 10 May 2010, Accepted 20 May 2010, Published 01 July 2010
Citation: Tan, R. S., & Wu, S. T. (2010). Anomalous Thermal Transport in Single-Layer Graphene Ribbons with Isotopic Defects. International Journal of Physics, 1(7), 49–56. DOI: 10.46882/2010/IJP/000007
International Journal of Physics | Vol. 1, No. 10, October 2010 | pp. 78–86
DOI: 10.46882/2010/IJP/000010
Article Type: Original Research Paper
Title: Thermoelectric Power Factor Enhancement in Nanostructured Silicon-Germanium Alloys via Energy Filtering Effects
Names of Authors: O. S. Adeyemi¹, K. N. Gupta²
Authors’ Affiliations: ¹Department of Physics, University of Abuja, Abuja, Nigeria; ²Department of Physics, Indian Institute of Science, Bangalore, India
Abstract: Silicon-germanium (Si-Ge) alloys are widely used in high-temperature thermoelectric generators, such as radioisotope thermoelectric generators for space exploration. However, their conversion efficiency remains limited by a coupled relationship between electrical conductivity and the Seebeck coefficient. This work presents a transport model designed to enhance the thermoelectric power factor of nanostructured n-type Si_0.8Ge_0.2 alloys by utilizing energy filtering effects at grain boundaries. The carrier transport equations were resolved using the Boltzmann transport equation under the relaxation time approximation. The model incorporates a series of potential barriers designed to scatter low-energy carriers while allowing high-energy electrons to pass unhindered. Our calculations indicate that introducing a potential barrier height of 0.15 eV increases the Seebeck coefficient from -140 μV/K to -215 μV/K at 900 K. Although the filtering barriers cause a 25% drop in total electrical conductivity, the net power factor (S²σ) rises by 38%, reaching a maximum value of 4.2 x 10^-3 W/(mK²). This enhancement is highly sensitive to the spatial distribution of doping impurities and the average grain size, with an optimal grain boundary spacing identified at 25 nm. These results suggest that tailoring grain boundary potential heights can optimize the power factor of bulk Si-Ge materials.
Keywords: Thermoelectric materials; Silicon-germanium alloys; Power factor; Seebeck coefficient; Energy filtering; Boltzmann transport equation; Grain boundaries; Carrier relaxation time.
Manuscript Timeline: Received: July 19, 2010; Revised: September 04, 2010; Accepted: September 29, 2010; Published: October 22, 2010.
Citation: Adeyemi, O. S., & Gupta, K. N. (2010). Thermoelectric Power Factor Enhancement in Nanostructured Silicon-Germanium Alloys via Energy Filtering Effects. International Journal of Physics, 1(10), 78–86.
International Journal of Physics | Vol. 1, No. 6, June 2010 | pp. 41–48
Research Article
Title: Laser-Induced Breakdown Spectroscopy Analysis of Trace Heavy Metals in Contaminated Agricultural Soils
Names of Authors: O. P. Silva¹, P. Q. Santos², Q. R. Lima³
Authors’ Affiliations: ¹Instituto de Física Gleb Wataghin, UNICAMP, Campinas, Brazil; ²Department of Chemistry and Physics, University of São Paulo, São Paulo, Brazil; ³Embrapa Solos, Rio de Janeiro, Brazil
Abstract: Laser-induced breakdown spectroscopy (LIBS) was optimized for rapid quantitative detection of lead (Pb), cadmium (Cd), and chromium (Cr) pollutants in agricultural topsoils. A Q-switched Nd:YAG laser operating at lambda = 1064 nm with pulse energy E = 50 mJ generated high-temperature micro-plasmas. Calibration curves constructed using isolated atomic emission lines (Pb I at 405.78 nm, Cd I at 228.80 nm, and Cr I at 425.43 nm) demonstrated high linearity, with correlation coefficients R² greater than 0.982. The limits of detection (LOD) achieved were 4.2 mg/kg for Pb, 1.8 mg/kg for Cd, and 3.1 mg/kg for Cr. Matrix effects compensated by internal standardization using dominant Fe lines significantly improved measurement reproducibility, holding relative standard deviation (RSD) below 4.8%. The LIBS methodology proved capable of field-deployable multi-element screening without extensive chemical digestion pre-treatments.
Keywords: Laser-induced breakdown spectroscopy, Heavy metals, Soil contamination, Atomic emission, Trace analysis
Manuscript Timeline: Received 05 March 2010, Revised 12 April 2010, Accepted 22 April 2010, Published 01 June 2010
Citation: Silva, O. P., Santos, P. Q., & Lima, Q. R. (2010). Laser-Induced Breakdown Spectroscopy Analysis of Trace Heavy Metals in Contaminated Agricultural Soils. International Journal of Physics, 1(6), 41–48. DOI: 10.46882/2010/IJP/000006