Open Access Short Research Article

The Case Studies of PtX2 (X = As, P) as High Thermo-power Materials

Adewumi I. Popoola, Adebayo T. Adepoju

Physical Science International Journal, Page 26-36
DOI: 10.9734/psij/2021/v25i230242

For thermoelectric applications, semiconductors are generally better than metals and insulators. PtAs2 and PtP2 are indirect energy gap semiconductors that have been predicted with high thermo-powers (PtP2 having higher thermopower than PtAs2). The crystal structure and the electronic structure of PtAs2 and PtP2 are similar except for the energy band gap of PtP2 that is wider than that of PtAs2. The generalized gradient approximation of the Density Functional Theory (DFT), the Density Functional Perturbation Theory (DFPT) were used to explore the full elastic tensors, phonon dispersion and the thermodynamics of PtP2 and PtAs2. This was done to understand the link, if any, between high thermo-power materials and the results. The two compounds are dynamically and elastically stable with higher mechanical properties recorded for PtP2 over PtAs2. The calculated entropy, vibration free energy and the heat capacity at constant volume for PtAs2 (PtP2) were 354.51 (264.18) J/K; -9.21 (27.84) kJ and 276.04 (250.36) J/K at 300 K respectively. The low frequency acoustic modes are between 100 - 170 cm-1 for PtAs2 while it is between100 - 190 cm-1 for PtP2. The calculated high frequency transverse optical (TO) mode for PtP2 is 410 cm-1 while it is 250 cm-1 for PtAs2.  Further analysis of the phonons spectrum showed that additional bond-bending modes can be created in PtP2 than in PtAs2.  All the results points toward PtP2 as better material over PtAs2 for thermoelectric application and these, with or without the knowledge of the energy bandgap can serve to guide material selection/modelling.

Open Access Minireview Article

A Study on Instabilities and Nonlinear Wave Energy Exchange Process in Terrestrial Ionospheric Plasma

S. J. Gogoi

Physical Science International Journal, Page 12-19
DOI: 10.9734/psij/2021/v25i230240

From ground and satellite based observatories, various forms of nonlinear effects and plasma waves instabilities are observed in the Earth’s ionosphere. In this paper we present a brief review on nonlinear wave-particle interaction energy exchange mode plasma maser instability and on probable growth rate of high frequency non-resonant waves at different regions of the Earth’s ionosphere.

Open Access Original Research Article

Structural Optimization, Electronic Band Structure, Mechanical and Thermodynamics Properties of Fe3Al

I. S. Okunzuwa, E. Aigbekaen Eddy

Physical Science International Journal, Page 1-11
DOI: 10.9734/psij/2021/v25i230239

We calculated the structural, electronic, mechanical and thermal properties of Fe3Al semiconducting using Quantum ESPRESSO, an open source first principles code based on density-functional theory, plane waves, and pseudopotentials. Structural parameter results (equilibrium lattice parameters, bulk modulus and its derivative pressure) have been reported. The underestimated band gap is obtained along with higher state density and energy bands around the fermi level. Mechanical properties of the rock-salt structure of Fe3Al, such as, shear modulus (G), Young’s modulus (E), and Poisson’s ratio () were investigated. The thermodynamic parameters are also present. The results are in good agreement with the available experimental and other theoretical results.

Open Access Original Research Article

Extragalactic Radio Sources: Jet/Lobe Internal Pressure and Consequences

Ezeugo Jeremiah Chukwuemerie

Physical Science International Journal, Page 20-25
DOI: 10.9734/psij/2021/v25i230241

In this work, we use analytical methods to describe expansion of Extragalactic Radio Sources (EGRS). Result shows that source size expansion depends on the following parameters: age of the source, lobe internal pressure, ambient medium density, and angle of observation.

Moreover, from the analyses, we have shown that the obtained results, and , suggestively implies that  and . This shows that since , jet internal pressure exceeds the lobe’s internal pressure. Therefore, for a typical EGRS, this simply indicates that ambient medium density is higher in the jet region than in the region of the lobe. This is expected since the ambient density thins out from the central core to the region where lobe is located. It is in consonance with the notion that for large extended EGRS, lobes are located outside the host galaxies rather than within the host galaxies. Moreover, we can conclude from these results that compact steep spectrum sources have denser ambient medium than their more extended counterparts.

Open Access Original Research Article

Re-interpretation of the Two-World Background of Special Relativity as Four-World Background II

O. Akindele Adekugbe Joseph

Physical Science International Journal, Page 37-57
DOI: 10.9734/psij/2021/v25i230243

Coexisting four universes in separate four-dimensional spacetimes constitute four-world background for the special theory of relativity (SR) in each universe, as developed in previous papers. The fact that the four universes exhibit perfect symmetry of state and perfect symmetry of natural laws is shown in this paper. The many universes concept involved is entitled compartment universes. Compartment universes are coexisting symmetrical universes in different fourdimensional spacetimes of identical extents. Material particles and bodies are symmetrically distributed in spacetimes and the same natural laws take on identical forms in compartment universes. These features differentiate the compartment universes concept from the multiverse of inflationary cosmology and the parallel branes of M-theory. The compartment universes concept opens new vista for many-world interpretations of the natural laws, as demonstrated for the special theory of relativity already, and it is a potential platform for the uniform formulation of the natural laws. Investigation of the possible existence of larger number of compartment universes than four and many-world interpretations of gravitation and other natural laws in the compartment universes picture are recommended.