A. Bakhtiari, T. Berberashvili, P. Kervalishvili

Today Graphene with its unusual properties is one of the most interesting materials useful in different applications. Graphene’s sensitive properties are highly correlated with its macro and nanostructure, hence the preparation process of Graphene structures is very significant. During the last decades, several methods of producing Graphene-like structures and their thin films onto a substrate were developed and each of them has some advantages. At the same, it is still problematic to receive thin nanostructures with suitable lattice quality and uniformity. In this regard, the flexibility and accuracy of a method play the main role. In this work, the Graphene thin film preparation process based on a precise, accurate, and feasible method as *Continuous* *Wavelength* *Laser* *Deposition* (CWLD) was introduced. However, this article focused on Graphene thin film, but CWLD can be used for different materials.

A. Bakhtiari, P. Kervalishvili

Atoms and molecules are known the smallest blocks of the matter. However, their substructure represent matter identification, but not sufficient to explain material physical properties like ductility, strength, work function, etc. Today matter structure (atoms or molecules arrangement) investigating is a stationary approach that particles are assumed fixed. Although particles untraceable movement is the main reason of stationary approach, but their nonregular motion is undeniable. Basically, the nonregular particles motion of the nanosystems is assumed as chaos in the common linear approach and then conducts investigations to the probability theory. But probability only focuses on the results of the random phenomenon, then the study of the reasons is disregarded. In this work, a new doctrine as *Dynamic* *Fractal* that comes out from *Dynamic* *Topologic* *Space* provides a new mathematical model for a lattice analysis as a *system* in space-time. Then, particles in the dynamic system are fractals components (in other words particles are not fragments) and they are in a harmonic movement. On the other hand, time is the main factor of any dynamic system, hence its role study is inevitable. As a matter of fact, the dynamic systematic approach by Dynamic Fractal doctrine shows a better understanding of nanomaterials structure. According to crystals strong dependency to material structure, this doctrine could be significant for crystals and crystallization analysis. Refer to crystals correlation to the crystallization process, this doctrine can provide more efficient crystals. Finally, more efficient products of industries as semiconductors, cutting machines, laser technology, watch industry, photovoltaic cells are expected.

Musa N., Onimisi M. Y., Ikyumbur J. T.

The dielectric constant and loss factor of pure ethanol was analyzed using the Cole-Cole relaxation theory for a temperature range 10°C - 50°C and frequency spectrum of 100kHz to 50MHz, The values obtained were plotted against the frequency and temperature respectively. At the lower rung of the frequency spectrum, the dielectric constant was high and uniformly decreased as the frequency increased until it gets to saturation at 50MHz. The loss factor have peaks of 4.59 at 100kHz and temperature 10°C, 4.38 at 600kHz and temperature of 20°C, 3.97 at 1100kHz and 30°C, 3.68 at 1500kHz and 40°C and 3.40 at 2000kHz and temperature of 50°C. The peaks correspond to the relaxation points at the various frequencies listed. For the temperature dependence, the dielectric constant showed a decrease as the temperature increased for a frequency range of 100 - 500kHz, maintained an almost constant value of dielectric constant for a frequency of 1000kHz then increase weakly as the temperature increased for a frequency range of (2000kHz - 50MHz). The dielectric constant showed a slow response to temperature change while the loss factor showed a quick response to temperature change because it is a temperature sensitive parameter compared to the dielectric constant. An analysis of real and imaginary parts of dielectric permittivity has been elucidated using Cole-Cole plot of the complex permittivity. With the aid of the Cole-Cole plot, the values of static dielectric constant (ε_{s}), optical dielectric constant (ε_{∞}) were determined within the frequency and temperature range of interest. The values obtained were in agreement with standard measurements.

Kiran G. Saija, Pooja Y. Raval, Nimish H. Vasoya, Uday N. Trivedi, Kunal B. Modi

The compositional and temperature (*T* = 300 – 525 K) dependence of Seebeck coefficient measurement has been carried out on microcrystalline ferrite samples of Zn_{0.3}Mn_{0.7+}_{x}Si_{x}Fe_{2-2}_{x}O_{4} (*x* = 0.0, 0.1, 0.2 and 0.3) series. The probable conduction mechanism is the exchange of electrons between Fe^{3+} and Fe^{2+} ions on the octahedral interstitial site of the spinel structure. The absolute concentration of ferrous and ferric ions has been deduced that used to determine the actual occupancy of metallic cations, oxygen deficiency, and to describe the compositional variation of dc resistivity. Finally, the Fermi energy values at *T* = 0 K have been derived.

A. B. Olanipekun

The structural and electronic properties of fluorite structures CaF_{2}, SrF_{2} and their ternary alloy Ca_{x}Sr_{1−x}F_{2} for concentrations x = 0.25, 0.50, 0.75 are studied using first principles calculation. The pseudopotential plane-wave (PPPW) method as used in the QUANTUM ESPRESSO code is applied. In this method, the generalized gradient approximation (GGA) is employed for the exchange-correlation (XC) potential. The lattice constants a_{0} and bulk modulus B, for CaF_{2}, SrF_{2} and their ternary alloy Ca_{x}Sr_{1−x}F_{2} compounds were first carried out, followed by the band gap energies calculation of the binary fluorides and the ternary alloys. In order to correct the huge underestimation of DFT(GGA) method, a model involving the generalized gradient approximation method of Perdew, Burke and Ernzerhof (PBE) is used for the calculation of the band gap and a good agreement with experiment is obtained for the binary compounds with little deviation. The electronic band structures and the density of states of the alloys are presented.

Yuri Mnyukh

The physical nature of ferroelectricity is intimately associated with the molecular mechanism of phase transitions. The conventional theory linking ferroelectricity with “soft-mode” phase transitions is invalid, since phase transitions do not materialize that way. Previous attempts to explain ferroelectricity could not be successful without detailed knowledge of the universal nucleation-and-growth mechanism of solid-state phase transitions, especially its *epitaxial* kind. Therefore, this mechanism is described again in the article. Its application to ferroelectricity has been done initially in the 2001 book *Fundamentals of Solid-State Phase Transitions, Ferromagnetism and Ferroelectricity*, but this time it is done in more complete form. The origin of ferroelectrics, their classification, formation of their domain structure, their stability, difference from pyroelectrics, formation of their hysteresis loops, parallelism with ferromagnetism, and more, are presented coherently in terms of the universal nucleation-and-growth mechanism of phase transitions.

Sami Youssef, Abdelfatteh Cherif, Bechir Yahmadi

An analytical Fourier series analysis of the elastic field of a misfit dislocations along a thin film-substrate interface is proposed in the context of a plane strain. When the period is sufficiently large, this solution tends assymptotically towards that of an isolated dislocation in the thin film substrate system. Numerical applications are illustrated to evaluate the effect of elastic properties of the materials used as well as the effect of the film thickness and the position of the dislocation in the substrate.

]]>Yuri Mnyukh

Critical phenomena are a part of physical science that deal with phase transitions accompanied by singularities like “critical opalescence” and “λ-anomalies”. The theory of critical phenomena assumes phase transitions are a cooperative process driven by thermal fluctuations and subject to statistical mechanics. Ferromagnetic phase transition is usually used as a typical critical phenomenon to analyze. Many theoretical physicists viewed the λ-anomalies as the most important unsolved problem in theoretical physics. In this article hard evidence is presented that the actual molecular mechanism of all phase transitions in solids, including ferromagnetic, is *antithesis* to the models utilized in the theories of critical phenomena. Real phase transitions materialize by rearrangement of crystal structure according to the universal nucleation-and-growth mechanism. It is the crystal rearrangement which alters the electric, magnetic, optical, *etc*. properties. The process is not cooperative; thermal fluctuations are not involved; statistical mechanics is not applicable. Another part of this article is devoted to the singularities. (1) “λ-Anomalies”. Believing that these peaks are *heat* *capacity* is a case of mistaken identity: they are *latent* *heat* of structural phase transitions. The same is true about the notorious “heat capacity λ-anomaly” in the liquid helium phase transition: it is a latent heat as well. (b) “Critical opalescence”. The literature for the subject was examined. The opalescence in solid-state phase transitions, observed by different authors, turns out not fluctuation-related. It is a light scattering by nuclei and interfaces of arising new phase. The only type of phase transition that stays somewhat apart from the above-enumerated is the *liquid* – *gas* in its critical point. The case was reconsidered. The physical cause of inability to compress gas into liquid is explained. The observed opalescence is a cloud of tiny drops of liquid phase appearing; no fluctuations are involved. The case is not “critical” either.

H. K. Limbu, G. P. Adhikari

The Regular Solution model has been used to describe thermodynamic properties, transport properties and structural properties at different temperatures theoretically. The interaction energy is temperature dependent and played an important role to explain the properties of Al-Mg liquid alloy at different temperatures. The theoretical values of interchange energy at different temperatures are obtained by best fit parameter approximation with the help of experimental values at 1073K. The properties have been studied with the help of computed theoretical interchange energy at different temperatures using interchange energy and temperature relation. A comparison of theoretical and experimental values at 1073K shows that they are in good agreement and using this basis we have studied properties at different temperatures.

]]>A. S. Doma, H. H. Hassan

In this paper, different rubber compounds were prepared by usingSMR-20 type of natural rubber (NR) and SBR-1502 type of styrene-butadiene rubber. The effect of blend ratio on the curing parameters, mechanical and electrical properties of NR/SBR blends have been studied. It was found that the increment of NR percentages increases the values of mooney viscosity (M.V.), low torque (ML), maximum torque (MH), tensile strength (TS), modulus at 300% (M_{300}) and dc conductivity. Moreover, the values of optimum cure time (T90), scorch time (Tsc), elongation at break (E_{b}), hardness and specific gravity (Sp. Gr.) have been decreased. The increase of the rheometric parameters upon increasing NR content could be attributed to the increase of the cross-linking density. The marked increase in the mechanical parameters (TS and M_{300}) could be attributed to the increase of E_{b} upon increasing the NR content is due to the uncoiling process of NR chains compared with that of SBR. The blending of SBR raised the value of specific gravity to 0.94 with respect to NR of lower value of 0.92 which satisfies the law of mixturing.