Journal of Theoretical and Applied Physics (JTAP)Effect of aging on the properties of TiO2 nanoparticleVolume 10, (2016)Issue 3, September 201620231117Effect of aging on the properties of TiO2 nanoparticle10.1007/s40094-016-0212-1ENJournal Article20231117AbstractEffect of aging on the properties of titanium dioxide nanoparticles produced by laser ablation process in water is investigated experimentally. The fundamental wavelength of a Q-switched Nd:YAG laser was employed to irradiate a high-purity Ti plate in distilled water at temperatures of 20, 35, 50 and 65 °C. Produced nanoparticles were diagnosed by UV–Vis–NIR spectroscopy, X-ray diffraction method, and dynamic light scattering device immediately after production and 1 week after. Bandgap energy of samples was extracted using Tauc method. Size of nanoparticles was increased after a week and their bandgap energy was decreased. Results show that the phase of TiO2 nanoparticles was transited from brookite to rutile after 1 week.Journal of Theoretical and Applied Physics (JTAP)High-pressure and temperature-induced structural, elastic, and thermodynamical properties of strontium chalcogenidesVolume 10, (2016)Issue 3, September 201620231117High-pressure and temperature-induced structural, elastic, and thermodynamical properties of strontium chalcogenides10.1007/s40094-016-0214-zENJournal Article20231117AbstractPressure- and temperature-dependent mechanical, elastic, and thermodynamical properties of rock salt to CsCl structures in semiconducting SrX (X = O, S, Se, and Te) chalcogenides are presented based on model interatomic interaction potential with emphasis on charge transfer interactions, covalency effect, and zero point energy effects apart from long-range Coulomb, short-range overlap repulsion extended and van der Waals interactions. The developed potential with non-central forces validates the Cauchy discrepancy among elastic constants. The volume collapse (VP/V0) in terms of compressions in SrX at higher pressure indicates the mechanical stiffening of lattice. The expansion of SrX lattice is inferred from steep increase in VT/V0 and is attributed to thermal softening of SrX lattice. We also present the results for the temperature-dependent behaviors of hardness, heat capacity, and thermal expansion coefficient. From the Pugh’s ratio (ϕ = BT/GH), the Poisson’s ratio (ν) and the Cauchy’s pressure (C12–C44), we classify SrO as ductile but SrS, SrSe, and SrTe are brittle material. To our knowledge these are the first quantitative theoretical prediction of the pressure and temperature dependence of mechanical stiffening, thermally softening, and brittle nature of SrX (X = O, S, Se, and Te) and still await experimental confirmations.Journal of Theoretical and Applied Physics (JTAP)Non-equilibrium phase transition in a two-species driven-diffusive model of classical particlesVolume 10, (2016)Issue 3, September 201620231117Non-equilibrium phase transition in a two-species driven-diffusive model of classical particles10.1007/s40094-016-0215-yENJournal Article20231117AbstractA two-species driven-diffusive model of classical particles is introduced on a lattice with periodic boundary condition. The model consists of a finite number of first class particles in the presence of a second class particle. While the first class particles can only hop forward, the second class particle is able to hop both forward and backward with specific rates. We have shown that the partition function of this model can be calculated exactly. The model undergoes a non-equilibrium phase transition when a condensation of the first class particles occurs behind the second class particle. The phase transition point and the spatial correlations between the first class particles are calculated exactly. On the other hand, we have shown that this model can be mapped onto a two-dimensional walk model. The random walker can only move on the first quarter of a two-dimensional plane and that it takes the paths which can start at any height and end at any height upper than the height of the starting point. The initial vertex (starting point) and the final vertex (end point) of each lattice path are weighted. The weight of the outset point depends on the height of that point while the weight of the end point depends on the height of both the outset point and the end point of each path. The partition function of this walk model is calculated using a transfer matrix method.Journal of Theoretical and Applied Physics (JTAP)Effect of temperature dependence ultrasonic velocities and attenuation of GaP nanowiresVolume 10, (2016)Issue 3, September 201620231117Effect of temperature dependence ultrasonic velocities and attenuation of GaP nanowires10.1007/s40094-016-0216-xENJournal Article20231117AbstractThe higher order elastic constants of the hexagonal wurtzite crystal structure of GaP nanowires have been evaluated using Lennard-Jones potential model at room temperature. The ultrasonic velocity increases with the temperature along particular orientation with the unique axis of crystals. Temperature variation of the thermal relaxation time and Debye average velocities is also calculated along the same orientation. The temperature dependency of the ultrasonic properties is discussed in correlation with elastic, thermal and electrical properties. It has been found that the thermal conductivity is the main contributor to the behaviour of ultrasonic attenuation as a function of temperature and the responsible cause of attenuation is phonon–phonon interaction. The mechanical properties of GaP nanowires at low temperature are better than at room temperature, because at low temperature it has low ultrasonic velocity and ultrasonic attenuation. A particularly interesting case is GaP, which is the only (Ga, In)-V semiconductor with an indirect gap in the bulk phase, and are indispensable in modern microelectronic industries.Journal of Theoretical and Applied Physics (JTAP)Theoretical analysis on nonlinear vibration of fluid flow in single-walled carbon nanotubeVolume 10, (2016)Issue 3, September 201620231117Theoretical analysis on nonlinear vibration of fluid flow in single-walled carbon nanotube10.1007/s40094-016-0217-9ENJournal Article20231117AbstractIn this study, the concept of nonlocal continuum theory is used to characterize the nonlinear vibration of an embedded single-walled carbon nanotube. The Pasternak-type model is employed to simulate the interaction of the SWNTs. The parameterized perturbation method is used to solve the corresponding nonlinear differential equation. The effects of the vibration amplitude, flow velocity, nonlocal parameter, and stiffness of the medium on the nonlinear frequency variation are presented. The result shows that by increasing the Winkler constant, the nonlinear frequency decreases, especially for low vibration amplitudes. In addition, it is resulted that influence of the nonlocal parameter is greater at higher flow velocities in comparison with lower flow velocities.Journal of Theoretical and Applied Physics (JTAP)Structural and optical characterization of ZrO2 thin films grown on silicon and quartz substratesVolume 10, (2016)Issue 3, September 201620231117Structural and optical characterization of ZrO2 thin films grown on silicon and quartz substrates10.1007/s40094-016-0218-8ENJournal Article20231117AbstractZirconium oxide thin films were grown successfully by thermal annealing of zirconium thin films deposited on quartz and silicon substrates by direct current magnetron sputtering technique. The structural and optical properties in relation to thermal annealing times were investigated. The X-ray diffraction patterns revealed that structure of films changes from amorphous to crystalline by increase of annealing times in range 60–240 min. The composition of films was determined by Rutherford back scattering spectroscopy. Atomic force microscopy results exhibited that surface morphology and roughness of films depend on the annealing time. The refractive index of the films was calculated using Swanepoel’s method. The optical band gap energy of annealed films decreased from 5.50 to 5.34 eV with increasing thermal annealing time.Journal of Theoretical and Applied Physics (JTAP)Effects of various deposition times and RF powers on CdTe thin film growth using magnetron sputteringVolume 10, (2016)Issue 3, September 201620231117Effects of various deposition times and RF powers on CdTe thin film growth using magnetron sputtering10.1007/s40094-016-0219-7ENJournal Article20231117AbstractCadmium telluride (CdTe) is a p-type II-VI compound semiconductor, which is an active component for producing photovoltaic solar cells in the form of thin films, due to its desirable physical properties. In this study, CdTe film was deposited using the radio frequency (RF) magnetron sputtering system onto a glass substrate. To improve the properties of the CdTe film, effects of two experimental parameters of deposition time and RF power were investigated on the physical properties of the CdTe films. X-ray Diffraction (XRD), atomic force microscopy (AFM) and spectrophotometer were used to study the structural, morphological and optical properties of the CdTe samples grown at different experimental conditions, respectively. Our results suggest that film properties strongly depend on the experimental parameters and by optimizing these parameters, it is possible to tune the desired structural, morphological and optical properties. From XRD data, it is found that increasing the deposition time and RF power leads to increasing the crystallinity as well as the crystal sizes of the grown film, and all the films represent zinc blende cubic structure. Roughness values given from AFM images suggest increasing the roughness of the CdTe films by increasing the RF power and deposition times. Finally, optical investigations reveal increasing the film band gaps by increasing the RF power and the deposition time.Journal of Theoretical and Applied Physics (JTAP)Synthesis, structural and optical properties of pure ZnO and Co doped ZnO nanoparticles prepared by the co-precipitation methodVolume 10, (2016)Issue 3, September 201620231117Synthesis, structural and optical properties of pure ZnO and Co doped ZnO nanoparticles prepared by the co-precipitation method10.1007/s40094-016-0221-0ENJournal Article20231117AbstractPure ZnO and Cobalt (Co) doped ZnO nanoparticles (NPs) were synthesized by the co-precipitation method. The synthesized nanoparticles retained the wurtzite hexagonal structure, which was confirmed by X-ray diffraction studies. From FESEM studies, ZnO and Co doped ZnO NPs showed Spherical and nanorod mixed phase and Spherical like morphology, respectively. The amount of dopant (Co2+) incorporated into ZnO sample was determined by EDAX. The FT-IR spectra confirmed the Zn–O stretching bands at 438 and 427 cm−1 for ZnO and Co doped ZnO NPs. From the UV–VIS spectroscopic measurements, the excitonic pecks were found around 376 and 370 nm for the respective samples. The photoluminescence measurements revealed that the broad emission was composed of seven different bands due to zinc vacancies, oxygen vacancies and surface defects. The dynamic light scattering (DLS) and Zeta potential measurements were used to find out the size and surface charges.Journal of Theoretical and Applied Physics (JTAP)Space charge formation and Bohm’s criterion in the edge of thermal electronegative plasmaVolume 10, (2016)Issue 3, September 201620231117Space charge formation and Bohm’s criterion in the edge of thermal electronegative plasma10.1007/s40094-016-0222-zENJournal Article20231117AbstractThe collisional electronegative plasma space charge is investigated in the presence of the thermal positive ions. The Boltzmann distribution is assumed for electrons and negative ions and fluid equations are used to treat the accelerated positive ion through the sheath region. The influence of the positive ion temperature on the profile of the space charge is obtained for different negative ion concentration and negative ion temperature for collisionless and collisional cases. It is shown that the position of the space charge peak is independent of positive ion temperature while its amplitude depends on the positive ion temperature. The presence of the negative ion leads to damping of the space charge amplitude. In addition the thermal effect of the positive ion on the kinetic energy of the ion extracted from an ion source is studied in difference of collisionality and electronegativity. It is shown that, in the presence of thermal positive ion, the influence of the negative ion temperature on the sheath characteristics disappears. It is observed that in the presence of the hot positive ion, the twofold feature of the space charge starts at higher values of negative ion temperature which is more pronounced in collisional case. Finally, the influences of the positive and negative ion temperature, as well as the electronegativity and collisionality on the net electric current are studied.Journal of Theoretical and Applied Physics (JTAP)Size control of L12-FePt3 nanocrystals by spin-coating methodVolume 10, (2016)Issue 3, September 201620231117Size control of L12-FePt3 nanocrystals by spin-coating method10.1007/s40094-016-0223-yENJournal Article20231117AbstractAnnealing is one of the stages of FePt nanoparticles preparation, during which the transition to a compositionally ordered phase occurs. In order to size and shape control of the nanoparticles in the mentioned stage, it is needed that they be distributed on a suitable surface. In the present work, the spin-coating method is suggested for preparing monolayer from L12-FePt3 nanoparticles colloidal solution on SiO2/Si substrates. FePt3 nanoparticles were gradually deposited as droplets on the center of a 500 rpm rotating substrate. This step was performed in hexane vapor atmosphere without any stopping time. The analyses revealed that a uniform surface distribution was formed so that, after annealing at 600 °C for 1 h the 6.1 nm L12-FePt3 nanoparticles were spherical in shape with standard deviation of 1.5 nm.