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The spin filtering ability of lead/poly-BIPO/lead model junction is investigated. A polaron excitation is considered at the center of polymer. Four polaron types are assumed as the spin and charge density distributions. The Su-Schrieffer-Heeger (SSH) Hamiltonian is modified by Hubbard and Heisenberg Hamiltonians to include the spin and charge interactions. The spin-oriented currents and spin-polarization ability of the model, in the presence/absence of polaron excitations are examined. We find that the complete spin-polarization for both of the excited and non-excited systems is possible and for a given voltage range it is a 100% plato. Our results predict that in the presence of polaron excitations the spin-oriented current is enhanced.

In this work, the electronic structure and optical properties of two-layered hydrogenated GaN were investigated. The results were obtained via first principle calculations based on density functional theory (DFT) using GW approximation and two particle Bethe–Salpeter equation along with electron-hole effect. The results show that direct band gap of the sample change from 1.67 eV to, 4.1 eV considering electron-electron effects. Based on our findings, the first peak obtained from the imaginary part of the dielectric function for the direction parallel to the nanosheet plane observed in 3 eV, the energy corresponding to the first bound exciton state was obtained as 1.1 eV. The first absorption peak was observed in two parallel and perpendicular directions to the plane being invisible region.

First principle calculations based on density functional theory using GW approximation and two particle Bethe–Salpeter equation with electron-hole effect were performed to investigate electronic structure and optical properties of two-layered hydrogenated AlN. According to many body green function due to decrease in dimension and considering electron-electron effect, direct (indirect) band gap change from 2 (1.01) eV to 4.83 (3.62) eV. The first peak in imaginary part of dielectric function was observed in parallel direction to a plane obtaining 3.4 was achieved by bound exciton states possess 1.39 eV. The first absorption peak was seen in two parallel and perpendicular directions to a plane which are in UV region.

In this paper, zinc oxide (ZnO), copper oxide (CuO), and titanium oxide (TiO2) nanoparticles were prepared using sol-gel method. The structural properties of these nanoparticles were characterized using X-Ray Di raction (XRD) and Transmission Electron Microscopy (TEM). SEM images revealed that the average sizes of zinc oxide, copper oxide, and titanium oxide nanoparticles are about 37 nm, 86 nm, and 50 nm, respectively. Then, nanocomposites of metal oxide were produced by Polyvinyl Alcohol (PVA). The antibacterial activities of zinc oxide, copper oxide, and titanium oxide nanocomposites against human pathogenic bacteria, mainly Escherichia coli HB101 (gram-negative), have been studied using drop test during the time periods of 15 minutes, 30 minutes, 1 hour, 2 hours, 12 hours, and 24 hours of generated reviews. According to the results obtained with the nanocomposite, zinc oxide nanoparticles exhibit the highest antibacterial properties.

In this work Fe doped TiO2 nanoparticles were synthesized at different Fe/Ti molar ratio from 1% to 5% by sol-gel technique. The post annealing of the samples was carried out at T=400, 600, and 800 °C. HRTEM of the samples revealed that the mean size of the nanoparticles increases from about 8 nm to about 100 nm as the annealing temperature increased. SQUID magnetometry of 1% and 5% Fe doped TiO2 has shown mixed ferromagnetic and paramagnetic phases within the crystal while ferromagnetic order with Tc about 350 K was only observed in 5% Fe:TiO2 sample annealed at T=800 °C. The oxygen vacancy mediated ferromagnetic (FM) interaction could be responsible for the observed FM.

An ab-initio study on the spin-polarized transport properties of H-passivated Fe-doped graphyne nanoribbons is presented. All the calculations were based on density functional theory (DFT). Doping single magnetic atom on graphyne nanoribbons leads to metallicity which can significantly improve the conductivity. The currents are not degenerate for both up and down spin electrons and they are considerably spin-polarized. Therefore a relatively good spin-filtering can be expected. For configurations with geometric symmetry spin-rectifying is also observed. Therefore they can be applied as a dual spin-filter or a dual spin-diode in spintronic equipment.

Rhenium, a valuable and rare metal, is a byproduct of Molybdenum. It is usually produced through the dust and smoke of roasting Molybdenum concentration. Heat roasting is the traditional method of producing Molybdenum from sulphuric resources (Molybdenum), which not only creates environmental problems but also wastes some of the existing Rhenium. To produce Rhenium, in this research, a Nano-technology-based solution is presented which is modern, fast, and economical. Rhenium, classified among the external mediator elements, is in group 7 of the periodic table. Regarding the arrangement of Rhenium's electron layer capacity, i.e. 5 d 5, its d orbital is completely sub-saturated and therefore, equipped with magnetic characteristic. As such, Rhenium can also be considered as a Para-magnetic metal. In this research, after providing metal ions solution, the absorption of Rhenium ions is examined under different operational conditions through the super Para-magnetic Nano-particles of Fe 3 O 4, which helped to determine the best conditions for absorption to occur. Washing the Nano-absorbent after recovering Rhenium ions from Nano-particles makes it prepared for further operations.

In present paper, the non-equilibrium Green function (NEGF) method along with the density functional theory (DFT) are used to investigate the effect of width on transport and electronic properties of armchair graphyne (γ-graphyne) nanoribbons. The results show that all the studied nanoribbons are semiconductor and their band gaps decrease as the widths of nanoribbons increase, which will result in increasing current at a certain voltage. Also our results show the promising application of armchair graphyne nanoribbons in nano-electrical devices.

In this work, we study the effects of electron-phonon and electron-photon interaction on the electronic and optoelectronic properties of nano systems consisting of graphene nano-flakes (small length armchair graphene nanoribbons) connected to two semi-infinite metal electrodes. Our calculations are based on the use of non-equilibrium Green's function formalism. The non-interacting Hamiltonian is written within the nearest neighbor tight binding approximation. The full interacting Hamiltonian is then obtained by addition the electron-phonon and electron –photon interaction to the above non-interacting Hamiltonian. Using unitary transformations the interacting Hamiltonian is renormalized into a non-interacting tight-binding form with effective onsite energy and hopping parameter which contain the interacting effects. The Landuer-Buttiker formalism can now be used for the system with renormalized non-interacting Hamiltonian for calculating the electronic current. Within the above framework, we calculate the electron current, density of states (DOS) and photocurrent in the presence and absence of electron-phonon interaction in a nano-system consisting of graphene nano-flake with different width as central molecule. Our results show that electron-phonon interaction leads to decreasing the number of peaks in the DOS. Also the photocurrent has oscillatory behavior versus electron-photon coupling for different widths of the nano-flake. Finally, incident photon energy dependence of threshold electron-photon coupling (i.e photocurrent becomes larger than Ballistic case) and its increasing trend versus photon energy are studied.

We calculated the electronic structure and optical properties of the AlN monolayer based on first principle many-body Green’s function and Bethe–Salpeter equation formalism. We computed that the indirect (direct) band gap of the AlN monolayer honeycomb using quasiparticle correction is 5.36 eV (6.07 eV), but it has a value of 2.93 eV (3.7 eV) within the density functional theory. The calculations reveal that the optical absorption is sensitive to excitonic effects such as electron–hole interaction with binding energy of the first exciton of over 2.05 eV within the GW + Bethe–Salpeter equation calculation. The enhanced excitonic effects in the AlN monolayer can be used to describe the optical properties in nano-optoelectronic devices.

In this article we study the role of Rashba spin–orbit coupling and electron–phonon interaction on the electronic structure of zigzag graphene nanoribbon with different width. The total Hamiltonian of nanoribbon is written in the tight binding form and the electron–electron interaction is modeled in the Hubbard term. We used a unitary transformation to reach an effective Hamiltonian for nano ribbon in the presence of electron–phonon interaction. Our results show that small Rashba spin orbit coupling annihilates the anti-ferromagnetic phase in the zigzag edges of ribbon and the electron–phonon interaction yields small polaron formation in graphene nano ribbon. Furthermore, Rashba type spin–orbit coupling increases (decreases) the polaron formation energy for up (down) spin state.

Using non-equilibrium Green׳s function and ab initio calculations we investigate structural, electronic, and transport properties of a junction consisting of armchair hexagonal boron phosphide nanoribbon (ABPNR) contacted by two semi-infinite electrodes composed of armchair graphene nanoribbons (AGNRs). We consider three different configurations including the pristine AGNR–BP–GNR and substitutions for Iron atoms, namely on phosphorus and boron atoms at one edge of the BP nanoribbon. The spin current polarization in all these cases is extracted for each structure and bias. Such hybrid system is found to exhibit not only significant spin-filter efficiency (SFE) but also tunable negative differential resistance (NDR).

Electronic, magnetic and transport properties of a triangle graphene quantum clot have been studied in the presence of Rashba type spin-orbit coupling. The non-interacting part is written in the tight-binding model, and we use the Kene-Mele-Hubbard (KMH) Hamiltonian to describe the electron-electron and the Rashba spin-orbit interaction. While the Hubbard tel split the spin up and down states, the Rashba tel mixed these states. The competition between these two effects produces an interesting situation in a nano-device. Our results indicate that the magnetization of zigzag edge and spin coherence are decreased due to the Rashba spin-orbit interaction in the triangle graphene quantum dot It is shown that the reduction of spin coherence is non-negligible even in the case of weak Rashba spin-orbit interaction. (C) 2014 Elsevier By. All rights reserved.

Sol-gel method was successfully used for synthesis of ZnO nanoparticles doped with 10 % Mg or Cu. The structure, morphology and optical properties of the prepared nanoparticles were studied as a function of doping content. The synthesized ZnO:(Mg/Cu) samples were characterized using XRD, TEM, FTIR and UV-Vis spectroscopy techniques. The samples show hexagonal wurtzite structure, and the phase segregation takes place for Cu doping. Optical studies revealed that Mg doping increases the energy band gap while Cu incorporation results in decrease of the band gap. The antibacterial activities of the nanoparticles were tested against Escherichia coli (Gram negative bacteria) cultures. It was found that both pure and doped ZnO nanosuspensions show good antibacterial activity which increases with copper doping, and slightly decreases with adding Mg.

In this paper, SiO2–Au–Cu2O core/shell/shell nanoparticles were synthesized by reducing gold chloride on 3-amino-propyl-triethoxysilane molecules attached silica nanoparticle cores for several stages. Cu2O nanoparticles were synthesized readily with the size of 4–5 nm using a simple route of sol–gel method Then, they were clung to the surface of Au seeds. The morphology of the resultant particles was studied using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Transmission electron microscopy images demonstrate growth of monodispersed gold seeds and Cu2O nanoparticles in narrow size up to 10 nm and 5 nm, respectively. The presence of gold and Cu2O coating was confirmed by X-ray diffraction, Fourier transform infrared spectroscopy and UV–Vis spectroscopy. Absorption spectroscopy shows considerably 40 nm blue shift in absorption edge for SiO2–Au–Cu2O nanostructure rather than SiO2–Au core/shell nanoparticles.

This paper describes the homogeneous growth of gold shells on the surfaces of spherical dielectric silica nanoparticle cores by two different approaches: common two-step method (the name) and deposition–precipitation process. The methods basically are different in forming the precursor gold seed particles on silica. The structural and optical properties and morphology of the nanoparticles were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), UV–Vis spectrophotometery, and photo luminescence spectroscopy (PL). The results showed that, although in both the methods the core–shell nanoparticles can be reliably prepared in a controlled fashion with a favorable uniformity, but deposition–precipitation method indicated a better mechanical stability while it was more cost and time effective too. A regular red shift, from 488 to 662 nm, and peak broadening was also risen for the striking plasmon absorption peak as gold nanoseeds created by each of the two methods grew in size on silica cores.

Electronic, magnetic and transport properties of a nano-graphene dot have been studied by using the DFT and tight binding methods. In the tight binding calculations, the interaction between electrons is modeled using the Hubbard Hamiltonian. By comparison between the eigen-values and density of states in the tight binding and DFT models, we tabulate a set of tight-binding parameters to describe graphene quantum dots for future works. The effects of a single vacancy and an in-plane external electric field on the spin-dependent transport of graphene quantum dot have been investigated. Transport through GQD between two GNR is studied by using Green's function formalism. Our results confirm an intrinsic spin-dependent current and relatively large spin polarization through the GQD in the presence of a single vacancy and zigzag edge. It is also shown that an in-plane external electric field controls the spin-polarization in graphene quantum dot.

Vanadium oxides condensed films are prepared on glass substrates, using spray pyrolysis (SP) technique. The effects of substrate temperature, vanadium concentration in initial solution and the solution spray rate on the nano-structural, electrical, and optical properties of deposited films were investigated. Characterizations of the samples were performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis spectroscopy methods. The type and concentration of the charge carriers were determined and measured by Hall effect experiment. XRD patterns showed that the prepared films had polycrystalline structure, mostly tetragonal β-V2O5 and V4O9 phases with the preferred orientation along (200) direction. The Hall effect experiment revealed that all samples were n-type, except the ones deposited at substrate temperatures T sub = 300 °C and T sub = 450 °C, vanadium concentration 0.1 mol/L and solution spray rate 10 mL/min. The charge carrier concentrations obtained were in the range 1016–1018 cm−3. The lowest sheet resistance (R s) was obtained for the samples prepared at T sub = 450 °C, vanadium concentration 0.05 mol/L and solution spray rate 10 mL/min. It was also found that the optical transparency of the samples changed from 20% to 75% and the optical band gap of the samples was from 2.22 eV to 2.58 eV, depending on the deposition conditions.

This paper describes a simple way for the coating of magnetite nanoparticles (MNPs) with amorphous silica. First, MNPs were synthesized by controlled co-precipitation technique under N2 gas and then their surface was modified with trisodium citrate in order to achieve particles with improved dispersibility. Afterward, magnetite-silica core/shell nanocomposites were prepared by a sol–gel approach, using magnetic fluid including electrostatically stabilized MNPs as seeds. The prepared samples were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, zeta potential analysis and vibrating sample magnetometer (VSM) in order to study their structural and magnetic properties. FT-IR and XRD results imply that resultant nanocomposites are consisted of two compounds; Fe3O4 and SiO2 and TEM images confirm formation of their core/shell structure. TEM images also show increase in silica shell thickness from ∼5 to ∼24 nm with increase in amount of tetraethyl orthosilicate (TEOS) used during the coating process from 0.1 to 0.3 mL. Magnetic studies indicate that Fe3O4 nanoparticles remain superparamagnetic after coating with silica although their Ms values are significantly less than pristine MNPs. These core/shell nanocomposites offer a high potential for different biomedical applications due to having superparamagnetic property of magnetite and unique properties of silica.

Aluminium doped zinc oxide (AZO) nanostructured thin films are prepared by radio frequency magnetron sputtering on glass substrate using specifically designed ZnO target containing different amount of Al2O3 powder as the Al doping source. The optical properties of the aluminium doped zinc oxide films are investigated. The topography of the deposited films were investigated by Atomic Force Microscopy. Variation of the refractive index by annealing temperature are considered and it is seen that the refractive index increases by increasing the annealing temperature.

Zn-doped SnS2 thin films have been deposited simply by spray pyrolysis technique. The doping level was changed from [Zn/Sn] = 0 to 7·5 at%. The films were characterized by means of X-ray diffraction, scanning tunneling microscopy (STM), energy dispersive X-ray analysis (EDX), photoluminescence and UV-Vis spectroscopy. XRD patterns of the films with different zinc contents show that all samples have polycrystalline structure with Berndtite dominant phase and preferred orientation of (001) growth plane. Zn insertion causes a significant decrease in grain size. Optical bandgap of the films have been calculated for different dopant concentrations and they lie in the region of 2·3–2·7 eV. Surprisingly, regardless of doping level, the luminescent properties of films are related to the fundamental bandgap energy and deep levels inside the bandgap. Photoconductivity of the films have been measured under visible light. Sensitivity to the light increases by zinc incorporation, which was a large amount for SnS2:Zn of 7·5%.

Coherent spin-dependent electron transport is investigated in three conditions: (1) a C60 molecule is connected to two ferromagnetic (FM) electrodes symmetrically, (2) a C59N molecule is connected to two FM electrodes symmetrically and (3) a C59N molecule is connected to two FM electrodes asymmetrically. This work is based on a single-band tight-binding model Hamiltonian and the Green’s function approach with the Landauer–Buttiker formalism. Electrodes used in this study are semi-infinite FM electrodes with finite cross-section. Obvious rectification effect is observed in the C59N molecule which is connected to the FMelectrodes asymmetrically. This effect is more in the P alignment of FM electrodes than in AP alignment of FM electrodes. This study indicates that the rectification behaviour is due to the asymmetry in molecule and junctions. Also in this investigation tunnel magnetoresistance (TMR) is calculated for these molecules. Asymmetry is observed in TMR of C59N which is coupled to the electrodes asymmetrically due to asymmetric junctions, but TMR of C60 is symmetric.

We present a first principle calculation on the electronic structure and the linear optical properties of (13-0) zigzag single walled carbon nanotube by using full potential linear augmented plane wave (FP-LAPW) method. It is found that zigzag (13-0) nanotube has semiconducting behavior with the band gap of 0.6 eV at Γ point. The optical spectra of (13-0) carbon nanotube have been calculated for both electric field polarizations, parallel and perpendicular to the tube axis. The dielectric function is found to be highly anisotropic and is much larger for the electric field applied along the tube axis than the perpendicular. The results show that unlike the optical absorption, the energy loss function of (13,0) SWCNT show weak anisotropy. It was also revealed that the energy loss function peaks for both electric fields happen almost at the same energies, but with rather difference in their amplitudes.

In this work, we present a theoretical study on the conductance of trans -polyacetylene ( trans- PA) nanowire in the presence of impurities and use of trans -PA as a molecular bridge sandwiched between two semi-infinite metallic electrodes with a simple cubic structure and square cross section. We use a tight-binding Hamiltonian model within the framework of a generalized Green's function technique and rely on the Landauer–Butikker formalism as the basis for studying the current–voltage characteristic of this system. Our calculations indicate that the presence of impurities gives rise to significant enhancement in the density of states within the bandgap and large enhancement in conductance and the current–voltage characteristic. Also our results show that the electronic properties of the system are sensitive to the molecule-to-impurity coupling strength.

In this paper, we report on the structural, microstructural and optical properties of nano-crystalline indium tin oxide (ITO) particle, which has been synthesized by sol–gel process using a simple starting hydro-alcoholic solution consisting of In(NO3)3.5H2O, SnCl4.5H2O, citric acid as complexing and ethylene glycol as polymerization agents. The structural properties of indium tin oxide nano-powders annealed at different temperatures (T=350–650 °C) have been characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses. The XRD patterns show In2O3-cubic phase in nano-powders without any indication of crystalline SnOx as an additional phase. The TEM images show the nano-particles as nearly spherical shaped with size in the range of 10–45 nm as the size of grains increases by increasing the annealing temperatures. The optical direct band gap of ITO nano-particles was calculated to be about 3.39–4.02 eV in the temperature range 350–650 °C by optical absorption measurements. The optical band gap shifts to a higher energy with increasing annealing temperature is due to the improvement of the crystallinity, thereby increasing the carrier concentration as determined from the Burstein–Moss effect.

We have carried out a first principles calculation on the electronic structure, dielectric function and energy loss spectra of single-walled carbon nanotubes (SWCNTs). Calculations of optical spectra have been performed under electric fields polarized both parallel and perpendicular with respect to the nanotube axis. Our results show that the dielectric function is strongly anisotropic and much larger for the applied electric field parallel than perpendicular to the tube axis. We have calculated first, second, and third optical transitions in several SWCNTs with different chiralities, diameters and lengths. It is revealed that the absorption spectra of 4 A single-walled carbon nanotubes depend strongly on their chiralities, while the absorption spectra of nanotubes with large diameter hardly show any chirality dependence. The results show that unlike the optical absorption, the energy loss function of SWCNTs does not significantly depend on chirality and show weak anisotropy. It is also found that the energy loss function peaks for electric fields polarized both parallel and perpendicular to the tube axis happen almost at the same energies, but with rather difference amplitudes.

This paper reports structural and electrical characteristics of F-doped [Formula: see text]V2O5 thin films of different F concentrations. The films were analyzed by X-ray diffraction. It was found that F-doping in vanadium pentoxide affects the crystallinity of the samples. The SEM images have shown that by increasing the F-doping level, the size of the nanobelt increases. Electrical measurements indicated that the F-doping in [Formula: see text]V2O5 makes the temperature of phase transition change from semiconductor to metallic phase.

Thermal conductivity enhancements of nanodiamond particles (NDs) suspended in pure deionized (DI) with different volume fractions in the range from 0.8% to 3% have been measured. The highest observed enhancement in the thermal conductivity is 7.2% for a volume fraction of 3% at a temperature of 30 °C. The thermal conductivity increases by about 9.8% as the temperature rises to 50 °C. The new Murshed model (Murshed et al. (2009) [31] ) was used to describe the heat transfer enhancement in the ND fluid. While the predicted results overestimate the experimental data, they are in agreement within the experimental errors.

We report ab initio calculations of electronic and the linear optical properties of a (4,1) chiral carbon nanotube, using the full-potential linear augmented plane-wave (FP-LAPW) method. The dielectric tensor is derived within the random-phase approximation (RPA). All optical spectra, such as: dielectric function, absorption coefficient, optical conductivity, extinction coefficient, loss function, sum rule, reflectivity, and the refractive index have been calculated for both electric field polarizations, parallel and perpendicular to the tube axis. It is revealed that the optical spectra are anisotropic along these two polarizations. For the parallel polarization, adding the intraband transition contributions, will change the optical spectra of a (4,1) nanotube significantly. The calculated optical gap, Eg, electronic dielectric constant, e(∞), and the refractive index, n, in the parallel polarization are obtained as 2.6 eV, 1.98, and 1.4, respectively. The results show that for small diameter of SWCNTs the chirality has a strong effect on their optical spectra. Adding the intraband transition contributions showed that the dielectric function has singularity at zero frequency, due to the metallic behavior of a (4,1) chiral nanotube.

CdS nanocrystals with different structures were synthesized by the method of solution precipitation using thiourea and cadmium acetate as starting materials in different solvents: water, methanol and N,N-dimethylformamide (DMF). Our results show that the solvent has direct effect on the structure and size of the final nanoparticles. It was found that using DMF, as a solvent, results in producing smaller nanoparticles with the cubic structures, while using the other solvents gives rise to larger nanoparticles with the hexagonal structure. It was also found that using heat during washing the precipitate results in a more homogenous size distribution of CdS nanocrystals. On the basis of our experimental results we also suggest a critical structure transformation size.

With Green's function method and single band tight binding Hamiltonian, we calculated coherence transport for trans-polyacetylene (T-PA) systems placed between ferromagnetic electrodes with non-collinear ones. Ferromagnetic electrodes are of two kinds: Fe and Ni. With increasing TMR angle it increases to a maximum at θ=π degree. Electric field on molecule causes a change in the value of TMR. Types of ferromagnetic electrodes also affect the value of TMR, which is caused by density of states related to electrodes.

In this work, Cu-doped SnO 2 thin films were deposited by spray pyrolysis method. The films were prepared using SnCl 4 ,5H 2 O and CuCl 2 ,2H 2 O hydro-alcoholic solution. Then, the sensitivity parameter of SnO 2 -based CO 2 -gas sensors is studied for various atomic percentages ([Cu]/[Sn] = 0, 2, 4, 6, 10,12.5,15, 20, 25). In addition, the effect of substrate temperature on the sensing behavior of films was also studied. The XRD and SEM structural analysis of thin film sensors confirm the nano-structure of the films with SnO 2 cassiterite phase. The optical band gap of Cu doped- SnO 2 films were obtained from optical absorption spectra by UV-Vis absorption spectroscopy. Measurement of the electrical resistivity of films shows that with increasing of Cu-doping in films up to 12.5%, the electrical resistivity increase sharply.

Co-doped TiO2 nanoparticles were synthesized via non hydrous complex-polymer sol-gel method. A series of Co(x):Ti1-x O2 samples with x = 0.01, 0.03, 0.05, 0.08 and 0.10, were prepared and subsequently annealed at 400 degrees, 600 degrees and 800 degrees C. Structural and magnetic properties of Co(x):Ti1-x O2 have been studied by means of X-ray diffraction and DC magnetometry. All samples annealed at 400 degrees C show a paramagnetic behavior with an average grain size of 11 nm. With increasing annealing temperatures a complete crystallization is seen with growth of the cluster size up to 31 nm with clear evidence of a presence of CoTiO3. For all concentrations and annealing conditions no sign of a metallic phase, even at x = 0.10, is seen.

In this research, S-doped vanadium oxide thin films, with doping levels from 0 to 40 at.%, are prepared by spray pyrolysis technique on glass substrates. For electrochemical measurements, the films were deposited on florin–tin oxide coated glass substrates. The effect of S-doping on structural, electrical, optical and electrochemical properties of vanadium oxide thin films was studied. The x-ray diffractometer analysis indicated that most of the samples have cubic β-V2O5 phase structure with preferred orientation along [200]. With increase in the doping levels, the structure of the samples tends to be amorphous. The scanning electron microscopy images show that the structure of the samples is nanobelt-shaped and the width of the nanobelts decreases from nearly 100 to 40 nm with increase in the S concentration. With increase in the S-doping level, the sheet resistance and the optical band gap increase from 940 to 4015 kΩ/square and 2.41 to 2.7 eV, respectively. The cyclic voltammogram results obtained for different samples show that the undoped sample is expanded and the sample prepared at 20 at.% S-doping level has sharper anodic and cathodic peaks.

Vanadium oxide thin films were prepared on glass substrates by using the spray pyrolysis technique. The effect of solution concentration (0.1 M, 0.2 M and 0.3 M) on the nanostructural, electrical, optical, and electrochromic properties of deposited films were investigated using X-ray diffraction, scanning electron microscopy, UV—vis spectroscopy, and cyclic volta-metrics. The X-ray diffraction shows that only the sample at 0.1 M has a single β-V2O5 phase and the others have mixed phases of vanadium oxide. The lowest sheet resistance was obtained for the samples prepared at 0.3 M solution. It was also found that the optical transparency of the samples changes from 70% to 35% and the optical band gap of the samples was in the range of 2.20 to 2.41 eV, depending on the morality of solution. The cycle voltammogram shows that the sample prepared at 0.3 M has one-step electerochoromic but the other samples have two-step electerochoromic. The results show a correlation between the cycle voltammogram and the physical properties of the films.

Vanadium oxide thin films were grown on glass substrates using spray pyrolysis technique. The effects of substrate temperature, vanadium concentration in the initial solution and the solution spray rate on the nanostructural and the electrochromic properties of deposited films are investigated. Characterization and the electrochromic measurements were carried out using X-ray diffraction, scanning electron microscopy and cyclic voltammogram. XRD patterns showed that the prepared films have polycrystalline structure and are mostly mixed phases of orthorhombic α- V 2 O 5 along with minor β- V 2 O 5 and V 4 O 9 tetragonal structures. The preferred orientation of the deposited films was found to be along [101] plane. The cyclic voltammogram results obtained for different samples showed that only the films with 0.2 M solution concentration, 5 ml/min solution spray rate and 450°C substrate temperature exhibit two-step electrochromic properties. The results show a correlation between cycle voltammogram, morphology and resistance of the films.

In this paper, a facile method for the synthesis of gold nanoseeds on the functionalized surface of silica nanoparticles has been investigated. Mono-dispersed silica particles and gold nanoparticles were prepared by the chemical reduction method. The thickness of the Au shell was well controlled by repeating the reduction time of HAuCl4 on silica/3-aminopropyltriethoxysilane (APTES)/initial gold nanoparticles. The prepared SiO2@gold core/shell nanoparticles were studied using x-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy and ultraviolet visible (UV–Vis) spectroscopy. The TEM images indicated that the silica nanoparticles were spherical in shape with 100 nm diameters and functionalizing silica nanoparticles with a layer of bi-functional APTES molecules and tetrakis hydroxy methyl phosphonium chloride. The gold nanoparticles show a narrow size of up to 5 nm and by growing gold nanoseeds over the silica cores a red shift in the maximum absorbance of UV–Vis spectroscopy from 524 to 637 nm was observed.

Tin sulfide thin films (SnxSy) with an atomic ratio of y/x = 0.5 have been deposited on a glass substrate by spray pyrolysis. The effects of deposition parameters, such as spray solution rate (R), substrate temperature (Ts) and film thickness (t), on the structural, optical, thermo-electrical and photoconductivity related properties of the films have been studied. The precursor solution was prepared by dissolving tin chloride (SnCl4, 5H2O) and thiourea in propanol, and SnxSy thin film was prepared with a mole ratio of y/x = 0.5. The prepared films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis spectroscopy. It is indicated that the XRD patterns of SnxSy films have amorphous and polycrystalline structures and the size of the grains has been changed from 7 to 16 nm. The optical gap of SnxSy thin films is determined to be about 2.41 to 3.08 eV by a plot of the variation of (αhν)2 versus hν related to the change of deposition conditions. The thermoelectric and photo-conductivity measurement results for the films show that these properties are depend considerably on the deposition parameters.

In this paper, thin films of tin sulfide (SnxSy) with atomic ratios of y/x=0.25, 0.50, 0.75, 1.00, 1.25 and 1.50 have been prepared on a glass substrate at T=420 °C using the spray pyrolysis technique. The initial materials for the preparation of thin films were an alcoholic solution consisting of tin chloride (SnCl4.5H2O) and thiourea (CS(NH3)2). The prepared thin films were characterized by x-ray diffraction, scanning electron microscopy, energy dispersive x-ray analysis, scanning helium ion microscopy and UV–vis spectroscopy. The photoconductivity and thermoelectric effects of SnxSy thin films have been studied. The SnxSy thin films had a polycrystalline structure with a nearly uniform surface and cluster-type growth. With increasing the atomic ratio of (y/x) in films, the optical gap, photosensitivity, thermal activation energy and Seebeck coefficient changed from 2.72 to 2.37 eV, from 0.05 to 0.78, from 0.07 to 0.48 eV (in the high temperature range) and from +0.17 to −0.22 mV K−1 (at T=350 K), respectively. In addition, the structure of tin sulfide thin films tends to a nearly single-crystal state in (001) preferred orientation corresponding to SnS2 phase with increasing (y/x) ratio. These structure situations considerably influence the photosensitivity and thermoelectric properties of thin films.

ZnO:Mg thin films with different amounts of Mg were deposited on a glass substrate using the spray pyrolysis technique. The structural, optical and antibacterial properties of the films were studied as a function of the dopant concentration. The ZnO:Mg films were characterized using methods such as x-ray diffractometry, scanning electron microscopy, scanning tunneling microscopy and UV–Vis spectroscopy. The samples display hexagonal wurtzite structure, with no secondary phase. Morphological studies indicated the deposition of a uniform film, and particle size decreases with Mg doping. Optical studies revealed that the optical band gap and optical transmittance increase with Mg concentration. The antibacterial activities of the samples against Escherichia coli (gram-negative) cultures were tested by the drop test method, which shows that Mg doping increases antibacterial activities of thin films.

Ni-doped TiO2 nanoparticles were synthesized by the non-hydrous complex-polymer sol–gel method. Titanium isopropoxide was used as precursor and acetyl acetone (AcAc) and citric acid were used as polymer and complex agent, respectively. A series of Nix: Ti1−xO2 samples with x=0.01, 0.03, 0.05 and 0.10 were prepared and subsequently annealed at 400, 600 and 800 °C. The structural and magnetic properties of Nix: Ti1−xO2 were studied by means of x-ray diffraction (XRD) and dc magnetometery. Samples annealed at 400 °C attained a particle size of 12 nm with structural phases of anatase, rutile and cubic NiO. From the blocking temperatures of the zero-field-cooled and field-cooled measurements, similar particle sizes (as from XRD) were obtained. The presence of ferro- and antiferromagnetic (AFM) interactions further confirms that the particles have different structural compositions. At 800 °C the particles have grown to about 30 nm with either a rutile or NiTiO3-type structure. The presence of NiTiO3 is also seen in the magnetic measurements, which show the characteristic AFM peak at 23 K.

In this paper, nanoparticles of copper–cobalt compound oxide have been prepared by the sol–gel technique with different mole ratios of Cu/Co (ranging from 0.05 to 0.15) for the detection of methane gas, which is chemically a very stable hydrocarbon. The structural properties and morphology of the powders were studied by x-ray diffraction (XRD), Fourier transform infrared spectroscopy and transmission electron microscopy (TEM). By XRD analysis, we confirm that Co3O4 and (CuO0.3CoO0.7) Co2O4 phases are formed and mean grain size is decreased with increasing Cu doping (from 28 to 24 nm). On the basis of TEM images, it is found that these particles possess a cubic structure with nearly uniform distribution. Also, gas-sensing measurements reveal that the optimal operating temperature is 300 °C, that the use of Cu as a dopant improved the sensing properties of cobalt oxide and that the sensitivity increased considerably with Cu concentration. The best sensitivity properties of nanosensors have been found at the mole ratios of Cu/Co of 0.125 and 0.15.