Microcrystalline titanium oxide (TiO2) particles of anatase crystal phase were prepared by the sol-gel route, varying thermal treatment conditions (400 °C and 600 °C), for a comparison purpose with commercial TiO2 (P25). Structural, optical and electrical properties were investigated for dye-sensitized solar cells (DSSCs) application. Both microcrystalline TiO2 particles, synthesized by the sol-gel method and obtained from the P25 powder were used to prepare a light scattering layer of the working electrode. The obtained electrodes were then immersed in a solution of N-719 (ruthenium) dye, at the ambient temperature, during 24 h. Finally, the DSSCs were assembled, the short circuit photocurrent, the open circuit photovoltage, and the power conversion efficiency were measured using an I-V measurement system. The overall conversion efficiencies for all elaborated DSSCs were proximate. A maximum efficiency of 2.3% was achieved for the sol-gel TiO2 thin film annealed at 400 °C, under one sun irradiation, with an open circuit voltage of 0.61 V and a current density of 6.54 mA/cm2. The higher efficiency value of the sol-gel TiO2 sample, annealed at 400 °C, was attributed to the uniformity of the prepared titanium oxide substrate, which provides a better surface for the dye absorption.

The aim of this work is to evaluate thermal stress of Er:YAG laser radiation on enamel and dentin of the dental. The transient state heat conduction equation for pulse wave laser regime with energy of 100 mJ, 300 mJ and steady state heat conduction equation for CW regime with powers of 1 W, 5 W was solved analytically. Then, the thermally induced stress was investigated following the calculation of the temperature distribution. Using the thermo-mechanical characteristics of the dentin and the enamel, all components of stress were obtained. The thermal stress of Er:YAG laser radiation on the enamel and the dentin calculated in this work may be useful for clinical applications.

In this contribution, the micro- and macro-structure of plasma grown hydrogenated nanocrystalline silicon (nc-Si:H) thin films were followed with respect to substrate temperature (Ts) ranging from 80 °C to 200 °C. nc-Si:H films were deposited by plasma enhanced chemical vapor deposition technique using silane gas highly diluted by hydrogen and high RF power density. Micro-structure analysis was performed with grazing angle X-ray diffraction (GAXRD) and dispersive Raman spectroscopies. Parallelly, morphological properties of the films were investigated via field emission scanning electron microscopy (FE-SEM) by taking both surface and cross-sectional micrographs. GAXRD results suggest the presence of 4–5 nm nanocrystallites with the size almost independent of Ts. The detailed analysis of the Raman spectra reveals one- and two-phonon modes due to amorphous and crystalline silicon (c-Si), where all c-Si related peaks shifted to lower frequencies. Raman nanocrystalline volume fraction is found to be greater than 50% for all Ts; it increases together with the short-range order at elevated Ts. This micro-structural improvement with Ts is considered to be slight when compared to the FE-SEM-observed drastic changes of morphology, particularly the size of large conglomerates (35–250 nm). The behavior of micro- and macro-structure with Ts is correlated well with the previously determined bonding and lateral conductivity measurements. It seems to be the macro-structure that accounts for bonding and electrical properties of nc-Si:H thin films.

Undoped zinc oxide (ZnO) thin films have been grown on glass substrates by sol-gel process associated with dip coating. Two different solvents are used such as: 2-methoxyethanol and ethanol. The influence of these solvents on structural and optical properties of ZnO thin films has been investigated. Crystallinity and surface morphology of ZnO films are analyzed using X-ray diffractometry (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The optical properties are characterized by ultraviolet-visible (UV-vis) and photoluminescence spectroscopy (PL). Humidity sensors have been prepared with deposited ZnO films. Results reveal that ZnO thin film synthesized with 2-methoxyethanol showed a better crystalline quality and ultraviolet emission performance. In addition, a smaller transmittance in visible range and a higher surface roughness are observed. Sensing humidity test exhibits better sensitivity for sensor prepared with film deposited using 2-methoxyethanol as solvent.

The photoelectrocatalytic activity of Zn-loaded reduced graphene oxide-titania (RGO-TiO2) composite coatings on mild steel substrate was investigated in detail. Zn-loaded RGO-TiO2 composite films were prepared by using DC electrochemical co-deposition technique onto mild steel substrate in an acid-sulphate bath electrolyte. The cyclic voltammetry and photocurrent response studies showed that the Zn-loaded RGO-TiO2 films have improved photoelectrocatalytic performance. The embedding of metallic Zn into the RGO-TiO2 promoted an effective charge carriers separation by minimizing the recombination losses. In this manner, metallic Zn will act as efficient photo-induced electron acceptors from the bulk of RGO-TiO2 film. Thus, the transportation of the electrons from the working electrode to the counter electrode was improved significantly.

Indium sulfide In2S3 thick films are deposited on glass substrates using spray technique over the optimum conditions experiments (Ts = 340 °C, S/In = 2). The films are polycrystalline and have thickness of about 1.8 μm. These films are annealed in a vacuum sealed pyrex tubes (10−5 torr). Physico-chemical characterizations by SEM observation, X-ray diffraction and EDX analysis are undertaked on these films. This treatment has improved crystallinity of samples. It has allowed thus to stabilize β and γ varieties of In2S3 material. In2O3 and In6S7 phases have appeared with very weak intensities at high temperatures. The best structure quality are obtained at 300 °C for the optimum annealed temperature (Ts = 340 °C, S/In = 2), for which samples are constituted in dominance by γ phase oriented preferentially towards (1 0 2). The grain size is 42 nm of this phase. Chemical composition of such films has changed relatively to non-treated film but it seems not be affected by treatment temperature. Atomic molar ratio S/In is obtained for 0.9. Optical study shows that these layers are transparent in the visible and optical direct band gap increases as function of annealed temperature.

Ge quantum dot formation on Si(1 0 0)-(2 × 1) by nanosecond pulsed laser deposition under laser excitation was investigated. Scanning tunneling microscopy was used to probe the growth mode and morphology. Excitation was performed during deposition using laser energy density of 25–100 mJ/cm2. Faceted islands were achieved at a substrate temperature of ∼250 °C only when using laser excitation. The island morphology changes with increased laser excitation energy density although the faceting of the individual islands remains the same. The size of the major length of islands increases with the excitation laser energy density. A purely electronic mechanism of enhanced surface diffusion of the Ge adatoms is proposed.

First-principles calculations have been performed to determine the structural, electronic and magnetic properties of transition metal TM (TM = Fe, Co and Ni) monatomic nanochain encapsulated inside and between (9, 0) beryllium oxide nanotube (BeONT) bundle. The generalized gradient approximation (GGA) was employed to describe the exchange-correlation potential. Our results show that the geometrical structure of the BeONT bundle is significantly changed after encapsulating TM nanochains. All configurations of TM chains @ (9, 0) BeONTs bundle systems have negative formation energy so they are stable and exothermic. Total density of states and partial densities of states analyses show that the spin polarization and the magnetic moment of TM chains @ BeONT systems come mostly from the TM atoms chain. The values of total and partial magnetic moment, spin polarization and Stoner parameter are calculated for all configurations of TM chains @ (9, 0) BeONTs bundle systems.

We investigated the effect of the deposition rate on the surface morphology of Si nanowhiskers (NW) deposited by e-beam evaporation using the vapor-liquid-solid growth mechanism. The roles of deposition rate and corresponding surface diffusion on the Si NW growth kinetics were examined. Two growth regimes were observed within the investigated range of deposition rates. Films belonging to these two regimes were found to have characteristically different formations and surface morphologies. We found that the length-diameter curves of NWs switch from decreasing to increasing at a certain critical evaporation rate. The surface morphology is composed of long whiskers (~1 μm) tapered with faceted sidewalls in the high deposition rate regimes (above 1.2 Å/s) due to their length which is comparable with the adatom diffusion and the direct adsorption of Si atoms on the sidewalls. The characteristic morphology was composed of shorter straight whiskers in the low deposition rate regimes (0.6–1 Å/s) because of the higher contribution of Si adatoms diffusing from the substrate to the NW growth.

Synthesis of In2O3 nanostructures grown on Si substrate by the resistive evaporation of metallic indium granules followed by dry oxidation process has been articulated. To prepare nucleation growth sites, selected samples pre-annealed around indium melting point in free-oxygen atmosphere and then to fabricate 1-D nanostructures, they annealed in a horizontal thermal furnace in presence of argon and oxygen. For comparison, one sample, the same origin as initially pre-annealed samples, was excluded in pre-annealing process but presented in annealing step. Characterization of the products with FESEM revealed that the pre-annealed obtained nanostructures are mostly nanorod and nanowire with different morphologies. For the comparative sample, no 1-D structures achieved. X-ray diffraction (XRD) patterns for pre-annealed samples indicated that they are crystalline and the comparative one is polycrystalline. Photoluminescence (PL) measurements carried out at room temperature revealed that emission band shifted to shorter wavelength from pre-annealed samples to comparative one.

In this study, CO2 laser treatment was used as a novel method for creating antibacterial properties on glass mat. Different metallic salts such as CuO, ZnO and AgNO3 were even applied on surface of glass fiber mat, then irradiated with the laser light beam (100 μs). Metal particles were deposited on the surface of samples, and the antibacterial has been developed, through incorporation of metal particles on glass mats. The antibacterial properties of the fabrics were connected with the presence of metal particles on their surface. The amounts of metal particles on the surface were compared using X-ray fluorescence (XRF) and energy dispersive X-ray spectrometer (EDS). Also the morphological properties of the fabrics were observed using a scanning electron microscope (SEM). The experimental work suggests that the change in properties induced by laser can effect an improvement in certain textile products.

The influence of inhomogeneous Rashba interaction on spin-transport of two-dimensional electron gas system (2DEG) is investigated. In the works which have been previously performed in this field it has been shown that in the non-equilibrium regime, the Rashba and Dresselhaus couplings cannot be responsible for spin-current and both transverse and longitudinal components of the spin-current identically vanish. In the present work by using a semi-classical method it was found out that a random Rashba field interaction cannot be considered as a underestimate effect on spin-dependent mechanisms. Regarding the inhomogeneous distribution of the Rashba field it was shown that the spin-current of the system, in general, does not go all the way to zero.

In this study, samples of dental porcelain bodies have been made by using the materials collected from selected deposits employing different mixing proportions of clay, quartz and feldspar. Dental porcelain ceramics have been successfully fabricated by using the sintering technique together with some Na2CO3 additive. The dental porcelain powder has been pressed into pellets at first and subsequently sintered at 700, 800, 900, 1000 and 1100 °C for 2 h. The physical and mechanical properties of the prepared samples have been investigated. The sintering behavior of the fired samples has been evaluated by bulk density, linear shrinkage, water absorption and apparent porosity measurements. This study includes the evaluation of the Vickers’s microhardness by microhardness tester. Phase analysis and microstructural study have been performed by XRD and optical microscope respectively. Optical properties have been investigated using UV-visible spectroscopy. Influence of firing conditions on leucite formation, densification and microstructural development of the sintered samples has been investigated. It has been found that the choice of sintering temperature is one of the key factors in controlling leucite crystallization in dental porcelain ceramics. It has also been found that the flux concentration of material and the effect of temperature on preparation of dental porcelain contribute to the firing shrinkage and hardness, which has been found to increase with the increase of treatment temperature.

Instrumented nanoindentation and STEM have been combined ex situ to study the adhesion of 450 nm thick InP membranes to Si substrates. Three distinct regimes are identified in the deformation of the InP/Si stacks during these experiments: the first is plastic flow of InP at low loads; the second is elastic debonding of the InP membrane, far from the indented zone at medium loads; lastly, the local amorphisation of the underlying Si substrate at high loads. The regime of intermediate loads is shown to be particularly useful in the evaluation of the surface bonding energy of InP to Si.

Nano structured TiN coatings were prepared by means of active screen plasma nitriding (ASPN) method at a constant temperature of 550 °C for 5, 7.5 and 10 h under three gas mixtures of H2:N2% = 3:1, 1:1 and 1:3. In order to investigate the coating properties such as the chemical composition, surface morphology, surface topography and hardness, several analysis techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and nano indentation were employed. The results indicated that the growth of the TiN film under active screen plasma nitriding deposition had a (2 0 0) preferred orientation. Moreover, it was found that N2-50%H2 atmosphere provides the highest deposition rate leading to the maximum roughness and minimum nano hardness values. Similar observation was obtained by increasing the nitriding time. Furthermore, a model was proposed for the relation between the hardness and the surface roughness of the coating in which higher surface roughness leads to lower hardness.