Journal of Applied Sciences and Nanotechnology

A cost-effective DC glow discharge plasma system was used to deposit a 75 nm titanium dioxide (TiO2) antireflective coating on 5 cm2 crystalline silicon solar cells (initial efficiency 10.13%). The plasma-deposited TiO2 film was nanocrystalline: X-ray diffraction revealed mixed anatase/rutile phases with an average crystallite size of ≈17.6 nm and an optical band gap Eg ≈ 3.5 eV. Atomic force microscopy (AFM) showed a granular surface with average roughness Ra ≈50.7 nm (Rq ≈ 67.7 nm) and grain size ≈ 13.1 nm. Optical reflectance measurements indicated a significant reduction in surface reflectance across the visible spectrum after coating, consistent with enhanced light trapping. Photovoltaic current-voltage (I-V) characterization under standard illumination showed a marked increase in performance: the TiO2-coated cells exhibited improved short-circuit current density and an enhanced power conversion efficiency (PCE) of 11.56% (up from 10.13%), corresponding to 14.1% relative increase. Notably, the fill factor also improved (from 0.614 to 0.639), reflecting reduced resistive losses in the device. The efficiency gain is attributed to the high refractive index and engineered thickness of the TiO2 layer, which improve light coupling into the silicon absorber and reduce front-surface reflection. These results demonstrate that a thin (75 nm) plasma-deposited TiO2 antireflection coating can substantially lower front-surface reflectivity and boost the efficiency of silicon solar cells, offering a straightforward route to higher-performance devices.

This study investigates the corrosion resistance of copper-coated reinforcing steel bars embedded in concrete and exposed to a simulated marine environment for 28, 56, and 90 days. At temperatures of (298, 308, and 318 Kelvin). A novel thermal spray technique was integrated into the hot rolling process to deposit copper powder onto heated steel bars. The coated bars were characterized using X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS), and atomic force microscopy (AFM), revealing a dense, uniform microstructure with reduced surface roughness (63.99 nm) and increased particle density (30.2 × 10⁶ particles/mm²) compared to the uncoated steel bar. Electrochemical measurements demonstrated a substantial decrease in corrosion current density (Icorr) for the coated specimens (1.11 × 10⁻⁷ A/cm²), along with the highest protection efficiency (92.29%). Electrochemical impedance spectroscopy (EIS) further confirmed the enhanced performance of the coated bars, with a superior total impedance resistance of 30,192 Ω•cm² and Warburg resistance of 18,320 Ω•cm² compared to uncoated ones (17,561 Ω•cm² and 9,363 Ω•cm²), respectively. These results highlight the potential of copper coatings as a viable solution for extending the service life of reinforced concrete structures in aggressive environments.

The green-synthesized silver-titanium dioxide (Ag/TiO2) nanocomposite was successfully produced in this study by the synergistic effects of the Cassia siamea leaf extract. In the visible portion of the electromagnetic spectrum, the absorbance improved when the nanoparticle was incorporated into TiO2. The energy gap of the composite reduced as the absorbance increased. Numerous functional groups in the formation of NP were detected by FTIR, and their possible role in NP formation was suggested. The synthesized nanoparticles and nanocomposites were found to be crystalline with X-Ray Diffraction (XRD) studies. The average crystallite size of the nanoparticle was 3.95 nm compared to nanocomposite of 4.53 nm. The shape of the surface of the synthesized nanocomposite appeared smoother and spherical in the scanning electron microscopy (SEM) image. The Energy Dispersive Spectra (EDS) of the TiO2 nanocomposite confirmed the existence of Ag and other elements. The formation of nanoparticles and nanocomposites having an average size of 4.85 nm and 6.92 nm was also verified on the basis of the analysis of the particles’ TEM micrographs. The incorporation of silver nanoparticles (AgNPs) increased the conductivity by 60.24% and resulted in promising electrical properties that suggest their potential application in a dye-sensitized solar cell (DSSC).

This work presents a solution to repair the deteriorating High-Pressure Turbine Blades (HPTB) instead of costly replacement by implementing a two-coating layer system for protection and repair. The first layer is a Bonding Coating (BC) that is made from a nickel-based alloy (NiCrBSi); the second layer is a Top Coating (TC), which is composed of a nickel-based composite material that contains tungsten carbide (WC) particles. Both layers were applied to a nickel-based substrate using a flame thermal spraying (FTHS) technique, with the spray parameters chosen based on the Taguchi method. The results were analyzed using optical microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The findings indicated that a coating layer with a thickness of 200–300 μm was successfully deposited using the FTHS method. The optimal spraying parameters determined by the Taguchi method were: a spraying distance (SOD) of 150 mm, a feed rate (FR) of 30 g/min, and a transverse velocity (TV) of 300 mm/min. Among these factors, SOD was identified as having the greatest influence on the spraying process, followed by FR, and then TV. A crack area on HPTB was successfully repaired using an improved FTHS process, resulting in a homogeneous, dense, and crack-free structure.

The microstructural and dielectric properties of Yttria-partially stabilized zirconia (Y-PSZ) were studied before and after sintering with BaTiO3 and WO3 doping. After sintering, FE-SEM analysis revealed increased grain coalescence and growth, with BaTiO3 causing 300 nm grain expansion and WO3 promoting uniform grain distribution without significant grain size increase (~200 nm). These microstructural changes dramatically altered dielectric behavior. All sintered samples had higher dielectric constants than pre-sintered ones between 100–1000 kHz due to reduced porosity and enhanced homogeneity. Dielectric constant was highest in BaTiO3-doped Y-PSZ at lower frequencies, while WO-doped showed superior frequency stability and lower dielectric loss across the spectrum. In doped crystals, sintering increased crystallinity, lowered defects, and lowered polarization losses. Dielectric loss (tan δ) varied with frequency, with BaTiO3 showing higher losses at low frequencies and showing more stability at higher frequencies, while WO3 showed a moderate, consistent loss. Sintering enhances AC conductivity, especially in BaTiO3-doped materials, via enhancing charge mobility through structural alignment and crystallinity. Due to fault-localized field concentrations, higher voltage increase rates (VIR), lower Weibull modulus and electrical breakdown strength. BaTiO3 and WO3 doping improved grain bonding, void filling, dielectric strength, and energy storage. Tradeoffs between dielectric constant and breakdown strength. High dielectric constants decreased breakdown strength and vice versa. WO-doped Y-PSZ exhibited the highest energy density (22.86 kJ/m3), followed by BaTiO3 (15.22 kJ/m3) and unaltered sintered (14.24 kJ/m3). These investigations demonstrate that alterations to microstructure and the incorporation of impurities improve the energy storage capacity and high-frequency performance of dielectric materials.