Among the main characteristics of silver and its alloys, tarnish resistance as well as surface brightness is essential. Alloying these materials with germanium has been shown to have considerable potential in providing tarnish protection. However, studies regarding the electrodeposited silver-germanium (Ag–Ge) alloy coatings are limited. The main objective of this study is to investigate the electrodeposition process of Ag-Ge alloy coatings with different Ge contents. In this regard, co-electrodeposition of Ag and Ge as an alloy coating was performed on pure copper substrates from a cyanide-based electrolyte. The effect of Ge incorporation on alloy composition, surface morphology, topography, texture, crystalline structure and cathodic efficiency of the obtained electrodeposits was investigated. Also corrosion properties of coatings were perused by polarization curves. Evaluation of the coatings was performed using different characterization techniques including XPS, SEM, FESEM, EDS, XRD, AFM, ICP, GIXRD, XRF, FTIR and electrochemical analysis. Results indicated that the optimum content of Ge in the coating was found to be 6 wt% regarding dense and uniform microstructure along with the best corrosion resistance. In addition, the X-ray diffraction patterns exhibited a shift in lattice parameter of Ag that was attributed to the Ag-Ge biphasic alloy formation. Moreover, the surface studies revealed a morphological transformation from nodular to cauliflower-like by increasing the Ge content of coating. The obtained polarization curves represent a remarkable decrease in Ag-6Ge alloy corrosion current density, about 20 times compared to Ag-0.5Ge and about 6 to pure silver. Discrepancies in characteristics between the Ag-Ge and pure Ag coatings were addressed and discussed.

Microstructural analysis and surface studies on Ag-Ge alloy coatings prepared by electrodeposition technique

Ruddlesden-Popper-type halide perovskites (RPPs) have been widely investigated because of their tunable optical properties. The BA2MAPb2I7 (BA = CH3(CH2)3NH3 and MA = CH3NH3) powder is synthesized by a chemical solution-based method at low temperature and deposited on a glass substrate by spin coating technique. The optical transmission, reflection, and absorption investigations are conducted to determine the optical constants of the nano-powder and thin film of BA2MAPb2I7. The obtained results reveal that the optical band gap energy of BA2MAPb2I7 thin film and BA2MAPb2I7 nanoparticles are ∼ 1.95 and ∼ 2.02 eV, which is close to the photoluminescence (PL) peak at around 2.15 eV (576 nm). The optical indexes such as n, k, ε1, and ε2 are assessed based on reflectance spectra data and the Kramers-Kronig (KK) method. Moreover, the third-order nonlinear optical (NLO) characteristics, including nonlinear absorption coefficient (β), nonlinear refractive index (n2), third-order susceptibility (χ(3)) and second-order hyperpolarizability (γ) are investigated at different laser power. The positive signs of the n2 and β reveal that the BA2MAPb2I7 thin film exhibits self-focusing and saturable absorption (SA) properties due to thermal nonlinearity under the continuous wave (CW) laser regime. The magnitude of χ3 is from 20.275 ×10-2 to 29.908 ×10-2esu and the value of γ is from 19.633 ×10-27 to 28.961 ×10-27esu. The superior NLO responses of BA2MAPb2I7 thin-film open the path for the future design and synthesis of desirable and distinct materials for optoelectronic devices. 

Investigation of dielectric, linear, and nonlinear optical properties of synthesized 2D Ruddlesden-Popper-type halide perovskite

While various crystalline carbon allotropes, including graphene, have been actively investigated, amorphous carbon (a-C) thin films have received relatively little attention. The a-C is a disordered form of carbon bonding with a broad range of the CC bond length and bond angle. Although accurate structural analysis and theoretical approaches are still insufficient, reproducible structure-property relationships have been accumulated. As the a-C thin film is now adapted as a hardmask in the semiconductor industry and new properties are reported continuously, expectations are growing that it can be practically used as active materials beyond as a simple sacrificial layer. In this perspective review article, after a brief introduction to the synthesis and properties of the a-C thin films, their potential practical applications are proposed, including hardmasks, extreme ultraviolet (EUV) pellicles, diffusion barriers, deformable electrodes and interconnects, sensors, active layers, electrodes for energy, micro-supercapacitors, batteries, nanogenerators, electromagnetic interference (EMI) shielding, and nanomembranes. The article ends with a discussion on the technological challenges in a-C thin films. 

Amorphous Carbon Films for Electronic Applications

Influence of aminated graphene nanosheets on electro–optical performance and nonlinear optical properties of nematic liquid crystal

Thermally-induced nonlinear optical properties near the band edge of one-dimensional Si/SiOx photonic crystal

Au–Ag–Al Nano-Alloy Thin Films as an Advanced Material for Photonic Applications: XPS Analysis, Linear and Nonlinear Optical Properties Under CW Regime

Malak Refaei

Papers

Au–Ag–Al Nano-Alloy Thin Films as an Advanced Material for Photonic Applications: XPS Analysis, Linear and Nonlinear Optical Properties Under CW Regime

Investigation of linear and nonlinear optical properties of amorphous carbon nanofilms prepared by electron beam evaporation

The nonlinear optical properties of nickel nano-films in the cw regime: Proposed model

Experiment-simulation comparison of luminescence properties of GaN/InGaN/GaN double graded structures