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Nickel acetylacetonate of 0.2 M aqueous solution is used to synthesize (NiO) thin films by pulsed spray pyrolysis method onto glass substrates. Structural and morphological properties of the deposited films were examined using (XRD) and (FESEM) techniques. The results revealed that at low substrate temperatures and short spray time, the obtained films were amorphous, whereas the films deposited at higher temperatures and long spray time has a cubic phase. Cross-sectional FESEM is used to properly estimate films thicknesses. The energy band gap is calculated to be 3.52–3.89 eV using optical spectrum measurements. Electrochromic properties of NiO films deposited on FTO working electrode substrates are measured in a three-electrode cell containing KOH with Ag/AgCl reference electrode at a scan rate of 20 mV/s. The charge density increases with the thickness, and it is 98.0 mC/cm2 at the thickness of 360 nm after 30-min deposition time at 400 °C and for most of the samples the film stability increases after cycling. Graphical abstract

Glasses belonging to the xWO3-(30-x) Bi2O3–15Li2O–15CaO–40B2O3 (0 ≤ x ≤ 10) have been obtained by melt-quenching technique. With increasing the concentration of WO3, an increase in the measured glass transition temperature $${T}_{\mathrm{g}}$$ T g and crystallization temperature $${T}_{\mathrm{c}}$$ T c are observed, while the values of the thermal expansion coefficient decrease. Due to the unpaired pentavalent ions, the electron spin resonance spectra of glasses doped with $${\mathrm{WO}}_{3}$$ WO 3 them show unique signals. The results of Raman spectra show that the glass network is mainly constituted by [$${\mathrm{BiO}}_{6}$$ BiO 6 ], [$${\mathrm{BO}}_{3}$$ BO 3 ], [$${\mathrm{BO}}_{4}$$ BO 4 ], and [$${\mathrm{WO}}_{4}$$ WO 4 ] basic structural units. The activation energies for all studied samples were observed to range from 0.02 to 0.08 eV, and the dielectric constant and the conductivities of the investigated glasses increased with increasing temperature. The electrical behavior of the prepared samples revealed their semiconducting character. The prepared samples are being investigated as potential semiconductor material candidates for use in electronic devices.

Photophysical properties of some 1-naphthol and 2-naphthol sulfonate derivatives and their efficiency as singlet oxygen photosensitizers in aqueous media are reported. The fluorescence emission is mainly from the deprotonated form (conjugate base) and their maxima cover the range of 433–529 nm. The fluorescence decay of these derivatives was found to be fitted with bi-exponential function with χ2 of about 1.0 ± 0.1 in all cases. Rate constants for oxygen quenching of the excited singlet states of these compounds in H2O are found to be (1.2 ± 0.2) × 1010 M−1 s−1 for the neutral form and much lower for the quenching of their conjugate bases. p K a values were found to be in the range 7.4–9.5 while p K a * are close to zero and about 3.3 for 2-naphthol and 2-naphthol-6-sulfonate using Forster equation and in the range of 1.4–3.0 using the fluorescence titration method obtained from the relative integrated fluorescence intensity. Singlet oxygen quantum yields photosensitized by these photoacids were reported in D2O and found to be in the range 0.13–0.35 for the sulfonated derivatives.

Preparation of LiTi2(PO4)3 (NASICON-type) glass ceramic from LiF.(2-x)TiO2.xB2O3.1.5P2O5 system were achieved via melt-quenching technique. The effect of gradual replacement of Ti4+ ions with B3+ ions was investigated. The prepared samples were characterized using differential thermal analysis, X-ray diffraction, Fourier transform infrared spectroscopy and high-resolution transmission electron microscope. The results revealed crystallization of LiTi2(PO4)3 as the major phase with traces of Li2TiF6 phase in the quenched samples. The quantities of these phases decreased with increasing B3+ ions until x = 1; beyond this value, B2O3 and β-Li4B2O5 were the dominant phases. After heat treatment at 800 °C/2 h, pure LiTi2(PO4)3 was detected till x = 1 then BPO4 appeared and increased with increasing B3+ ions. At x = 2, pure BPO4 was achieved. TEM revealed nanocrystalline size for the formed phase. In deduction, the substitution of Ti4+ ions by B3+ ions in the glass matrix improved the dc-conductivity at room temperature from 1.29 × 10−10 Ω−1 cm−1 in boron-free sample to 3.41 × 10−3 Ω−1 cm−1 for x = 2 sample due to the precipitation of β-Li4B2O5 in addition to B2O3. However, after heat treatment free boron sample (B0) showed the highest dc-conductivity at room temperature ∼1.23 × 10−4 Ω−1 cm−1 and lowest activation energy 0.032 eV. Therefore, the high conductivity, low activation energy and high diffusion coefficient (1.8 × 10−7 cm2/s) suggesting the use of the prepared materials in Li-ion battery applications.

This work pointed out the preparation of glass-ceramic based on fluoramphibole using different alkalis. Phases were crystallized using heat-treatment at 850 °C/2.5 h and were identified using XRD. Fluorophlogopite, fluorrichterite, enstatite and cristobalite were found in the heat-treated glasses. Crystallization of fluorophlogopite or fluorrichterite was detected in samples containing high K and Na, respectively, accompanied with crystallization of enstatite in the last sample. Cristobalite was crystallized only in equal alkali-containing glass beside enstatite and richterite. Nanoparticles of silver have grown within a silicate glass via modification of ion exchange process. The metal particle diameters were detected using XRD and TEM. The particles size ranges from 4 to 10 nm. The amount of silver ions exchanged was varied according to type and amount of alkali on fluoramphibole compositions. The composites show low values of dielectric permittivity (10–30) due to the formation of interconnected metal nanoparticle chains. The resistivity of the specimen dropped from 10 8 to 10 10 Ω cm 2 to 10 4 to 10 8 Ω cm 2 after ion exchange process which shows metallic and semiconducting behavior according to the reduction temperature.

The electrochemical behavior of Cu–Ni alloys with different Ni contents (5–65 mass%) in acidic sulfate solutions was investigated. The effects of working conditions e.g. concentration of sulfate ions, immersion time and temperature were studied and discussed. In this respect, open-circuit potential measurements, polarization techniques and electrochemical impedance spectroscopy (EIS) were used. Potentiodynamic measurements revealed that the increase in the Ni content improves the stability of the Cu–Ni alloys. The polarization measurements were confirmed by EIS experiments. The stability of the alloys with higher Ni contents is due to the increased amount of Ni in the surface film. The corrosion process of the cupronickels in the acidic sulfate solution was found to be diffusion controlled. The experimental impedance data were fitted to theoretical data according to an equivalent circuit model representing the electrode/electrolyte interface.

Porous titania, TiO 2 , films on Ti substrates were prepared electrochemically. The adsorption of biologically compatible ions, like calcium and phosphate ions, on the formed TiO 2 films was investigated by electrochemical impedance spectroscopy, EIS, and electron diffraction X-ray, EDX, techniques. The morphology of the formed oxide films and the adsorbed layers on their surfaces was investigated by the scanning electron microscopy, SEM. The experimental impedance data were fitted to theoretical data according to proposed equivalent circuit models. The impedance data fitting enabled the explanation of the structure of the oxide film and the adsorption phenomena occurred on its surface. The film characteristics under different conditions were discussed and the adsorption of Ca 2+ and PO 4 3− was explained. The results have shown that the oxide films formed potentiostatically on Ti in H 2 O 2 containing H 2 SO 4 are capable to adsorb biologically compatible ions. The adsorbed layer thickness was found to increase with the increase of concentration of calcium ions present in the ambient electrolyte. The biocompatibility of these materials depends essentially on the apatite-forming ability of TiO 2 due to calcium ion incorporation in the adsorbed films. The formed oxide films with the relatively thick apatite-like adsorbed layer are good implants for bone surgeries and dental applications.

The electrochemical behavior of Cu–Ni alloys in acidic chloride medium was investigated. Commercial Cu–Ni alloys were investigated using potentiodynamic techniques, complemented by electrochemical impedance spectroscopy. The influence of alloy composition, chloride ion concentration and immersion time on the electrochemical response of the alloys was analyzed. Results of present investigations with pure metals (Cu and Ni) are also considered in this paper for the sake of comparison. Potentiodynamic measurements reveal that the increase in nickel content decreases the corrosion rate of the alloy and when the nickel content exceeds 30%, an increase in the corrosion rate was recorded. Also, the corrosion current density increases with increasing the concentration of chloride ions up to 0.6 M. The experimental impedance data were fitted to an equivalent circuit model representing the electrode/electrolyte interface. The relevance of the proposed model to the corrosion/passivation phenomena occurring at the electrode/solution interface was discussed.

The corrosion and passivation behaviors of alloys with different Cu–Ni ratios were investigated in acidic sulfate solutions. The corrosion rate was calculated and the corrosion inhibition process was investigated using different amino acids as corrosion inhibitors. For these investigations conventional electrochemical techniques and electrochemical impedance spectroscopy (EIS) were used. Fitting of the experimental impedance data to theoretical values enables understanding of the corrosion inhibition mechanism and the suggestion of a suitable electrical model to explain the behavior of the alloys under different conditions. The investigation of the electrochemical behavior of alloys before and after the corrosion inhibition processes has shown that some amino acids like lysine have promising corrosion inhibition efficiency at very low concentrations. A model for the electrode/electrolyte interface during the corrosion inhibition processes was suggested and the validity of the model for the explanation of the corrosion inhibition phenomena was discussed.

The electrochemical behaviour of copper–nickel alloys with different Ni content (5–65%) in sulphate solutions of pH 12 was investigated. The effects of temperature, immersion time, and concentration of sulphate ions were also studied. Different electrochemical methods such as open-circuit potential measurements, polarization techniques and electrochemical impedance spectroscopy (EIS) were used. Potentiodynamic measurements reveal that the increase in nickel content increases the corrosion rate of the alloy in sulphate solution linearly. Nevertheless, an increase in the nickel content along with increase in immersion time improves the stability of the Cu–Ni alloys due to the formation of a stable passive film. An equivalent circuit model for the electrode/electrolyte interface under different conditions was proposed. The experimental impedance data were fitted to theoretical data according to the proposed model. The relevance of the model to the corrosion/passivation phenomena occurring at the electrode/solution interface was discussed.