In this study, the mechano-chemical properties of aromatic polymer polyetheretherketone (PEEK) samples, irradiated by high energy electrons at 200 and 400 kGy doses, were investigated by Nanoindentation, Brillouin light scattering spectroscopy and Fourier-transform infrared spectroscopy (FTIR). Irradiating electrons penetrated down to a 5 mm depth inside the polymer, as shown numerically by the monte CArlo SImulation of electroN trajectory in sOlids (CASINO) method. The irradiation of PEEK samples at 200 kGy caused the enhancement of surface roughness by almost threefold. However, an increase in the irradiation dose to 400 kGy led to a decrease in the surface roughness of the sample. Most likely, this was due to the processes of erosion and melting of the sample surface induced by high dosage irradiation. It was found that electron irradiation led to a decrease of the elastic constant C₁₁, as well as a slight decrease in the sample’s hardness, while the Young’s elastic modulus decrease was more noticeable. An intrinsic bulk property of PEEK is less radiation resistance than at its surface. The proportionality constant of Young’s modulus to indentation hardness for the pristine and irradiated samples were 0.039 and 0.038, respectively. In addition, a quasi-linear relationship between hardness and Young’s modulus was observed. The degradation of the polymer’s mechanical properties was attributed to electron irradiation-induced processes involving scission of macromolecular chains.

In this work, the mechanical and tribological characteristics of polyetheretherketone (PEEK) sheets were enhanced by electron beam irradiation. PEEK sheets irradiated at a speed of 0.8 m/min with a total dose of 200 kGy achieved the lowest specific wear rate of 4.57 ± 0.69 (10⁻⁶ mm³/N⁻¹m⁻¹), compared to unirradiated PEEK with a rate of 13.1 ± 0.42 (10⁻⁶ mm³/N⁻¹m⁻¹). Exposure to an electron beam at 9 m/min for 30 runs, with a dose of 10 kGy per run for a total dose of 300 kGy, resulted in the highest improvement in microhardness, reaching 0.222 GPa. This may be due to the decrease in crystallite size, as indicated by the broadening of the diffraction peaks in the irradiated samples. According to the results of thermogravimetric analysis, the degradation temperature of the irradiated samples remained unchanged at 553 ± 0.5 °C, except a sample irradiated at dose 400 kGy, where the degradation temperature shifted towards a lower position of 544 ± 0.5 °C. Differential scanning calorimetry results revealed that the melting temperature ($T_m$) of the unirradiated PEEK was about 338 ± 0.5 °C, while a high temperature shift of the $T_m$ was observed for the irradiated samples.

Impedance spectroscopy provides relevant knowledge on the recombination and extraction of photogenerated charge carriers in various types of photovoltaic devices. In particular, this method is of great benefit to the study of crystalline silicon (c-Si)-based solar cells, a market-dominating commercial technology, for example, in terms of the comparison of various types of c-Si devices. This study investigates the dark and light electrophysical characteristics of a heterojunction silicon solar cell fabricated using plasma-enhanced chemical vapor deposition. The measurements are performed at various applied biases, enabling the determination of complex resistance, characteristic time, capacitive response and impurity concentration within the semiconductor junction and to correlate them with the device performance. In addition, the impedance spectra of the studied cell were investigated as a function of temperature. Studies of the frequency and temperature dependences of capacitance do not reveal a significant presence of thermally activated centers of free carrier capture, concomitant with a very small value of the activation energy extracted from an Arrhenius-type analysis. This leads to a conclusion that these centers are likely not impactful on the device operation and efficiency.

Atomistic insights into bisphosphate-enhanced graphene oxide-epoxy composites for durable wind turbine materials in renewable energy.

Understanding the atomic-level behavior of photocatalysts under hydrated conditions is essential for improving hydrogen production efficiency. In this work, density functional theory calculations and classical all-atom molecular dynamics simulations were performed to investigate the intra- and intermolecular interactions of rod- and cluster-shaped cadmium sulfide in the presence of implicit and explicit water, respectively. The density functional theory optimized geometries, reduced density gradient, noncovalent interaction, critical point, and molecular electrostatic potential maps were examined using the LC-ωPBE functional with the LANL2DZ basis set and the IEFPCM implicit solvation model, while explicit hydration was modeled via classical all-atom molecular dynamics simulations by obtaining molecular snapshots and radial distribution functions. Density functional theory results revealed that rod-shaped cadmium sulfide exhibits stronger directional bonding and higher electronic localization compared to cluster-shaped cadmium sulfide, while classical all-atom molecular dynamics simulations showed that water molecules preferentially interact with surface S atoms of cadmium sulfide sites. This atomistic insight clarifies how morphology and hydration jointly modulate cadmium sulfide electronic structure and reactivity, providing guidance for the rational design of efficient cadmium sulfide-based photocatalysts for solar-driven water splitting.