Amirhossein Kazemi, Arash Fattah-Alhosseini, Maryam Molaei, Meisam Nouri,
Volume 19, Issue 2 (June-Biomaterials Special Issue- 2022)
Abstract
In this study, for the first time, the Forsterite (Mg2SiO4) nanoparticles (NPs) with the size of about 25 nm were added to the phosphate-based electrolyte, and the characteristics and properties of the obtained plasma electrolytic oxidation (PEO) coating on AZ31 Mg alloy was investigated. The results of the potentiodynamic polarization measurements revealed that after one week of exposure to simulated body fluid (SBF) solution, the coating with Mg2SiO4 NPs possessed 12.30 kΩ cm2 polarization resistance, which was more than two times greater than that of the coating without NPs. The thicker coating layer, lower wettability, and also presence of Mg2SiO4 NPs inside the pores were responsible for enhanced corrosion protection in the Mg2SiO4 NPs incorporated coating. After three weeks of immersion in SBF solution, the in-vitro bioactivity test results indicated the ability of the NPs-containing coating to form apatite (Ca/P ratio of 0.92) was weaker than the coating without NPs (Ca/P ratio of 1.17). This could be attributed to the lower wettability of the coating with NPs and supports that the addition of the nanoparticles is not beneficial to the bioactivity performance of the coating.
Mohammad Jafar Molaei,
Volume 20, Issue 2 (June 2023)
Abstract
The introduction of the 2D materials in recent years has resulted in an emerging type of the constructed structures called van der Waals heterostructures (vdWHs) that take advantage of the 2D materials in forming atomically thin components and devices. The vdWHs are constructed by the stacking of 2D materials by van der Waals interactions or edge covalent boning. The electron orbitals of the 2D layers in vdWHs extend to each other and influence the electronic band structures of the constituent layers. The tunable optical response over a wide range of the wavelengths (NIR to visible) can be obtained by assembling vdWHs through combining of the monolayers. By application of 2D layers in vdWHs, p-n heterojunctions without lattice mismatch can be formed. The photodiodes based on the van der Waals interactions could be considered as promising candidates for future optoelectronic devices. Furthermore, on-chip quantum optoelectronics can move to the next generation by using 2D materials in vdWHs. In this review, the vdWHs are introduced and their properties and applications in light-emitting diodes (LEDs) have been discussed. The vdWHs allow bandgap engineering, and hence, LEDs working in a range of the wavelengths can be realized. The applications of vdWHs in forming atomically thin components in optoelectronic devices and LEDs have been addressed.
