A DFT based prediction of a new 2D zirconium disulfide Pmmm-ZrS2 monolayer: A quasi direct band gap semiconductor

A new 2D stable crystal of zirconium-sulfur compound namely Pmmn-ZrS2 monolayer by using density functional theory is predicted. Our computations confirm that our proposed ZrS2 monolayer indicates good energetic, kinetic, and thermal stabilities as proved by the crystal energy analysis, phonon modes computation, and the molecular dynamic assessment respectively. Investigation in its electronic properties shows the new Pmmn-ZrS2 monolayer is a quasi direct semiconductor with a band gap of about 1.53 eV obtained by HSE06 hybrid functional method can be modulated by external in-plane strain effects. These results suggest this monolayer as a useful material for application in nano-electronic devices. Keywords: Density functional theory, ZrS2 monolayer, Quasi-direct semiconductor, Electronic properties, Compressive strain, Tensile strai

Enhanced structural, electrical, mechanical properties and antibacterial activity of Cs/PEO doped mixed nanoparticles (Ag/TiO2) for food packaging applications

In this paper, silver (Ag) nanoparticles were synthesized by utilizing an aqueous extract of fresh leaves of Chenopodium murale which is considered a cost-effective and eco-friendly approach. The sol-gel technique was used to syntheses TiO2 nanoparticles and different methods were used to characterize the nanoparticles (Ag and TiO2) including UV–Vis spectroscopy, XRD, and TEM. Also, new nanocomposites were prepared using the solution casting method. The prepared films were characterized by different analytical methods. The absorption peak of the silver nanoparticles shown by the UV–visible spectrum was around 430 nm. The crystalline average size of the Ag NPs was 20 nm while TiO2 NPs was 15 nm as displayed by the XRD pattern. Meanwhile, the degree of amorphicity of the Cs/PEO blend was increased as a result of adding Ag and TiO2 NPs. It was evident through the FTIR spectroscopy that there was an interaction between the functional groups of the polymer blend and the Ag/TiO2 nanofiller. In addition, there was an increase of mechanical properties of the prepared films such as the Young's modulus, elongation, and tensile strength with increasing the Ag/TiO2 content. It was clear through the impedance spectroscopic study that the iconic conductivity was improved with the addition of Ag and TiO2 nanoparticles into the polymer blend system. The highest conductivity was log −9.34 S cm−1 at Cs/PEO/0.3%Ag/0.8%TiO2. It was also evident from the results that the antibacterial activity of the pure Cs/PEO blend was increased as a result of doping Ag/TiO2 nanoparticles to the polymer blend. The activity index (%) of the antibacterial activity at sample blend + (0.3%) Ag + (0.8%) TiO2 of the E. coli, S. aureus, C. Albicans, A. niger was 32, 45.8, 77.8, and 92 (%) respectively. Thus, these results indicate the applicability and potential of the nanocomposites for use in food packaging applications

Effect of X-ray irradiation on the structure, thermal and mechanical properties of polyester

Samples from sheets of the polymeric material polyester have been exposed to X-rays from a 50 kV X-ray tube in the dose range 10–100 kGy. The resultant effect of X-rays has been investigated using different techniques such as X-ray diffraction XRD, thermogravimetric analysis TGA, differential thermal analysis DTA and stress-strain measurements. The results indicate that the polyester decomposes in one weight loss stage. Also, the X-ray irradiation in the dose range 30–100 kGy led to a more compact structure of polyester, which resulted in an improvement in its thermal stability. The variation of transition temperatures with the X-ray dose has been determined using DTA. The polyester thermograms were characterized by the appearance of an endothermic peak due to the melting of the crystalline phase. The melting temperature of the polymer Tm was investigated to probe the crystalline domains of the polymer. At the dose range 30–100 kGy, the defect generated destroys the crystalline structure, thus reducing the melting temperature. In addition, the stress-strain measurements indicate that the X-ray irradiation at the same dose range 30–100 kGy yields crosslinked polyester of high resilience that is suitable for manufacturing protective clothes that reduce heat stress

Microwave synthesis of Zn:Mn:PbI2 micro-size nanosheets and their characterizations

Herein, we are reporting, for the first time, a microwave-assisted synthesis of lead iodide (PbI2) nanosheets (NSs) with codoping of Zn and Mn, confirmed by SEM/EDX. In the co-doping Mn concentration was kept at a constant level (i.e. 15 %) while Zn concentration was varied from 1 wt.% to 10 wt.%. The morphological analysis confirming presence of the dopant was done through SEM/EDX. The single phase and polytypic nature of NSs were established by XRD and FT-Raman examinations. Homogeneous doping of Mn and Zn in prepared PbI2 NSs was confirmed by SEM mapping analysis. The dielectric and electrical properties were measured by preparing a compact pellet of NSs at 49820 Pa pressure. The dielectric constant and electrical conductivity were enhanced by Zn:Mn co-doping in PbI2. The radiation activity was tested by cesium-137 (137Cs) radioactive source and its increase resulting from the doping was observed. The enhanced properties suggest that the prepared NSs may be useful in electro-optic and radiation detection device applications