Journal of Metastable and Nanocrystalline Materials Vol. 37

Abstract: Carbon Dots (CDs) have gained the attention of many researchers since its discovery in 2004 due to their unique nanostructure and properties. These are very promising carbonaceous nanomaterials having wide range of applications in sensors, imaging, energy storage, nanomedicine, electrocatalysis and optoelectronics. CDs have shown excellent physical and chemical properties like, high crystallization, good dispersibility and photoluminescence. Besides, these are now known to have excellent biocompatibility, long-term chemical stability, cost-effectiveness and negligible toxicity. Due to favourable physical structure and chemical characteristics, these nanocarbon-based materials have drawn an interest as supercapacitor (SC) electrode materials, opening upnew opportunities to increase the energy density and lifespan of SCs. Thus, variety of quick and affordable methods i.e., the arc-discharge method, microwave pyrolysis, hydrothermal method, and electrochemical synthesis have been developed to synthesize this versatile nanomaterial. There are undoubtedly many methods for creating CDs that are effective and affordable, but due to the safety and simplicity of synthesis, CDs made from waste or using environmentally friendly methods have been innovated. In order to devise sustainable chemical strategies for CDs, green synthetic methodologies based on "top-down" and "bottom-up" strategies have been prioritised. This review summarizes numerous synthetic strategies and studies that are essential for the creation of environment friendly processes for CDs. The recent developments in the use of CDs for photoluminescence and supercapacitance have been highlighted providing a clear understanding of the new source of energy and optoelectronic materials with a futuristic perspective.

Abstract: Exploration of the optoelectronic memristor is required to investigate the photoelectric properties of materials. The traditional memristor material GeAs₂Te₄ is hopeful to be developed into a new type of optoelectronic memristor. However, acquiring high-quality single crystals remains challenging, and the electrical properties of single crystals of GeAs2Te4 need to be explored. Herein, a controlled method is introduced to grow reliable quality GeAs₂Te₄ single crystals, and the electrical and optoelectronic properties are studied. The photodetector based on GeAs₂Te₄ exhibits acceptable optoelectronic performance at designed low temperatures. The responsivity and detectivity of the GeAs₂Te₄-based photodetector reached the value of about 0.137 A W^-1 and 6.9×10⁷ Jones, respectively. It is promising to introduce this family of materials into the field of photodetector and also maybe further in the area of optoelectronic memristors.

Abstract: Nanotechnology has an ever-growing interest due to their utilizations in various platforms of science. With their unique features in structures and morphology, they have dominated the arena of research and development. In this review, we have delt with applications of nanomaterials as both photocatalytic and biological functions. The raising concerns pertaining to diseases and infections worldwide, our work was intended to review nanoparticles which could potentially target such problems. To study the preparations of nanoparticles both by chemical and biological methods. We have also observed for bactericidal ability against pathogenic organisms and found to be effective in controlling the growth of such microbes. Further as per the survey they were also found to have the ability to scavenge certain oxidants like DPPH, ABTS and NO etc. Keywords: Nanotechnology, antioxidant ability, antibacterial capacity, biocatalysis

Abstract: The research in nanocomposites is accelerating with greater velocity due to its wide range of properties and applications in various sectors like construction, marine, automobile, aerospace, defense, and biomedical fields. Most of the researchers are trying to improve the properties further by dispersing various nanomaterials to the matrix to improve the matrix properties. In the present review article, we have discussed in brief the nanocomposites and their various synthesis routes along with their advantages and disadvantages. Why nanocomposites are more preferable over conventional composite materials is also discussed. Important characterization techniques like X-Ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetry (TG) and differential scanning calorimetry (DSC) used to investigate the nanocomposites are also discussed.

Abstract: In this study, the use of the Fourier synthesis and the so-called Maximum Entropy Method (MEM) are evaluated in order to reveal the crystalline defect of the T’-type structure of one of 214 cuprate system, namely Pr_2-xCe_xCuO₄ (PCCO) powders. In the low-level density, the MEM calculations give a clear picture of the scattering and can eliminate the secondary scattering which may bother the main electron distribution of the specific atomic site. The covalent-bond is even clearer to be seen rather than the one obtained by the Fourier synthesis. This brings a further suggestion to use the MEM calculations in case of describing the scattering density of electron. Moreover, by means the used of the MEM calculations, the defect induced magnetism including the role of the tetravalent ionic doping and the annealing reduction effect is briefly discussed in this report.

Abstract: Au nanocluster may exhibit magnetic behaviour in contrast to its bulk state diamagnetic characteristic. We have used four functionals, namely, B3LYP, LSDA, HSEH1PBE and PBEPBE, in DFT calculations to examine the effect of different functionals on the structure of Au₂₃(SR)₁₆ nanocluster. The correct optimized structure Au₂₃(SR)₁₆ nanocluster that has a lower energy was found to be important to study possible muon sites and its associated hyperfine coupling constant. Our computational investigation shows that the B3LYP functional optimized structure resulted in lower total energy of the system as compared to the one produced by using the other functionals.