A Scalable Solution Route to Porous Networks of Nanostructured Black Tungsten

This paper studied the feasibility of a new solution-processed method to manufacture black tungsten nanostructures by laser conversion of tungsten hexacarbonyl precursor on the Inconel 625 substrate under argon atmosphere at ambient pressure. The results show that sublimation of the precursor can be prevented if the decomposition temperature (>170 °C) is achieved using the laser heating method. Three different laser powers from 60–400 W were used to investigate the role of laser parameters on the conversion. It was found that lower laser power of 60 W resulted in a mixture of unconverted precursor and converted tungsten. Higher laser powers >200 W resulted in α-W (BCC) in one step without further heat treatment. Different oxygen concentrations from 0.5 ppm to 21 vol% were used in the laser canister to investigate the effect of oxygen concentration on the conversion. It was found that the hard vacuum (>10−4 torr) or hydrogen is not necessary to obtain α-W (BCC). The solar absorptance varied from 63–97%, depending on the amount of precursor deposited on the substrate and oxygen content in the laser canister. This solution-based laser conversion of tungsten precursor is a scalable method to manufacture tungsten coatings for high-temperature applications.

Synthesis of Copper Nanoparticles on Cellulosic Fabrics and Evaluation of their Multifunctional Performances

Two different kinds of copper nanoparticles (CuNPs) (brown colour and greenish colour) were synthesised by using simple solution route and applied on cotton by exhaust method to achieve multidimensional functionalization on one of the most popular cellulose materials e.g., cotton fabric. The synthesised CuNPs imparted different colours to cotton textile due to different conditions of synthesis and localized surface plasmon resonance. Physico-chemical characterizations of the synthesized nanoparticles were performed by using scanning electron microscope (SEM) and EDX analysis whereas the optical properties of the nanoparticles were studied using UV-visible spectroscopy. The prepared CuNPs of both the types demonstrated very good antimicrobial activity up to 97%. In addition, cotton fabric treated with CuNPs showed very high catalytic activity for reduction of 4-nitroaniline in presence of sodium borohydride to phenylene diamine. Washing durability and rubbing fastness of the treated fabric have also been measured by following standard testing methods and found to be very good with a rating 4.

Effects of Carbon Doping and Annealing Temperature on Magnetic MnAl Powders and MnAl Polymeric Composites

Process parameters leading to magnetic polymer composites, an essential ingredient in the additive manufacturing of rare-earth-free magnets, are investigated. The induction melting of manganese (Mn) and aluminum (Al), and subsequent annealing at 450, 500, or 550 °C for 20 min, gave rise to ferromagnetic τ–MnAl phase, as well as other phases. The nonmagnetic Al4C3 and oxide phases were then removed by the magnetic separation. Magnetic powders from the magnetic separation were incorporated in polylactic acid (PLA) matrix via a solution route. The remanent magnetization as high as 4.3 emu/g in the powder form was reduced to 2.3–2.6 emu/g in the composites. The reduction in coercivity was minimal, and the largest value of 814 Oe was obtained when the powder annealed at 450 °C was loaded in the composite. The phase composition and hence magnetic properties were even more sensitive to the carbon (C) doping. Interestingly, the addition of 3% C led to coercivity as high as 1445 Oe in MnAl–C powders without further annealing. The enhanced coercivity was attributed to the domain wall pinning by the AlMn3C phase, and magnetizations are likely increased by this phase.

Functionalization of Doped ZnO through Solution Route Synthesis: A study Using Spectroscopy & Density of States

ZnO is one of the widely studied materials for multidimensional applications, viz. semiconductor material, catalysts, solid-state devices, etc. The primary functionalization is carried out by doping the required element (s) within the ZnO matrix, which can exist in either zinc blend or the wurtzite form. The present research reports synthesis of ZnO doped by Cr, Y, and Eu at two dopant concentrations. The synthesis technique is optimized using dual fuels during solution auto combustion synthesis. Detailed analysis of X-ray diffraction study reveals a comparative analysis of the peak area and FWHM magnitude. The influence of the doping element on the ZnO is studied in terms of UV and photoluminescence spectra. The highest bandgap of 3.08 eV is reported with Eu as the dopant within ZnO compared to Y, which shows lower bandgap energy of 2.44 eV. The density of states study of ZnO is found to be continuous with a significant nodal region within -3.4 to -2.4 eV. However, in the doped systems, irrespective of the dopant, nodal regions are more with specific band regions in the ZnO-Y/ZnO-Eu system. Irrespective of dopant type, doping within ZnO significantly influences the states in the conduction band.