Narrow Results

An interest in the study of the structural and optical properties of topological insulators, led to the selection of Bismuth telluride thin films. Among the topological insulators, Bismuth telluride is one of the promising materials that exhibit applications in the field of thermoelectric power generation. The films were prepared using the thermal evaporation method under vacuum conditions of ${10}^{-5}$ mbar on glass substrates maintained at a temperature of 120^∘C. The thickness of the film samples ranges from 400 Å to 1400 Å. Pure phases of Bi₂Te₃ with a rhombohedral structure are confirmed using X-ray Diffraction. The crystallite size was calculated using Debye–Scherrer’s formula. Structural morphology and compositions are examined using SEM and EDAX. The UV–Vis study reflects the optical behavior of the thin film samples. The absorption spectra gives the direct and allowed transition band gap of the Bi₂Te₃ thin film samples for various thicknesses. The band gap decreases with the increase in the thickness of the Bi₂Te₃ thin films, suggesting that the material has significant absorption towards the visible spectrum. The Photoluminescence (PL) emissions for Bi₂Te₃ thin film samples of various thicknesses are examined and analysed. Raman study reveals the presence of two active modes.

Potassium niobate KNbO₃ and some compounds of (K_1-xNa_x)NbO₃ (x = 0.3, 0.4, 0.6, 0.7) ceramics powders were successfully prepared by the solid-state reaction method using a non-stoichiometric mixture of starting materials. A possible formation of these phases was proposed based on the experimental results. All of the prepared compounds were characterized using the X-ray diffraction method, and grain size has been calculated using SEM images, and their stoichiometry was obtained from the EDAX results.

Near-stoichiometric and stoichiometric Cu(InAl)Se₂ (CIAS) thin films have been prepared by successive ionic layer adsorption and reaction (SILAR) onto well-cleaned substrates. energy dispersive X-ray analysis (EDAX) spectra of the prepared thin films enabled to determine the film composition, stoichiometry nature, type of conductivity, lattice constants, volume of the unit cell and density of CIAS thin films. The estimated compositional, structural and electrical parameters are presented and discussed in this paper in detail.

Europium-doped (0.01–0.04) Al${}_{0.8}$La${}_{0.2}$TiO₃ (AELTO) nanoparticles (NPs) series were synthesized using a hydrothermal method. These NPs were investigated for structural, and morphological studies through XRD, FTIR, FESEM and TEM analysis. Scherrer’s formula and Williamson–Hall (W–H) analysis were employed to determine crystallite size and lattice strain. The crystallite size was decreased with an increase in Eu content up to 0.03 wt.%. The surface morphology and percentage of elementals of AELTO NPs were investigated using FESEM with EDX as well as TEM analysis. The vibrational modes of AELTO NPs were attained by employing FTIR spectra. These modes are deferred mainly on chemical composition, crystallinity, morphology and strain of the AELTO NPs. Optical bandgaps of AELTO NPs were calculated and found to be in the range of 3.40–3.37eV with the increase of Eu content. These NPs could find potential applications for solid state lighting and down-shifter for solar energy harvesting.

This work estimates the optimum process parameters for the double-layer deposition of aluminum 6063 over EN8 medium carbon steel using friction surfacing. The control process parameters like axial force and feed rate of the consumable rod on two different deposition surface conditions, i.e. a good interface and a course interface during the process were investigated. The second layer deposition was performed over the roughness developed after the first layer deposition and contributed largely to the mechanical anchoring mechanism at the second coating interface. Assessment of the mechanical strength at the first coating interface (substrate/ coating 1) and second coating interface (coating 1/ coating 2) through bending and microhardness tests at both the interfaces was performed. The bending test results disclosed the existence of small delamination with no cracking at the second interface with a feed rate of 150mm/min at axial force of 5kN. An increase of 16.2% in the hardness value of consumable aluminum was seen at the first coating interface region. In contrast, the mean hardness at the second coating interface region was nearly the same as that of the consumable rod. Extensive studies of the surface coating and the microstructural features at both interfaces were performed through FESEM and EDAX analyses.

This research focuses on the fabrication of Al6061/B₄C/Gr metal matrix composites as well as the mechanical and wear properties analysis. A liquid metallurgy stir casting process was used to cast the Al6061 alloy matrix composites with specific wt.% of B₄C and constant wt.% of graphite. In this work, newly developed composites of Gr (particle grain size: 0–20$\mu$m) and B₄C (particle grain size: 0–30$\mu$m) are reinforced with Al6061 pure alloy, which enhanced the mechanical and wear properties when compared to Al6061 pure alloy. Microstructure analysis was carried out concerning the developed mechanical properties. Furthermore, the dry sliding wear behavior of Al6061/B₄C/Gr metal matrix composites was investigated at a sliding speed of 1m/s and a sliding distance of 1500mm against a hardened EN-31 disc under the corresponding load of 19.68N. The minimum wear rate is $1.15\times 10^{-2}$mm³/m found at 15wt.% B₄C and 2wt.% graphite and the coefficient of friction is 0.54 that decreases with graphite addition, with the lowest value obtained with 5wt.% B₄C and 2wt.% graphite. Al6061/10wt.% B₄C/2wt.% Gr particles-reinforced composite material demonstrated the highest tensile and flexural strengths. The hardness,compressive and tensile strength of the Al6061/15wt.% B₄C/2wt.% Gr particles-reinforced composite material were the highest. Scanning electron microscopy was used to examine the worn surfaces of wear specimens. The main objective of this work is to develop hybrid Al6061/B₄C/Gr composites with improved mechanical and wear properties when compared with the base alloy. Al6061 is widely used in automobiles parts like engine block, piston rings, alloy wheels, marine industries, etc. B₄C used in the composite improves strength and is used commonly in armed bullet proof. The Gr present in the composite improves wear resistance, and therefore applied in wear-resistant parts like brake, piston with cylinder, etc.

The nanoalumina particles were produced by the wire explosion process. The size and the shape of the particles were measured using Transmission Electron Microscope (TEM) studies. The Scanning Electron Microscope (SEM) studies were carried out to confirm that the particles are of sub-micron size. The compositions of the material were characterized through the Energy Dispersive Angle X-ray Analysis (EDAX) results. The Wide Angle X-ray Diffraction (WAXD) and the Fourier Transform Infra-Red (FTIR) results confirmed the nanosize powder formed by the process as crystalline γ-Al₂O₃ powder. The thermal characteristics were analyzed using Thermo-gravimetric Differential thermal analysis (TG-DTA). It is identified that the local temperature of the medium at the time of formation of nanopowder decides the phase characteristics of the powder material. The formation mechanism of nanopowder by wire explosion technique was explained in detail. The mechanism of nanopowder formation and the characteristic changes that occur during the explosion process were recorded using a high-speed digital camera.

Bionanotechnology approaches are used by researchers to create nanoparticles and nanomaterials in an environmental friendly and cost-effective manner. Because of biologically active plant secondary metabolites that aid in green synthesis, as well as their specific biological applications, biosynthesized nanoparticles are gaining traction. This work describes a simple, eco-friendly, dependable and cost-effective method for making silver nanoparticles from aqueous leaf extract of Psychotria octosulcata, as well as their anti-inflammatory properties in vitro. UV-Visible spectroscopy, Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Zeta potential (ZP) were used to analyze the biosynthesized Psychotria octosulcata silver nanoparticles. Under a scanning electron microscope, the silver nanoparticles had a spherical shape and sizes ranging from 1 to 100 nm. The peaks from the Fourier Transform for the functional groups C=O, –C=C, C–H and OH in the infrared spectroscopy spectra of silver nanoparticles demonstrate the stability of the produced silver nanoparticles. The particles were crystalline and had a face-centered cubic structure with broad peaks in nature, according to the XRD studies. Protein denaturation was used to test the anti-inflammatory activity of the synthesized silver nanoparticles in vitro.

Nickel pyrophosphate is very popular material having applications in energy storage devices as well as supercapacitors. In this study, a surfactant-mediated approach was adapted to synthesis nickel pyrophosphate nanoparticles. The prepared material was subjected to structural, optical, electrical and electrochemical property studies. Peak broadening in the powder XRD pattern confirmed the nanostructured nature and monoclinic structure of pure $\alpha$-Ni₂P₂O₇ nanoparticle with unit cell parameters of $a=13.09$$\underset{\AA }{\overset{}{´}}$, $b=8.05$$\underset{\AA }{\overset{}{´}}$, $c=8.974$$\underset{\AA }{\overset{}{´}}$, $\alpha =90.00$, $\beta =104.94$, $\gamma =90.00$. Pure $\alpha$-Ni₂P₂O₇ samples calcined at 300^∘C, 600^∘C, 900^∘C show monoclinic structure. The average crystallite size and the internal strain were evaluated using Scherrer’s formula and Williamson–Hall (W-H) respectively. The TEM analysis confirmed the particle size in the range of 5–10nm for Ni₂P₂O₇. Presence of symmetric and asymmetric stretching vibrations of P–O–P and PO₃ was determined by FT-IR spectroscopy. The spectral range of 210–1200nm was employed by the UV-NIR absorption spectroscopy, and the energy band gap calculated from Tauc’s plot is found to be 5.38eV for pure Ni₂P₂O₇. The EDAX analysis confirmed the elemental composition. The TGA analysis reveals that the sample becomes anhydrous and remain stable beyond 600^∘C. The higher dielectric constant observed for the sample is promising for semiconductor, DRAM memory devices and ceramic capacitors. The a.c. conductivity increases with increasing frequency and follows Jonscher’s Power law. On the basis of Jonscher parameters, small polaron QMT conduction model is prevailing. The cyclic voltammetry study was carried out to ascertain the application potential for supercapacitors.

The present work deals with the synthesis of chemically deposited nickel–phosphorous (Ni–P) coating on copper substrate. The process parameters are optimized for maximum hardness based on L${}_{27}$ Taguchi orthogonal design with three process parameters, viz., bath temperature, concentration of nickel Sulphate (a nickel source) and concentration of sodium hypophosphite (a reducing agent), respectively. This is considered and fitted into an L${}_{27}$ orthogonal array (OA) to find out the optimized condition for improved hardness of the coating. The optimized results were obtained from 35g/L of Nickel Sulphate, 20g/L of Sodium Hypophosphite and 90^∘C of temperature. Analysis of variance (ANOVA) was performed to determine the significance of the individual process parameters. ANOVA showed that the factor Nickel Sulphate, the interaction between Sodium Hypophosphite and Temperature were significant in determining the hardness of the coating deposited in the optimized condition. The surface morphology, compositional and phase structure analysis of optimized sample are conducted with the help of scanning electron microscope (SEM), energy-dispersive X-ray analysis and X-ray diffraction (XRD) analyzer, respectively.