Dip-coating sol-gel method was applied to deposit thin films of Al5AgX(ZnO)95-X on soda-lime glass substrates. This research helps us understand how Ag affects the physical and optical properties of the films. We used advanced techniques like HRTEM, HRSEM, and XRD to analyze the films' structure. This approach explores potential uses for these materials in various fields. These studies suggest that as-deposited thin films are composed of rod-shaped particles, and the shape was found to change from thick to fine with the increase in Ag content. The amount of dopant has a significant impact on its properties and crystallinity. We observed an increasing number of particles transitioning into smaller sizes with the rise in Ag content. Optical absorptions (300–900 nm) at room temperature suggest a direct bandgap that increases with an increase in doping content. This is an indication of the presence of defect states and the high density of localized states. The width of the Urbach tails in the localized states shows a narrowing trend with an increase in doping content. This could potentially be attributed to a decrease in the band tails, leading to an increase in the optical band gap. Moreover, as-synthesized material indicated superb chemical stability. We observed significantly higher binding energy and transparency in our as-synthesized samples. We also observed a remarkable blue shift in the absorption spectra, which shifted towards the lower wavelength side with the addition of more Ag content.

Thin films of Polypyrrole/Zinc Oxide (PPy/ZnO) nanocomposite were fabricated using electrodeposition and subjected to 100 MeV Ag10+ ion beam irradiation at various fluences ranging from 1.0 × 1010 to 1.0 × 1012 ions cm-2. We characterized the well-synthesized PPy/ZnO nanocomposite thin films and examined the modification induced by irradiation using XRD, Raman, FTIR, FESEM-EDS, and AFM techniques. FESEM and AFM images reveal that PPy/ZnO exhibits a cauliflower-like nanosphere structure. An increase in roughness indicates a larger surface area of the electrode, which improves capacitive performance at 1.0 × 1010 ions cm-2, enhancing ion transport from the electrode surface to the bulk. The damage tracks formed by highly energetic ions along their path may contribute to more charge storage by increasing the roughness of the nanocomposite thin film electrodes for energy storage applications. We evaluated the electrochemical performance of thin films using CV, EIS, and GCD measurements. Electrochemical studies reveal enhanced capacitive properties up to 1.0 × 1010 ions cm-2 fluence and decrease at higher fluences. The irradiated nanocomposites achieve a higher specific capacitance of 323.11 F g-1, and the fabricated device shows cyclic stability of 86 %, a remarkable power density (P) of 0.72 kW kg-1, and an energy density (Ep) of 6.32 Wh kg-1.

Aluminium doped zinc oxide (Al4(ZnO)96) nanoparticles were synthesized using new sogel method at 40 °C, with zinc acetate dihydrate (Zn(CH3COO)2·2 H2O) and aluminium nitrate nonahydrate (Al(NO3)3·9 H2O) as precursors. The samples underwent analysis using various structural and optical techniques to investigate the effect of calcination duration on the properties. Prolonged calcination durations led to a significant reduction of oxygen at the grain boundaries, influencing particle size and crystallization. According to TEM-histogram analysis, the most probable size for 28.5 % of nanoparticles fell within the range of 15–20 nm, which aligns closely with the estimated particle size determined by XRD analysis. The material displayed a significant direct bandgap of approximately 3.283 eV, which increased with the duration of calcination. The band gap was affected by changes in phase, strain, and particle size, attributed to the presence of defect states and a substantial concentration of localized states. Additionally, the material exhibited excellent chemical stability and a significantly high binding energy. Moreover, the optical bandgap widened as the width of the Urbach tails in the localized states decreased with an increase in the duration of calcination.

The electrochemical synthesis and ion irradiation effects of polyaniline/zinc oxide (PANI/ZnO) nanocomposite films on stainless steel substrates were investigated in this study. The structural, morphological and electrical properties of the films were characterized by Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and current-voltage (I-V) measurements. The results show that the films have a nanofiber network structure with an average diameter of 50-60 nm. The vibrational modes and structural properties of the films are influenced by ion fluence. The electrical conductivity and mobility of the films increase significantly at low fluence (1.0 × 1011 ions/cm2), reaching values of 1.14 × 10-2 S/cm and 3.56 × 10-5 cm2/V-s, respectively. However, at high fluence, electrical properties degrade due to the damage caused by the ion irradiation. This study demonstrates the potential of PANI/ZnO nanocomposite films for applications in the optoelectronic devices and energy storage devices.

A fuel-based sol-gel auto-combustion method was used to synthesize Sr-substituted copper ferrites. The structural, morphological, and optical properties were studied. XRD pattern depicted the individual phase of the constituents of the prepared samples. SEM images revealed the formation of particle platelets, hexagons, and agglomerates which was found to correlate with the Zeta potential. The Magnetic properties were investigated through a vibrating sample magnetometer under an applied magnetic field of ±20k Oe. The samples were tested for adsorption and photocatalysis for dyes Malachite Green, Crystal Violet, and Congo Red. SrFe2O4 showed relatively higher adsorption and photocatalytic efficiency than other compositions.

We design and synthesize nanohybrids composed of Silver nanoparticle (AgNPs) with Nitrogen doped (N-rGO) and Nitrogen-Sulphur co-doped (NS-rGO) with GO, SERS probes for the detection of hazardous materials. Gra-phene oxide (GO) was synthesized using Hummer's method, subsequently N-rGO and NS-rGO were achieved by hydrothermal treatment. GO showed sheet structure with partly folds and N-rGO and NS-rGO maintain ultrathin-layered structure even after doping with N and S molecules. The ID/IG ratio of N-rGO and NS-rGO composites were higher than neat GO, indicating incorporation of defects by replacing sp2 C atoms by N and S atoms. The N-rGO and NS-rGO were further decorated with AgNPs by wet chemical route. Thereafter, nano-hybrids, Ag-N-rGO and Ag-NS-rGO were used as SERS probes for the detection of DNT, PA and DPA molecules. The unique prop-erties of hybrid SERS substrate enables it to achieve nM LOD with excellent reproducibility and five orders of enhancement in Raman intensity.

Polymers-inorganic hybrid nanocomposites have attracted enormous research due to their wide range of applications in many fields. In this work, we have synthesized hybrid nanomaterials with unique properties that individual Polypyrrole (PPy) and Zinc Oxide (ZnO) couldn’t offer. Firstly, PPy Nanotubes (size ~ 50 nm) were synthesized by a modified chemical oxidative polymerization using Pyrrole monomer and Ammonium Peroxodisulphate (APS) as an oxidant. ZnO urchins (size ~ 50 nm) were prepared by the sol-gel method. The dispersion solution of PPy and ZnO was prepared by using common solvent N-Methyl Pyrrolidine (NMP) and then thin films were grown by the drop-casting method. Secondly, PPy/ZnO nanocomposites were grown by the electrochemical method on the Stainless Steel (grade 304) substrate. Characterizations like XRD, I-V studies, SEM and EDAX were carried out to analyse their structural, electrical properties, surface morphology and chemical composition respectively. Uniform thin films were grown by electrochemical method.

In this study, carbon black (CB) powder-loaded polyurethane (PU) composites (CB–PU composites) were prepared by melt mixing method with different volume percentages (45, 50, 55, 58 and 61 vol.%) of CB in the PU matrix. The prepared CB–PU composites had been further studied for surface morphology using the field-emission scanning electron microscopy (FESEM) technique. Dielectric properties in terms of real permittivity ([Formula: see text] and imaginary permittivity ([Formula: see text] of the fabricated composites were computed using an Agilent E8364B vector network analyzer in the frequency range of 8–12 GHz ([Formula: see text]-band). Dielectric loss factor of the prepared CB–PU composites was computed in terms of the dielectric loss tangent (tan [Formula: see text] = [Formula: see text]/[Formula: see text]. Microwave absorbing properties were appraised in terms of the reflection loss (RL) which in turn was calculated for varying thicknesses of the prepared composites from the measured real and imaginary permittivity data. The minimum RL was observed as −20.10 dB for the absorber with a thickness of 2.2 mm and the bandwidth achieved was 1.92 GHz for RL [Formula: see text]10 dB. Based on the above results these CB–PU composites have potential use as effective microwave absorbers in 8–12-GHz ([Formula: see text]-band) frequency range.

Various constituent ratios with 50:30, 40:40 and 30:50 wt % of U-type barium hexaferrite (Ba4Co2Fe36O60) and Gamma iron oxide (gamma Fe2O3) have been used to designing the radar absorbing composites within epoxy resin system. In the current work, studies are done on electromagnetic and absorbing properties of gamma Fe2O3 powder dispersed Ba4Co2Fe36O60-epoxy composites. X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM) and Vibrating Sample Magnetometer (VSM) tools have been used for structural, surface morphology and magnetic properties respectively of the synthesized powder and fabricated composites. The electromagnetic properties (epsilon', epsilon '', mu' & mu '') of fabricated composites were retrieved from measured reflection (S-11 & S-22) and transmission (S-12 & S-21) parameters in 2-18 GHz frequency range. Experimental finding show that the fabricated composite having 50 wt % of gamma Fe2O3 of designed Ba4Co2Fe36O60 /gamma Fe2O3-epoxy composites possesses maximum absorption of 98.8% (RLmin, of -19.89 dB) at 13.2 GHz for sample thickness of 3.2 mm. The fabricated microwave absorbers confirm the effective absorption performance which has potential for strategic applications and stealth technology.

In the current study, U-type barium hexaferrite (BHF) poly-crystalline powder with chemical formula Ba4Co2-xZnxFe36O60 (0.5 <= x <= 1.5 in step of 0.5) were successfully synthesized by solid state reaction route at the sintering temperature of 1400 degrees C in air medium. The effect of Zn+2 substitutions on the crystalline structural and magnetic properties of BHF powders were examined through nondestructive X-ray diffraction (XRD) technique and vibrating sample magnetometer (VSM) respectively. Upon increasing Zn+2 content the lattice parameters a and c decreases which is leading to the X-ray density up to a small degree, due to a smaller ionic size of Zn+2 as compared to Co+2 ions and saturation magnetization (M-s) from 56.08 emu/g for the zinc substituted sample down to 54.79 emu/g was observed. The transmission electron microscope (TEM) depicted that the particle size reached a minimum at x = 0.5 and then grown with x = 1.5 zinc content, getting a value of 103.06 nm with hexagonal phase and finer grains having the size range of similar to 0.51-1.0 mu m thick and 5 mu m long which is confirmed by field emission scanning electron microscopy (FESEM). A series of BHF-epoxy composites has been further transformed into toroidal shaped composites with fix volume percentage (54.3 vol%) of BHF powder in epoxy matrix. Electromagnetic properties; complex permittivity (epsilon(r) = epsilon' - j epsilon '') and complex permeability (mu(r) = mu' - j mu '') of the prepared composites were computed through coaxial measurement techniques by using an Agilent E8364B vector network analyzer. Minimum return loss (RLmin) was observed as -32.98 dB (maximum absorption " 99.92) for matching frequency 10.3 GHz of the absorber with thickness of 3.1 mm and the bandwidth achieved was 7.38 GHz. Absorption values for prepared composites have potential use as excellent microwave absorbers over the frequency band C-band, X-band and Ku-band. (C) 2021 Elsevier B.V. All rights reserved.

We demonstrate the detection of dipicolinic acid, (DPA), a biomarker of bacterial spores for Bacillus anthracis, 2,4-Dinitrotoluene (DNT) and picric acid (PA) nitroaromatic hazardous chemicals on ultra-sensitive, reusable femtosecond laser textured Au nanostructures decorated with hierarchical AuNPs as a SERS substrate. The AuNPs were achieved by ablating an Au sheet using two different laser scan speeds (1 and 0.1 mm/s) in linear and crossed patterns. The morphological studies revealed dense hierarchical nanostructures decorated with spherical AuNPs possessing 30-40 nm in size in 0.1 mm/s laser scan. The limits of detection (LOD) of the sensor were determined from the detailed SERS measurements and were estimated to be 0.83 pg/L, 3.6 pg/L and 2.3 pg/L for DPA, DNT, and PA, respectively. To the best of our knowledge, the achieved sensitivity is nearly 2 orders improved for DPA when compared with the currently reported LODs using other techniques and 1 order in the case of SERS. Moreover, for DNT and PA the LODs were found to be either superior or comparable with recent reports. We have also demonstrated the competence of our SERS substrates by testing a few real samples (water spiked with these analytes) and again obtained very good sensitivity.

Cupro-spinel (CuFe2O4) nano-particles have been synthesized by sol gel auto combustion method in this work. The sample has been characterized by X-ray diffraction (XRD) pattern and Scanning Electron Microscopy (SEM). Powder X-ray diffraction pattern (XRD) analysis indicates crystalline single phase nature, and cubic structure of copper ferrite with space group Fd3m. The surface morphology of the samples is studied by Scanning electron microscopy (SEM) which indicates the occurrence of cubical growth, with some cracks due to the presence of voids.

Micron size U-type barium hexaferrite powder have been synthesized by solid state reaction process. Powder X-ray diffractometer technique has been used to confirm the phase of hexagonal through the calculate lattice parameters. Field emission scanning electron microscope was used to morphology of synthesized powder and prepared composites. Complex permittivity, complex permeability and absorbing properties have been studied for all polymeric composites by using the Agilent vector network analyzer in the frequency range of 2-18 GHz. The minimum RL was observed as -32.38dB for the absorber with thickness of 3.6mm.

Surface functionalization has been shown to allow tailoring of graphene lattice thus making it suitable for different applications like sensing, supercapacitance devices, drug delivery system and memory devices. In this work, surface functionalization of epitaxial graphene on SiC (EG/SiC) was done by ion beam technology (30 keV Ag- ions at fluences ranging from 5 x 10(12) ions/cm(2) to 5 x 10(14) ions/cm(2)), which is one of the most precise techniques for introducing modifications in materials. Atomic force microscopy showed presence of nanostructures in ion implanted samples and Photoluminescence and X-ray photoelectron spectroscopy revealed that these are probably silicon oxy carbide. High-resolution transmission electron microscopy (HRTEM) showed decoupling of buffer layer from SiC substrate at many places in ion implanted samples. Further, HRTEM and Raman spectroscopy showed amorphization of both graphene and SiC at highest fluence. Fluence dependent increase in absorbance and resistance was observed. Gas sensors fabricated on pristine and ion implanted samples were able to respond to low concentration (50 ppb) of NO2 and NH3 gases. Detecting NH3 gas at low concentration further provides a simple platform for fabricating highly sensitive urea biosensor. We observed response inversion with increasing fluence along with presence of an optimal fluence, which maximized gas sensitivity of EG/SiC. (C) 2019 Elsevier Ltd. All rights reserved.

Electromagnetic absorbers based on carbonaceous materials, i.e., carbon black, polyaniline, polypyrrole, carbon fiber, etc., are prominently employed to attenuate incident electromagnetic waves. In the current work, exfoliated graphite (EG) was synthesized with swollen expanded volume from graphite flake by using a simple and inexpensive method. After synthesis, a series (8.9, 22.9, 33.3, 41.4 and 44.7 volume percentage) of EG–epoxy composites were prepared using a wet mixing method. EG and the prepared composites were characterized by x-ray diffraction analysis, field-emission scanning electron microscopy, and energy-dispersive x-ray analysis. An Agilent vector network analyzer (model PNA E8364B) was employed to compute the complex permittivity (εr = ε′ − jε″) of the prepared composites in the frequency range of 2 GHz to 18 GHz. The dielectric loss of the prepared EG–epoxy composites was quantified in terms of the loss tangent (tanδe = ε″/ε′). Their radar absorption properties were evaluated in terms of the return loss (RL), which in turn was calculated for varying thicknesses of the prepared composites using the computed complex permittivity data. The measured minimum RL was −26.4 dB for the absorber with thickness of 4.0 mm, and the bandwidth achieved was 5.2 GHz for RL ≤ − 10 dB in the effective frequency region of 8 GHz to 14 GHz. The matching frequency shifted towards downwards with increasing EG content in the epoxy thermosetting matrix according to both the calculated and measured data. Consequently, the prepared composites exhibited good complex permittivity, dielectric tangent loss, and microwave absorption and could be utilized in the design of electromagnetic interference shielding and absorbers for stealth applications.

We investigate the effects of pH and Fe doping on the size, structural and physical properties of Mg0.95Mn0.05-xFexO (x = 0, 0.04) nanoparticles. All the nanoparticles were synthesized by the sol-gel autocombustion method by varying the pH of the solution. Furthermore, the phase purity, size, and size distribution of the nanoparticles were studied by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Irrespective of the pH, Rietveld refinement analysis of the XRD data reveals single crystallographic cubic phases with MgO-type wurtzite structure (space group Fm (3) over barm) along with a lattice parameter of 4.2121(8) angstrom for x = 0.0 and 4.2083(5) angstrom for x = 0.04. This change in lattice parameter with Fe doping is due to the smaller size of Fe2+ (78 p.m.) compared with Mn2+ (83 p.m.). The size of the nanoparticles increases monotonically from approximately 10 nm to approximately 16 nm for x = 0.0 and from approximately 18 nm to approximately 23 nm for x = 0.04 with increasing pH. SEM micrographs of the powders show highly agglomerated nanoparticles with porous and irregular morphology. The TEM findings support the XRD results, showing that the nanoparticles increase in size with increase in pH. Because Raman modes should be absent in bulk MgO and present in MgO nanoparticles, the strong intensity of the three Raman modes at approximately 380 cm(-1), 470 cm(-1), and 608 cm(-1) further supports the formation of small nanoparticles of Mg0.95Mn0.05-xFexO (x = 0, 0.04). The decrease in peak intensity with increase in pH suggests an increase in the size of the nanoparticles. The peak at 470 cm(-1) corresponds to a transverse optical phonon, while the peak at 380 cm(-1) corresponds to a transverse acoustic phonon.

We demonstrate an ultrafast laser-ablated hierarchically patterned silver nanoparticle/graphene oxide (AgNP/GO) hybrid surface-enhanced Raman scattering (SERS) substrate for highly sensitive and reproducible detection of an explosive marker 2,4-dinitrotoluene (2,4-DNT). A hierarchical laser-patterned silver sheet (Ag-S) is achieved by ultrafast laser ablation in air with pulse energies of 25, 50, and 100 μJ. Multiple laser pulses at a wavelength of 800 nm and a pulse repetition rate of 50 fs at 1 kHz are directly focused on Ag-S to produce and deposit AgNPs onto Ag-S. The surface morphology of ablated Ag-S was evaluated using atomic force microscopy, optical profilometry, and field emission scanning electron microscopy (FESEM). A rapid increase in the ablation rate with increasing laser energy was observed. Selected area Raman mapping is performed to understand the intensity and size distribution of AgNPs on Ag-S. Further, GO was spin-coated onto the AgNPs produced by ultrafast ablation on Ag-S. The hierarchical laser-patterned AgNP/GO hybrid structure was characterized using FESEM, high-resolution transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. Further, hierarchical laser-patterned AgNP/GO hybrid structures have been utilized as SERS-active substrates for the selective detection of 2,4-DNT, an explosive marker. The developed SERS-active sensor shows good stability and high sensitivity up to picomolar (pM) concentration range with a Raman intensity enhancement of ∼1010 for 2,4-DNT. The realized enhancement of SERS intensity is due to the cumulative effect of GO coated on Ag-S as a proactive layer and AgNPs produced by ultrafast ablation.

In the present work, TiO2 thin films were deposited on quartz substrate by ion beam sputtering method at varying oxygen partial pressure. The film deposition on the substrate was confirmed by x-ray photoelectron spectroscopy technique. From the results of closed aperture z-scan performed using He-Ne laser, the value of non-linear refractive indices were found decreasing with increase in partial pressure. Thermo-optic coefficient also decreased with increase in oxygen partial pressure, operated during the process of deposition.

Selectivity and enhanced sensitivity for surface-enhanced Raman scattering (SERS) substrates are highly desirable attributes for their analytical applications. SERS substrate interaction with target molecules plays a key role in determining the enhancement magnitude and spectral profile of the SERS signal as well as their applications. Herein, we demonstrate a SERS active substrate based on reduced graphene oxide/silver nanoparticles (rGO/Ag NPs) composite material synthesized by a facile wet chemical route. The Ag NPs decorated rGO nanosheet has been achieved by reducing AgNO3 with ethylene glycol in the presence of poly vinyl pyrrolidone (PVP) and NaCl over layered graphene oxide. The addition of PVP stimulates the nano-phase growth as well as uniform distribution of the Ag NPs on rGO nanosheet. The well synthesized rGO/Ag composite was confirmed by using various characterization techniques such as FESEM, HRTEM, XRD, FTIR and Raman. Further, the rGO/Ag NPs composite material has been utilized as a platform for SERS based selective detection of Rhodamine-6G, 4-mercapto benzoic acid, and 2,4-dinitrotoluene analytes. The rGO/Ag NPs substrate demonstrates good homogeneity, stability and nanomolar sensitivity with Raman intensity enhancement of the order of 5 for Rh-6G and 4-MBA whereas 3 for 2,4-DNT. The observed enhancement of SERS signal for all the analytes has been attributes to the cumulative effect of rGO and Ag NPs.

We hereby report the synthesis of Mg0.95Mn0.05O nanostructures using auto-combustion method. Effect of incorporation of different transition metal dopants (cobalt, nickel and copper) on structural, optical, morphological and dielectric properties of pristine Mg0.95Mn0.05O is investigated. X-ray diffraction plots confirm the cubic crystal structure of these samples. The crystallite size is found to be 78.2, 67.02, 78.11 and 64 nm for pure, Co, Cu and Ni doped MgMnO, respectively. Raman analysis clearly envisages the purity of the presently synthesized samples. Optical transmission spectrum shows that samples are highly transparent in the UV–Visible region. In addition, the FTIR results established the presence of magnesium oxide in all samples. Dielectric characterization depicts a reasonable decrease in the dielectric constant ε′ as function of improving frequency, which in turn confirms its dispersive nature.