Field Emission Scanning Electron Micrographs Research Articles

Growth and degradation of methylammonium lead tri-bromide perovskite thin film at metal/perovskite interfaces

We have studied the crystal growth and degradation of sequential physical vapor deposited thin methylammonium lead tri-bromide (MAPbBr3) perovskite films on glass, aluminum (Al), tin (Sn), silver (Ag), gold-zinc (Au-Zn), and gold (Au) substrates. The structural and morphological properties of the MAPbBr3 were observed as-deposited and 60 days later. X-ray diffractograms of as-deposited films on glass confirmed a cubic MAPbBr3 structure with Pm3¯m space group. However, different crystallographic textures occurred on the metals, and a significant (200) preferred orientation was observed on Sn. The extent of degradation of MAPbBr3 was variable, and each decay led to a significant reduction in crystallite size and change in micro-strain from tensile to compressive. Significant percentage loss in crystallite size occurred the most on Al and least on Au-Zn. Field-emission scanning electron micrographs of the as-deposited films showed compact and bimodal distributed grains. The average grain size increased linearly with the work function of the metals, from 294 nm for Al to 850 nm for Au. Grains remained attached on Sn, Ag, Au-Zn, and Au substrates for 60 days but quickly delaminated on the Al substrate. These findings shed light on possible metal/MAPbBr3 interface interactions for a stable charge transport layer-free MAPbBr3 device structure.

Enhancing the properties of CdO thin films by co-doping with Mn and Fe for photodetector applications

In this communication, we report on how the co-doping of two transition metal ions (Fe and Mn) effectively improves the structural, morphological, optical, electrical and photodetection properties of CdO thin films than individual doping. For this, pure-CdO, Fe-doped, Mn-doped and (Fe-Mn) co-doped CdO thin films are deposited by spray pyrolysis technique. X-ray diffraction (XRD) patterns reveal that these films possess cubic structure and belong to the Fm-3 m space group. The Field Emission Scanning Electron micrographs hold a qualitative agreement with the crystalline sizes obtained from the XRD analysis. Energy Dispersive X-Ray Analysis approved the existence of constituent elements in the prepared films. The photoluminescence spectra identified the quality of crystal structure and the presence of defects in the prepared films. Analyzing the absorption spectra unveiled the direct bandgap values in the range 2.32 eV (for pure-CdO) - 1.96 eV (for CdO:Fe(1%):Mn(1%)). The Hall Effect measurements established n-type behavior with the values of resistivity (ρ), carrier concentration (n) and carrier mobility values in the range 5.8–7.1 mΩcm, 6.7−2.4 × 1019 cm−3 and 16−37 cm2/Vs, respectively. Three different transport mechanisms such as ohmic, recombination-tunneling and space-charge limited current are found to play roles in the three distinct ranges of the I–V data measured for the films under study. The ideality factor values are obtained from the region where the recombination-tunneling mechanism is prevalent. The photoelectric parameters such as photo-responsivity, and external quantum efficiency are obtained. The values of these quantities pertaining to pure-CdO, CdO:Mn, CdO:Fe and CdO:Fe:Mn films vary in the range 128.4–561.3 mA/W, and 30–131.1 %, respectively. From the current study, it was found that photoresponsivity and external quantum efficiency are enhanced by a factor of four in codoped CdO films than the undoped CdO film and can find potential photodetector applications.

Carbon Nanotube Reinforced Natural Fibers for Biodegradable Nanocomposites

Natural fiber-reinforced nanocomposites (NFRCs) are proved as the best alternative for synthetic composites in view of cost and environmental effects. NFRCs have been produced from agro-waste such as banana tree fiber (BFs), because of BF are strong, light-weight, have smaller elongation. To improve the quality of BF, multiwall carbon nanotubes (MWCNTs) are used as reinforcing filler, which are functionalized by an ecofriendly radio frequency oxygen plasma processing method. cellulose nano-crystals (CNC) is extracted from BFs by double hydrolysis process and a simple dip-drying technique has been used to produce NFRCs. Field emission scanning electron micrographs and transmission electron microscopy conform the well dispersion of MWCNTs in the BF matrix. Thermal stability and mechanical strength of the NFRCs are improved owing to the incorporation of MWCNTs. Functional groups in the BFs, CNC and NFRCs are investigated by Fourier transform infrared spectroscopy. The current density of the sample is increased 1000 times and conductivity increases up to 17 Sm−1, which increases with temperature. Therefore, these light-weight biodegradable NFRCs encourage its ability as cost effective industrial conductive composite as usable in electronic devices.

Carbon Nanotube Reinforced Natural Fibers for Biodegradable Nanocomposites

Natural fiber-reinforced nanocomposites (NFRCs) are proved as the best alternative for synthetic composites in view of cost and environmental effects. NFRCs have been produced from agro-waste such as banana tree fiber (BFs), because BF are strong, light-weight, and have smaller elongation. To improve the quality of BF, multiwall carbon nanotubes (MWCNTs) are used as reinforcing filler. MWCNTs are functionalized by an ecofriendly radio frequency oxygen plasma processing method. Cellulose nano-crystals (CNC) are extracted from BFs by double hydrolysis process and a simple dip-drying technique has been used to produce NFRCs. Field emission scanning electron micrographs and transmission electron microscopy conform the well functionalization of MWCNTs and also ensure homogeneous incorporation in the BF matrix. The composites continue thermally stable corresponding to BFs. Mechanical strength of the NFRCs are improved owing to the incorporation of MWCNTs. Functional groups in the BFs, CNC and NFRCs are investigated by Fourier transform infrared spectroscopy. The current density of the sample is increased 1000 times than the raw fibers and conductivity increases up to 17 Sm^-1, which increases with temperature under the applied voltage 100 V and shows the linier characterization. Therefore, these light-weight biodegradable NFRCs encourage its ability as cost effective industrial conductive composite as usable in electronic devices.

Biomimetic [MoO3@ZnO] semiconducting nanocomposites: Chemo-proportional fabrication, characterization and energy storage potential exploration

Current work reports the first investigation on the nanocomposites of molybdenum and zinc oxide [MoO3@ZnO] synthesized via chemosynthetic and biomimetic routes. Chemosynthetic and biomimetic MoO3@ZnO nanocomposites expressed a direct band gap of 4.5 and 3.5 eV, explored via ultraviolet spectrophotometry capped with organic functional groups shown by Fourier transform infra-red spectroscopy. Polycrystalline patterns expressing average crystallite sizes of 36.9 and 22.5 nm for nanocomposites were revealed by X-ray diffraction. Nanocomposites expressed capsule and spherical shapes shown by field emission scanning electron micrographs with strong signals for Mo, Zn and O shown via energy dispersive X-ray spectroscopy. Raman spectroscopy revealed the successful synthesis of the MoO3@ZnO nanocomposite. Electrochemical studies included cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Redox peaks revealed the pseudo-capacitive behavior shown. EIS Nyquist plot with an arc radius pointed the existence of resistance mechanism arising from interfacial layer taking place at the electrode MoO3@ZnO nanocomposite surficial region with charge transfer resistance Rct of = 22.02 Ω. The semi-conducting and capacitive behavior of the biogenic nanocomposite makes it a future candidate for utilization in solar cells and other photovoltaic devices marked by profound sustainability, eco-friendliness, economic viability and scalability in comparison to environmentally damaging chemosynthetic solvo-thermal pathway.

Facile preparation and application of fluoroalkyl end-capped vinyltrimethoxysilane oligomer/methyltrimethoxysilane nanocomposite lipogels possessing superoleophilic/superhydrophobic characteristic

Two fluoroalkyl end-capped vinyltrimethoxysilane oligomer/methyltrimethoxysilane nanocomposites [RF-(VM-SiO3/2)n-RF/MeSiO3/2] were prepared through the acid-base sol-gel reactions of the corresponding fluorinated oligomer [RF-(CH2-CHSi(OMe)3)n-RF: n = 2, 3; RF = CF(CF3)OC3F7: RF-(VM)n-RF] and methyltrimethoxysilane [MeSi(OMe)3: MTMS] under acidic (acetic acid) and successively under alkaline (ammonium carbonate or aqueous ammonia) conditions. FE-SEM (field emission scanning electron micrographs) measurements showed that the RF-(VM-SiO3/2)n-RF/MeSiO3/2 nanocomposites thus obtained consist of clear monolithic structures, affording a lower bulk specific gravity value (~ 0.06 g/cm3) than that (0.49 g/cm3) of the corresponding original RF-(VM-SiO3/2)n-RF oligomeric nanoparticles, which were prepared in the absence of MTMS under similar acid-base sol-gel conditions. Interestingly, the obtained monolithic fluorinated oligomeric silica nanocomposite powders were found to form the corresponding lipogels toward the traditional organic media, such as methanol, ethanol, 2-propanol (IPA), tetrahydrofuran (THF), 1,2-dichloroethane (DE), N,N-dimethylformamide (DMF), and ethyl isopropyl sulfone except for water. It was demonstrated that the RF-(VM-SiO3/2)n-RF/MeSiO3/2 nanocomposite lipogels can provide a superoleophilic/superhydrophobic characteristic on the modified glass surface, although the corresponding RF-(VM-SiO3/2)n-RF oligomeric nanoparticles afforded an oleophobic/superhydrophobic property on the surface. Such unique surface wettability enabled these fluorinated nanocomposite lipogels to apply to not only the packing material for the column chromatography to separate the water-in-oil (W/O) emulsions but also the selective adsorbent for the fluorinated organic aromatic compounds from aqueous methanol solution.

Ion conductor barrier height for the switching time improvement of all-thin-film inorganic complementary electrochromic devices

In this study, an all-thin-film inorganic complementary electrochromic device (ECD) with the lithium doping zirconium dioxide (ZrO2:Li) ion conductor layer has demonstrated for the lower cost ECD applications. Even though the ZrO2:Li has demonstrated a lower lithium (Li) ion conductivity of 1.62 × 10−8 S/cm and ion mobility of 8.67 × 10−12 cm2/Vs, the switching characteristic of the ECDs has been improved. According to the refractive index measurement, the ion conductor ZrO2:Li with the higher refractive index value is also indicated a higher energy bandgap material. As a result, the possible mechanism is due to the electron energy barrier height 1.2 eV between the interface of electrochromic layer tungsten oxide (WO3) and ion conductor layer ZrO2:Li. Besides, the induction of an electric field between the WO3 and high bandgap ZrO2:Li material interface also accelerates the Li ion transported through the interface. Furthermore, the ZrO2:Li with the lower ion conductivity and mobility is due to the dense material structure, which is verified by the cross-sectional field emission scanning electron micrograph profile. Additionally, the dense material structure has also provided better surface morphology for thin-film device structures with the layer-by-layer deposition process.

Insight Into the Anomalous Electrical Behavior, Dielectric and Magnetic Study of Ag-Doped CoFe2O4 Synthesised by Okra Extract-Assisted Green Synthesis

The effect of substitution of silver (Ag) on the structural, electric, dielectric and magnetic properties of nano-CoFe2O4 synthesized via green synthesis using okra plant extract is investigated. The lattice parameters and inverse spinel structure of Ag-substituted CoFe2O4 is confirmed from Rietveld refinement of the x-ray diffraction measurements, Fourier transform infrared (FT-IR) and Raman spectra. A lattice expansion is observed due to the incorporation of larger Ag ions into the CoFe2O4 lattice. Field emission scanning electron micrography analyses elucidate the formation of poly-faceted surfaces with reduction in particle size on Ag doping. The temperature dependent impedance and modulus study reveals the presence of relaxation phenomenon which is dependent on frequency and temperature. Frequency dependent dielectric measurements with increasing temperature obey the modified Debye model. Dielectric loss in the negative region for Ag-doped CoFe2O4 signifies the change of polarization direction due to an increase of Co2+/Fe2+ ratio for the substitution of Ag ions in the B site. Magnetic hysteresis curves exhibit a low field hysteresis loop at room temperature indicating the long-range ferromagnetic ordering nature of the samples. Low loss and high dielectric values make these materials a promising candidate for high frequency devices.

An electrochemical DNA biosensor fabricated from graphene decorated with graphitic nanospheres

Graphene decorated with graphitic nanospheres functionalized with pyrene butyric acid (PBA) is used for the first time to fabricate a DNA biosensor. The electrode was formed by attaching a DNA probe onto PBA, which had been stacked onto a graphene material decorated with graphene nanospheres (GNSs). The nanomaterial was drop-coated onto a carbon screen-printed electrode (SPE) to create the GNS-PBA modified electrode (GNS-PBA/SPE). A simple method was used to produce GNS by annealing graphene oxide (GO) solution at high temperature. Field emission scanning electron micrographs confirmed the presence of a spherical shape of GNS with a diameter range of 40–80 nm. A stable and uniform PBA-modified GNS (GNS-PBA) was obtained with a facile ultrasonication step. Thus allowing aminated DNA probes of genetically modified (GM) soybean to be attached to the nanomaterials to form the DNA biosensor. The GNS-PBA/SPE exhibited excellent electrical conductivity via cyclic voltammetry (CV) and differential pulse voltammetry (DPV) tests using potassium ferricyanide (K3[Fe(CN)6]) as the electroactive probe. By employing an anthraquinone monosulfonic acid (AQMS) redox intercalator as the DNA hybridization indicator, the biosensor response was evaluated using the DPV electrochemical method. A good linear relationship between AQMS oxidation peak current and target DNA concentrations from 1.0 × 10−16 to 1.0 × 10−8 M with a limit of detection (LOD) of less than 1.0 × 10−16 M was obtained. Selectivity experiments revealed that the voltammetric GM DNA biosensor could discriminate complementary sequences of GM soybean from non-complementary sequences and hence good recoveries were obtained for real GM soybean sample analysis. The main advantage of using GNS is an improvement of the DNA biosensor analytical performance.

Effect of pretreatments on cellulosic composition and morphology of pine needle for possible utilization as substrate for anaerobic digestion

Waste residues from agricultural and forest resources have received much attention as potential source of lignocellulosic biomass (LCB) especially after the “food-versus-fuel” conflict. Therefore, exploring the potential of LCB (especially forest biomass) as a resource for sustainable bioenergy generation is highly promising. The present study reports the structural modification in the cross-linking of lignocellulosic complex in pine needle forest biomass after pretreatments: milling, steam explosion and acid-base-acid treatments. The changes in morphology and composition of the cellulose and lignin in pine needles after pretreatments was evaluated using Field Emission Scanning Electron Microscopy (FE-SEM), Fourier Transform Infrared (FT-IR) microspectroscopy, Energy Dispersive Spectroscopy (EDS) and Scanning Electron Microscopy (SEM). Field Emission Scanning Electron micrographs revealed that pretreatments resulted in changes in orderly arrangement of interwoven fibrils, surface abnormalities in cells surrounding stomatal opening and exposure of vascular bundle. FT-IR of pretreated substrate indicated significant changes in functional moieties of ester bond between lignin and hemicelluloses, phenol hydroxyl moieties and aromatic ring associated with lignin and hydrogen bonding in cellulose. The findings in the present study thus open up avenues for exploring potential of pretreated pine needles for renewable bioenergy generation. Anaerobic digestion (AD) of the pretreated biomass resulted in 21.4% higher methane levels as compared to untreated pine litter. Appearance of lignin droplets and deposition of coalescent materials on pre-treated biomass surface was also observed in the present study. These colloidal lignin particles could serve as potential nanocomposites, for application in biomaterial applications.

Synergetic Surface Behavior of Sol–Gel ZrO2–Nb2O5 Coated 316L Stainless Steel for Biomedical Applications

The porous outer layer and compact inner layer of zirconium/niobium mixed oxide coatings were deposited on medical grade 316L stainless steel by sol gel dip-coating method. The obtained coatings were homogeneous and polyphased crystalline in nature. The Scanning Transmission Electron Microscopy analysis revealed that the distribution of zirconium and niobium were uniform over the coated film. The Field Emission Scanning Electron Micrographs exhibited fine pores on the outer surface of the mixed oxide coating. Further, these pores were not directly connected to the 316L stainless steel substrate, which was evinced by the Scanning Electron Micrograph cross-sectional analysis. The corrosion performance of zirconium/niobium mixed oxide coated 316L stainless steel was evaluated by electrochemical techniques in simulated body fluid solution. The zirconium /niobium mixed oxide coating exhibited an enhanced corrosion resistance for 316L stainless steel as indicted by the reduced current density and enhanced corrosion potential toward the noble direction. The formation of synergetic and stable zirconium/niobium mixed oxide coating was proposed to account for enhanced corrosion protection and bioactive behavior for the long-term implant applications.

Preparation of monolithic fluoroalkyl end-capped vinyltrimethoxysilane oligomer /methyltrimethoxysilane/magnetite composites: Application to selective removal of fluorinated aromatic compounds from aqueous methanol solution under magnetic field

Monolithtic fluoroalkyl end-capped vinyltrimethoxysilane oligomer /methyltrimethoxysilane/magnetite composites [RF-(VM-SiO3/2)n-RF/MeSiO3/2/Mag] were prepared through two simple processes which consist of the sol-gel reaction of the corresponding oligomer [RF-(CH2CHSi(OMe)3)n-RF: n = 2, 3; RF = CF(CF3)OC3F7: RF-(VM)n-RF] with methytrimethoxysilane (MTMS) under acidic conditions, and successively the sol-gel reaction in the presence of magnetic fine particles (Mag) under alkaline conditions. TEM (Transmission Electron Microscopy) pictures show that Mag particles can be effectively encapsulated into fluorinated oligomeric composite cores to produce the expected composites [RF-(VM-SiO3/2)n-RF/MeSiO3/2/Mag]. In addition, field emission scanning electron micrographs (FE-SEM) indicate that the obtained composites consists of monolithic structures to afford an extremely lower bulk specific gravity (0.32 g/cm3); although the corresponding RF-(VM-SiO3/2)n-RF/Mag composites prepared under similar conditions and the RF-(VM-SiO3/2)n-RF oligomeric particles prepared by the sol-gel reaction of the oligomer under alkaline conditions afforded the relatively higher values: 0.68 and 0.50 g/cm3, respectively. The surface wettability of the RF-(VM-SiO3/2)n-RF/MeSiO3/2/Mag composite particles was studied by the dodecane and water contact angle measurements to exhibit a superoleophilic/superhydrophobic characteristic on their surface. Interestingly, these composite particle powders were applied to the facile removal of aromatic compounds such as bisphenol A, bisphenol AF, 4, 4′-biphenol, octafluoro-4, 4′-biphenol, acetophenone, 2′, 3′, 4′, 5′, 6′-pentafluoroacetophenone, trans-cinamic acid and trans-2,3,4,5,6-pentafluorocinamic acid from aqueous methanol solution under a magnetic fields. More interestingly, it was demonstrated that we can observe the more efficient removal ability for the fluorinated aromatic compounds, compared to that of the corresponding non-fluorinated ones. Especially, such monolithic composites were found to provide the higher removal ability for these aromatic compounds than that for the usual RF-(VM-SiO3/2)n-RF/Mag composite powders under similar conditions.

Green Synthesis of CuO nanoparticles via Plectranthus amboinicus leaves extract with its characterization on structural, morphological, and biological properties

Synthetic synthesis of nanoparticles is harmful to human and environment due to pollution. The use of harmful chemicals in synthetic method has avoided in the biosynthesis. To overcome the hurdles in synthesis of nanoparticles, the biogenic synthesis of CuO nanoparticles has been done with Plectranthus amboinicus leaf extracts. The biosynthesis provides the enhanced efficiency compared to synthetic methods. It establishes the environmentally friendly and pollution-free approach. The powder X-ray diffraction (XRD) pattern exhibited a crystalline nature with the crystallite size in 20–35 nm. The Fourier-Transform InfraRed (FTIR) spectrum explicated the Cu and O metal oxide bonds. The UV–visible analysis emphasized the stability of CuO nanoparticles with the inference of the Surface Plasmon Resonance band at 398 nm. The photoluminescence study displayed the bluish–green emission nature peak at 491 nm. The particle size analyzer manifested the synthesized CuO nanoparticles majority in 5–40 nm. The field-emission scanning electron micrographs (FESEM) and high-resolution transmission electron micrographs (HRTEM) exposed the spherical, circular-shaped nanoparticles with size in 5–30 nm range. The energy dispersive X-ray diffraction (EDAX) spectrum and mapping proved the CuO nanoparticles formation. The antimicrobial activity reported the potent nature of formed CuO nanoparticles on bacteria and fungi. The antioxidant activity identified the effective free-radical scavenging activity nature at 95% in 80 μg/mL and IC50 value at 40.10 μg/mL concentration. The anti-inflammatory activity assessed the efficient nature of CuO nanoparticles in protein denaturation of Egg albumin at 92% in 500 μg/mL and IC50 value at 243.08 μg/mL concentration. The anti-diabetic activity established the effective inhibition on α-Amylase at 94% in 500 μg/mL and IC50 value at 317.19 μg/mL concentration. The anti-larvicidal activity manifested the potent inhibition on Anopheles subpictus mosquito larvae within 24 h in 100 ppm concentration and which exhibited low LC50 value.

Safely functionalized carbon nanotube–coated jute fibers for advanced technology

Biodegradable jute fibers become conductive when varying amounts of carbon nanotubes (CNTs) are incorporated onto it using a simple dip-drying technique. For uniform and efficient coating, CNTs have been functionalized safely by citric-acid-assisted oxygen plasma, and different properties of the fibers are investigated. The method is safe because no strong acids are used and the plasma is operative to the surface of the CNTs only, hence less destructive to the structure of the CNTs. Field emission scanning electron micrographs confirm uniform attachment of CNTs on the surfaces of jute fibers. Owing to coating, the crystallinity and mechanical strength of the composite fibers increase significantly. The thermal stability and flame retardancy are also observed to be enhanced especially for the treated jute fibers coated with functionalized CNTs. The resistance per meter of these fibers sharply decreases from 2.30 to 0.02 kΩ depending on the amount of CNTs integrated on to it. Current density through the samples increases 1000 times and conductivity increases up to 5 S m−1, which also increases with temperature. The activation energy is observed to be decreased from 330 to 68 kJ mole−1. Therefore, these fibers can be applied in different electrical and electronic devices as well as in polymer composites as conductive fillers.

Iron sulfide effects on AC susceptibility and electrical properties of Bi1.6Pb0.4Sr2CaCu2O8 superconductor

Magnetism and superconductivity are mutually exclusive phenomena and their interactions are interesting to study. In this work we studied the effects of antiferromagnetic FeS additions on the superconducting properties of Bi1.6Pb0.4Sr2CaCu2O8 (Bi-2212). Samples with starting composition Bi1.6Pb0.4Sr2CaCu2O8(FeS)x for x = 0–5.0 wt% were prepared using the solid state reaction method. The powder X-ray diffraction (XRD) patterns showed that the Bi-2212 phase was dominant in samples with x ≤ 0.2 wt% (≥92% volume fraction). Field emission scanning electron micrographs showed plate-like structure which increased in flakiness with FeS addition. The non-added samples showed the highest zero resistance temperature, Tc-zero and onset temperature, Tc-onset at 72 K and 83 K, respectively. The peak temperature, Tp of the imaginary part of the AC susceptibility increased for x ≤ 0.2 wt% samples indicating an increase in the flux pinning force. The x = 5.0 wt% samples showed the Bi-2212 (63%) and Bi-2201 (37%) phase and semiconducting-like behavior without any superconducting transition. This work showed that nano-sized FeS can be used to increase the flakiness and flux pinning force of Bi1.6Pb0.4Sr2CaCu2O8 for x ≤ 0.2 wt%.

Structural, optical, and electrical transport properties of some rare-earth-doped nickel ferrites: A study on effect of ionic radii of dopants

Different rare-earth (Ho, Gd, Sm, Pr, and La)-doped nickel ferrites were prepared through the sol-gel citrate auto-combustion method. Rietveld refinement of the X-ray diffraction patterns confirmed the formation of an orthorhombic impurity phase for each doped sample. Structural parameters, including lattice parameter, crystallite size, microstrain, and different bond lengths, were calculated. Field emission scanning electron micrographs showed spherical grains and the existence of secondary phases for the doped samples. Elemental analysis of each component were performed using energy dispersive X-ray spectra. The shifting of the absorption bands of the Fourier transform infrared spectra depicted the rare earth-to-Fe substitution in octahedral sites of nickel ferrites. The optical band gap decreased with the smaller ionic radii of dopants. The study of ac and dc conductivity provided information about the conduction and dielectric relaxation mechanism and the effect of impurity phases. The electrical conductivity and dielectric study suggested that La- and Sm-doped samples showed the highest resistivity with high losses, whereas Ho- and Gd-doped samples showed moderate resistivity with minimum losses.

Designing rational and cheapest SeO2 electrocatalyst for long stable water splitting process

A SeO2 nanostructure was prepared employing stabilized solvothermal method for water oxidation process in three electrodes cell set-up. Reducing agent influence on material morphology and its domination on electrochemical properties were investigated. Tetragonal structure of SeO2 was confirmed from the crystal plane of (211) through X-ray diffraction (XRD) study. Reducing agent concentration was highly dominated the particle size and shape which was explored by field emission scanning electron micrograph (FESEM) images. The superior electrochemical specific capacitance of 572 F/g at 10 mV/s was afforded by SeO2 nanoparticles synthesized via 15 M NaBH4 by cyclic voltammogram (CV) study. The highest water oxidation performance of 292 mA/g at 10 mV/s was also demonstrated by the same electrode from linear sweep voltammogram (LSV), with better charge transfer and excellent stability. The exceptional performance of the SeO2 electrocatalyst prepared by using highest NaBH4 concentration evidenced its great role for potential applications.

Investigation on the effect of tungsten doping and sintering temperature on microwave dielectric properties of lithium magnesium silicate ceramics

Demand for dielectric ceramics has been increasing due to their broad range of applications in microwave communication domains. Lithium Magnesium Silicate (LMS) can be categorized as a dielectric ceramic which owns good dielectric properties suitable for substrates in microwave integrated circuits. Effect of tungsten doping on the structural and dielectric characteristics of LMS is examined in this work. Tungsten-doped LMS ceramic systems were synthesized through conventional solid-state method. Doping effect on crystal structure and microstructure of the samples was analyzed using X-ray diffractograms and field emission scanning electron micrographs. Impact of dopant concentration and sintering temperature on the microstructural densification was investigated. Parallel plate capacitor method using DUT in LCR meter was employed to measure the relative permittivity and dielectric loss values of tungsten-doped LMS ceramics. 10% tungsten-doped LMS (Li2Mg0.90W0.10SiO4) ceramic was sintered at 1100 C for 4 h and it exhibited a lowest dielectric loss value of 9.65 × 10−3 and relative permittivity of 7.22.

High-Resolution Fiber Optic Sensor based on Coated Linearly Chirped Bragg Grating

a fiber optic strain sensor is proposed and experimentally demonstrated using fiber Bragg grating (FBG) based interrogation scheme. Due to fast response time and better sensitivity of graphene oxide (GO) material, coated linearly chirped fiber Bragg grating (LCFBG) is used in this work. Interrogation scheme is used for the efficient strain sensing by placing LCFBG within the Sagnac loop (wavelength dependent receiver). The GO deposition is confirmed by ultraviolet–visible spectroscopy, atomic force microscopy (AFM), and field emission scanning electron micrograph (FESEM). Our proposed fiber optic strain sensor possesses better resolution, stable operation in the infra-red region. In addition, sensor demonstrates 5.25 με static strain and 0.645 με/√Hz dynamic strain resolutions, respectively.

Temperature measurement in double-sided laser-heated diamond anvil cell and reaction of carbon

In this work, a double-sided laser-heated diamond anvil cell facility for studies at extreme conditions of pressure and temperature that has been developed is described in detail. Phase transitions occurring at extreme conditions can be mapped by accurate measurements of pressure and temperature. Micrometer-sized diamond crystals having regular facets have been synthesized at a pressure of 18 GPa and temperature 1785 K, which is confirmed by visual inspection, micro-Raman and field emission scanning electron micrograph measurements. A low-temperature gradient is observed across the sample surface during the formation of micrometer-sized diamond crystals. Our observation restricts the use of steel gasket as it can react with carbon (C) transported from the diamond anvil. The reaction of C with one of the potential thermal insulating medium Al $$_2$$ O $$_3$$ is observed in the X-ray diffraction measurements.