Search

In this paper, quasi‐solid electrolytes (QSEs) "PEO + xwt.% BMIMPF6" for x = 0–20 were prepared by the immobilization of ionic liquid (IL), 1‐butyl‐3‐methylimidazolium hexafluorophosphate (BMIMPF6) to the PEO polymer matrix by solution casting technique. These quasi‐solid electrolytes (QSEs) are in the thin film form of good mechanical integrity. The QSEs are characterized by X‐ray diffraction (XRD), Attenuated total reflectance Infrared (ATR‐IR) spectroscopy, differential scanning calorimetry (DSC)/thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), impedance spectroscopy, and electrochemical techniques. XRD/DSC results confirm an increase in the flexibility (and hence polymer chain mobility) with the increasing amount of IL in the QSEs, as confirmed by the analysis of degree of crystallinity (Xc). The maximum room temperature ionic conductivity ~1.32 × 10−5 S. cm−1 is obtained for the 20 wt.% IL (BMIMPF6) added QSEs. The interaction/complexation between the dopant IL‐cation BMIM+ with the ether oxygen (i.e., COC bond of PEO) has been confirmed by FTIR spectroscopic analysis. FESEM results confirm the appearance of crystalline spherical grains (spherulites), whose size decreases with the increasing amount of IL in the membranes and shows overall semicrystalline microstructures. The TGA analysis confirmed that the onset decomposition temperature of the QSEs is found to be ~175°C, which is the sufficient temperature range of operation for the solid‐state electrochemical devices. The electrochemical performances of the QSEs were examined by fabricating the symmetrical electrical double‐layer capacitor (EDLC) device. The fabricated EDLC cell with optimized QSE "PEO + 20 wt.% BMIMPF6" with biomass‐based honeycomb activated carbon (HCAC) electrodes offers specific energy ~5.8 Wh kg−1 at power density ~ 79.9 W kg−1. It also displays excellent cycling stability with 81.3% of the initial specific capacitance after 2500 charge–discharge cycles. [ABSTRACT FROM AUTHOR]

CaCu3Ti4O12 (CCTO) nanomaterials were synthesized using the low-cost facile sol-gel technique. X-ray diffraction (XRD) patterns confirmed the cubic structure of the prepared sample. Scherrer's formula and the W-H (Williamson-Hall) plot was used to calculated the average crystallite size of the prepared sample and it was found to be 27 nm and 31.3 nm, respectively, while the strain created in the lattice is 5.008 × 10−4. Based on the absorbance plot, the band-gap (Eg) of the sample was determined using Tauc's plot and it was found out to be 2.74 eV. The frequency dependence of dielectric permittivity (ε) and tangent loss (tan δ) of CCTO was analyzed at different temperature range from 300 K to 663 K over a frequency range from 10 Hz to 1 MHz. ε and tan δ decrease monotonically in entire frequency range and an anomalous frequency-dependent behavior was observed at different temperatures. High ε (in the range of 104) was found out at lower frequency range. Electrical conductivity was also analyzed in range of frequencies and temperature, it was found out that in higher region of frequency conductivity slightly increases. The room temperature values of ε, tanδ and conductivity was 7.5 × 103, 1.5 and 0.4 × 10−5 Ω−1 m−1, respectively. The reduction in Eg is achieved which was the major concern in this work. Furthermore, we have extensively studied the ε along with tan δ and ac conductivity for electronic application usage. According to these observations, CCTO is particularly prepared so that it could be suitable for microelectronic applications due to its high ε and low tan δ. [ABSTRACT FROM AUTHOR]

Cobalt disulfide (CoS2) is a highly sophisticated metal chalcogenide that has garnered significant attention due to its distinctive properties such as its electrical, optical, catalytic, and magnetic capabilities and potential for use in a range of applications. In this work, pure CoS2 nanoparticles were synthesized using the economical and facile hydrothermal method. The X-Ray diffraction (XRD) method was used to characterize the synthesized sample, confirming that it has a cubic crystal structure with space group P a −3. The Debye-Scherrer's formula was implemented to determine the average crystallite size of nanoparticles and found to be 24.24 nm. Through the use of Field Emission Scanning Electron Microscopy (FESEM), the morphology and effective grain size of the obtained sample was determined. FTIR spectrophotometry was used to examine the vibrational stretching of the various bonds in CoS2. UV-Vis spectroscopy is employed to measure the optical property of the sample. The optical bandgap calculated from the Tauc Plot is around 1.90 eV reflecting the presence of photovoltaic properties in the sample. The change in dielectric permittivity and loss have been observed for the sample in the frequency range of 100 Hz to 10KHz at different temperatures between 303K and 423K. The frequency-dependent electrical conductivity of CoS2 is also explained. The observations revealed the presence of unique electrical and structural properties in the synthesized sample. [ABSTRACT FROM AUTHOR]

Sol-gel method is used to synthesize the Bi0.90Dy0.10FeO3-BaTi0.95Hf0.05O3 (BDyFO-BTHfO composite) multiferroic composite material. The structural formation was examined utilizing an X-ray diffraction (XRD) pattern preceded by Rietveld refinement utilizing the FULLPROF programme to confirm the presence of tetragonal and partially rhombohedral structures having space group P4mm and R3c, respectively. The dielectric characteristics of the BDyFO-BTHfO composite have been measured with respect to frequency (100 Hz to 1 MHz) and temperature (RT to 663K). Dielectric permittivity (ε) shows low-frequency dispersion which can be addressed by Maxwell-Wanger-type interfacial polarization. The synthesized composite material exhibits a negative magneto-dielectric (MD) effect when a magnetic field is operated (0.0 T to 2.0 T) and the obtained values are −9.61% and −19.68% for the ε and tanδ, respectively, at 1 kHz. The contribution of the grains, grain boundaries and electrode effects on the resistive characteristics of the samples was evaluated using comprehensive impedance spectroscopy using a Nyquist plot. The band gap (Eg) absorption of the synthesized sample was determined using Tauc's formula and found to be 2.05 eV. The BDyFO-BTHfO composite has improved magneto-dielectric, magneto impedance, and optical properties that support their potential usage in microelectronics, energy storage devices, and optoelectronic devices. [ABSTRACT FROM AUTHOR]

The present work reports the synthesis of nanostructured thin films on glass substrate by dip coating. The thickness of thin film was varied by varying the no. of dips of glass substrate in the aqueous solution of Ca(NO3)2⋅4H2O and NaOH. Deposited films were studied by the X‐Ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), Fourier Transform Infrared Spectroscopy (FTIR), and Ultraviolet‐visible (UV‐Vis) spectroscopy techniques. The thickness of film was increased almost linearly with number of dips. Accordingly, the nanocrystalline size and band gap was varied. Interestingly the nanoflower like structure of calcite thin films was observed in FESEM and that varied with the thickness of film. The calcite thin film formation was discussed in terms of reactivity due to nanostructure and surface structure was discussed in terms of nucleation and growth of film on the substrate. Finally, the implications of these results in terms of microstructurally tuned nano calcite thin films development for prospective futuristic industrial applications are highlighted. [ABSTRACT FROM AUTHOR]

Turbulent heat transfer and friction factor of nanodiamond-nickel (ND-Ni) hybrid nanofluids flow in a horizontal tube has been investigated experimentally. The ND-Ni nanoparticles were synthesized using in-situ growth and chemical co-precipitation method and characterized by XRD, TEM and VSM. The hybrid nanofluids were prepared by dispersing ND-Ni hybrid nanoparticles in distilled water. The thermal conductivity and viscosity enhancements were observed as 29.39% and 23.24% at 0.3% volume concentration of hybrid nanofluid at 60 °C compared to distilled water. The heat transfer and friction factor experiments were conducted at different Reynolds numbers (3000–22,000) and particle volume concentrations (0.1% and 0.3%). The Nusselt number enhancement of 0.3% volume concentration of hybrid nanofluid is 35.43% with a friction factor penalty of 1.12-times at a Reynolds number of 22,000 compared to distilled water data. The obtained experimental Nusselt number of hybrid nanofluids was compared with other kind of hybrid nanofluids available literature. New Nusselt number and friction factor correlations were proposed based on the experimental data. [ABSTRACT FROM AUTHOR]

Abstract: A magnetic nanofluid was prepared by dispersing magnetic Ni nanoparticles in distilled water. The nanoparticles were synthesized by chemical co-precipitation method and characterised by X-ray diffraction and atomic force microscopy. The average particle size was measured by the dynamic light scattering method. Thermal conductivity and absolute viscosity of the nanofluid were experimentally determined as a function of particle concentration and temperature. In addition, the Nusselt number and friction factor were experimentally estimated as a function of particle concentration and Reynolds number for constant heat flux condition in forced convection apparatus with no phase change of the nanofluid flowing in a tube. The experiments were conducted for a Reynolds number range of 3000–22,000, and for a particle concentration range from 0% to 0.6%. The results indicate that both Nusselt number and friction factor of the nanofluid increase with increasing particle volume concentration and Reynolds number. For 0.6% volume concentration, the enhancement of Nusselt number and friction factor is 39.18% and 19.12%, respectively, as compared to distilled water under the same flow conditions. It was verified the classical Gnielinski and Notter–Rouse correlations under predict the Nusselt number of the nanofluid; therefore, new generalized correlations are proposed for the estimation of the Nusselt number and friction factor based on the experimental data. [Copyright &y& Elsevier]

Nanodiamond–water nanofluids were prepared and estimated the thermal conductivity, viscosity and also estimated their potential use in heat transfer applications. The purchased ultradispersed diamond (UDD) nanoparticles were treated with strong acid solution to make it into almost single nano-diamond (ND) particles. The acid treated ND particles were characterized by XRD, TEM, FTIR and XPS. The thermal conductivity and viscosity of ND nanofluids were investigated experimentally, whereas the density and specific heat were estimated theoretically. At 1.0 vol%, the thermal conductivity enhancements of 12.7% and 22.8%, at 1.0 vol%, the viscosity enhancements of 1.57-times and 1.8-times were observed at temperatures of 293 K and 333 K compared to water data. The theoretical models of Maxwell and Einstein have failed to estimate the thermal conductivity and viscosity of nanofluids as a function of temperature. New thermal conductivity and viscosity correlations were proposed by including the effects of volume concentrations and temperatures. Prasher et al. model and the Mouromtseff number were used to study the heat transfer capability of ND nanofluid under laminar and turbulent flow conditions. [ABSTRACT FROM AUTHOR]

Graphical abstract showing the synthesis procedure and different characterization plots (XRD, Tauc plot, FESEM and antimicrobial plot). [Display omitted] • The study examined the influence of the solvent used to synthesize CZTS nanoparticles through a solvothermal approach. • The structural analysis showed that both CZTS1 and CZTS2 nanoparticles had a tetragonal kesterite phase. • CZTS2 had better surface morphology and composition, while CZTS1 showed more rougher surface and texture. • The bandgap observed for CZTS1 (1.45 eV) and CZTS2 (1.50 eV) reflects CZTS1 is closer to the ideal photovoltaic material. • CZTS1 nanoparticles showed strong antimicrobial properties against the tested microorganisms compared to CZTS2. In this study, two distinct reaction media- water (CZTS1) and ethylene glycol (EG) (CZTS2) were used to synthesize nanocrystalline Cu2ZnSnS4 (CZTS) samples using the facile solvothermal method. X-ray diffraction (XRD) analysis indicated the presence of a tetragonal kesterite phase in both samples with CZTS2 exhibiting broader peaks and smaller crystallite size (6.04 nm) compared to CZTS1 (8.78 nm). Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray (EDX) analysis revealed the superior surface morphology and better stoichiometric composition of CZTS2 nanoparticles. In terms of optical properties, the direct bandgap values of CZTS1 and CZTS2 show variation from 1.45 eV to 1.50 eV , as determined from the Tauc plot. Furthermore, the antimicrobial assay of samples was identified by their zone of inhibition of a bacterial (Bacillus subtilis) and a fungal (Tilletia indica) strain demonstrating CZTS1 exhibited more robust antimicrobial activity compared to CZTS2 suggesting its potential in agriculture, food safety, and healthcare. [ABSTRACT FROM AUTHOR]

In the present study, we address a few unsolved aspects involved in the hydrogen storage mechanism of the MgH 2 /Nb 2 O 5 system. The mixture, 6MgH 2 +Nb 2 O 5 , was mechanochemically reacted for 30 h under an inert atmosphere using two different milling medium, steel and zirconia, under identical experimental conditions. The product contained Nb dissolved MgO phase(s) in both cases. A detailed analysis of crystal structure, particle size and chemical environment of Mg x Nb y O x+y was performed. Rietveld occupancy analysis and elemental chemical analysis confirmed the population of oxygen to be nearly equal to the sum of metal atoms in the product. X-ray photoelectron spectroscopy analyses showed the existence of Nb in two different valance states, both belonging to oxide phases. A combined study of thermogravimetry – differential scanning calorimetry and Sieverts volumetric hydrogen absorption/desorption kinetics measurements confirmed the good catalytic activity of Nb dissolved MgO products for MgH 2 . A plausible mechanism is explained on the basis of a diffusion barrier cracking model. [ABSTRACT FROM AUTHOR]

Nanodiamond (ND) attached with magnetite (Fe 3 O 4 ) nanoparticles have been synthesized successfully by in-situ and chemical reduction of Fe 3 + and Fe 2 + cations on the acid treated-ND surface by using sodium hydroxide as a reducing agent. The synthesized magnetic ND-Fe 3 O 4 nanocomposite was characterized by XRD and TEM. The results indicate that Fe 3 O 4 nanoparticles were homogeneously dispersed on the outer surface of the ND particles. The stability of ND-soot, acid treated-ND and ND-Fe 3 O 4 dispersed in distilled water were investigated by zeta potential and optical images. The electrical conductivity was measured by using four probe technique by considering dry ND-Fe 3 O 4 powder make it into 1 cm circular pellet. The stable magnetic nanofluids were prepared by dispersing ND-Fe 3 O 4 nanocomposite in water and ethylene glycol/water mixtures and then measured both thermal conductivity and viscosity with effects of particle loadings and temperatures experimentally. Results indicate that thermal conductivity enhancements are 17.8%, 13.4%, 13.6%, 14.6% and viscosity enhancements are 1.72-times, 2.19-times, 1.50-times, 1.79-times for water, 20:80%, 40:60% and 60:40% EG/W-based nanofluids at 0.2% volume concentration at a temperature of 60 °C, respectively. Correlations for the thermal conductivity and viscosity of nanocomposite nanofluids have been proposed based on the experimental data. [ABSTRACT FROM AUTHOR]