Increase In Crystallite Size Research Articles

Enhanced multifunctional attributes of Tellurium incorporated CuGaS2 thin films employing spray pyrolysis route

CuGaS2 (CGS) chalcopyrite semiconductor is a promising candidate for thin-film based photovoltaic devices due to its exceptional optical absorption coefficient and flexibility in tuning the optical bandgap. Unfortunately, though, desorption of sulfur (S) atoms during deposition of CGS thin films at elevated temperatures results in the formation of defects and alters the material attributes. Post sulfurization may minimize S deficit, but it is still challenging to control S content due to its high vapour pressure. Therefore, this work investigates the effect of Tellurium (Te) doping during deposition on CGS’s crystallinity and optical properties, expecting relatively low vapour pressure of Te to stabilize the CGS structure. X-ray diffraction reveals the formation of a tetragonal phase indicating a better crystallinity and an enhanced crystallite size. Electrical mobility increased with Te doping, potentially due to the reduced grain boundary scattering with increased crystallite size. The optical bandgap energy of the deposited material decreases from 2.45 eV to 2.00 eV with increasing the concentration of dopant. These results make the CuGa(S,Te)2 a potential absorber material with a tuneable bandgap for solar cell application in a high energy spectrum.

Effect of A-site doping on electrical properties of La2-xPrxFeCoO6 double perovskite prepared by sol-gel technique

The present work deals with the synthesis, characterization, and thermoelectric properties of La2-xPrxFeCoO6 (x ​= ​0.0, 0.25, 0.50, 0.75, and 1.0) ceramics. The crystal structure, microstructural characteristics, electrical properties, and thermal transport characteristics of the sintered samples were studied. The samples prepared by sol-gel technique resulted in the presence of nanocrystalline single phase material after 6 ​h of sintering, and the increased crystallite size with increasing Pr concentration alongwith the occurrences of multivalent oxidation states of La, Pr, Fe, Co and O. The conductivity investigation revealed the presence of a nearest neighbor hopping charge carrier conduction mechanism in the entire samples, i.e., an increasing Pr-content result in enhanced conductivity at every examined temperature. For the entire composition range (x), conductivity increases with increasing temperature up to maximum value at a transition temperature followed by a downward trend, indicating the metallic behavior (reduction in semiconducting behavior) due to the presence of oxygen deficiency at higher temperature. Positive S values indicate the presence of p-type charge carrier in La2-xPrxFeCoO6 double perovskite and intrinsic behavior was conserved with increasing doping concentration (x). Temperature dependent power factor increases with increasing Pr-content and the maximum values were observed at their transition temperatures. Within recorded temperature, the highest Figure of Merit (ZT ​= ​∼0.87) was observed at x ​= ​1.0 in La2-xPrxFeCoO6 compound, which was 5.4 times more as compare to x ​= ​0.0.

Correction to: One-step hydrothermal synthesis of Sb2WO6 nanoparticle towards excellent LED light driven photocatalytic dye degradation

Pristine Antimony tungstate nanoparticles prepared via a simple hydrothermal process showcase interesting photocatalytic efficiency, degrading Methylene Blue (MB) completely in 180 min under visible light. In this study, the impact on crystalline quality and related optical properties as well as photocatalytic efficiency of antimony tungstate due to temperature variation during hydrothermal synthesis are explored. While X-ray diffraction (XRD) shows the polycrystalline nature of all synthesized samples, however a systematic increase in crystallite size is revealed by analysing the XRD peak broadening. XRD spectra are further examined by Rietveld analysis showing a change in unit cell volume. Additionally, the overall changes in the corresponding grain size and micro-strain developed in the crystals are determined using the Williamson-Hall plot. Moreover, significant variations in few Raman modes are observed with increasing synthesis temperature. A notable modification in the optical band gap as determined from the absorbance of the UV-Vis spectra is perceived with the change in synthesis temperature within the range of ~2.38-2.57 eV. Further, the photoluminescence measurement indicates that the synthesized antimony tungstate is weak luminescent material with a band-to-band emission at ~468 nm. Finally, photocatalytic efficiencies of the samples are ascertained to change with the synthesis parameter, estimated by decomposing methylene blue (MB), highest degradation rate constant (k) value is observed as 0.015 min -1 for the sample prepared at 180 o C. While the sample with the highest efficiency is also applied for degrading the Rhodamine B (RhB) and Potassium Dichromate (K 2 Cr 2 O 7 ) under visible light irradiation.

Investigation of Optical, Structural, Morphological and Electrical Properties of Electrodeposited Cobalt Doped Copper Selenide (Cu_(1-x) Co_x Se) Thin Films

Undoped and cobalt doped copper selenide thin films have been successfully prepared unto fluorine tin oxide (FTO) substrates by electrodeposition method using copper acetate, cobalt nitrate and selenium (IV) oxide as precursors for copper, cobalt and selenium ions respectively. Deposited thin films were subjected to optical, structural, morphological, compositional and electrical analysis using spectrophotometer, x-ray diffractometer, scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDS) and 4-point probe. Optical results observed between the wavelength range of 300 nm and 1,000 nm showed that the films have good optical responses. Absorbance values ranged between 0.1 and 0.81 while transmittance lies between 15.59 and 78.68 %. Energy band gap of the films was found to vary from 2.10 to 2.28 eV. These results showed that cobalt as a dopant could be used to modify properties of copper selenide thin films. Structural analysis showed that the deposited films are polycrystalline in nature with hexagonal structural phase. Crystallite sizes of range 27.56 to 34.27 nm were obtained while dislocation density lied between and . Microstrain ranged between and . Micrograph images showed flake-like particles that increased in size as percentage of cobalt increased. Energy dispersive spectroscope (EDS) results confirmed the incorporation of cobalt on the deposited copper selenide films. Electrical resistivity of the films increased from to while conductivity decreased from to as a result of variation in cobalt ion concentration. These properties of the deposited thin films positioned them for solar cell and optoelectronics device applications.
 HIGHLIGHTS
 
 Energy band gap of electrosynthesized cobalt doped copper selenide ranged from 2.10 to 2.28 eV
 Film thickness values ranged from 48.41 and 176.79 nm. Thickness values of the films were found to increase as concentration of cobalt increase
 Increase in dopant concentration resulted to shift in diffraction peaks towards larger angles
 Increase in crystallite size from 27.56 - 34.27 nm was observed as dopant concentration increases
 SEM images of the films revealed flake - like particles of different sizes
 
 GRAPHICAL ABSTRACT

One-step hydrothermal synthesis of Sb2WO6 nanoparticle towards excellent LED light driven photocatalytic dye degradation

Pristine Antimony tungstate nanoparticles prepared via a simple hydrothermal process showcase interesting photocatalytic efficiency, degrading Methylene Blue (MB) completely in 180 min under visible light. In this study, the impact on crystalline quality and related optical properties as well as photocatalytic efficiency of antimony tungstate due to temperature variation during hydrothermal synthesis are explored. While X-ray diffraction (XRD) shows the polycrystalline nature of all synthesized samples; however, a systematic increase in crystallite size is revealed by analysing the XRD peak broadening. XRD spectra are further examined by Rietveld analysis showing a change in unit cell volume. Additionally, the overall changes in the corresponding grain size and micro-strain developed in the crystals are determined using the Williamson-Hall plot. Moreover, significant variations in few Raman modes are observed with increasing synthesis temperature. A notable modification in the optical band gap as determined from the absorbance of the UV–Vis spectra is perceived with the change in synthesis temperature within the range of ~ 2.38–2.57 eV. Further, the photoluminescence measurement indicates that the synthesized antimony tungstate is weak luminescent material with a band-to-band emission at ~ 468 nm. Finally, photocatalytic efficiencies of the samples are ascertained to change with the synthesis parameter, estimated by decomposing methylene blue (MB), highest degradation rate constant (k) value is observed as 0.015 min−1 for the sample prepared at 180 °C. While the sample with the highest efficiency is also applied for degrading the Rhodamine B (RhB) and Potassium Dichromate (K2Cr2O7) under visible light irradiation.

Strain-induced magnetic anisotropy of REIG thin films grown on YAG(111) substrates by pulsed laser deposition

Several studies have revealed using rare earth (RE) elements instead of yttrium to regulate the strain-induced magnetic anisotropy of garnet films in recent years. In this study, we used pulsed laser deposition to fabricate RE iron garnet (REIG) thin films on (111)-oriented yttrium aluminum garnet (YAG) substrates. The REIG films are 100 nm in thickness and crystalline with (111)-orientation. The out-of-plane (444)-plane spacing decreases as the ionic radius of RE metal ions decreases, while the crystallite size increases. Samarium, holmium, and yttrium iron garnet (SmIG, HoIG, and YIG) have out-of-plane compressive strain, while erbium and thulium iron garnet (ErIG and TmIG) have weak out-of-plane tensile strain. The strain of the REIG films is resulted from lattice mismatch, off-stoichiometry, and the recrystallization process by thermal annealing. SmIG has a rather rough surface because of the crystalline distortion due to the largest ionic radius of Sm and the lattice mismatch between SmIG and YAG substrates. Due to negative magnetostriction constant and out-of-plane compressive strain, SmIG and HoIG films show strong perpendicular magnetic anisotropy (PMA) in vibrating sample magnetometry and magneto-optical Faraday effect (MOFE). MOFE also revealed that the REIG films have different sensitivities at different wavelengths of light. With further tuning PMA on SmIG and HoIG by decreasing the thickness and lateral size, our findings could pave the way for high-density nano-scale magnetic information storage based on REIG thin films.

X-ray diffraction analysis by Rietveld refinement of FeAl alloys doped with terbium and its correlation with magnetostriction

Fe81Al19 polycrystalline alloys doped with Tb (0–0.25 at%) were obtained by arc melting. The introduction of Tb favors the formation of columnar grains in the microstructure of the alloys, which develops a texture in the [100] crystal direction. Microstructural examination shows that the alloys are composed in great proportion by the disordered body-centered cubic (bcc), A2 phase and by a small proportion of the ordered bcc, B2 phase. As a consequence of doping with Tb, the lattice parameter increases, so the calculated apparent crystallite size increases, indicating a decrease in dislocation density and therefore in microstrains. The change in the magnetostriction with the magnetic field, dλT/dH, is directly related to strain anisotropy that can favor the iron easy magnetization axis on the [100] direction. An increase in total magnetostriction is found in the doped alloys with a maximum of 90 × 10−6 at 300 K for the alloy containing 0.027 at% Tb. This enhancement is a threefold value of the undoped alloy, which is attributed to the smaller maximum strain value and the preferential orientation formation by the columnar grains.

Understanding the Effects of Different Engineered Carbon Supports (ECS) Supports on the Sintering Processes of Pt Nanoparticles

Polymer Electrolyte Membrane Fuel Cell (PEMFC) technology is an advantageous solution for clean energy applications due to its zero-emission, high efficiency, low maintenance cost, and high energy density. The maturity of this technology has been the product of considerable scientific and industry efforts devoted to developing highly efficient and reliable systems increasingly adopted in the transportation and energy generation sectors. PEMFCs produce electricity by converting the electrochemical reactions of hydrogen oxidation and oxygen reduction into electrical energy. However, fabricating catalysts materials with high performance at scale is still a challenge that needs to be tackled to enable a marketable increase in the energy generated from this technology. For this reason, tunability of the catalyst materials at the core of this technology is more than essential to meet certain energy demands. Here we investigate commercially available catalysts based on platinum nanoparticles (Pt NPs) supported on Engineered Carbon Supports (ECS)TM produced by Pajarito Powder, LLC.Heat treatments (HT) were performed on base catalyst materials containing 30 wt% Pt supported on two different types of ECS, labeled as 3701 and 4601 (both made with similar materials and procedures, 4601 has more pore formers). The treatments were performed at temperatures ranging from 400 to 1000 °C in 7% H2/N2, N2, He, and Ar atmospheres for 1hr. The main goal of this study is to understand the effects and the properties of these types of ECS (having different degrees of porosity) on the stability of the Pt NPs, to get a clearer vision of how those different environments and temperatures affect the sintering processes taking place on the Pt NPs which can be correlated to the catalyst performance.Our preliminary results by X-ray diffraction (XRD) have shown an increase of the Pt crystallite size as temperature increases and 1000 °C in an atmosphere of 7% H2/N2 appears to have a stronger effect on Pt crystallite growth when compared to N2 or Ar, while such growth seems to have the same trend in both N2 and Ar atmosphere. Additionally, CO chemisorption showed a reduction of the active metallic surface area with increasing temperature, verifying the trend measured by XRD. For every treated sample, Raman characterization did not show a dramatic change in the ratios between the G-mode peak (representing crystalline sp2 hybridized carbon), and the D-mode peak (attributed to disordered sp3 diamond-like carbon). This can shed a light on the amorphization or graphitization processes taking place under these conditions and the degree of graphitization of the carbon support. Transmission Electron Microscopy (TEM) will be performed to further clarify any conclusion. X-ray Photoelectron Spectroscopy (XPS) surface characterization revealed that there is a reduction in the Pt NPs oxidation from 600 to 1000 °C. Treatments in N2, the O 1s spectra were different than the other conditions possibly due to the lower presence of atmospheric oxygen during this treatment. On the other hand, the C 1s spectra show a minor shift to higher binding energy in the main peak as a result of the treatments, indicating a slight increment in the amount of sp3 and a decrease in the amount of sp2 carbon nature.This research will be expanded with TEM imaging and physisorption data to get a more quantitative and qualitative interpretation of the phenomena taking place in the mobility and sintering processes of Pt NPs on the ECS surfaces and the role of the porosity and carbon morphology. Finally, direct measurements of the mass transport from which surface diffusivity can be determined during the process of Pt sintering will be also performed using in-situ TEM, simulating the furnace conditions using a methodology that would allow us to scrutinize how the nanoscale characteristics of these powders influence the coalescence and sintering processes in these nanoparticles.

Polyol Synthesis of Ni and Fe Co-Incorporated Tungsten Oxide for Highly Efficient and Durable Oxygen Evolution Reaction

The development of inexpensive transition metal-based catalysts for water splitting has attracted global attention, which should be accomplished in the simplest and most scalable way feasible. In this study, nickel and iron co-incorporated tungsten oxides (NixFe1-xWO4) were synthesized using a simple polyol method, and the materials achieved a highly efficient and stable oxygen evolution reaction (OER) in an alkaline electrolyte. The product as-synthesized using the polyol method consisted of an undeveloped wolframite structure, which was converted to its complete crystal by heat treatment at 600 °C, with an increase in crystallite size. The OER properties of NixFe1-xWO4 could be controlled by the ratio of Ni and Fe present and heat treatment temperature. A ternary tungsten oxide (Ni0.5Fe0.5WO4) with a Ni:Fe:W molar ratio of 0.5:0.5:1 deposited on a glassy carbon electrode required 297 mV to reach a current density of 10 mA cm−2 in 1.0 M KOH solution. The 10 mA cm−2 electrolysis with the electrode was continued for at least 100 h. This was quite different from a similarly-synthesized NiFe oxide without W, which required an additional 47-mV overpotential to reach 10 mA cm−2 and had inferior durability.

Effect of Synthesis Temperature on Structural and Magnetic Properties in Hematite (α-Fe2O3) Nanoparticles Produced by Co-Precipitation Method

Modification of nanometer size order in anode material of hematite nanoparticles is believed to be one of the keys to increasing the specific capacity of Li-ion batteries application. So that, the synthesis temperature dependence of nanocrystallite size properties in co-precipitated hematite nanoparticles is studied. Sample of Hematite nanoparticles is modified the physical properties by synthesis temperature and then annealed of 700°C for 4 hours. The crystallite size increase with the increase of the synthesis temperature i.e., 23.06 to 29.64 nm. It is indicated that the synthesis temperature affects crystallite formation. Furthermore, the magnetic properties show that the coercive field decrease from 869 to 211 Oe with the increase of the temperature synthesis. It is related to the change in the nanosize-order of the sample crystallite.

EFFECT OF CALCINATION TEMPERATURE ON THE PROPERTIES AND CATALYTIC PERFORMANCE OF NICKEL OXIDE IN THE ETHANE OXIDATIVE DEHYDROGENATION REACTION

In this paper, the catalytic behavior of nonstoichiometric nickel oxides was investigated in the ethane oxidative dehydrogenation reaction (ODH). The oxide was obtained by heat treatment in the range 250 – 400°C of β-Ni(OH)2 synthesized by precipitation-oxidation. The structural properties of the catalysts were characterized by XRD, FTIR, UV-vis, and SEM. The selective ODH reaction was quantified by gas chromatography. The samples showed pure NiO cubic structure with different degrees of crystallinity, crystallite size, and specific surface area. The increase of calcination temperature caused an increase in the average crystallite size from 28 Å at 250 °C to 104 Å at 400 °C, whereas the shape of the particles showed no significant differences; pore diameter increased from 35 Å to 69 Å and specific surface area decreased from 245 to 82 m2/g. The test carried out at 240°C showed a decrease in conversion, from 8.75% to 4.25%; the more crystalline samples displayed the highest intrinsic activity with selectivity to ethene close to 60%. No influence of band-gap energy on catalytic properties was observed.

Influence of temperatures on structure, thermoelectric, and mechanical properties of nanocrystalline SnSe thin films deposited by thermal evaporation

The Tin Selenide (SnSe) thermoelectric materials’ high heat-electricity inter-conversion capability makes it a potential energy resource material to tap the waste heat from different industrial processing. The present work has optimized parameters for the deposition of single-phase nanocrystalline SnSe thin films using the thermal evaporation technique. The XRD, Raman Spectroscopy, SEM, EDS, Seebeck Coefficient, Electrical Conductivity, and Thermal Conductivity data analyses were used to optimize and establish the structure-thermoelectric property relationship for nanocrystalline SnSe films. The phase analysis of the SnSe thin films deposited at various substrate heating temperatures (Ts) reveals a significant influence of Ts in the evolution of a single phase of SnSe film. The films deposited at Ts ≤ 200 °C evolved with the phases of Sn, Se, and SnSe, whereas films deposited at Ts ≥ 300 °C grew with single-phase polycrystalline SnSe. An increase in crystallite size with a shape transformation from circular to elongated grains was observed with Ts. The maximum ZT value of 0.64 with a power factor value of ~2.2 μWcm-1K-2 at 750 K measuring temperature (Ta) was obtained for the SnSe film deposited at Ts = 300 °C. The change in thermoelectric properties with Ta, including a p-type to n-type transition observed at ~600 K, was correlated with the alteration of structure and the elemental composition of the deposited films after heating at 350 °C. The heating temperature significantly influenced the hardness and elastic modulus values of the films deposited at Ts ≤ 300 °C.

Role of pH value on electrophoretic deposition of nano-silica onto carbon fibers for a tailored bond behavior with cementitious matrices

Electrophoretic deposition (EPD) of nano-silica (NS) onto carbon fiber (CF) surfaces may considerably improve the bond properties toward cementitious matrices. In the article at hand, varied pH conditions (neutral, acidic, and alkaline environments) are studied during EPD for a tailorable interfacial bond. Zeta potential measurements and cyclic voltammetry (CV) confirmed the importance of pH with regard to the EPD process. Scanning electron microscopy (SEM) and X- ray photoelectron spectroscopy (XPS) revealed that an acidic environment enables the most pronounced and homogeneous NS coating on the CF surfaces. X-ray diffraction (XRD) analysis delivered deeper insights into the microstructures of modified CFs, indicating a decreased graphite interlayer spacing d002 and an increased crystallite size Lc after treatment. This results in a changed temperature-stability as well as mechanical properties, as revealed by thermogravimetric analysis (TGA), single-fiber tensile tests, and Weibull analysis.To assess the interaction of the modified CFs with cementitious matrices, single-fiber pullout tests were performed, showing the highest bond strength and total pullout work of CFs treated in an acidic environment. This is mainly explained by a reaction of the high number of NS particles with calcium hydroxide to form calcium silicate hydrate (C-S-H) gel and, thus, intensifying the interfacial transition zone, subsequently increasing the bond properties of CF to a matrix. As well, abundant oxygen-related functional groups were introduced on the CF surfaces from anodic oxidation, leading to an enhanced bond by promoting precipitation of cement hydration products onto the CF surfaces.

Synthesis and characterization of exfoliated beta-cyclodextrin functionalized graphene oxide for adsorptive removal of atenolol

In this present work, a low-cost adsorbent is reported using exfoliated graphene oxide (GO) functionalized with cyclic polysaccharide via an easily scalable, sustainable, and eco-friendly method for the removal of atenolol, a beta-blocker from an aqueous solution. The beta-cyclodextrin (BCD) functionalized GO (BCDGO) adsorbent was characterized using Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared Spectrometer (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), Thermogravimetric analyzer (TGA), Dynamic Light Scattering (DLS) analysis, Zeta potential analysis, and BET analyzer. IFFT analysis using a TEM image was done, which indicated an increase in d-spacing from 0.22 nm in GO to 0.74 nm in BCDGO. It was observed that BCDGO is an efficient adsorbent in removing atenolol and showed faster kinetics compared to GO as determined from a UV–Visible spectrophotometer. FTIR and Raman spectroscopy confirmed functionalization by BCD molecules. XRD analysis indicated an increase in crystallite size, and BET analysis showed that BCDGO had increased surface area by 25 times compared to conventional GO synthesized by modified Hummer's method. The mechanistic insight corresponding to the electrostatic interaction of atenolol at the interface of the BCDGO is established using zeta potential analysis. The recyclability of BCDGO was established as it could remove 60% atenolol after four consecutive cycles with an atenolol concentration of 50 μM.

Grain growth in pulse reverse electrodeposited copper foil: Contrasting effects of duty cycle during deposition and annealing

The present study reports the opposite effects of the duty cycle in a pulse reverse electrodeposited copper foil during electrodeposition and further annealing. With increasing duty cycles from 60 to 90 %, while the average grain size decreases from 8.5 ± 6 μm to 4 ± 2.7 μm, the fraction of twin boundaries and crystallite size increase continuously in the as-deposited conditions. After annealing at 1050 °C, the average grain size increases, and the fraction of coherent twin boundaries reduces with an increase in the duty cycle. The differences in the anodic period at different duty cycles regulate the twin probability and grain size during deposition, while the stored energy governs the twinning probability during annealing. Interestingly, after annealing for 6 h, significant fractions of interconnected twinned regions are visible in all Cu foils. These results show that it is possible to maintain a high fraction (>60 %) of twin boundaries in high-temperature annealed Cu foils.

Synthesis, characterization, and photocatalytic activity of CuAl2O4–Ag nanocomposite for water treatment

A novel copper aluminate-silver (CuAl2O4–Ag) nanocomposite was synthesized through an organic acid-assisted sol-gel method. Organic acid plays an important role as a chelating agent, reducing agent, and capping agent in synthesizing multicomponent nanocomposites. The photocatalytic performance of the synthesized CuAl2O4–Ag nanocomposite was studied for the degradation of methylene blue under visible light illumination. The products were characterized via Fourier-transform infrared spectroscopy, scanning electron microscope, X-ray diffraction, transmission electron microscope, and UV–Visible spectroscopy. The XRD results showed that crystalline Ag and CuAl2O4 are formed in the samples after calcination at 800 °C. The findings indicated that the crystallite size and average particle size increase by increasing Ag concentration. Nanocomposites containing 3 wt% Ag (CuAl2O4-3wt.%Ag) revealed the maximum photocatalytic yield (97%) and suitable structural stability after several uses. The mechanism of dye photodegradation was discussed. Photocatalytic tests by adding trapping agents revealed that methylene blue photodegradation in this system occurs through photogenerated holes and superoxide radicals.

Lithium doping effect on microstructural and electrical properties of zinc oxide thin film grown by metal-organic chemical vapor deposition

In this study, the undoped and Li-doped ZnO thin films were grown on Si(100) substrate using metal-organic chemical vapor deposition (MOCVD). Zinc acetylacetonate hydrate and lithium acetylacetonate solution were used as ZnO thin film precursor and Li dopant source. The effect of lithium doping on microstructural was characterized using a scanning electron microscope (SEM) and X-ray diffractometer (XRD). XRD diffractogram analysis shows that undoped and Li-doped ZnO thin films have polycrystalline hexagonal wurtzite structures with preferred peak crystal orientation (103). Li doping slightly changes the lattice parameters and cell volume of ZnO thin films through the increase of crystallite size and slightly affects the surface morphology of ZnO thin films. Current-voltage (I-V) measurement and four-point probe method were used to measure the electrical properties of lithium doped ZnO thin films. The electrical conductivity of ZnO thin films increases as Li doping is given compared to undoped films. These results are also supported by the I-V curve of Li-doped ZnO thin films by having a higher slope, indicating improvement in electrical properties.

Microwave radiation technique for the isolation of Sunn Hemp natural fiber in the application of material processing

Experimental works have been done on Sunn Hemp fiber and its reinforced composite to investigate various properties. Sunn Hemp fiber is modified physically by a multimode microwave oven (2.45 Hz) at the power of 160W–800W with 120W with varying time from 2 to 10 min with 4 min of interval. The fiber and composite properties are characterized structurally and physically. An increase in crystallinity and crystallite size in treated fiber is observed in X-Ray Diffraction (XRD) study, where Fourier Transmission Infrared (FTIR) shows no change in basic crystallinity in fiber. Morphology of treated fiber shows fibrillation and rough surface, but a higher treatment makes the fiber brittle and carbonized. Change in hydrophilicity from contact angle study and crosslinking density from equilibrium swelling theory affects the flexural and tensile properties of treated composites.

The influence of reaction and annealing temperature on physical and magnetic properties of CuFe2O4 nanoparticles : Hydrothermal method

Pure copper ferrite nanoparticles (CuFe2O4 NPs) were synthesized by using a simple hydrothermal method and annealed at different levels of temperatures. The single–phase cubic spinel structure was confirmed by X-ray diffraction pattern and average crystallite size was found to increase from 34 to 42 nm as the annealing temperature increases. FT-IR spectra confirmed metal oxides Fe-O and Cu-O, the formation of pure spinel magnetic copper ferrite nanoparticles. The five Raman active modes of vibrations confirmed the cubic structure of prepared yield (A1g + Eg + 3T2g). The average particle size identified by TEM analysis exists within the nano range with cubic structures. The magnitudes of the zeta potential indicated the potential stability and surface charge of the nanoparticles. The pore size was estimated by BJH technique and the obtained distribution as 18.5 nm in diameter. The optical study revealed the decreasing nature of the bandgap with increasing annealing temperature. The dielectric parameters were analysed with varying frequency range and it was observed that decreasing nature of dielectric loss is suitable for microwave application. The influence of annealing temperature revealed the increase of saturation magnetization, remanence and coercivity owing to the increased crystallite size. The electrochemical analyses of as-prepared and the annealed (750 °C) CuFe2O4 NPs exhibited high specific capacitance at a low scan rate which indicates the good result for supercapacitor application.

Surface structure modification of ReSe2 nanosheets via carbon ion irradiation

The effects of C ion irradiation on multilayer ReSe2 flakes are studied by utilizing different kinds of technologies. The domain sizes, thickness, morphologies of the multilayer ReSe2 flakes on the Al2O3 substrates before and after 1.0-MeV C ion irradiation with different fluence rates are studied by atomic force microscope and scanning electron microscopy. The atomic vibrational spectra of multilayer ReSe2 flakes are detected by micro-Raman spectra. The redshifts of the Raman modes after 1.0-MeV C ion irradiation are observed from the micro-Raman spectra. The elemental compositions and bonding configurations of the multilayer ReSe2 samples before and after irradiation processes are characterized by x-ray photoelectron spectroscopy. The structural properties are also investigated by x-ray diffraction, and it is concluded that after 1.0-MeV C ion irradiation process, multilayer ReSe2 samples continue to grow on Al2O3 substrates, the increase of crystallite size also reveals that the crystallinity is improved with the increase of the layer number after 1.0-MeV C ion irradiation.