Elemental Mapping Images Research Articles

Synthesis and luminescence characterization of Ce3+ activated Y2CaAl2MgZr2O12 garnet phosphor for white light emitting diodes

A series of novel Ce3+ activated Y2CaAl2MgZr2O12 phosphors were synthesized via a modified solid-state method. The formation of garnet structure was clearly observed from the XRD studies. The elemental mapping images confirmed the homogeneous distribution of all elements in Y2CaAl2MgZr2O12:Ce3+. Y2CaAl2MgZr2O12:Ce3+ emitted greenish yellow emission peaking at 530 nm by absorbing blue light of 420 to 460 nm. The greenish yellow emission was due to the 5d-4f transition of Ce3+ ions. The optimum photoluminescence intensity was observed for 3 mol% concentration of Ce3+ ions. The thermal stability of photoluminescence emission of Y2CaAl2MgZr2O12:0.03Ce3+ was also investigated at 300 to 480 K and the activation energy was calculated to be 0.32 eV. Commercial red (Sr, Ca)AlSiN3:Eu phosphors blended with Y2CaAl2MgZr2O12:0.03Ce3+ and coated on blue emitting LED chips to fabricated white light emitting diodes (WLEDs). The electroluminescence spectra of the fabricated WLEDs exhibited pure white chromaticity (0.36, 0.37) with high CRI of 94 and low CCT of 4381 K. The spectral characteristic results indicated a promising garnet phosphor for blue excited white light emitting diode applications.

Pd Nanoparticles Decorated on Jute Sticks: Dip‐Catalyst of Suzuki‐Miyaura and Mizoroki‐Heck C–C Bond Formation Reactions in Water

AbstractAchieving C−C bond formation using Suzuki‐Miyaura and Mizoroki‐Heck cross‐coupling reactions with reusable, cost‐efficient, highly regioselective, and naturally available supported catalysts is rare and challenging. In the current study, naturally available jute plant sticks (green support ‐ GS) decorated with Pd nanoparticles, denoted as Pd@GS, were prepared by reducing K2PdCl4 using NaBH4 in water. This ‘dip‐catalyst’ construct was used to catalyze the Suzuki‐Miyaura and Mizoroki‐Heck cross coupling‐reactions in water. SEM, TEM, and elemental mapping images reveal the homogeneous distribution of Pd nanoparticles with average dimensions within a narrow range of 7–10 nm on solid support. For the Suzuki‐Miyaura cross‐coupling reaction, the highest conversion achieved is 97% with a TOF of 4692 h−1 for the reaction of 4‐acylphenylboronic acid and iodobenzene in the presence of KOH in an aqueous medium. For the Mizoroki‐Heck reaction, a 98% yield (TOF=237 h−1) of the coupling product was obtained with an exclusive selectivity towards the targeted olefinic product using 4‐methylstyrene and iodobenzene as the reactants in water‐DMF as a mixed solvent at 90 °C. The same catalyst sample can be used for 7 consecutive cycles, i. e., without addition of any fresh catalyst, while retaining its original crystallinity without any leaching of Pd.

Ionic liquid functionalized biogenic synthesis of Ag[sbnd]Au bimetal doped CeO2 nanoparticles from Justicia adhatoda for pharmaceutical applications: Antibacterial and anti-cancer activities

The noble metal such as Ag and Au doped CeO2 nanoparticles was successfully prepared by ionic liquid assisted hydrothermal method in the presence of Justicia adhatoda leaves extract and were used as an antibacterial and anticancer agent. The FT-IR and Raman spectrum exhibit the peaks at 460 and 464 cm−1 assigned to CeO stretching vibrations of NPs. The electron microscopic micrographs confirmed the spherical shaped morphology of prepared NPs. The insertion of Ag and Au ions into the CeO2 surface creates lattice defects the leads to reduce the band gap energy of Ag-Au/CeO2 at 3.15 eV. The XRD results suggested the average crystalline size of the silver‑gold loaded CeO2 was 28 nm. From the elemental mapping images, we have visualized that existence and uniform distribution of Ag, Au, Ce, and O in the prepared nanomaterials. The antibacterial activity of unloaded and bimetal loaded CeO2 NPs was evaluated with Gram-positive and Gram-negative bacteria using disc diffusion assay. The AgAu loaded CeO2 NPs exhibited the highest zone of inhibition against E. coli and S. aureus strains when compared with pristine CeO2, Ag loaded CeO2, and Au loaded CeO2 NPs. In addition, the 100 μg mL−1 of CeO2, Ag/CeO2, Au/CeO2 and Ag-Au/CeO2 NPs exposed the 50, 51, 52 and 56% of anticancer activity against the HeLa cells respectively. Overall, this study concludes that the ionic liquid functionalized green synthesized bimetal loaded cerium oxide NPs showed potent antibacterial and anticancer activities.

In-situ homodispersely immobilization of Ag@AgCl on chloridized g-C3N4 nanosheets as an ultrastable plasmonic photocatalyst

Despite their impressive plasmonic photocatalytic activity, nanosized silver and silver halides always suffer from serious agglomeration and photocorrosion, thus are severely restricted in the practical wastewater restoration applications. The design and realization of plasmonic heterojunction nanostructures is an effective way to solve this stability problem, yet the ideal plasmonic catalyst dispersion and immobilization remains a great challenge. In this work, a highly immobilized Ag@AgCl/g-C3N4 plasmonic photocatalyst was developed through a rational in-situ implanting approach, in which the Ag can be homodispersely distributed and strongly coupled with prefixed Cl sites on g-C3N4 nanosheets (CNNS). The X-ray diffraction (XRD) pattern, X-ray photoelectron spectroscopy (XPS) spectra and element mapping images clearly proved the homodispersely distribution of nanosized Ag@AgCl on the CNNS. The optimal Ag@AgCl-3/CNNS plasmonic photocatalyst with a narrow band gap of 2.45 eV and large specific surface area of 52.9 m2/g performs well in model pharmaceutical wastewater bleaching reactions under visible light. More importantly, the Ag@AgCl-3/CNNS show good stability compared with the conventional inhomogeneously coupled AgCl/g-C3N4 control as verified by their ultralow silver leakage rate in water (0.00152 mg/g·d, accounts 6.9% that of the control) and a much lower corrosion current density (Icorr = 1.63 vs. 3.45 μA), recorded by Tafel slopes. The synergetic effect of surface plasmon resonance effect of nanosized Ag@AgCl with strong visible light harvesting ability and strong coupling between Ag@AgCl and exfoliated porous g-C3N4 nanosheets can support the fast separation of photogenerated electron–hole pairs, thus significantly improving the photocatalytic efficiency in the bleaching of antibiotic pollutants and bacteria. This work affords the great potential of the rational in-situ implanting design for high-performance and stable plasmonic photocatalysts.

Removal of Tetrachloroethene in Water with Nano Pd/Fe Bimetal Immobilized in Alginate Beads

In this study, nZVI, nPd/Fe and nPd/Fe-B particles were synthesized and used to remove PCE in solution to investigate the effects of several parameters such as the types of metal particles and their mass concentration. From the elemental mapping images of energy dispersive spectrometer (EDS), amorphous Fe and Pd were tightly integrated into the alginate matrix, which cannot be solely exfoliated from the whole composites. The results showed that the removal efficiency (r) and observed reaction rate constants (kobs) was the highest for nPd/Fe, followed by nPd/Fe-B and nZVI particles. Moreover, the larger the reductant dosage, the higher the r of PCE for nZVI, nPd/Fe, and nPd/Fe-B particles is. The pH in solution quickly raised from about 5-6 to 8-9 at the beginning of tests and then maintained at around 8-9 to the end of tests. The ORP in solutions descended to reductive state immediately at the beginning of tests and kept in the range between -730 and -770 mV to the end of tests indicating that the system maintained in a stable reductive state.

Analysis of Pr co-doped Al:ZnO thin films using feasible nebulizer spray technique for optoelectronic technology

The rare earth element, i.e., praseodymium (Pr) co-doped aluminium zinc oxide (AZO) thin films is coated on a well-cleaned glass substrate by facile and cost-effective nebulizer spray technique. The Pr co-doping concentrations varied from 0 to 1.5% with the AZO structure in the steps of 0.5%. The structural analysis was characterized by X-ray diffraction (XRD), showing that all the diffracted peaks exhibit polycrystalline hexagonal wurtzite structure and the size of the crystallites is abridged with increasing Pr doping level due to lattice defects. In Raman analysis, the existence of high mode peak E2 at 437 cm−1; confirmed ZnO wurtzite structure. From the morphological study, it is clearly visualized that the film possesses spherical shaped grains which were uniformly distributed without any pinholes and voids. The surface roughness of the films was increased considerably from 22 to 39 nm on growing Pr doping from 0 to 1.5% as seen using atomic force microscope. Energy dispersive X-ray analysis and elemental mapping images clearly showed the subsistence of Al, Zn, O and Pr elements in Pr:AZO film. The prepared films exposed good transmittance range between 84 and 90% and the optical band gap was found to be 3.28 eV for initial Pr (0.5%) doping concentration. The PL spectra clearly showed that a high intense emission peak observed at 390 nm are associated with NBE which indicates that the film has good optical quality. Hall measurement revealed that the prepared film, i.e., 1.5% Pr-doped AZO film has low resistivity and high carrier concentration which is perfectly suit for optoelectronic device applications.

An effect of Gd3+ doping on core properties of ZnS thin films prepared by nebulizer spray pyrolysis (NSP) method

Herein, the study on structural, optical and electrical properties of various concentrations (0, 1, 3, 5 wt %) of Gadolinium doped zinc sulphide (Gd: ZnS) thin films by simple nebulizer spray pyrolysis (NSP) method has been presented. X-ray diffraction patterns displayed that the prepared films are of polycrystalline hexagonal structures with (102) a preferred orientation. SEM images showed a smooth surface with nano sized spherical grains. Enhancement of surface roughness viewed from AFM images. Presence of Zn, S, and Gd elements in prepared samples were confirmed through EDAX and Elemental mapping images. E1(LO), (LA + LO), 2TO, 2LO and 3LO mode of vibrations were explored in the Raman spectrum. Newly, the luminescent center raised at red region (725 nm) was seen in RT Photoluminescence studies. Optical spectra illustrated band gap enrichment and high transparent film (average of 86%) both in Vis-IR region. Activation energy measured from four-point probe method also discussed here.

The Synthesis of SiO2@AuAg@CeO2 Sandwich Structures with Enhanced Catalytic Performance Towards CO Oxidation

AbstractNovel sandwich structure SiO2@AuAg@CeO2 nanospheres (SACs), as low‐temperature CO oxidation catalysts, were designed and prepared in this work. The SACs include SiO2 nanosphere support, embedded bimetallic AuAg nanoparticles, and CeO2 shell. The transmission electron microscope (TEM), elemental mapping images, and ultraviolet‐visible (UV‐vis) spectroscopy indicated the successful fabrication of the SACs sandwich structure. The catalytic performance of SACs varies with the AuAg composition and achieves the best catalytic activity when Au/Ag atomic ratio is 2:1. The strong synergistic effect of AuAg alloy remarkably promotes the CO oxidation through facilitating the adsorption of CO and O2 on the AuAg nanoparticles. The CeO2 non‐compact shell not only provides effective protection for AuAg nanoparticles from aggregation but also gives CO full access to the catalysts. With unique sandwich structure and specific chemical composition, the SiO2@Au2Ag1@CeO2 nanospheres with CeO2 shell thickness of 5 nm present excellent low‐temperature catalytic activity and high‐temperature thermal stability.

RETRACTED: Dispersing Bi2Mo2O9 nanoparticles into Bi0.5Sb1.5Te3 alloys for enhanced thermoelectric figure of merit (ZT) through phonon scattering

Abstract Bi2Mo2O9 nanoparticles were introduced into bismuth antimony tellurium (BST) alloys by ball milling, and the composite particles were then fabricated into pellets by hot press for thermoelectric property measurement. Both elemental mapping and TEM image confirmed that Bi2Mo2O9 nanoparticles were evenly distributed among BST matrix. The impacts of Bi2Mo2O9 volume percentage on the electrical resistivity, Seebeck coefficient, thermal conductivity, and thermoelectric figure of merit (ZT) of BST/Bi2Mo2O9 composites were investigated. The results told that the composite presented the highest thermoelectric ZT when Bi2Mo2O9 was 0.3 vol%, which was increased by 12.15% from the ZT of pure BST at room temperature. This could be attributed to the balance between the decreased thermal conductivity and increased electrical resistivity, and phonons could are blocked when charge carriers passing through the dispersed Bi2Mo2O9 nanoparticles.

Effect of novel Nd3+ doping on physical properties of nebulizer spray pyrolysis fabricated ZnS thin films for optoelectronic technology

Neodymium doped zinc sulphide (Nd: ZnS) thin films were coated on glass substrates at 450 °C through low cost nebulizer spray pyrolysis (NSP) method. Structure, morphology, opto-electrical characteristics of Nd doped ZnS films with various Nd doping concentrations (0%, 1, %, 3% and 5%) were studied. X-ray diffraction patterns revealed that all coated films were polycrystalline hexagonal structure with (102) as a preferential direction. SEM images showed smooth and uniform spherical grains without any cracks and pinholes. Topological view by AFM described the increasing of roughness of the film through doping concentration. EDAX and Elemental mapping images confirmed the presence of Zn, S and Nd without any other impurities. Raman spectra reveals that E1(LO), 2TO, 2LO and 3LO emission modes with corresponding to the wave number. PL spectra showed high intense visible and broad UV emission band at 463 nm and 397 nm, respectively. Thickness of the films increased with Nd doping concentration reflecting the reduction of transparency of the films from 86% to 78% for 0% and 5% of Nd. UV–Vis Spectrum was used to study the energy gap (Eg), dielectric constant(ε), refractive index(n), and extinction coefficient (k) of the prepared films. Four-point probe method was used to calculate the activation energy of Nd: ZnS thin films from the graph drawn between ln (ρ) and (1/T).

In-situ chemical deposition as a new method for the preparation of Fe3O4 nanopaeticles embedded on anodic aluminum oxide membrane (Fe3O4@AAO): Characterization and application for arsenic removal using response surface methodology

In the present work, a novel modified Fe3O4@AAO nanocomposite membrane was synthesized via the anodization of Al sheets and in-situ chemical deposition of Fe3O4 nanoparticles through a hydrothermal method. The Fe3O4 nanoparticles were arranged regularly and uniformly on the surface and also inside the pores. The membrane modification was confirmed by transmission electron microscopy, field emission scanning electron microscopy, energy dispersive X-ray Spectroscopy, element mapping images, fourier transform infrared spectroscopy and X-ray diffraction. The synthesized nanocomposite membrane was applied as an adsorbent for the arsenic removal from the aqueous media. The effective parameters for arsenic removal including pH, the initial concentration of arsenic and the removal time were investigated and optimized using central composite design and response surface methodology. Maximum arsenic removal was obtained under optimum conditions including pH: 6, initial arsenic concentration: 350 μg L–1 and removal time: 40 min. The behavior of arsenic adsorption was studied by isotherm models that the equilibrium results well fitted with the linear Langmuir isotherm model. The maximum removal capacity of As (V) as calculated from the linear Langmuir isotherm was 83.3 mg g–1. Also, The kinetics of the adsorption process follows by the linear pseudo-first-order model with higher R2 (0.9878). Thermodynamic results showed that the adsorption of As (V) on Fe3O4@AAO membrane was a spontaneous, endothermic and feasible process. The obtained results from real samples showed that the synthesized membrane has the excellent ability to remove As (V) from the aqueous media.

In-situ N/S Co-doping three-dimensional succulent-like hierarchical carbon assisted by supramolecular polymerization for high-performance supercapacitors

Three-dimensional N/S co-doped succulent-like hierarchical carbon (3D NS-SHC) is synthesized by carbonization of a supramolecular cluster. In this supramolecular process, potassium citrate can act as a reliable carbon source, while the thiourea as a N/S source and then, two molecules gradually tend to generate a giant “all-in-one” precursor via hydrogen bonding verified by Independent Gradient Model (IGM) calculation. TEM and SEM images show the N/S co-doped carbon holds a novel 3D succulent-like hierarchical structure. For NS-SHC-8:8 sample, element mapping images display the uniform N/S atoms distribution. These distinct features can be related to the supramolecular polymerization which promotes in-situ N/S co-doping homogenously and conduces to build 3D structure. Typically, NS-SHC-8:8 electrode exhibits prominent specific capacitance (258.5 F g−1 at 0.5 A g−1) and excellent cycle stability (94.4% after 20000 cycles) in three-electrode system. Furthermore, an assembled quasi-solid state symmetric supercapacitor delivers good energy density (10.2 Wh kg−1 at 250 W kg−1) and steady cycle endurance (85.1% after 10000 cycles). These eximious behaviors of NS-SHC-8:8 are mainly attributed to (1) the uniform N/S atoms distribution and their synergistic effect, which brings extra Faradaic reaction to higher specific capacitance, (2) the charming 3D succulent-like hierarchical structure, which serves as a multifunctional reservoir that can accommodate the ion/charge and facilitate their migration to further promote the electrochemical performance. Above mentions suggest that this uniformly heteroatom-modified carbon material produced by supramolecular technique is promising for high-performance energy storage devices.

Nano‐Sized AlPO4 Coating Layer on Graphite Powder to Improve the Electrochemical Properties of High‐Voltage Graphite/LiNi0.5Mn1.5O4 Li‐Ion Cells

A high‐voltage graphite/LiNi0.5Mn1.5O4 (LNMO) system is a promising candidate for next‐generation Li‐ion batteries with a high energy density. However, it has the drawback of severe capacity fading caused by the consumption of active Li+ ions due to the reduction of the products of electrolyte oxidation and LNMO dissolution from the LNMO cathode on the graphite anode. Herein, graphite coated with different amounts of AlPO4 (0.5, 1, and 2.5 wt%) is prepared by an electrostatic attraction combined with a precipitation conversion method, and used as an anode for the LNMO/graphite full cell. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and elemental mapping images show that AlPO4 disperses homogeneously on the surface of graphite, and its thickness is between 10 and 30 nm. Electrochemical measurement results show that LNMO/AlPO4@graphite cells show better cycling stability and higher coulombic efficiency than the LNMO/graphite cell. Among them, the LNMO/0.5 wt% AlPO4@graphite cell shows the best cycling stability. By combining all the analytical results, the improvement mechanism of LNMO/AlPO4@graphite cells is mainly that the side reactions that consume the active Li+ ions are greatly reduced because the AlPO4 coating can block the migration of the products of electrolyte oxidation and LNMO dissolution to the graphite.

Synthesis of superparamagnetic biocidal superior solar photocatalytic Fe3O4-implanted Ag2S-capped ZnO micro-clubbells

Semiconductor-photocatalytic mineralization of organics is an emerging technology. However, recovery of the photocatalytic particles post pollutant-mineralization is a stumbling block for adoption of this technique. Implantation of magnetic core in the particulate photocatalyst ensures magnetic recovery. The magnetic core, deeply buried in the photocatalytic semiconductor lattice, is secluded from the photocatalyst/effluent interface and has insignificant influence on the photocatalytic processes. As the magnetic core is concealed its photocorrosion is overcome. With this, we report synthesis of Fe3O4-implanted Ag2S-capped ZnO microstructure by a two-step hydrothermal process. Scanning electron micrograph shows the synthesized particles as micro-clubbell-shaped. The energy dispersive X-ray spectrum confirms the presence of the constituent elements and the elemental mapping images display the even distribution of the constituent elements in the micro-clubbells. The X-ray diffractogram and the Raman spectrum show ZnO in zincite structure and Ag2S in acanthite phase. The synthesized microstructure and precursor Fe3O4 nanocrystals are superparamagnetic and their magnetic properties are comparable. The charge-transfer resistance of the microstructure is more than 20-fold that of Fe3O4 nanocrystals (New J Chem 40:1845–1852, 2016). The micro-clubbells absorb in the entire visible region and displays strong absorption in the UV-A region. The microcomposite exhibits green and strong blue-green emissions and the lifetime of photogenerated charge carriers is 10 ps. The synthesized microsized clubbell is mesoporous and its specific surface area is comparable to those of nanostructured composites. The synthesized microcomposite (1) displays superior photocatalytic activity under natural sunlight and (2) is reusable and magnetically recoverable. In addition, the title microstructure exhibits bactericidal activity, even without direct illumination.

Synthesis of Fe2O3/biochar nanocomposites by microwave method for magnetic energy-storage concentration cells

Magnetic nanocomposites have attracted increasing attention due to its widely applications in different areas in recent years. The conventional synthesis of magnetic nanocomposites is usually based on high temperature annealing technique from biomass. In this paper, a microwave method has been developed to prepare iron oxide based magnetic nanocomposites using ferric acetylacetonate ((Fe(acac)3), oleylamine (OAm), oleic acid (OA), and commercial biochar. The reaction is completed in several minutes. Composite structure composed of γ-Fe2O3 nanoparticles with the size of 6–17 nm and biochar is confirmed by TEM, SEM EDX element mapping images. The iron oxide size can be controlled by the microwave time and the ligand ratio. Magnetic properties of the magnetic nanocomposites are studied. The application of the prepared magnetic nanocomposites in magnetic concentration cells are tested with different magnetic fields and different biochar to iron oxide ratios. The method developed in this work on magnetic nanocomposite synthesis will not only facilitate the research progress of magnetic nanocomposite synthesis but also provide an alternative technique to be used in magnetic concentration cells.

Palladized dysprosium fluoride nanorods as a new performance catalyst in direct methanol fuel cell

Fuel cells are a new type of batteries that produce electricity from a continuous source of alcohols as long as fuel is inserted. In this study, decorated palladium nanoparticles (PdNPs) on dysprosium fluoride (DyF3) nanorods (DyFNRs)-multiwalled carbon nanotubes (MWCNTs) were used for electrooxidation of methanol. DyFNRs were synthesized by the hydrothermal method, and the proposed multifunctional catalyst (DyFNRs/MWCNT-PdNPs) was identified by several methods such as X-ray diffraction, elemental mapping images, field emission scanning electron microscopy, energy dispersive analysis of X-rays, and transmission electron microscopy which demonstrated a uniform distribution and high dispersion of the PdNPs on the supports. The electrocatalytic activity toward methanol electrooxidation on glassy carbon electrode (GCE) with DyFNRs/MWCNT-PdNPs (DyFNRs/MWCNT-PdNPs/GCE) was investigated by cyclic voltammetry (CV) and chronoamperometry (CA). Experimental results showed a high improvement in oxidation potential and peak current of methanol electrooxidation by DyFNRs/MWCNT-PdNPs in comparison to DyFNRs and PdNPs. The values of the catalytic rate constant (k) and physical dimension (Ds) for methanol oxidation on the DyFNRs/MWCNT-PdNPs/GCE catalyst were calculated 0.008 s−1 and 1.43, respectively. Moreover, the order of reaction was determined to be 0.43 and 0.13 for CH3OH and NaOH, repectively. Finally, the synthesized catalyst was evaluated in direct methanol fuel cell (DMFC). The single DMFC with proposed anodic catalyst, DyFNRs/MWCNT-PdNPs, indicated a power density of 4.4 mW·cm−2 at a current density of 18 mA·cm−2 in alcohol (1 M) and NaOH (1 M).

Investigation of the effect of boron carbide nanoparticles on the structural, electrical and mechanical properties of Al-B4C nanocomposites

Aluminum is widely used in the electrical, automotive, transport and aerospace industries due to its remarkable properties, such as low density and relatively low costs. However, due to the low hardness and low yield strength, there are limitations in application of aluminum. To solve these limitations, aluminum is made with other hard materials in the form of nanocomposites. For this purpose, in this work, using B4C nanoparticles, Aluminum-boron carbide nanocomposites (Al-B4C) nanocomposites were prepared via ball milling processing. The ball milling process was carried out at room temperature under argon atmosphere using a planetary ball milling for 10 h at 300 rpm. The B4C nanoparticles content employed in these nanocomposites were 0, 5 and 10 wt%. To investigate the structural, mechanical and electrical properties of the Al-B4C nanocomposites, the powders were pressed and then sintered under argon atmosphere at 650 °C. The structure, density, hardness and electrical conductivity of the Al-B4C nanocomposites sintered tablets were investigated by X-ray Diffraction (XRD), Field Emission Scanning Electron microscopy (FESEM) with energy dispersive x-ray spectroscopy (EDS), Archimedes method, nanoindentation and eddy current test, respectively, and the results are discussed. The XRD patterns confirmed the presence of aluminum and B4C and the lack of any interphase and secondary phase in the Al-B4C nanocomposite. Distribution of B4C nanoparticles in Al-B4C nanocomposite was described via EDS assisted elemental mapping images. Moreover, with the addition of 5 and 10%wt. B4C nanoparticles in aluminum matrix, the hardness values of the Al-B4C nanocomposites was measured to be 138HV and 172HV which were higher than 67HV for the pure aluminum, respectively. Consequently, nanoindentation analysis showed that the hardness of Al-B4C nanocomposites was better than that of pure aluminum. Density values of Al-B4C nanocomposites were measured to be 2.5776 g/cm3 and 2.4949 g/cm3 which were lower than 2.6346 g/cm3 for the pure aluminum, respectively. Electrical conductivity of Al-B4C nanocomposites was measured to be 23%IACS and 13%IACS which were lower than 39% IACS for the pure aluminum, respectively. To evaluate the effect of particle size on the properties of Al-B4C composites, under the same conditions of Al-B4C nanocomposites preparation, Al-B4C microcomposites were prepared. With increasing B4C content, the hardness of Al-B4C nanocomposites were obtained higher than those for Al-B4C microcomposites. This behavior has been explained by Hall–Petch Model and Orowan strengthening. The density of the Al-B4C nanocomposites was obtained higher than those for Al-B4C microcomposites and the electrical conductivity of Al-B4C nanocomposites less than the resulting for Al-B4C microcomposites.

Equiatomic quaternary (Y1/4Ho1/4Er1/4Yb1/4)2SiO5 silicate: A perspective multifunctional thermal and environmental barrier coating material

Equiatomic quaternary (Y1/4Ho1/4Er1/4Yb1/4)2SiO5 solid solution is investigated as a multifunctional thermal and environmental barrier coating (TEBC) material in this work. Dense and pure materials were prepared by hot pressing method, and the compositional homogeneity at macroscale and atomic scale were confirmed by electron-dispersive spectrometer elemental mapping and high-angle annular dark-field images. The quaternary solid solution displays balanced optimal properties on Young's modulus, thermal conductivity, thermal expansion, and high temperature water vapor resistance. The moderate cocktail effects also provide suggestions on the design of rare earth monosilicate TEBC materials.

Fabrication and characterization of La doped PbI2 nanostructured thin films for opto-electronic applications

Herein, we report a facile, cost-effective, solution processed fabrication method for pure and lanthanum (La3+) doped lead iodide (PbI2) thin films and investigated structural, optical, dielectric and electrical properties. Synthesis of PbI2 was confirmed by X-ray diffraction (XRD) and FT-Raman spectroscopy analyses. The fabricated films were grown along (001) plane, with crystallite size in the range of 12–14 nm and observed that crystallinity increases and defects decreases with the increase of La doping concentration. The morphology of fabricated films was observed to be spherical nanoparticles assembled nanosheets, distributed uniformly throughout the films. Moreover, homogeneous La doping in PbI2 was seen via EDX elemental mapping image. Optical band gap was calculated from Ultra violet–visible–near infrared (UV–Vis–NIR) spectra. The band gap of pure PbI2 film was noticed ∼2.44 eV which increase to 2.63 eV for 3% La3+ doped film. Absorption index, refractive index and dielectric constant values were calculated from optical data and found to be strongly dependent on incident photon energy and all parameters show higher values for La doped PbI2 films. I-V characteristics of pure and La-doped PbI2 thin films were carried out in the device configuration viz. FTO/PbI2 (or La-doped PbI2)/Au at room temperature. I-V curve for the pure PbI2 films shows the ohmic behavior while La doped PbI2 films shows non ohmic behavior attributed to space charge limited current. The electrical resistivity values for pure PbI2 film is found to be very high about 1.8 × 1011 Ω-cm.

Facilely synthesized Cu:PbS nanoparticles and their structural, morphological, optical, dielectric and electrical studies for optoelectronic applications

In this study, synthesis of pure and Cu doped lead sulfide (PbS) nanoparticles was facilely achieved. The good crystalline nature of the nanoparticles was confirmed via X-ray diffraction (XRD) analysis. Specifically, XRD data was also used to estimate the diffraction planes, lattice constants, size of crystallites, density of dislocations, and strain produced in the lattice. The XRD pattern was indexed after identifying the diffraction planes. The crystallite size was estimated to be in the range of 18–23 nm. The absence of any additional vibrational mode in Raman spectra was observed, and this confirmed the purity of PbS even at a higher Cu doping level. However, the vibrational modes exhibited some shift towards lower wavenumbers. Low dimension nanoparticles morphology and presence of Cu were investigated via scanning electron microscope/ Energy Dispersive X-Ray (SEM/EDX) analysis. Additionally, homogeneous Cu doping in final product was observed in an EDX elemental mapping image. Optical measurements were performed by recording diffused reflectance. Both direct energy gap values were estimated in the range of 1.15–1.50 eV, and this significantly exceeded that of the bulk (i.e., 0.41 eV). Dielectric and J-V electrical measurements were performed. The dc conductivity and mobility values were observed extremely high for 2.5% Cu doped PbS NPs [which correspond to 2.48 × 10−5 S/cm and 1.3 × 104 cm2/(V s)] when compared to those of pure and other doped PbS NPs.