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ZnS nanoparticles were synthesized by hydrothermal method. The influences of reaction temperature, holding time and S/Zn molar ratio on the structure, morphology, optical and electrical properties of ZnS nanoparticles were studied systematically at the range of 90 °C to 180 °C, 6 h to 15 h and 1:2 to 2.5:1, respectively. The results indicate that the reaction temperature, holding time and S/Zn molar ratio have no influence on phase structure. All the samples belong to zinc blende cubic structure of ZnS. However, the reaction temperature has strong influences on the growth of crystals, optical and electrical properties due to LaMer theory and two-stage growth kinetics. When the reaction temperature increases from 90 °C to 180 °C, the crystallite sizes increase from 7.0 nm to 9.7 nm and the average particle sizes decrease from 21 nm to 14 nm; the emission peaks are red shifted from 445 nm to 460 nm and the emission intensity is increased by 4.4 times; the dielectric constant and dielectric loss decrease from 4.86 to 4.71 and 2.86 × 104 to 2.70 × 104, respectively. While, the holding time has slight influences on the growth of crystals, optical and electrical properties. And the emission band and emission intensity of ZnS nanoparticles can be adjusted by the S/Zn molar ratio. When the S/Zn molar ratio is less than 1:1 or equal to 1:1, the emission bands range from 400 nm to 600 nm centered at ~ 450 nm. When the S/Zn molar ratio is greater than 1:1, the emission bands range from 400 nm to 700 nm centered at ~ 540 nm. [ABSTRACT FROM AUTHOR]

Abstract: "Herein, we consider the technologies of obtaining composite structures that can exhibit the properties of metamaterials, namely layered metal-dielectric (metal-polymer) structures and fish-net metal-polymeric structures. The dielectric and resonance properties of the synthesized structures are studied both theoretically and experimentally, and the excitation features of new types of quasi-non-diffraction plasmon-polaritons generated in them are established. Original methods and tools for characterizing the optical properties of the created composite structures (in particular, a differential polarization interferometer, a method and a device for detecting a negative refractive index) are proposed. Based on the developed and created metamaterials, a number of new devices are proposed and implemented, in particular, new configurations of flat lenses (so-called superlenses) of the near and far fields in the spectral range from ultraviolet to infrared radiation". [ABSTRACT FROM AUTHOR]

Abstract: The thermal stability of surface plasmon resonance in a-C:H〈Ag〉 and a-C:H〈Ag + TiО2〉 nanocomposite films is studied. The films were deposited by ion-plasma magnetron sputtering of a combined graphite-metal target in the atmosphere of the argon and methane mixture. The structure and optical properties of nanocomposite films were studied using transmission electron microscopy and optical spectroscopy, respectively. It is found that surface plasmon resonance in the a-C:H〈Ag + TiО2〉 films persists to the annealing temperature of 450°C in argon atmosphere, whereas in a-C:H〈Ag〉 films, surface plasmon resonance disappears at the annealing temperature of 350°C. It is shown that annealing at 350°C leads to the significant increase in the diameter of silver nanoparticles in the structure of the a-C:H〈Ag〉 films. In the a-C:H〈Ag + TiO2〉 films, along with the appearance of silver nanoparticles with a large diameter, silver nanoparticles with a small diameter are present, which remain after annealing at this temperature. The higher thermal stability of surface plasmon resonance in the a-C:H〈Ag + TiО2〉 films is explained by the presence of TiO2 nanoparticles in the structure of films, which inhibit the coalescence of silver nanoparticles at high temperatures. [ABSTRACT FROM AUTHOR]

Abstract: In order to improve optical properties of materials made of nanocellulose and also minimalize costs, small amounts of mineral fillers such as different forms of calcium carbonate are added. In this work nanocellulose was obtained from apple pomace. The precipitated calcium carbonate (PCC) in amount of 3.74 ± 1.36% of a sample dry matter was deposited on cellulose fibers during isolation process. Isolated cellulose was then treated with ultrasonic method in order to obtain apple cellulose nanofibrills (ACNF)/PCC nanocomposites. Different ultrasonication conditions were applied in order to evaluate how time (0-60 min) and power (0-400 W) influence on the ACNF/PCC nanocomposites properties. Moreover structure, chemical composition, morphology and rheological properties of both cellulose and composites were characterized. Also the mechanical properties of nanopapers made of ACNF/PCC nanocellulose were measured. The nanofibril structure of ultrasound processed cellulose was confirmed. In all cases samples were pseudoplastic fluids with quite low viscosity. The mean hydrodynamic diameter of particle dispersions decreased the most after use of ultrasounds for 60 min and the obtained dispersions were also the most homogeneous. The elastic modulus of obtained nanopapers were 2-3 GPa and tensile strength 60-70 MPa and in general ultrasonication improved their rigidity.Graphical Abstract: [ABSTRACT FROM AUTHOR]

BiFeO3-ZnFe2O4 heterojunction nanocomposites have been produced by a chemical synthesis method using one- and two-pot approaches. X-ray diffraction patterns of as-calcined samples indicated formation of pure zinc ferrite (ZnFe2O4) and bismuth ferrite (BiFeO3) phases, each retaining its crystal structure. Diffuse reflectance spectrometry was applied to calculate the optical bandgap of the photocatalysts, revealing values in the range from 2.03 eV to 2.17 eV, respectively. The maximum photodegradation of methylene blue of about 97% was achieved using two-pot-synthesized photocatalyst after 120 min of visible-light irradiation due to the higher probability of charge separation of photogenerated electron-hole pairs in the heterojunction structure. Photoluminescence spectra showed lower emission intensity of twopot- synthesized photocatalyst, due to its lower recombination rate originating from greater charge separation. [ABSTRACT FROM AUTHOR]

To probe the potential utilities in the photocatalyst and optical materials, a series of CaWO4/NiO samples have been prepared via the co-precipitation preparation with different capping agents. The obtained CaWO4/NiO nanocomposite was characterized by UV–vis diffuse reflectance spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray microanalysis (EDX) and vibrating sample magnetometer (VSM) techniques. To examine the catalytic characteristics of the obtained CaWO4/NiO nanocomposite, the photocatalytic degradation of rhodamine B dyes under ultraviolet illumination were performed. Recycling experiments that were also carried out proved the good stability of the survey samples. The combination of CaWO4/NiO nanocomposite is expected to become a new generation material for photodegradation with excellent performance. [ABSTRACT FROM AUTHOR]

ZnCuMnS [(0 ≤ x ≤ 0.1), (0 ≤ y ≤ 0.1)] nanostructures have been synthesized by facile chemical co-precipitation technique at room temperature. Crystallographic, topographical and morphological characterization of synthesized nanomaterials have been done by X-ray diffraction, Scanning Electron Microscope and Transmission Electron Microscope, respectively. Synthesized nanoparticles crystallizes in zinc blende structure having average crystallite size nearly 2-3 nm. Comparison of the diffraction and electron microscopy studies reveal the formation of single nanocrystals. The energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopic studies have been carried for the detailed quantitative and qualitative analysis of synthesized nanostructures. Optical characterization of synthesized nanomaterials has been done by UV-visible absorption and steady state photoluminescence spectroscopic studies. The room temperature energy resolved photoluminescence (PL) spectra show multi-chromatic emissions originating from the host and dopant related defect states. The photo-catalytic activity of synthesized nanomaterials under UV irradiation have been tested using methylene blue (MB) dye as test contaminant in aqueous media. Photo-physical and photo-chemical behaviour dependence on doping concentration has been thoroughly studied to explore the potential of synthesized nanomaterials for next era opto-electronic industrial applications as well as polluted water purification. [ABSTRACT FROM AUTHOR]

We report the structural and optical properties of ZnO/ZnTiO nanocomposites synthesized at various calcination temperatures ranging from 500 to 900 °C by a simple hydrothermal process without using any dispersant agents. The XRD results reveal the coexistence of ZnO and ZnTiO phases when calcined at 600-900 °C, however, only pure ZnO phase appears when calcined at 500 °C for 1 h. Functional groups were identified by FTIR spectroscopic technique, which exhibit characteristic infrared absorption bands of ZnO/ZnTiO nanocomposites. The synthesized composites have absorbance at a wavelength of 300 and 370 nm and the band gap energy of the ZnO/ZnTiO nanocomposite system is tuned by varying the calcination temperature. The morphology of the particles were visualized by TEM analysis which shows the morphology changing from irregular particles to uniform spherical, rod and cubic structures while increasing the temperature from 500 to 900 °C. All the samples show interesting broad blue and green emission at about 490 and 530 nm. Incidentally, the emission intensity of the composite ZnO/ZnTiO phase is stronger than that of pure ZnO phase prepared at 700 and 900 °C. [ABSTRACT FROM AUTHOR]

We report the hybridization of ZnO with natural dyes [Laali, Zobo] or synthetic dye [methyl red] forming ZnO-laali, ZnO-zobo and ZnO-methyl red nanocomposites in bright colours. The structural, optical and dye photosensitization influence of the hybrid nanocomposites were studied by X-ray diffraction (XRD), scanning electron microscope (SEM), UV-Visible absorption spectroscopy and photoluminescence (PL). The surface plasmon absorption band of ZnO-laali and ZnO-zobo shifts towards red and blue, respectively, with significantly enhanced absorption intensities, indicating the interaction and optical influence of the respective dyes in photosensitization. Optical and absorption character of ZnO methyl red and bare ZnO are similar indicating the insignificant effect of methyl red on photosensitization. PL spectra of ZnO-laali and ZnO-zobo display enhanced UV light emission due not only to the surface electron transfer from their respective inherent isoplumbagin and anthocyanin to ZnO but also to the extension of the Fermi energy level to the ZnO. Dyes adopted influence the optical band gaps of the evolved hybrid nanocomposites. [ABSTRACT FROM AUTHOR]

In this work, the optical and mechanical properties of FeO nanoparticles (NPs)/chitosan nanocomposite films have been investigated. Nanocomposite films of different weight ratios of FeO NPs/chitosan (0, 1, 5, 10, 20 and 30 wt%) were fabricated using casting technique. The optical properties of colloidal FeO NPs and FeO NPs/chitosan nanocomposite films were recorded using UV-visible spectrophotometer. As the ratio of FeO NPs to chitosan increases from 0 to 30%, the energy band gap of FeO NPs/chitosan films decreases from 3.16 to 2.11 eV. This decrease is due to quantum confinement effect. The mechanical properties of the nanocomposite films as a function of sweeping temperature were measured using a dynamic mechanical analyzer. An enhancement in storage modulus, stiffness and glass transition temperature (T) has been observed as the ratio of FeO NPs/chitosan increases. T of FeO NPs/chitosan nanocomposite film shifts towards higher temperature side with respect to pure chitosan film from 152.1 to 166.3 °C as the ratio of FeO NPs/chitosan increases from 0 to 30 wt%. The increase in T is mainly attributed to the decrease in free volumes and vacancies in the nanocomposite films as the weight ratio of FeO NPs/chitosan increases. [ABSTRACT FROM AUTHOR]

We report a synthesis of well dispersed Graphene Quantum Dot (GQD) nanocomposites in a host cellulose acetate (CA) polymer system. It was systematically characterized using X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), Atomic force microscope (AFM), Fourier transform infrared spectroscopy (FTIR) and Ultra-violet and Visible (UV-Vis), Photoluminescence (PL) techniques. Carboxylic and hydroxyl functional groups of GQD have chemically interacted with hydroxyl functional group of polymer network that leads to stabilization of the nanocomposite system. We observed that the amorphous to semi-crystalline phase disparity as a function of GQD loading which predominantly influenced the properties of nanocomposites. Decreased direct band gap of nanocomposites was analyzed by UV-Vis spectroscopic technique. Due to uniform dispersion and optimal loading of GQD in CA matrix an intense photoluminescence spectrum was observed. The existence of GQD occupied in the polymer system was examined by SEM, AFM and TEM microscopic techniques. It has been found that electrical conductivity of the composite was depended on temperature and similarly, decreased softness was related to the function of GQD loading. This investigation can be extendable for the devolvement of optical and electrical devices. [ABSTRACT FROM AUTHOR]

MnO-TiO nanocomposites is synthesized by the novel sol-gel method by using of manganese (II) chloride dihydrate and tetra-n-butyl titanate (TNBT). To control particle sizes of the nanocomposites, different acids such as oxalic acid, aspartic acid, and salicylic acid are applied. Acids played role as chelate agent to produce MnO-TiO nanocomposites. The formation of pure crystallized MnO-TiO nanocomposites occurred when the precursor was heat-treated at 700 °C in air for 150 min. The prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (UV-Vis), and energy dispersive X-ray microanalysis (EDX). Alternating gradient force magnetometer illustrated paramagnetic behaviour of MnO-TiO nanocomposites. The photocatalytic behaviour of MnO-TiO nanocomposites was evaluated using the degradation of methyl orange under ultraviolet light irradiation. [ABSTRACT FROM AUTHOR]

In this work, Ag and Au nanoparticles (AgNPs and AuNPs) stable colloid solution were prepared by laser ablation of chemically pure silver rod and gold film in liquid monomer isodecyl acrylate (IDA). Sizes of obtained nanoparticles were determined by scanning electron microscope and vary from 30 to 130 nm. Nanocomposites films were prepared from obtained stable colloid solution by photocuring. To prepare solid film based on aliphatic polymer IDA long molecules cross-linking, 1,6-Hexandiol diacrylate was used. Obtained films were transparent, homogenous and colored in brown for AgNPs and purple for AuNPs-filled nanocomposites. Prepared nanomaterials exhibit strong third-order nonlinear optical responses under CW laser irradiation at 532 nm, which was estimated by using z-scan technique performed with open and close aperture. The real and imaginary parts of third-order nonlinear optical coefficients of the studied nanocomposites were found to be up to Reχ = 1.31 × 10 (esu) and Imχ = 7.64 × 10 (esu), for samples negative nonlinear refractive index was obtained, which corresponds to self-defocusing effect. [ABSTRACT FROM AUTHOR]

The synthesis of Ni-doped silica-titania nanocomposite is performed by sol-gel method. The samples prior and after heat treatment at 300 °C for 1 h are characterized by analytical instrumental techniques. FE-SEM and AFM results indicate the regular morphology with low surface roughness without any cracks. EDX analysis verifies the formation of nanocomposites. XRD of the films reveals crystalline titania phases after annealing at 300 °C. The FTIR confirms the bond linkage between silica, titania and nickel molecules. High surface area ~155 m/g, pore volume of 0.2 cm/g and pore diameter of 48.10 Å are obtained after heat treatment. The magnetic results show that the composite content is reminiscent of ferromagnetic hysteresis loop, with remanence magnetization Mr of 45.35 and 13.20 emu/g for both samples. The organic dye phenol red is used for the evaluation of photocatalytic activity of the synthesized magnetic material. The homogeneous surface morphology, crystalline nature, good solubility of magnetic nanoparticles into the silica-titania matrix show that the Ni/SiO-TiO magnetic photocatalyst can be efficient and reusable. [ABSTRACT FROM AUTHOR]

The dielectric properties of 3D nanocomposites based on opal matrices containing the particles of compounds with spinel structure have been studied. Microwave measurements have been carried out in the frequency range from 26 to 38 GHz. The frequency dependences of transmission and reflection coefficients are obtained. The values of the real and imaginary parts of complex dielectric permittivity have been retrieved. The X-ray phase analysis of the nanocomposites is performed and their structures are studied. [ABSTRACT FROM AUTHOR]

The optical properties of nanocomposite layers prepared by incorporation of tributylphosphine oxide (TBPO)-capped CdSe nanocrystals (NCs) in a P3HT polymer matrix are studied using different nanocrystal concentrations. Reflection spectra analyzed through Kim oscillator model lead to the determination of optical constants such as refractive index n, extinction coefficient k, dielectric permittivity ε and absorption coefficient α.Using the common Cauchy, Drude-Lorentz, Tauc and single-effective-oscillator theoretical models, we have determined the values of static refractive index n and permittivity ε, plasma frequency $$\omega_{\text{p}}$$ , carrier density N, optical band gap E and oscillator and dispersion energies E and E, respectively. It is found that TBPO-capped CdSe NCs concentration affects the optoelectronic parameters of the nanocomposite thin films. Moreover, the disorder of this hybrid system is also studied by the determination of Urbach energy, which increases with TBPO-capped CdSe concentration. [ABSTRACT FROM AUTHOR]

In this paper, nanocomposite (NC) films of polycaprolactone (PCL)/ZnO-DA were prepared by casting/solvent evaporation method. For this purpose, ZnO nanoparticles were first modified with diacid (DA) based on bioactive amino acid ( N-trimellitylimido- l-alanine), at room temperature using methanol as solvent and ultrasound irradiation method. Then, PCL/ZnO-DA NCs were obtained by addition of various weight percentages (2, 4, and 6 wt%) of ZnO-DA into the PCL matrix, under vigorous stirring and subsequent ultrasonic irradiation. The structural characterization of the NC films was carried out using Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. It was found that relative changes in the peaks and morphology were observed, as the concentration of filler was increased. In addition, embedding the NPs into PCL exhibited a reduction in thermal stability of NCs as compared to the pure PCL. FE-SEM and TEM morphological analysis did not show any aggregation of the NPs in the prepared NCs. It was also found that chemical composition of NC films had influenced their optical absorption and mechanical behaviors. [ABSTRACT FROM AUTHOR]

The optimum conditions (pH and ionic strength of solution, concentration of polymer) for the formation of nanocomposite films of poly(diallyldimethylammonium chloride) (PDDA) with CdTe/CdS nanocrystals by layer-by-layer deposition of the components on glass were determined. It was shown that the multilayer composites with highest optical density are formed at pH 7.5-8.0. A procedure for determining the amount of adsorbed PDDA based on the deposition of plasmon nanoparticles of silver as markers is proposed. [ABSTRACT FROM AUTHOR]

Steady state and time-resolved spectroscopic measurements are carried out to understand the fluorescent optical properties of the conjugated polymer poly(9,9-di-(2-ethylhexyl)-9H-fluorene-2,7-vinylene) (PFV) in liquid phase and solid phase. Quite significant color tuning is observed in the fluorescence emission of PFV in the blue side of the spectra in the solid phase, especially in powder form, when the polymer is doped with 30B nanoclay (organically modified Montmorillonite) and graphene nanoparticles. Interestingly, the average fluorescence lifetime of PFVgraphene nanocomposite in thin film is found to be much higher (8.1 ns) compared to that for PFV only in thin film (3 ns). These novel nanocomposites may have potential applications in polymer optoelectronics industry. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to evaluate the color stability in relation to the opacity of the nanocomposite Filtek™ Ultimate (3M™ ESPE™), by immersing the specimens in different types of natural and artificial staining solutions. Material and methods: Eighty disks of the shades A1 body (A1B), A1 dentine (A1D), A1 enamel (A1E), and white enamel (WE) ( n = 4) of the nanocomposite Filtek™ Ultimate (3M™ ESPE™) were immersed in staining solutions Orange II, Amaranth, coffee, tea, and artificial saliva. Color coordinates Commission Internationale de l'éclairage (CIE) L*a*b* were collected before and after immersion at 4, 6, 12, 24 h and 7 days. Two-way repeated measurements ANOVA was used in order to assess the effect of immersion time, staining solutions, and materials on CIE L*a*b* parameters, translucency parameter (TP), and color difference (ΔE*). For comparisons between staining solutions and materials, pairwise contrasts adjusted by Bonferroni method were used. Results: The color difference (ΔE*) after 7 days of immersing in staining solution ranged between 0.9 and 15.8. The highest ΔE* after 7 days was obtained for WE, followed by A1E, A1B, and A1D (for all of the immersion solutions, except coffee). There were differences among staining solutions regarding the induced color changes. Coffee induced the most pronounced color differences. However, Orange II, Amaranth, and artificial saliva generated similar behavior in time, for all tested materials. Conclusions: No statistically significant differences were found among various opacities of Filtek Ultimate regarding the ΔE*, TP, ΔL*, and Δb* overtime. In contrast, Δa* was significantly affected by the type of material. Clinical relevance: The purpose of this study was to predict the color change of different layers of composites, in cases of complex stratified dental restorations. [ABSTRACT FROM AUTHOR]

A new method for formation of the cross-linked polymer films at the solid surface as well as the thin nanocomposite films based on them with embedded CdS nanocrystals is reported in this paper. The process involves several stages, namely, (i) thin polymer film formation on glass slide by spin coating of an organic solution of reactive peroxide-containing copolymer (RC), polyethylene glycols (PEG) of various molecular weight, and cadmium acetate [Cd(Ac)] as nanocrystal precursor; (ii) melting and cross-linking of the polymer film; and (iii) synthesis of CdS nanocrystals inside the polymer film via sol-gel technique. The X-ray diffraction analysis and UV-visible spectroscopy prove formation of the CdS nanocrystals in the thin polymer films. This method allows forming multilayered nanocomposite films with tuned properties. The obtained results reveal that size of the CdS nanocrystals and optical properties (absorption and photoluminescence spectra) of the nanocomposite films depend on the nature of polymer matrix, PEG/RC ratio, Cd(Ac) concentration, and the number of layers composing the films. [ABSTRACT FROM AUTHOR]

In this work, different compositions of lanthanum hexaboride (LaB) and tin-doped indium oxide (ITO) nanoparticles were doped into poly(vinylbutyral) (PVB) matrix to prepare PVB/LaB-ITO nanocomposite (PLINC) films by a solution casting method. X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, thermogravimetric analysis (TGA) and ultraviolet-visible-near infrared spectroscopy (UV-vis-NIR) were employed to characterize the PLINCs. The TGA and UV-vis-NIR results reveal that the nanocomposite films possessed outstanding thermal stability. The temperature where 5 % weight loss of the PVB matrix was improved after the addition of LaB and ITO particles and the property for blocking near infrared light was also enhanced as compared with the case of pure PVB film. [ABSTRACT FROM AUTHOR]

Pure zinc oxide and zinc oxide/barium carbonate nanoparticles (ZnO-NPs and ZB-NPs) were synthesized by the sol-gel method. The prepared powders were characterized by X-ray diffraction (XRD), ultraviolet-visible (UV-Vis), Auger spectroscopy, and transmission electron microscopy (TEM). The XRD result showed that the ZnO and BaCO nanocrystals grow independently. The Auger spectroscopy proved the existence of carbon in the composites besides the Zn, Ba, and O elements. The UV-Vis spectroscopy results showed that the absorption edge of ZnO nanoparticles is redshifted by adding barium carbonate. In addition, the optical parameters including the refractive index and permittivity of the prepared samples were calculated using the UV-Vis spectra. PACS: 81.05.Dz; 78.40.Tv; 42.70.-a. [ABSTRACT FROM AUTHOR]

Zinc sulphide-polyaniline (ZnS-PANI) nanocomposites are prepared by preparing ZnS nanoparticles in the same reaction bath for synthesis of PANI. Three different composites have been prepared by varying the concentration of zinc source. The films obtained from the colloidal dispersion are characterized by Scanning electron microscopy, energy dispersive analysis of X-rays, transmission electron microscopy, X-ray diffraction studies, Fourier transform infrared spectroscopy, UV-visible optical absorption, photoluminescence and current-voltage studies. Broadening of X-ray diffraction peaks suggest change in crystallite size and this is in agreement with the results from transmission electron microscopy. Fourier transform infrared spectra indicate crosslinking in the composite film. UV-visible absorption spectra of the film exhibit enhancement of doping level which is assigned to the existence of greater number of charges on the polymer backbone. Optical properties of the films are studied by measuring photoluminescence spectra. This shows decrease in intensity and blue shift with the increase in zinc source concentration. The blue shift indicates strong quantum confinement. Current-voltage characteristics exhibit excellent light response indicating tunneling type of conduction. [ABSTRACT FROM AUTHOR]

Hematite ( α-Fe2O3) nanorods with an average diameter of 40 nm were prepared using a template-free sol-gel method. These nanorods then mixed with polyvinyl alcohol (PVA)/polyethylene glycol (PEG) blend at concentrations of 0.0, 0.5, and 1.0 wt.%. The transmittance percentage ( T%) of the films showed a decrease from 80.26 to 33.24 %. The direct optical band gap also decreased from 5.28 to 4.83 eV whereas the refractive index significantly increased with increasing the hematite content. The dielectric measurements were performed in the temperature range 303-413 K and frequency range 30 kHz-3.0 MHz. According to the temperature dependence of the dielectric constant (ε'), αa-relaxation peaks observed in all films and assigned to the micro-Brownian motion of the polymer blend chains. The behavior of the ac conductivity, σac (f), of the nanocomposite films indicated that the homogenous distribution of α-Fe2O3 nanorods allows the formation of conductive three-dimensional networks throughout the nanocomposite film. Also, indicated that the correlated barrier hopping is the most suitable conduction mechanism. [ABSTRACT FROM AUTHOR]

Prospective applications of plasmonic nanocomposites in photonic and optoelectronic devices demand innovative means of material syntheses, as well as a comprehensive understanding of the influence of material composition and processing on resulting properties. In this work, it is shown that a phosphate glass matrix prepared with stoichiometric amounts of CuO and SnO dopants by the melting technique may well be effective for the precipitation of Cu nanoparticles (NPs) upon heat treatment (HT). Optical absorption and photoluminescence (PL) spectroscopy, including emission decay dynamics, are employed in the characterization of the melt-quenched glass, and for investigating the influence of HT on material optical properties. The as-prepared material appeared highly luminescent; the data suggests contributions from both twofold-coordinated tin centers and Cu ions to light emission. The PL depends strongly on excitation wavelength; e.g. excitation at 260 nm shows a blue-white emission for which a significant contribution from tin is indicated, whereas excitation at 360 nm produces an orange emission in association with Cu ions. Thermal processing results in the chemical reduction of ionic copper via Sn ultimately producing Cu NPs in the matrix, as evidenced by the appearance of the surface plasmon resonance around 574 nm. As a result, Cu PL decreases and the emission band shows a dip due to reabsorption by Cu NPs in resonance. [ABSTRACT FROM AUTHOR]

The annealing effect on structural and optical properties of the Diamond-like Nanocomposite (DLN) thin film deposited on glass substrate by Plasma Assisted Chemical Vapor Deposition (PACVD) method has been investigated. The films were annealed at temperature ranging from 300 to 600 °C, with 100 °C interval for 9 minutes by rapid thermal process (RTP) under vacuum. The structural changes of the annealed films have been studied using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Scanning Electron Microscope (SEM), and optical parameters have been determined using transmittance and reflectance spectra in UV-UIS-NIR range. The result shows that the refractive index increases gradually from 1.79 to 2.84 with annealing temperature due to out-diffusion of H by breaking Si-H and C-H bond leads to Si-C bond, i.e. more cross linking structure. In higher temperature range, graphitization also enhanced the refractive index. However, the optical band gap at up to 400 °C initially increases from 3.05 to 3.20 eV and then decreases due to graphitization. The film has a great potential to be used as anti-reflection coating (ARC) on silicon-based solar cell. [ABSTRACT FROM AUTHOR]

Zirconia modified by gadolinium (Gd/ZrO) nanocomposite has been successfully prepared by NaCl-assisted method. The effects of gadolinium introduction on phase, composition, optical properties, and photocatalytic activities were investigated in detail. Results reveal that the introduction of gadolinium could enlarge the lattice space, create structural defects, and restrict the product growth. At the same time, the generated structural defects further influence the optical properties of Gd/ZrO nanocomposite with single phase. Photocatalytic experiments indicate that GdZrO nanocrystals have better visible-light-responsive photocatalytic activities which results from the special structural defect, smaller size (30-55 nm), and larger specific surface area (~50.60 m/g). Hence, GdZrO nanocrystals are promising visible-light-responsive photocatalysts with potential prospects in wastewater treatment and environmental protection. Also, the present NaCl-assisted method might be generalized to synthesize other nanocomposite with more complicated structures. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

A polyaniline-based composite cation-exchange material was synthesized by way of sol-gel method and studied to explore its analytical and environmental applications. It was characterized by using instrumental analyses [Fourier transform infrared (spectrometer), X-ray, thermogravimetric analysis/differential thermal analysis, standard electron microscopy, and transmission electron microscopy]. Physicochemical studies, such as ion-exchange capacity, pH titrations, and chemical stability, along with effect of eluent concentration and elution, were also performed to exploit the ion-exchange capabilities. pH titration studies showed that the material presents monofunctional strong cation-exchange behavior. This nanocomposite material is semicrystalline in nature and exhibits improved thermal and chemical stability. The partition coefficient studies of different metal ions in the material were performed in demineralised water and different surfactant media, and it was found to be selective for Pb(II) and Hg(II) ions. To exploit the usefulness of the material as an adsorbent, some important quantitative binary separations of metal ions were performed on polyaniline Zr(IV) molybdophosphate columns. This composite cation exchanger can be applied for the treatment of polluted water to remove heavy metals. [ABSTRACT FROM AUTHOR]

Optical properties of 2D nanocomposite-based photonic crystals with a lattice defect are studied. The nanocomposite comprises metallic nanospheres dispersed in a transparent matrix and is characterized by an effective resonant permittivity. Transmission spectrum for s-polarized waves at oblique incidence is calculated. Spectral manifestation of the splitting of the defect mode when its frequency coincides with the resonant frequency of the nanocomposite is studied. The essential dependence of the splitting on the angle of incidence and concentration of metallic nanospheres in the nanocomposite matrix is established. Specific features of spatial distribution of the electric field intensity in defect modes of crystals are analyzed. [ABSTRACT FROM AUTHOR]

To study the absorption spectra and photocurrent densities of metallic Ag nanoparticle/titania (Ag NP)/TiO2 composite thin films, COMP-Ag n, with various amounts of Ag (10 mol% ≤ n ≤80 mol%) were fabricated on a quartz glass substrate at 600 °C using the molecular precursor method. Respective precursor solutions for Ag-nanoparticles and titania were prepared from Ag salt and a titanium complex. Apart from a surface plasmon resonance (SPR) peak around 400 nm, additional wide-range absorption spread in the wide vis-region at wavelengths greater than 400 nm was observed in the composite thin films. The wide-range absorption is due to a tip-tip plasmon mode, intraparticle plasmonic coupling of tip and cavity resonances (LSPR). The absorption spectral patterns could be categorized into three types, depending on the Ag NP content. The photocurrent density of the TiO2 thin film and COMP-Ag n was measured under natural potential by a conventional three-electrode method using a Ag plate as a counter electrode. The photocurrent densities of COMP-Ag n were comparable to those of the three patterns categorized according to their absorption spectra. The cathodic photocurrent densities generated by COMP-Ag n with Ag content greater than 45 mol% could be observed under both UV- and visible (vis-) light irradiation. The enhanced photocurrent density was observed till the Ag content was increased up to 70 mol%. Under dark conditions, cathodic current densities were 1/5-1/20 of those under vis-light irradiation probable due to chemical redox reactions that may occur to the system. On the basis of photoexcited electron transfer from Ag NPs to the TiO2 conduction band and the electrical conductivity of COMP-Ag n, the excellent response to vis-light and major factors affecting the photoresponse and photocurrent polarity were clarified by LSPR. [ABSTRACT FROM AUTHOR]

Thin films of semiconducting polyaniline (PANi) nanofibers reinforced with copper oxide (CuO) nanoparticles (NPs) were prepared on glass substrate using spin coating technique. Polyaniline (PANi) have been synthesized by chemical oxidative polymerization method with monomer aniline in presence of (NH)SO as an oxidant at 0 °C. The copper oxide (CuO) nanoparticles were synthesized by sol-gel method. Physical properties of nanocomposite (NCs) films were characterized and analyzed by X-ray diffraction, Scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, UV-vis spectroscopy, Two probe resistivity measurement technique and Thermo-emf measurement. Structural analysis showed that the crystal structure of CuO is not disturbed in the PANi-CuO hybrid nanocomposite. Surface morphology study shows the uniform distribution of CuO nanoparticles in PANi matrix. FTIR and UV-Visible studies confirm the presence of polyaniline in emeraldine base form in the composites and suggest incorporation of CuO in polymer. Two probe electrical resistivity measurements of nanocomposites (NCs) film revealed that the resistivity of PANi increases with increasing content of CuO NPs. [ABSTRACT FROM AUTHOR]

Fe3O4 nanoparticles were prepared by solvothermal reaction, and structure-tailored Fe3O4/poly(glycidyl methacrylate-ethyleneglycol dimethacrylate- N-vinylcarbazole) (FeO/P(GMA-EGDMA-NVCz)) core-shell microspheres were achieved by distillation-precipitation polymerization of GMA, EGDMA, and NVCz in the presence of Fe3O4 nanoparticles. The properties of Fe3O4/P(GMA-EGDMA-NVCz) microspheres were characterized by transmission electron microscopy(TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), and fluorescence spectroscopy. The results showed that the size of Fe3O4/P(GMA-EGDMA-NVCz) core-shell microspheres could be controlled to 930-470 nm by adjusting the amount of shell monomers, corresponding magnetic content of 45-82 wt%, and saturation magnetization of 32-63 emu/g. Moreover, the intensity of the fluorescence increased considerably with the decrease of shell thickness and the increase of NVCz concentration in the monomer mixture. [ABSTRACT FROM AUTHOR]

Sole components of titania (TiO2), silica (SiO2) nanoparticles, and binary TiO2-SiO2 nanocomposites with various molar ratios of silica contents were prepared by modified sol-gel method. The samples were calcined at 500 °C for 5 h and characterized by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), UV-Vis spectroscopy, Brunauett-Emmett-Teller (BET), and photoconductivity. The crystallite size for TiO2/SiO2 nanocomposites was calculated using Scherrer's formula and found to be 5 nm for TiO2 nanoparticles. The binary oxide shows the anatase type of TiO2 at the mole ratio up to 80 mol% of TiO2 added. The band gap for as-synthesized nanocomposites was calculated and it was found that the band gap decreases with increase of SiO2 content and then decreases with excess SiO2 content. FTIR confirms that both TiO2 and SiO2 phases have been formed. The BET surface area for TiO2/SiO2 nanocomposite is found to be 303 m/g, and pore size distribution has an average pore diameter about 10 nm for 40 mol% of TiO2 added. It also confirms the absence of macropores and the presence of micro and mesopores. The field-dependent dark and photoconductivity studies reveal that the dark and photocurrent increase linearly with applied field confirming the ohmic nature of the electric contacts. The dark and photocurrent increase slightly with increase of SiO2 content and decrease with excess amount of SiO2. [ABSTRACT FROM AUTHOR]

Thin-film hybrid nanocomposites based on poly- n-phenylvinylene with various contents of the CdS semiconductor nanoparticles are obtained using the pyrolytic polymerization of dichloro- n-xylene from the gas phase and the simultaneous sedimentation of the CdS vapor with the subsequent thermal processing of the precursor. The structure of the nanocomposite is studied, and the optical properties of the materials are analyzed. It is demonstrated that a variation in the concentration of the inorganic component in the polymer matrix leads to a variation in the maximum fluorescence wavelength and optical band gap. The material parameters (degree of conjugation of poly- n-phenylvinylene, band gap, Huang-Rhys factor, Stokes shift, and vibronic energy of molecules) are determined. [ABSTRACT FROM AUTHOR]

The present study aims to produce a light weight electromagnetic interference (EMI) shielding material from carbon nanofibers (CNFs)-based polysulfone (PSU) nanocomposites. EMI shielding effectiveness (EMI SE) was studied by analyzing the electromagnetic wave transmission, reflection, and absorption characteristics of nanocomposites. The electrical conductivity and EMI SE of the nanocomposite with different weight percentage of CNFs (3-10 wt%) were investigated at room temperature and the measurement of EMI SE was carried out in a frequency range of 8.2-12.4 GHz (X-band). The mechanism of EMI shielding of PSU/CNFs nanocomposite has been well explained by comparing the contribution of reflection and absorption to the total EMI SE. The state of dispersion of CNFs and PSU-CNFs interaction was studied by high resolution transmission electron microscopy and scanning electron microscopy. The thermal stability of nanocomposite studied from thermogravimetric analysis was increased after addition of CNFs to PSU matrix. Electrical conductivity of nanocomposite followed power law model of percolation theory having a percolation threshold Φc = 0.0079 vol% (0.9 wt%) and exponent t = 1.73. The EMI SE of nanocomposites with thickness of 1 mm was 19-45 decibel (dB) at 3-10 wt% CNFs loading. This high thermal stability and high EMI SE suggest the potential use of PSU/CNFs nanocomposite as effective lightweight EMI shielding material in different electronic applications. [ABSTRACT FROM AUTHOR]

This work reports the formulation of water-based graphene oxide/acrylic nanocomposite inks, and the structural and electrical characterization of test patterns obtained by inkjet direct printing through a commercial piezoelectric micro-fabrication device. Due to the presence of heavily oxygenated functional groups, graphene oxide is strongly hydrophilic and can be readily dispersed in water. Through a process driven by UV irradiation, graphene oxide contained in the inks was reduced to graphene during photo-curing of the polymeric matrix. Printed samples of the nanocomposite material showed a decrease of resistivity with respect to the polymeric matrix. The analysis of the influence of printed layer thickness on resistivity showed that thin layers were less resistive than thick layers. This was explained by the reduced UV penetration depth in thick layers due to shielding effect, resulting in a less effective photo-reduction of graphene oxide. [ABSTRACT FROM AUTHOR]

Spherical ZnS/Au nanocomposites have been synthesized through a fast one-step microwave-hydrothermal route. Surfactant polyvinylpyrrolidone (PVP) was used as shape modifier to control the size of products. The use of different sulfur sources also resulted in nanospheres with different sizes. The formation mechanism of the nanocomposites is discussed. The UV-vis and photoluminescence properties of the as-prepared nanocomposites with different Au doping concentrations showed tunable UV and visible emission intensity. [ABSTRACT FROM AUTHOR]

Rare-earth (RE) complexes can be easily adsorbed on the surface of graphene oxide sheets (GOSs) by a simple noncovalent approach. The resulting nanocomposite materials, RE complexes functionalized GOSs, have been comprehensively characterized via transmission electron microscopy, X-ray photoelectron spectroscopy, FT-IR spectra, X-ray diffraction, and thermogravimetric analysis. The luminescence properties of GOSs-RE were also investigated. Under the excitation of UV light, these samples display the characteristic emissions of Eu3+ ions. The photophysical investigations revealed that the presence of GOSs do not quench the lanthanide-centered luminescence stemming from the characteristic electronic transitions within the 4 f shell of the Eu3+ ions. The GOSs-RE complex hybrids and their dispersion can emit bright red luminescence. Moreover, the presence of GOSs can elongate the fluorescence lifetime of the RE complexes to 983 μs. These properties make them useful in many practical fields, such as in the lighting and biological labeling. [ABSTRACT FROM AUTHOR]

The synthesis of new ZnFeO-TiO crystalline nanocomposites with enhanced visible-light catalytic performance is reported. Zinc ferrite powders were prepared by a wet method through oxalate precursor at 400 ºC during 12 h and the nanocomposite materials were obtained through TiO incorporation before (ZnFeO/TiO) and after (TiO/ZnFeO) the ZnFeO synthesis. The influence of the nanocomposite design in the structural, morphological, and optical properties of the composite oxide materials was studied, by XRD, SEM/TEM, BET measurements, and DRS. New and improved optical features were observed in the ZnFeO-TiO absorption spectra comparatively with the TiO and ZnFeO ones. These results are discussed based on the interface effect and a proposal for the photogenerated electron transitions in the ZnFeO-TiO is presented. The photocatalytic performance of the prepared samples was evaluated for the methyl orange (MO) degradation process. From all the tested materials, the TiO/ZnFeO was the one with the best photocatalytic activity, even superior to the nanocrystalline TiO one. 100 % reduction of the MO concentration was achieved after 10 min of UV-Vis irradiation on a 10 ppm dye aqueous solution with 0.43 g L of TiO/ZnFeO catalyst. By performing visible-light experiments, it was possible to discuss the influence of the visible-light absorption, charge separation, and photogenerated charge-carrier recombination in the TiO/ZnFeO photocatalytic performance. [ABSTRACT FROM AUTHOR]

This work studies corrosion-electrochemical properties of three-phase composites of α-Fe+ FeC + VC in acidic and alkaline sulfate solutions. Nanosize carbide inclusions are characterized by a high level of activity in the reaction of cathodic hydrogen evolution and result in a high rate of composite dissolution in acidic solutions. The presence of carbides and carbon has a negative effect on passivation of the iron matrix. The resistance of vanadium carbide inclusions to anodic oxidation increases upon a decrease in the amount of carbon in the carbide. [ABSTRACT FROM AUTHOR]

SPR based fiber optic sensor using nanocomposite is presented. Nanocomposites comprising of Pt nanoparticles with various volume fractions embedded in dielectric matrices of TiO2 and SnO2 are considered. Sensitivity enhances with increase in thickness of nanocomposite and volume fraction of nanoparticles for both nanocomposites. Optimized thicknesses are obtained to be 40 and 50 nm for Pt-TiO2 and Pt-SnO2 nanocomposites respectively while optimized volume fraction is found to be 0.85 for both nanocomposites. 40 nm thick Pt-TiO2 nanocomposite based sensor with 0.85 volume fraction possesses utmost sensitivity. [ABSTRACT FROM AUTHOR]