Processing-structure-properties relationships in PLA nanocomposite films

NASA Astrophysics Data System (ADS)

Di Maio, L.; Scarfato, P.; Garofalo, E.; Galdi, M. R.; D'Arienzo, L.; Incarnato, L.

2014-05-01

This work deals on the possibility to improve performances of PLA-based nanocomposite films, for packaging applications, through conveniently tuning materials and processing conditions in melt compounding technology. In particular, two types of polylactic acid and different types of filler selected from montmorillonites and bentonites families were used to prepare the hybrid systems by using a twin-screw extruder. The effect of biaxial drawing on morphology and properties of the nanocomposites, produced by film blowing, was investigated.

High oxygen nanocomposite barrier films based on xylan and nanocrystalline cellulose

Treesearch

Amit Saxena; Thomas J. Elder; Jeffrey Kenvin; Arthur J. Ragauskas

2010-01-01

The goal of this work is to produce nanocomposite film with low oxygen permeability by casting an aqueous solution containing xylan, sorbitol and nanocrystalline cellulose. The morphology of the resulting nanocomposite films was examined by scanning electron microscopy and atomic force microscopy which showed that control films containing xylan and sorbitol had a more...

Physicochemical and antifungal properties of bio-nanocomposite film based on gelatin-chitin nanoparticles.

PubMed

Sahraee, Samar; Milani, Jafar M; Ghanbarzadeh, Babak; Hamishehkar, Hamed

2017-04-01

The gelatin-based nanocomposite films containing chitin nanoparticles (N-chitin) with concentrations of 0, 3, 5 and 10% were prepared and their physical, thermal and anti-microbial properties were investigated. Scanning electron microscopy (SEM) micrographs showed that N-chitin size distribution was around 60-70nm which dispersed appropriately at low concentration in gelatin matrix. The results showed that incorporation of N-chitin significantly influenced apparent color and transparency of the gelatin films. The reduced water vapor permeability (WVP) and solubility and higher surface hydrophobicity of the nanocomposite films were obtained by enhancing N-chitin concentration in film formulation. The use of N-chitin up to 5% concentration in the gelatin based nanocomposite film led to improved mechanical properties. Also, the results of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) confirmed improved stability of nanocomposite films against melting and degradation at high temperatures in comparison to neat gelatin film. The well compatibility of chitin nanoparticles with gelatin polymer was concluded from Fourier transform infrared (FTIR) spectra and X-ray diffraction (XRD) plots. Finally, the gelatin based nanocomposite films had anti-fungal properties against Aspergillus niger in the contact surface zone. Increasing the concentration of N-chitin up to 5% enlarged inhibition zone diameter, but the nanocomposite film containing 10% N-chitin showed smaller inhibition zone. Copyright © 2016 Elsevier B.V. All rights reserved.

Rapid fabrication of hierarchically structured supramolecular nanocomposite thin films in one minute

DOEpatents

Xu, Ting; Kao, Joseph

2016-11-08

Functional nanocomposites containing nanoparticles of different chemical compositions may exhibit new properties to meet demands for advanced technology. It is imperative to simultaneously achieve hierarchical structural control and to develop rapid, scalable fabrication to minimize degradation of nanoparticle properties and for compatibility with nanomanufacturing. The assembly kinetics of supramolecular nanocomposite in thin films is governed by the energetic cost arising from defects, the chain mobility, and the activation energy for inter-domain diffusion. By optimizing only one parameter, the solvent fraction in the film, the assembly kinetics can be precisely tailored to produce hierarchically structured thin films of supramolecular nanocomposites in approximately one minute. Moreover, the strong wavelength dependent optical anisotropy in the nanocomposite highlights their potential applications for light manipulation and information transmission. The present invention opens a new avenue in designing manufacture-friendly continuous processing for the fabrication of functional nanocomposite thin films.

Microstructures, mechanical behavior and strengthening mechanism of TiSiCN nanocomposite films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Wei; Liu, Ping; Xue, Zenghui

Recently, the arguments have existed in the strengthening mechanism and microstructural model of the nanocomposite film due to lack of the convincible experimental evidences. In this investigation, the quarternary TiSiCN nanocomposite films with the different C and Si contents are synthesized by the reactive-magnetron-sputtering technique. The TiSiCN film is characterized as the nanocomposite structure with the TiN nanocrystallites surrounded by the (Si 3N 4 + C + CN x) interface phase. When the C/Si content ratio is 2:2, the TiSiCN nanocomposite film is remarkably strengthened with the maximal hardness and elastic modulus of 46.1 GPa and 425 GPa, respectively. Meanwhile,more » the (Si 3N 4 + C + CN x) interfaces exhibit as a crystallized form, which can coordinate the growth misorientations and maintain the coherently epitaxial growth between the TiN nanocrystallites and interfaces. Through the high-resolution transmission electron microscopy (HRTEM) observations, this investigation firstly provides the direct experimental evidence for the crystallized feature of the interfaces when the TiSiCN nanocomposite film is strengthened, suggesting that the strengthening effect of the TiSiCN nanocomposite film can be attributed to the coherent-interface strengthening mechanism, which is expressed as the “nc-TiN/c-Si 3N 4/c-C/c-CN x” model.« less

Microstructures, mechanical behavior and strengthening mechanism of TiSiCN nanocomposite films

DOE PAGES

Li, Wei; Liu, Ping; Xue, Zenghui; ...

2017-05-18

Recently, the arguments have existed in the strengthening mechanism and microstructural model of the nanocomposite film due to lack of the convincible experimental evidences. In this investigation, the quarternary TiSiCN nanocomposite films with the different C and Si contents are synthesized by the reactive-magnetron-sputtering technique. The TiSiCN film is characterized as the nanocomposite structure with the TiN nanocrystallites surrounded by the (Si 3N 4 + C + CN x) interface phase. When the C/Si content ratio is 2:2, the TiSiCN nanocomposite film is remarkably strengthened with the maximal hardness and elastic modulus of 46.1 GPa and 425 GPa, respectively. Meanwhile,more » the (Si 3N 4 + C + CN x) interfaces exhibit as a crystallized form, which can coordinate the growth misorientations and maintain the coherently epitaxial growth between the TiN nanocrystallites and interfaces. Through the high-resolution transmission electron microscopy (HRTEM) observations, this investigation firstly provides the direct experimental evidence for the crystallized feature of the interfaces when the TiSiCN nanocomposite film is strengthened, suggesting that the strengthening effect of the TiSiCN nanocomposite film can be attributed to the coherent-interface strengthening mechanism, which is expressed as the “nc-TiN/c-Si 3N 4/c-C/c-CN x” model.« less

Biopolymer-modified graphite oxide nanocomposite films based on benzalkonium chloride-heparin intercalated in graphite oxide

NASA Astrophysics Data System (ADS)

Meng, Na; Zhang, Shuang-Quan; Zhou, Ning-Lin; Shen, Jian

2010-05-01

Heparin is a potent anticoagulant agent that interacts strongly with antithrombin III to prevent the formation of fibrin clots. In the present work, poly(dimethylsiloxane)(PDMS)/graphite oxide-benzalkonium chloride-heparin (PDMS/modified graphite oxide) nanocomposite films were obtained by the solution intercalation technique as a possible drug delivery system. The heparin-benzalkonium chloride (BAC-HEP) was intercalated into graphite oxide (GO) layers to form GO-BAC-HEP (modified graphite oxide). Nanocomposite films were characterized by XRD, SEM, TEM, ATR-FTIR and TGA. The modified graphite oxide was observed to be homogeneously dispersed throughout the PDMS matrix. The effect of modified graphite oxide on the mechanical properties of the nanocomposite film was investigated. When the modified graphite oxide content was lower than 0.2 wt%, the nanocomposites showed excellent mechanical properties. Furthermore, nanocomposite films become delivery systems that release heparin slowly to make the nanocomposite films blood compatible. The in vitro studies included hemocompatibility testing for effects on platelet adhesion, platelet activation, plasma recalcification profiles, and hemolysis. Results from these studies showed that the anticoagulation properties of PDMS/GO-BCA-HEP nanocomposite films were greatly superior to those for no treated PDMS. Cell culture assay indicated that PDMS/GO-BCA-HEP nanocomposite films showed enhanced cell adhesion.

Structural mechanical and antibacterial properties of HPMC/SF-AgNPs nanocomposite films

NASA Astrophysics Data System (ADS)

Harish, K. V.; Rao, B. Lakshmeesha; Asha, S.; Vipin, C.; Sangappa, Y.

2018-04-01

In the present study, Hydroxypropyl Methylcellulose (HPMC) pure and HPMC/SF-AgNPs biopolymer nanocomposite films were prepared by simple solution casting method. The prepared nanocomposite films were characterized using UV-Visible spectroscopy(UV-Vis), X-ray diffraction (XRD) measurements. The mechanical properties of HPMC/SF-AgNPs nanocomposites were found to be decrease with increase in the AgNP's concentrations. The HPMC/SF-AgNPs nanocomposites showed very good antibacterial activity against human pathogens P. aeruginosa, E.coli, and S.aureus.

Poly(vinyl acetate)/clay nanocomposite materials for organic thin film transistor application.

PubMed

Park, B J; Sung, J H; Park, J H; Choi, J S; Choi, H J

2008-05-01

Nanocomposite materials of poly(vinyl acetate) (PVAc) and organoclay were fabricated, in order to be utilized as dielectric materials of the organic thin film transistor (OTFT). Spin coating condition of the nanocomposite solution was examined considering shear viscosity of the composite materials dissolved in chloroform. Intercalated structure of the PVAc/clay nanocomposites was characterized using both wide-angle X-ray diffraction and TEM. Fracture morphology of the composite film on silicon wafer was also observed by SEM. Dielectric constant (4.15) of the nanocomposite materials shows that the PVAc/clay nanocomposites are applicable for the gate dielectric materials.

Effect of halloysite content on carboxymethyl cellulose/halloysite nanotube bio-nanocomposite films

NASA Astrophysics Data System (ADS)

Suppiah, Kathiravan; Leng, Teh Pei; Husseinsyah, Salmah; Rahman, Rozyanty; Keat, Yeoh Cheow

2017-04-01

Carboxymethyl cellulose/halloysite nanotube (CMC/HNT) bio-nanocomposite films were prepared by solution casting method. The effect of HNT content on tensile properties and morphology were studied. The results showed that the tensile strength of the CMC/HNT bio-nanocomposite films achieved optimum at 10 wt% of HNT content. The elongation at break and modulus of elasticity increased with increasing HNT content. The morphology of CMC/HNT bio-nanocomposite films showed that the poor distribution of HNT filler was observed at 20 wt% of HNT content.

Organic-Inorganic Hydrophobic Nanocomposite Film with a Core-Shell Structure

PubMed Central

Liu, Peng; Chen, Ying; Yu, Zhiwu

2016-01-01

A method to prepare novel organic-inorganic hydrophobic nanocomposite films was proposed by a site-specific polymerization process. The inorganic part, the core of the nanocomposite, is a ternary SiO2–Al2O3–TiO2 nanoparticles, which is grafted with methacryloxy propyl trimethoxyl silane (KH570), and wrapped by fluoride and siloxane polymers. The synthesized samples are characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrscopy, X-ray diffractometry (XRD), contact angle meter (CA), and scanning electron microscope (SEM). The results indicate that the novel organic-inorganic hydrophobic nanocomposite with a core-shell structure was synthesized successfully. XRD analysis reveals the nanocomposite film has an amorphous structure, and FTIR analysis indicates the nanoparticles react with a silane coupling agent (methacryloxy propyl trimethoxyl silane KH570). Interestingly, the morphology of the nanoparticle film is influenced by the composition of the core. Further, comparing with the film synthesized by silica nanoparticles, the film formed from SiO2–Al2O3–TiO2 nanoparticles has higher hydrophobic performance, i.e., the contact angle is greater than 101.7°. In addition, the TEM analysis reveals that the crystal structure of the particles can be changed at high temperatures. PMID:28774141

Large critical current densities and pinning forces in CSD-grown superconducting GdBa2Cu3O7-x -BaHfO3 nanocomposite films

NASA Astrophysics Data System (ADS)

Cayado, Pablo; Erbe, Manuela; Kauffmann-Weiss, Sandra; Bühler, Carl; Jung, Alexandra; Hänisch, Jens; Holzapfel, Bernhard

2017-09-01

GdBa2Cu3O7-x -BaHfO3 (GdBCO-BHO) nanocomposite (NC) films containing 12 mol% BHO nanoparticles were prepared by chemical solution deposition (CSD) following the TFA route on SrTiO3 (STO) single crystals and buffered metallic tapes supplied by two different companies: Deutsche Nanoschicht GmbH and SuperOx. We optimized the preparation of our GdBCO-BHO solutions with acetylacetone making the film synthesis very robust and reproducible, and obtained 220 nm films with excellent superconducting properties. We show the structural, morphological and superconducting properties of the films after a careful optimization of the processing parameters (growth temperature, oxygen partial pressure and heating ramp). The films reach critical temperatures (T c) of ˜94 K, self-field critical current densities (J c) of >7 MA cm- 2 and maximum pinning force densities (F p) of ˜16 GN m- 3 at 77 K on STO and T c of ˜94.5 K and J c > 1.5 MA cm- 2 on buffered metallic tapes. The transport properties under applied magnetic fields are significantly improved with respect to the pristine GdBCO films. The GdBCO-BHO NC films on STO present epitaxial c-axis orientation with excellent out-of-plane and in-plane texture. The films are, in general, very dense with a low amount of pores and only superficial indentations. On the other hand, we present, for the first time, a systematic study of CSD-grown GdBCO-BHO NC films on buffered metallic tapes. We have used the optimized growth conditions for STO as a reference and identified some limitations on the film synthesis that should be overcome for further improvement of the films’ superconducting properties.

Nano CaCO₃ imprinted starch hybrid polyethylhexylacrylate\\polyvinylalcohol nanocomposite thin films.

PubMed

Prusty, Kalyani; Swain, Sarat K

2016-03-30

Starch hybrid polyethylhexylacrylate (PEHA)/polyvinylalcohol (PVA) nanocomposite thin films are prepared by different composition of nano CaCO3 in aqueous medium. The chemical interaction of nano CaCO3 with PEHA in presence of starch and PVA is investigated by Fourier transforms infrared spectroscopy (FTIR). X-ray diffraction (XRD) is used in order to study the change in crystallite size and d-spacing during the formation of nanocomposite thin film. The surface morphology of nanofilms is studied by scanning electron microscope (SEM). The topology and surface roughness of the films is noticed by atomic force microscope (AFM). The tensile strength, thermal stability and thermal conductivity of films are increased with increase in concentrations of CaCO3 nanopowder. The chemical resistance and biodegradable properties of the nanocomposite thin films are also investigated. The growth of bacteria and fungi in starch hybrid PEHA film is reduced substantially with imprint of nano CaCO3. Copyright © 2015 Elsevier Ltd. All rights reserved.

Methods of making non-covalently bonded carbon-titania nanocomposite thin films and applications of the same

DOEpatents

Liang, Yu Teng; Vijayan, Baiju K.; Gray, Kimberly A.; Hersam, Mark C.

2016-07-19

In one aspect, a method of making non-covalently bonded carbon-titania nanocomposite thin films includes: forming a carbon-based ink; forming a titania (TiO.sub.2) solution; blade-coating a mechanical mixture of the carbon-based ink and the titania solution onto a substrate; and annealing the blade-coated substrate at a first temperature for a first period of time to obtain the carbon-based titania nanocomposite thin films. In certain embodiments, the carbon-based titania nanocomposite thin films may include solvent-exfoliated graphene titania (SEG-TiO.sub.2) nanocomposite thin films, or single walled carbon nanotube titania (SWCNT-TiO.sub.2) nanocomposite thin films.

Mineralized agar-based nanocomposite films: Potential food packaging materials with antimicrobial properties.

PubMed

Malagurski, Ivana; Levic, Steva; Nesic, Aleksandra; Mitric, Miodrag; Pavlovic, Vladimir; Dimitrijevic-Brankovic, Suzana

2017-11-01

New mineralized, agar-based nanocomposite films (Zn-carbonate and Zn-phosphate/agar) were produced by a combination of in situ precipitation and a casting method. The presence of minerals significantly influenced the morphology, properties and functionality of the obtained nanocomposites. Reinforcement with the Zn-mineral phase improved the mechanical properties of the carbonate-mineralized films, but had a negligible effect on the phosphate-mineralized samples. Both nanocomposites showed improved optical and thermal properties, better Zn(II) release potential in a slightly acidic environment and exhibited antimicrobial activity against S. aureus. These results suggest that Zn-mineralized agar nanocomposite films could be potentially used as affordable, eco-friendly and active food packaging materials. Copyright © 2017 Elsevier Ltd. All rights reserved.

Physical-mechanical properties of agar/κ-carrageenan blend film and derived clay nanocomposite film.

PubMed

Rhim, Jong-Whan

2012-12-01

Binary blend films with different mixing ratio of agar and κ-carrageenan were prepared using a solution casting method with and without nanoclay and the effect of their composition on the mechanical, water vapor barrier, and water resistance properties was tested. The tensile strength (TS) of the κ-carrageenan film was greater than that of agar film. The water vapor permeability (WVP) of the agar film was lower than that of κ-carrageenan film, the swelling ratio (SR) and water solubility (WS) of κ-carrageenan film were higher than those of agar film. Each property of the binary blend films varied proportionately depending on the mixing ratio of each component. The XRD result indicated that the nanocomposite with agar/κ-carrageenan/clay (Cloisite(®) Na(+)) was intercalated. Consequently, the mechanical strength, water vapor barrier properties, and water contact angle (CA) were significantly (P < 0.05) improved through nanocomposite formation. © 2012 Institute of Food Technologists®

Study on swift heavy ions induced modifications of Ag-ZnO nanocomposite thin film

NASA Astrophysics Data System (ADS)

Singh, S. K.; Singhal, R.; Siva Kumar, V. V.

2017-03-01

In the present work, swift heavy ion (SHI) irradiation induced modifications in structural and optical properties of Ag-ZnO nanocomposite thin films have been investigated. Ag-ZnO nanocomposite (NCs) thin films were synthesized by RF magnetron sputtering technique and irradiated with 100 MeV Ag7+ ions at three different fluences 3 × 1012, 1 × 1013 and 3 × 1013 ions/cm2. Rutherford Backscattering Spectrometry revealed Ag concentration to be ∼8.0 at.%, and measured thickness of the films was ∼55 nm. Structural properties of pristine and irradiated films have been analyzed by X-ray diffraction analysis and found that variation in crystallite size of the film with ion irradiation. X-ray photoelectron spectroscopy (XPS) indicates the formation of Ag-ZnO nanocomposite thin film with presence of Ag, Zn and O elements. Oxidation state of Ag and Zn also estimated by XPS analysis. Surface plasmon resonance (SPR) of Ag nanoparticle has appeared at ∼475 nm in the pristine thin film, which is blue shifted by ∼30 nm in film irradiated at fluence of 3 × 1012 ions/cm2 and completely disappeared in film irradiated at higher fluences, 1 × 1013 and 3 × 1013 ions/cm2. A marginal change in the optical band gap of Ag-ZnO nanocomposite thin film is also found with increasing ion fluence. Surface morphology of pristine and irradiated films have been studied using Atomic Force Microscopy (AFM). Raman and Photo-luminance (PL) spectra of nanocomposite thin films have been investigated to understand the ion induced modifications such as lattice defects and disordering in the nanocomposite thin film.

Optical properties of diamond like carbon nanocomposite thin films

NASA Astrophysics Data System (ADS)

Alam, Md Shahbaz; Mukherjee, Nillohit; Ahmed, Sk. Faruque

2018-05-01

The optical properties of silicon incorporated diamond like carbon (Si-DLC) nanocomposite thin films have been reported. The Si-DLC nanocomposite thin film deposited on glass and silicon substrate by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) process. Fourier transformed infrared spectroscopic analysis revealed the presence of different bonding within the deposited films and deconvolution of FTIR spectra gives the chemical composition i.e., sp3/sp2 ratio in the films. Optical band gap calculated from transmittance spectra increased from 0.98 to 2.21 eV with a variation of silicon concentration from 0 to 15.4 at. %. Due to change in electronic structure by Si incorporation, the Si-DLC film showed a broad photoluminescence (PL) peak centered at 467 nm, i.e., in the visible range and its intensity was found to increase monotonically with at. % of Si.

Impressive nonlinear optical response exhibited by Poly(vinylidene fluoride) (PVDF)/reduced graphene oxide (RGO) nanocomposite films

NASA Astrophysics Data System (ADS)

Sabira, K.; Saheeda, P.; Divyasree, M. C.; Jayalekshmi, S.

2017-12-01

In the present work, the nonlinear optical properties of free-standing films of Poly(vinylidene fluoride) (PVDF)/reduced graphene oxide (RGO) nanocomposite are investigated to assess their suitability as efficient optical limiters. The PVDF/RGO nanocomposite films are generated by mixing different concentrations of RGO as the filler, with PVDF, using solution casting method. The XRD and FTIR data of these nanocomposite films confirm the enhancement in the β phase of PVDF when RGO is added to PVDF, which is one of the prime factors, enhancing the nonlinear response of the nanocomposite. The open aperture and closed aperture Z-scan technique under nanosecond excitation (532 nm, 7 ns) is used to investigate the nonlinear optical characteristics of the PVDF/RGO nanocomposite films. These films are found to exhibit two photon absorption assisted optical non linearity in the nanosecond regime. The highlight of the present work is the observation of quite low values of the normalized transmittance and low optical limiting threshold power in free standing films of PVDF/RGO nanocomposite. These flexible, free-standing and stable nanocomposite films offer high application prospects in the design of efficient optical limiting devices of any desired size or shape.

Ultrasonically assisted single screw extrusion, film blowing and film casting of LLDPE/clay and PA6/clay nanocomposites

NASA Astrophysics Data System (ADS)

Niknezhad, Setareh

The major objective of this study was to investigate the effect of ultrasonic treatment on the dispersion of modified clay particles in LLDPE and PA6 matrices and the final properties of nanocomposites. LLDPE and PA6 are two polymers that are widely used in packaging industry. Blown and cast films were manufactured from the prepared nanocomposites. To achieve one step film processing, an online ultrasonic film casting was developed. Ultrasonic waves caused high-energy mixing and dispersion due to the acoustic cavitation, causing the clay agglomorates to separate into individual platelets in polymer matrix. Ultrasonic waves also broke down the polymer molecular chains reducing viscosity of the melt, facilating dispersion of the clay platelets throughout the matrix. Ultrasound also led to a breakage of the clay platelets reducing the particle size and improving their distribution. Clay particles acted as a heterogenous nucleation agent generating smaller size polymer crystals. In turn, these improved different properties including mechanical properties, oxygen permeability and transparency of films. In LLDPE/clay 20A nanocomposites, the effect of ultrasound was more obvious at higher clay loadings. Exfoliated structure for ultrasonically treated nanocomposites containing 2.5, 5 and 7.5 wt% of clay 20A and highly intercalated structure for ultrasonically treated nanocomposites containing 10 wt% of clay 20A were achieved. However, in blown films, the exfoliated structure transferred to the intercalated structure due to the addition of more shear and thermal degradation of surfactants of the clay particles. While, manufacturing cast films using the new developed online ultrasonic cast film machine revealed the exfoliated structure with ultrasonic treatment till 7.5 wt% of clay loadings. Cast films of nanocomposites containing 5 wt% of clay loadings were also prepared with addition of different compatibilizers. The compatibilizer containing higher amount of grafted

Effect of annealing temperatures on the morphology and structural properties of PVDF/MgO nanocomposites thin films

NASA Astrophysics Data System (ADS)

Rozana, M. D.; Arshad, A. N.; Wahid, M. H. M.; Habibah, Z.; Sarip, M. N.; Rusop, M.

2018-05-01

This study investigates the effect of annealing on the topography, morphology and crystal phases of poly(vinylideneflouride)/Magnesium Oxide (MgO) nanocomposites thin films via AFM, FESEM and ATR-FTIR. The nanocomposites thin films were annealed at temperatures ranging from 70°C to 170°C. The annealed PVDF/MgO nanocomposites thin films were then cooled at room temperature before removal from the oven. This is to restructure the crystal lattice and to reduce imperfection for the PVDF/MgO nanocomposites thin films. PVDF/MgO nanocomposites thin films with annealing temperatures of 70°C, 90°C and 110°C showed uniform distribution of MgO nanoparticles, relatively low average surface roughness and no visible of defects. High application of annealing temperature on PVDF/MgO nanocomposites thin films caused tear-like defects on the thin films surface as observed by FESEM. The PVDF/MgO nanocomposites thin films annealed at 70°C was found to be a favourable film to be utilized in this study due to its enhanced β-crystalites of PVDF as evident in ATR-FTIR spectra.

High energy density and efficiency achieved in nanocomposite film capacitors via structure modulation

NASA Astrophysics Data System (ADS)

Zeng, Yi; Shen, Zhong-Hui; Shen, Yang; Lin, Yuanhua; Nan, Ce-Wen

2018-03-01

Flexible dielectric polymer films with high energy storage density and high charge-discharge efficiency have been considered as promising materials for electrical power applications. Here, we design hierarchical structured nanocomposite films using nonlinear polymer poly(vinylidene fluoride-HFP) [P(VDF-HFP)] with inorganic h-boron nitride (h-BN) nanosheets by electrospinning and hot-pressing methods. Our results show that the addition of h-BN nanosheets and the design of the hierarchical multilayer structure in the nanocomposites can remarkably enhance the charge-discharge efficiency and energy density. A high charge-discharge efficiency of 78% and an energy density of 21 J/cm3 can be realized in the 12-layered PVDF/h-BN nanocomposite films. Phase-field simulation results reveal that the spatial distribution of the electric field in these hierarchical structured films affects the charge-discharge efficiency and energy density. This work provides a feasible route, i.e., structure modulation, to improve the energy storage performances for nanocomposite films.

Flexible Transparent Supercapacitors Based on Hierarchical Nanocomposite Films.

PubMed

Chen, Fanhong; Wan, Pengbo; Xu, Haijun; Sun, Xiaoming

2017-05-31

Flexible transparent electronic devices have recently gained immense popularity in smart wearable electronics and touch screen devices, which accelerates the development of the portable power sources with reliable flexibility, robust transparency and integration to couple these electronic devices. For potentially coupled as energy storage modules in various flexible, transparent and portable electronics, the flexible transparent supercapacitors are developed and assembled from hierarchical nanocomposite films of reduced graphene oxide (rGO) and aligned polyaniline (PANI) nanoarrays upon their synergistic advantages. The nanocomposite films are fabricated from in situ PANI nanoarrays preparation in a blended solution of aniline monomers and rGO onto the flexible, transparent, and stably conducting film (FTCF) substrate, which is obtained by coating silver nanowires (Ag NWs) layer with Meyer rod and then coating of rGO layer on polyethylene terephthalate (PET) substrate. Optimization of the transparency, the specific capacitance, and the flexibility resulted in the obtained all-solid state nanocomposite supercapacitors exhibiting enhanced capacitance performance, good cycling stability, excellent flexibility, and superior transparency. It provides promising application prospects for exploiting flexible, low-cost, transparent, and high-performance energy storage devices to be coupled into various flexible, transparent, and wearable electronic devices.

Development of biodegradable metaloxide/polymer nanocomposite films based on poly-ε-caprolactone and terephthalic acid.

PubMed

Varaprasad, Kokkarachedu; Pariguana, Manuel; Raghavendra, Gownolla Malegowd; Jayaramudu, Tippabattini; Sadiku, Emmanuel Rotimi

2017-01-01

The present investigation describes the development of metal-oxide polymer nanocomposite films from biodegradable poly-ε-caprolactone, disposed poly(ethylene terephthalate) oil bottles monomer and zinc oxide-copper oxide nanoparticles. The terephthalic acid and zinc oxide-copper oxide nanoparticles were synthesized by using a temperature-dependent precipitation technique and double precipitation method, respectively. The terephthalic acid synthesized was confirmed by FTIR analysis and furthermore, it was characterized by thermal analysis. The as-prepared CuO-ZnO nanoparticles structure was confirmed by XRD analysis and its morphology was analyzed by SEM/EDS and TEM. Furthermore, the metal-oxide polymer nanocomposite films have excellent mechanical properties, with tensile strength and modulus better than pure films. The metal-oxide polymer nanocomposite films that were successfully developed show a relatively brighter colour when compared to CuO film. These new metal-oxide polymer nanocomposite films can replace many non-degradable plastics. The new metal-oxide polymer nanocomposite films developed are envisaged to be suitable for use in industrial and domestic packaging applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Transport, mechanical and global migration data of multilayer copolyamide nanocomposite films with different layouts.

PubMed

Scarfato, P; Garofalo, E; Di Maio, L; Incarnato, L

2017-06-01

Transport, mechanical and global migration data concern multilayer food packaging films with different layouts, all incorporating a layered silicate/polyamide nanocomposite as oxygen barrier layer, and a low-density polyethylene (LDPE) as moisture resistant layer in direct contact with food. The data are related to "Tuning of co-extrusion processing conditions and film layout to optimize the performances of PA/PE multilayer nanocomposite films for food packaging" by Garofalo et al. (2017) [1]. Nanocomposite multilayer films, with different relative layer thicknesses and clay types, were produced using a laboratory scale co-extrusion blown-film equipment and were analyzed in terms of transport to oxygen and water vapor, mechanical properties and overall migration. The results have shown that all the multilayer hybrid films, based on the copolyamide layer filled with Cloisite 30B, displayed the most significant oxygen barrier improvements and the best mechanical properties compared to the unfilled films. No significant alteration of the overall migration values was observed, as expectable [2], [3], [4]. The performance improvement was more relevant in the case of the film with the thinner nanocomposite layer.

Microstructural parameters and high third order nonlinear absorption characteristics of Mn-doped PbS/PVA nanocomposite films

NASA Astrophysics Data System (ADS)

Ramezanpour, B.; Mahmoudi Chenari, Hossein; Sadigh, M. Khadem

2017-11-01

In this work, undoped and Mn-doped PbS/PVA nanocomposite films have been successfully fabricated using the simple solution-casting method. Their crystalline structure was examined by X-ray powder diffraction (XRD). XRD pattern show the formation of cubic structure of PbS for Mn-doped PbS in PVA matrix. Microstructure parameters of Mn-doped PbS/PVA nanocomposite films were obtained through the size-strain plot (SSP) method. The thermal stability of the nanocomposite film was determined using Thermogravimetric analysis (TGA). Furthermore, Z-scan technique was used to investigate the optical nonlinearity of nanocomposite films by a continuous-wave laser irradiation at the wavelength of 655 nm. This experimental results show that undoped PbS/PVA nanocomposite films indicate high nonlinear absorption characteristics. Moreover, the nanocomposite films with easy preparation characteristics, high thermal stability and nonlinear absorption properties can be used as an active element in optics and photonic devices.

Enhanced mechanical properties of hydrothermal carbamated cellulose nanocomposite film reinforced with graphene oxide.

PubMed

Gan, Sinyee; Zakaria, Sarani; Syed Jaafar, Sharifah Nabihah

2017-09-15

Cellulose carbamate (CC) was synthesized via hydrothermal process and mixed with graphene oxide (GO) to form a homogeneous cellulose matrix nanocomposite films. The properties of CC/GO nanocomposite films fabricated using simple solution-mixing method with different GO loadings were studied. Transmission electron microscope analysis showed the exfoliation of self-synthesized GO nanosheets within the CC matrix. X-ray diffraction results confirmed the crystalline structure of CC/GO films as the CC/GO mass ratio increased from 100/0 to 100/4. The mechanical properties of CC/GO film were significantly improved as compared to neat CC film. From thermogravimetric analysis result, the introduction of GO enhanced the thermal stability and carbon yields. The 3D homogeneous porous structures of the CC/GO films were observed under Field emission scanning electron microscope. These improvements in nanocomposite film properties could be confirmed by Fourier transform infrared spectroscopy due to the strong and good interactions between CC and GO. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dielectric properties and effect of electrical aging on space charge accumulation in polyimide/TiO2 nanocomposite films

NASA Astrophysics Data System (ADS)

Zha, Jun-Wei; Dang, Zhi-Min; Song, Hong-Tao; Yin, Yi; Chen, George

2010-11-01

In situ polymerized polyimide/TiO2 (PI/TiO2) nanocomposite films with good electrical aging resistance are studied. Space charge distribution in the PI/TiO2 nanocomposite films are measured using the pulsed electroacoustic method. Dielectric properties of the films are measured in the frequency range of 102 Hz-106 Hz by an impedance analyzer (Agilent 4294A) at room temperature. These nanocomposite films are also characterized by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM). It is demonstrated that the nano-TiO2 particles strongly affect dielectric breakdown, lifetime and space charge distribution, and increase the voltage endurance of the nanocomposite films significantly. SEM analyses show that the nanocomposite films are destroyed after corona aging. The relation of space charge distribution with the concentration of the nano-TiO2 particles and the aging time is explored. Results show that an increase in dielectric permittivity of the nanocomposite films is observed with increasing filler concentration. However, the accumulation of space charge decreases with increasing nano-TiO2 particles concentration for the same corona aging time, and depends on the dielectric permittivity of the nanocomposite films.

High Performances of Artificial Nacre-Like Graphene Oxide-Carrageenan Bio-Nanocomposite Films.

PubMed

Zhu, Wenkun; Chen, Tao; Li, Yi; Lei, Jia; Chen, Xin; Yao, Weitang; Duan, Tao

2017-05-16

This study was inspired by the unique multi-scale and multi-level 'brick-and-mortar' (B&M) structure of nacre layers. We prepared the B&M, environmentally-friendly graphene oxide-carrageenan (GO-Car) nanocomposite films using the following steps. A natural polyhydroxy polymer, carrageenan, was absorbed on the surface of monolayer GO nanosheets through hydrogen-bond interactions. Following this, a GO-Car hybridized film was produced through a natural drying process. We conducted structural characterization in addition to analyzing mechanical properties and cytotoxicity of the films. Scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses showed that the nanocomposite films had a similar morphology and structure to nacre. Furthermore, the results from Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Thermogravimetric (TG/DTG) were used to explain the GO-Car interaction. Analysis from static mechanical testers showed that GO-Car had enhanced Young's modulus, maximum tensile strength and breaking elongation compared to pure GO. The GO-Car nanocomposite films, containing 5% wt. of Car, was able to reach a tensile strength of 117 MPa. The biocompatibility was demonstrated using a RAW264.7 cell test, with no significant alteration found in cellular morphology and cytotoxicity. The preparation process for GO-Car films is simple and requires little time, with GO-Car films also having favorable biocompatibility and mechanical properties. These advantages make GO-Car nanocomposite films promising materials in replacing traditional petroleum-based plastics and tissue engineering-oriented support materials.

High Performances of Artificial Nacre-Like Graphene Oxide-Carrageenan Bio-Nanocomposite Films

PubMed Central

Zhu, Wenkun; Chen, Tao; Li, Yi; Lei, Jia; Chen, Xin; Yao, Weitang; Duan, Tao

2017-01-01

This study was inspired by the unique multi-scale and multi-level ‘brick-and-mortar’ (B&M) structure of nacre layers. We prepared the B&M, environmentally-friendly graphene oxide-carrageenan (GO-Car) nanocomposite films using the following steps. A natural polyhydroxy polymer, carrageenan, was absorbed on the surface of monolayer GO nanosheets through hydrogen-bond interactions. Following this, a GO-Car hybridized film was produced through a natural drying process. We conducted structural characterization in addition to analyzing mechanical properties and cytotoxicity of the films. Scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses showed that the nanocomposite films had a similar morphology and structure to nacre. Furthermore, the results from Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Thermogravimetric (TG/DTG) were used to explain the GO-Car interaction. Analysis from static mechanical testers showed that GO-Car had enhanced Young’s modulus, maximum tensile strength and breaking elongation compared to pure GO. The GO-Car nanocomposite films, containing 5% wt. of Car, was able to reach a tensile strength of 117 MPa. The biocompatibility was demonstrated using a RAW264.7 cell test, with no significant alteration found in cellular morphology and cytotoxicity. The preparation process for GO-Car films is simple and requires little time, with GO-Car films also having favorable biocompatibility and mechanical properties. These advantages make GO-Car nanocomposite films promising materials in replacing traditional petroleum-based plastics and tissue engineering-oriented support materials. PMID:28772897

Negative capacitance in (FeCoZr)-(PZT) nanocomposite films

NASA Astrophysics Data System (ADS)

Kołtunowicz, T. N.; Fedotova, J. A.; Zhukowski, P.; Saad, A.; Fedotov, A.; Kasiuk, J. V.; Larkin, A. V.

2013-03-01

In this work, attention was focused on the inductive contribution to the real part of admittance G(T, f) in (Fe0.45Co0.45Zr0.10)x(PZT)(1-x) nanocomposite films deposited in a mixed argon-oxygen atmosphere. The observed G(x, f, T) dependences for the films on the dielectric side of the insulator-metal transition demonstrated the negative capacitance (NC) effect that was maximal for the nanocomposites with 0.40 < x < 0.60, where the metallic FeCoZr nanoparticles were totally oxidized. The NC effect was explained by a specially developed model for the ac hopping conductance of the electrons between the fully oxidized nanoparticles embedded in the PZT matrix. In accordance with the model, under the determined conditions the observed structure of nanocomposites led to an increase in the hopping electron mean lifetime on nanoparticles and hence to the possibility of positive angles of the phase shifts θ and a proper NC (inductive-like contribution) effect.

Doxorubicin loaded carboxymethyl cellulose/graphene quantum dot nanocomposite hydrogel films as a potential anticancer drug delivery system.

PubMed

Javanbakht, Siamak; Namazi, Hassan

2018-06-01

Creating anticancer properties in the hydrogel film could make it as a candidate for treating cancer tissues. In this work, a novel hydrogel nanocomposite films with anticancer properties were designed via incorporation of graphene quantum dot (GQD) as a nanoparticle into carboxymethyl cellulose (CMC) hydrogel and using doxorubicin (DOX) as drug model with broad-spectrum anticancer properties. Drug release studies carried out at two different pHs and the MTT assay was evaluated for DOX-loaded CMC/GQD nanocomposite hydrogel films against blood cancer cells (K562). The prepared nanocomposite hydrogel films were characterized using Fourier transform infrared (FT-IR), UV-Vis spectroscopy, scanning electron microscopy (SEM), permeability and mechanical properties. The prepared CMC/GQD nanocomposite hydrogel films showed an improvement in vitro swelling, degradation, water vapor permeability and pH-sensitive drug delivery properties along with not significant toxicity against blood cancer cells (K562). According to the obtained results, this nanocomposite hydrogel films can be proposed to use as an anticancer film and drug delivery system. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of potassium sorbate on antimicrobial and physical properties of starch-clay nanocomposite films.

PubMed

Barzegar, Hassan; Azizi, Mohammad Hossein; Barzegar, Mohsen; Hamidi-Esfahani, Zohreh

2014-09-22

Using fresh foods which undergo the least processing operations developed widely in recent years. Active packaging is a novel method for preserving these products. Active starch-clay nanocomposite films which contained potassium sorbate (PS) at a level of 0, 5, 7.5 and 10 g PS/100 g starch were produced and their physical, mechanical and antimicrobial properties were evaluated. In order to evaluate antimicrobial properties of films Aspergillus niger was used. The results showed that 5% of the PS did not produce antimicrobial property in the film, but by increasing the content of the additive in film formulation, antimicrobial effect increased. PS increased water permeability and elongation at break of the films, but decreased tensile strength. The rate of PS migration into the semi-solid medium in starch-nanocomposites was lower than starch films. This shows that nanocomposite films could retain their antimicrobial property for longer time. Copyright © 2014 Elsevier Ltd. All rights reserved.

Development of polylactic acid nanocomposite films reinforced with cellulose nanocrystals derived from coffee silverskin.

PubMed

Sung, Soo Hyun; Chang, Yoonjee; Han, Jaejoon

2017-08-01

Bio-nanocomposite films based on polylactic acid (PLA) matrix reinforced with cellulose nanocrystals (CNCs) were developed using a twin-screw extruder. The CNCs were extracted from coffee silverskin (CS), which is a by-product of the coffee roasting process. They were extracted by alkali treatment followed by sulfuric acid hydrolysis. They were used as reinforcing agents to obtain PLA/CNC nanocomposites by addition at different concentrations (1%, 3%, and 5% CNCs). Morphological, tensile, and barrier properties of the bio-nanocomposites were analyzed. The tensile strength and Young's modulus increased with both 1% and 3% CNCs. The water vapor permeability decreased gradually with increasing addition of CNCs up to 3% and good oxygen barrier properties were found for all nanocomposites. These results suggest that CNCs from CS can improve the physical properties of PLA-based biopolymer film. The developed PLA/CNC bio-nanocomposite films can potentially be used for biopolymer materials with enhanced barrier and mechanical properties. Copyright © 2017 Elsevier Ltd. All rights reserved.

Work function measurements of copper nanoparticle intercalated polyaniline nanocomposite thin films

NASA Astrophysics Data System (ADS)

Patil, U. V.; Ramgir, Niranjan S.; Bhogale, A.; Debnath, A. K.; Muthe, K. P.; Gadkari, S. C.; Kothari, D. C.

2017-05-01

The nature of contact between the electrode and the sensing material plays a crucial role in governing the sensing mechanism. Thin films of polyaniline (PANI) and copper-polyaniline nanocomposite (NC) have been deposited at room temperatures by in-situ oxidative polymerization of aniline in the presence of Cu nanoparticles. For sensing applications a thin film Au (gold) ˜100 nm is deposited and used as a conducting electrode. To understand the nature of contact (i.e., ohmic or Schottky) the work function of the conducting polyaniline and nanocomposite films were measured using Kelvin Probe method. I-V characteristics of PANI and NC films investigated at room temperatures further corroborates and confirms the formation of Ohmic contact as evident from work function measurements.

Preparation of Electrically Conductive Polystyrene/Carbon Nanofiber Nanocomposite Films

ERIC Educational Resources Information Center

Sun, Luyi; O'Reilly, Jonathan Y.; Tien, Chi-Wei; Sue, Hung-Jue

2008-01-01

A simple and effective approach to prepare conductive polystyrene/carbon nanofiber (PS/CNF) nanocomposite films via a solution dispersion method is presented. Inexpensive CNF, which has a structure similar to multi-walled carbon nanotubes, is chosen as a nanofiller in this experiment to achieve conductivity in PS films. A good dispersion is…

Understanding physicochemical properties changes from multi-scale structures of starch/CNT nanocomposite films.

PubMed

Liu, Siyuan; Li, Xiaoxi; Chen, Ling; Li, Lin; Li, Bing; Zhu, Jie

2017-11-01

From the view of multi-scale structures of hydroxypropyl starch (HPS)/carbon nanotube (CNT) nanocomposite films, the film physicochemical properties were affected by comprehensive factors including molecular interaction, short range molecular conformation, crystalline structure and aggregated structure. The less original HPS hydrogen bonding that was broken, less decreased order of HPS short range molecular conformation, lower film crystallinity and larger size of micro-ordered regions contributed to higher tensile strength and Young's modulus of the film with CNT content of 0.5% (g/g, CNT in HPS). The higher film overall crystallinity and larger size of micro-ordered regions of the film with CNT content of 0.05%-0.3% compared with those of control contributed to better film barrier property. The addition of CNT with the content of 0.05%-0.5% broke the original HPS hydrogen bonding and decreased the order of starch short range molecular conformation, which counteracted the positive effect of CNT on the thermal stability of the material, thus thermal degradation temperature of these nanocomposite films did not increase. But the sharp increase of film crystallinity increased film thermal degradation temperature. This study provided a better understanding of film physicochemical properties changes which guides to rational design of starch-based nanocomposite films for packaging and coating application. Copyright © 2017. Published by Elsevier B.V.

Natural biopolymer-based nanocomposite films for packaging applications.

PubMed

Rhim, Jong-Whan; Ng, Perry K W

2007-01-01

Concerns on environmental waste problems caused by non-biodegradable petrochemical-based plastic packaging materials as well as the consumer's demand for high quality food products has caused an increasing interest in developing biodegradable packaging materials using annually renewable natural biopolymers such as polysaccharides and proteins. Inherent shortcomings of natural polymer-based packaging materials such as low mechanical properties and low water resistance can be recovered by applying a nanocomposite technology. Polymer nanocomposites, especially natural biopolymer-layered silicate nanocomposites, exhibit markedly improved packaging properties due to their nanometer size dispersion. These improvements include increased modulus and strength, decreased gas permeability, and increased water resistance. Additionally, biologically active ingredients can be added to impart the desired functional properties to the resulting packaging materials. Consequently, natural biopolymer-based nanocomposite packaging materials with bio-functional properties have a huge potential for application in the active food packaging industry. In this review, recent advances in the preparation of natural biopolymer-based films and their nanocomposites, and their potential use in packaging applications are addressed.

ZnO-PVA nanocomposite films for low threshold optical limiting applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Viswanath, Varsha; Beenakumari, C.; Muneera, C. I.

Zinc oxide-PVA nanocomposite films were fabricated adopting a simple method based on solution-casting, incorporating small weight percentages (<1.2 wt%) of ZnO in PVA (∼0.625×10{sup −3}M to 7×10{sup −3}M), and their structure, morphology, linear and low threshold nonlinear optical properties were investigated. The films were characterized as nanostructured ZnO encapsulated between the molecules/chains of the semicrystalline host polymer PVA. The samples exhibited low threshold nonlinear absorption and negative nonlinear refraction, as studied using the Z-scan technique. A switchover from SA to RSA was observed as the concentration of ZnO was increased. The optical limiting of 632.8 nm CW laser light displayedmore » by these nanocomposite films is also demonstrated. The estimated values of the effective coefficients of nonlinear absorption, nonlinear refraction and third-order nonlinear susceptibility, |χ{sup (3)}|, compared to those reported for continuous wave laser light excitation, measure up to the highest among them. The results show that the ZnO-PVA nanocomposite films have great potential applications in future optical and photonic devices.« less

Thermally stimulated nonlinear refraction in gelatin stabilized Cu-PVP nanocomposite thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tamgadge, Y. S., E-mail: ystamgadge@gmail.com; Atkare, D. V.; Pahurkar, V. G.

2016-05-06

This article illustrates investigations on thermally stimulated third order nonlinear refraction of Cu-PVP nanocomposite thin films. Cu nanoparticles have been synthesized using chemical reduction method and thin films in PVP matrix have been obtained using spin coating technique. Thin films have been characterized by X-ray diffraction (XRD) and Ultraviolet-visible (UV-vis) spectroscopyfor structural and linear optical studies. Third order nonlinear refraction studies have been performed using closed aperture z-scan technique under continuous wave (CW) He-Ne laser. Cu-PVP nanocomposites are found to exhibit strong nonlinear refractive index stimulated by thermal lensing effect.

Non-conductive ferromagnetic carbon-coated (Co, Ni) metal/polystyrene nanocomposites films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takacs, H., E-mail: helene.takacs@gmail.com; LTM-CNRS-UJF, CEA, LETI, Minatec Campus, Grenoble 38054; Viala, B.

2016-03-07

This article reports non-conductive ferromagnetic properties of metal/polymer nanocomposite films intended to be used for RF applications. The nanocomposite arrangement is unique showing a core double-shell structure of metal-carbon-polystyrene: M/C//P{sub 1}/P{sub 2}, where M = Co, Ni is the core material, C = graphene or carbon is the first shell acting as a protective layer against oxidation, P{sub 1} = pyrene-terminated polystyrene is the second shell for electrical insulation, and P{sub 2} = polystyrene is a supporting matrix (// indicates actual grafting). The nanocomposite formulation is briefly described, and the film deposition by spin-coating is detailed. Original spin-curves are reported and analyzed. One key outcome is the achievementmore » of uniform and cohesive films at the wafer scale. Structural properties of films are thoroughly detailed, and weight and volume fractions of M/C are considered. Then, a comprehensive overview of DC magnetic and electrical properties is reported. A discussion follows on the magnetic softness of the nanocomposites vs. that of a single particle (theoretical) and the raw powder (experimental). Finally, unprecedented achievement of high magnetization (∼0.6 T) and ultra-high resistivity (∼10{sup 10 }μΩ cm) is shown. High magnetization comes from the preservation of the existing protective shell C, with no significant degradation on the particle net-moment, and high electrical insulation is ensured by adequate grafting of the secondary shell P{sub 1}. To conclude, the metal/polymer nanocomposites are situated in the landscape of soft ferromagnetic materials for RF applications (i.e., inductors and antennas), by means of two phase-diagrams, where they play a crucial role.« less

Switchable 3-0 magnetoelectric nanocomposite thin film with high coupling.

PubMed

McDannald, Austin; Ye, Linghan; Cantoni, Claudia; Gollapudi, Sreenivasulu; Srinivasan, Gopalan; Huey, Bryan D; Jain, Menka

2017-03-02

A mixed precursor solution method was used to deposit 3-0 nanocomposite thin films of PbZr 0.52 Ti 0.48 O 3 (PZT) and CoFe 2 O 4 (CFO). The piezoelectric behavior of PZT and magnetostrictive behavior of CFO allow for magnetoelectric (ME) coupling through strain transfer between the respective phases. High ME coupling is desired for many applications including memory devices, magnetic field sensors, and energy harvesters. The spontaneous phase separation in the 3-0 nanocomposite film was observed, with 25 nm CFO particle or nanophases distributed in discrete layers through the thickness of the PZT matrix. Magnetic-force microscopy images of the nanocomposite thin film under opposite magnetic poling conditions revealed in-plane pancake-like regions of higher concentration of the CFO nanoparticles. The constraints on the size and distribution of the CFO nanoparticles created a unique distribution in a PZT matrix and achieved values of ME coupling of 3.07 V cm -1 Oe -1 at a DC bias of 250 Oe and 1 kHz, increasing up to 25.0 V cm -1 Oe -1 at 90 kHz. Piezo-force microscopy was used to investigate the ferroelectric domain structure before and after opposite magnetic poling directions. It was found that in this nanocomposite, the polarization of the ferroelectric domains switched direction as a result of switching the direction of the magnetization by magnetic fields.

NIR-Vis-UV Light-Responsive Actuator Films of Polymer-Dispersed Liquid Crystal/Graphene Oxide Nanocomposites.

PubMed

Cheng, Zhangxiang; Wang, Tianjie; Li, Xiao; Zhang, Yihe; Yu, Haifeng

2015-12-16

To take full advantage of sunlight for photomechanical materials, NIR-vis-UV light-responsive actuator films of polymer-dispersed liquid crystal (PDLC)/graphene oxide (GO) nanocomposites were fabricated. The strategy is based on phase transition of LCs from nematic to isotropic phase induced by combination of photochemical and photothermal processes in the PDLC/GO nanocomposites. Upon mechanical stretching of the film, both topological shape change and mesogenic alignment occurred in the separated LC domains, enabling the film to respond to NIR-vis-UV light. The homodispersed GO flakes act as photoabsorbent and nanoscale heat source to transfer NIR or VIS light into thermal energy, heating the film and photothermally inducing phase transition of LC microdomains. By utilizing photochemical phase transition of LCs upon UV-light irradiation, one azobenzene dye was incorporated into the LC domains, endowing the nanocomposite films with UV-responsive property. Moreover, the light-responsive behaviors can be well-controlled by adjusting the elongation ratio upon mechanical treatment. The NIR-vis-UV light-responsive PDLC/GO nanocomposite films exhibit excellent properties of easy fabrication, low-cost, and good film-forming and mechanical features, promising their numerous applications in the field of soft actuators and optomechanical systems driven directly by sunlight.

Synthesis and characterization of CdS/PVA nanocomposite films

NASA Astrophysics Data System (ADS)

Wang, Hongmei; Fang, Pengfei; Chen, Zhe; Wang, Shaojie

2007-08-01

A series CdS/PVA nanocomposite films with different amount of Cd salt have been prepared by means of the in situ synthesis method via the reaction of Cd 2+-dispersed poly vinyl-alcohol (PVA) with H 2S. The as-prepared films were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) absorption, photoluminescence (PL) spectra, Fourier transform infrared spectroscope (FTIR) and thermogravimetric analysis (TGA). The XRD results indicated the formation of CdS nanoparticles with hexagonal phase in the PVA matrix. The primary FTIR spectra of CdS/PVA nanocomposite in different processing stages have been discussed. The vibrational absorption peak of Cd sbnd S bond at 405 cm -1 was observed, which further testified the generation of CdS nanoparticles. The TGA results showed incorporation of CdS nanoparticles significantly altered the thermal properties of PVA matrix. The photoluminescence and UV-vis spectroscopy revealed that the CdS/PVA films showed quantum confinement effect.

Achieving 3-D Nanoparticle Assembly in Nanocomposite Thin Films via Kinetic Control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Jingyu; Xiao, Yihan; Xu, Ting

Nanocomposite thin films containing well-ordered nanoparticle (NP) assemblies are ideal candidates for the fabrication of metamaterials. Achieving 3-D assembly of NPs in nanocomposite thin films is thermodynamically challenging as the particle size gets similar to that of a single polymer chain. The entropic penalties of polymeric matrix upon NP incorporation leads to NP aggregation on the film surface or within the defects in the film. Controlling the kinetic pathways of assembly process provides an alternative path forward by arresting the system in nonequilibrium states. Here, we report the thin film 3-D hierarchical assembly of 20 nm NPs in supramolecules withmore » a 30 nm periodicity. By mediating the NP diffusion kinetics in the supramolecular matrix, surface aggregation of NPs was suppressed and NPs coassemble with supramolecules to form new 3-D morphologies in thin films. Lastly, the present studies opened a viable route to achieve designer functional composite thin films via kinetic control.« less

Achieving 3-D Nanoparticle Assembly in Nanocomposite Thin Films via Kinetic Control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Jingyu; Xiao, Yihan; Xu, Ting

Nanocomposite thin films containing well-ordered nanoparticle (NP) assemblies are ideal candidates for the fabrication of metamaterials. Achieving 3-D assembly of NPs in nanocomposite thin films is thermodynamically challenging as the particle size gets similar to that of a single polymer chain. The entropic penalties of polymeric matrix upon NP incorporation leads to NP aggregation on the film surface or within the defects in the film. Controlling the kinetic pathways of assembly process provides an alternative path forward by arresting the system in nonequilibrium states. Here, we report the thin film 3-D hierarchical assembly of 20 nm NPs in supramolecules withmore » a 30 nm periodicity. By mediating the NP diffusion kinetics in the supramolecular matrix, surface aggregation of NPs was suppressed and NPs coassemble with supramolecules to form new 3-D morphologies in thin films. The present studies opened a viable route to achieve designer functional composite thin films via kinetic control.« less

Achieving 3-D Nanoparticle Assembly in Nanocomposite Thin Films via Kinetic Control

DOE PAGES

Huang, Jingyu; Xiao, Yihan; Xu, Ting

2017-02-20

Nanocomposite thin films containing well-ordered nanoparticle (NP) assemblies are ideal candidates for the fabrication of metamaterials. Achieving 3-D assembly of NPs in nanocomposite thin films is thermodynamically challenging as the particle size gets similar to that of a single polymer chain. The entropic penalties of polymeric matrix upon NP incorporation leads to NP aggregation on the film surface or within the defects in the film. Controlling the kinetic pathways of assembly process provides an alternative path forward by arresting the system in nonequilibrium states. Here, we report the thin film 3-D hierarchical assembly of 20 nm NPs in supramolecules withmore » a 30 nm periodicity. By mediating the NP diffusion kinetics in the supramolecular matrix, surface aggregation of NPs was suppressed and NPs coassemble with supramolecules to form new 3-D morphologies in thin films. Lastly, the present studies opened a viable route to achieve designer functional composite thin films via kinetic control.« less

Preparation and characterization of nanocrystalline cellulose/Eucommia ulmoides gum nanocomposite film.

PubMed

Sun, Qianqian; Zhao, Xinkun; Wang, Dongmei; Dong, Juane; She, Diao; Peng, Pai

2018-02-01

The nanocomposite films were prepared using Eucommia ulmoides gum (EUG) matrix reinforced with nanocrystalline cellulose (NCC) at different concentrations. Subsequently, the obtained films were characterized by Raman spectra, AFM, XRD, TGA, and DSC. Meanwhile, the wettability, mechanical, and water vapor barrier properties of these films were analyzed. AFM noticed that the average sizes of NCC were 81.95×50.17×13.06nm, while the size of molecular chain for EUG was 2530×57.33×1.28nm. In comparison with control film, a certain amount of NCC obviously improved elongation at break and enhanced their crystallinity and ΔH m . More importantly, NCC/EUG nanocomposite films presented lower thermal stability, glass transition temperature (T g ), melting temperature (T m ), and water vapor permeability (WVP) values, especially the WVP values of 4% NCC film were the lowest as 0.28×10 -9 , 0.30×10 -9 , and 0.58×10 -9 g/m/h/Pa at RH 34%, 55%, and 76%, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Properties of solid solutions, doped film, and nanocomposite structures based on zinc oxide

NASA Astrophysics Data System (ADS)

Lashkarev, G. V.; Shtepliuk, I. I.; Ievtushenko, A. I.; Khyzhun, O. Y.; Kartuzov, V. V.; Ovsiannikova, L. I.; Karpyna, V. A.; Myroniuk, D. V.; Khomyak, V. V.; Tkach, V. N.; Timofeeva, I. I.; Popovich, V. I.; Dranchuk, N. V.; Khranovskyy, V. D.; Demydiuk, P. V.

2015-02-01

A study of the properties of materials based on the wide bandgap zinc oxide semiconductor, which are promising for application in optoelectronics, photovoltaics and nanoplasmonics. The structural and optical properties of solid solution Zn1-xCdxO films with different cadmium content, are studied. The samples are grown using magnetron sputtering on sapphire backing. Low-temperature photoluminescence spectra revealed emission peaks associated with radiative recombination processes in those areas of the film that have varying amounts of cadmium. X-ray phase analysis showed the presence of a cadmium oxide cubic phase in these films. Theoretical studies of the solid solution thermodynamic properties allowed for a qualitative interpretation of the observed experimental phenomena. It is established that the growth of the homogeneous solid solution film is possible only at high temperatures, whereas regions of inhomogeneous composition can be narrowed through elastic deformation, caused by the mismatch of the film-backing lattice constants. The driving forces of the spinodal decomposition of the Zn1-xCdxO system are identified. Fullerene-like clusters of Znn-xCdxOn are used to calculate the bandgap and the cohesive energy of ZnCdO solid solutions. The properties of transparent conductive ZnO films, doped with Group III donor impurities (Al, Ga, In), are examined. It is shown that oxygen vacancies are responsible for the hole trap centers in the zinc oxide photoconductivity process. We also examine the photoluminescence properties of metal-ZnO nanocomposite structures, caused by surface plasmons.

Silver/poly(vinyl alcohol) nanocomposite film prepared using water in oil microemulsion for antibacterial applications.

PubMed

Fatema, Ummul K; Rahman, M Muhibur; Islam, M Rakibul; Mollah, M Yousuf A; Susan, Md Abu Bin Hasan

2018-03-15

Water in oil microemulsion (w/o) is a simple preparative route for nanoparticles where water droplets (dispersed in continuous oil medium and stabilized by surfactants and cosurfactants) act as nanoreactors to carry out chemical reactions. If polymeric matrix is incorporated inside the core of the microemulsions, it should prevent the agglomeration of nanoparticles after separation from microemulsions. Thus polymer nanocomposite films prepared from w/o microemulsions are expected to give narrow and homogeneous size distribution of nanoparticles throughout the polymer host. Silver/poly(vinyl alcohol) (Ag/PVA) nanocomposite film was successfully prepared, for the first time, using Triton X-100 (TX-100)/1-butanol/cyclohexane/water microemulsion. Reduction of the metal salt was carried out in the core of w/o microemulsion droplets containing PVA polymeric matrix. After separation from the microemulsion, Ag/PVA nanocomposite film was then prepared by solution casting method. The antibacterial activity of the nanocomposites was tested against Gram-negative, Escherichia coli and Gram-positive, Staphylococcus aureus by agar diffusion method. Ag nanoparticles with an average diameter of 105 nm could be synthesized using PVA, whereas in the absence of PVA the nanoparticles agglomerated. The distribution of Ag nanoparticles on PVA surface of the nanocomposite film prepared using microemulsion was uniform, whereas the film prepared through in situ generation of Ag nanoparticles by chemical reduction process on PVA host showed non-uniform, coagulated, bunches of Ag nanoparticles. The film synthesized using microemulsion exhibited enhanced antibacterial efficacy compared to that prepared through in situ synthesis under the same test condition. Copyright © 2017 Elsevier Inc. All rights reserved.

Preparation and characteristics of TFMB functionalized graphene oxide/polyimide nanocomposite films

NASA Astrophysics Data System (ADS)

Liu, Lin; Wang, Yiyao; Gao, Yixin

2018-04-01

Polyimide(PI), with its great thermal and mechanical properties, has been widely used in various fields, such as aerospace and microelectronics. However, with the development of high technology, common PI materials can not satisfy the demands, due to its high resistance. In this work, we used 2,2'- Bis(trifluoromethyl) benzidine(TFMB) to functionalize GO and further form GO-TFMB/PI nanocomposite film. In the end, we got GO-TFMB/PI nanocomposite films with excellent thermal stability, better toughness and better electrical conductivity. As shown in results, the incorporation of GO-TFMB maintained excellent thermal stability. With the addition of GO-TFMB, the resistivity of the composite film decreased continuously. And when the content of GO-TFMB was 0.8 wt%, the resistivity could achieve the excellent antistatic material standard.

Nanoscale deformation mechanism of TiC/a-C nanocomposite thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, C. Q.; Pei, Y. T.; Shaha, K. P.

2009-06-01

This paper concentrates on the deformation behavior of amorphous diamondlike carbon composite materials. Combined nanoindentation and ex situ cross-sectional transmission electron microscopy investigations are carried out on TiC/a-C nanocomposite films, with and without multilayered structures deposited by pulse dc magnetron sputtering. It is shown that by controlling the distribution of nanocrystallites forming nanoscale multilayers, the system can be used as a 'microstructural ruler' that is able to distinguish various deformation patterns, which can be hardly detected otherwise in a homogeneous structure. It is shown that rearrangement of nanocrystallites and displacement of a-C matrix occur at length scales from tens ofmore » nanometer down to 1 nm. At submicrometer scale homogeneous nucleation of multiple shear bands has been observed within the nanocomposites. The multilayered structure in the TiC/a-C nanocomposite film contributes to an enhanced toughness.« less

Investigation of Zinc Oxide-Loaded Poly(Vinyl Alcohol) Nanocomposite Films in Tailoring Their Structural, Optical and Mechanical Properties

NASA Astrophysics Data System (ADS)

Aslam, Muhammad; Kalyar, Mazhar Ali; Raza, Zulfiqar Ali

2018-04-01

Wurtzite ZnO nanoparticles, as a nanofiller, were incorporated in a poly(vinyl alcohol) (PVA) matrix to prepare multipurpose nanocomposite films using a solution casting approach. Some advanced analytical techniques were used to investigate the properties of prepared nanocomposite films. The mediation of ZnO nanofillers resulted in modification of structural, optical and mechanical properties of nanocomposite films. A comprehensive band structure investigation might be useful for designing technological applications like in optoelectronic devices. The experimental results were found to be closely dependent on the nanofiller contents. Some theoretical models like Tauc's and Wemple-DiDomenico, were employed to investigate the band structure parameters. The imaginary part of the dielectric constant was used to investigate the band gap. Then, the Helpin-Tsai model was employed to predict Young's moduli of the prepared nanocomposite films. On 3 wt.% ZnO nanofiller loading, the optical band gap of the PVA-based nanocomposite film was decreased from 5.26 eV to 3 eV, the tensile strength increased from 25.3 MPa to 48 MPa and Young's modulus increased from 144 MPa to 544 MPa.

Investigation of Zinc Oxide-Loaded Poly(Vinyl Alcohol) Nanocomposite Films in Tailoring Their Structural, Optical and Mechanical Properties

NASA Astrophysics Data System (ADS)

Aslam, Muhammad; Kalyar, Mazhar Ali; Raza, Zulfiqar Ali

2018-07-01

Wurtzite ZnO nanoparticles, as a nanofiller, were incorporated in a poly(vinyl alcohol) (PVA) matrix to prepare multipurpose nanocomposite films using a solution casting approach. Some advanced analytical techniques were used to investigate the properties of prepared nanocomposite films. The mediation of ZnO nanofillers resulted in modification of structural, optical and mechanical properties of nanocomposite films. A comprehensive band structure investigation might be useful for designing technological applications like in optoelectronic devices. The experimental results were found to be closely dependent on the nanofiller contents. Some theoretical models like Tauc's and Wemple-DiDomenico, were employed to investigate the band structure parameters. The imaginary part of the dielectric constant was used to investigate the band gap. Then, the Helpin-Tsai model was employed to predict Young's moduli of the prepared nanocomposite films. On 3 wt.% ZnO nanofiller loading, the optical band gap of the PVA-based nanocomposite film was decreased from 5.26 eV to 3 eV, the tensile strength increased from 25.3 MPa to 48 MPa and Young's modulus increased from 144 MPa to 544 MPa.

Optical, mechanical and structural properties of PMMA/SiO2 nanocomposite thin films

NASA Astrophysics Data System (ADS)

Soni, Gyanesh; Srivastava, Subodh; Soni, Purushottam; Kalotra, Pankaj; Vijay, Y. K.

2018-01-01

We have fabricated PMMA/SiO2 nanocomposite flexible thin films of 60 μm thicknesses by using solution casting method in the presence of transverse electric field. In this paper, we have investigated the effect of SiO2 nanoparticle (NP) loading on optical and mechanical properties of the composite thin film. The SEM images show that nanocomposite thin films have a smoother and uniform morphology. The transmittance peak near 1103 cm-1 in FT-IR spectrum confirms the presence of SiO2 NPs in the composite thin film. It is observed that optical bandgap decreases with an increase in the SiO2 NP concentration. Dynamic mechanical analysis shows that presence of SiO2 NP enhances the mechanical strength of the composite thin film.

Preparation and characterization of gamma irradiated Starch/PVA/ZnO nanocomposite films

NASA Astrophysics Data System (ADS)

Akhavan, Azam; Khoylou, Farah; Ataeivarjovi, Ebrahim

2017-09-01

In this study starch/PVA/ZnO nanocomposite films with antibacterial activity were prepared and modified using gamma irradiation for packaging applications. ZnO nanoparticles (NPs) were synthesized from Zn(OH)2 using hydrothermal process and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The prepared ZnO NPs were incorporated into blend films of starch and poly (vinyl alcohol) (PVA) with different concentrations from 0.1 to 1 wt% using solution casting method. The results of SEM confirmed good dispersion of ZnO NPs into the films while FTIR spectroscopy showed interactions between ZnO particles and starch/PVA blend. The nanocomposite films were irradiated at the dose range of 1-5 kGy. It was found that gamma irradiation induces a significant reduction in water absorptions of the films at the dose of 3 kGy. Different trends were observed for the tensile and elongation properties of the irradiated films. Based on the results, the bacterial growth on the films was effectively inhibited when the dosage of ZnO NPs was only 0.5 wt%.

Evaporation-induced self-assembly of quantum dots-based concentric rings on polymer-based nanocomposite films.

PubMed

Zhang, Shaofu; Luan, Weiling; Zhong, Qixin; Yin, Shaofeng; Yang, Fuqian

2016-10-12

The "ball-on-film" template is used to construct concentric rings on the surface of PMMA-QDs (polymethyl methacrylate - quantum dots) nanocomposite films via the evaporation of pure chloroform droplets, which are confined by a steel ball. The concentric rings consist of QDs, as revealed by the fluorescence images of the concentric rings. The photoluminescence intensity of the concentric rings increases with the increase of the distance to the ball center, suggesting that the amount of QDs accumulated around the contact line at individual stick state increases with the increase of the distance to the ball center. Both the wavelength and cross-sectional area (width) of the concentric rings increase approximately linearly with increasing distance to the ball center, independent of the ball size, the film thickness and the QDs concentration. For the PMMA-QDs nanocomposite films prepared from the same QDs concentration in chloroform, the thicker the PMMA-QDs nanocomposite film, the larger the wavelength for the same distance to the ball center. The effect of confinement of two steel balls on the surface patterns over the PMMA-QDs nanocomposite films is studied via a template of "two spheres on film". Symmetric surface patterns are formed. There exist two types of featureless zone between the two balls, depending on the distance between the two balls: one is the inner featureless zone and the other is the outer featureless zone. The size of both featureless zones increases with the increase of the ball distance.

Stretchable Electronic Sensors of Nanocomposite Network Films for Ultrasensitive Chemical Vapor Sensing.

PubMed

Yan, Hong; Zhong, Mengjuan; Lv, Ze; Wan, Pengbo

2017-11-01

A stretchable, transparent, and body-attachable chemical sensor is assembled from the stretchable nanocomposite network film for ultrasensitive chemical vapor sensing. The stretchable nanocomposite network film is fabricated by in situ preparation of polyaniline/MoS 2 (PANI/MoS 2 ) nanocomposite in MoS 2 suspension and simultaneously nanocomposite deposition onto prestrain elastomeric polydimethylsiloxane substrate. The assembled stretchable electronic sensor demonstrates ultrasensitive sensing performance as low as 50 ppb, robust sensing stability, and reliable stretchability for high-performance chemical vapor sensing. The ultrasensitive sensing performance of the stretchable electronic sensors could be ascribed to the synergistic sensing advantages of MoS 2 and PANI, higher specific surface area, the reliable sensing channels of interconnected network, and the effectively exposed sensing materials. It is expected to hold great promise for assembling various flexible stretchable chemical vapor sensors with ultrasensitive sensing performance, superior sensing stability, reliable stretchability, and robust portability to be potentially integrated into wearable electronics for real-time monitoring of environment safety and human healthcare. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Biopolymer-based nanocomposites: effect of lignin acetylation in cellulose triacetate films

PubMed Central

Nevárez, Laura Alicia Manjarrez; Casarrubias, Lourdes Ballinas; Celzard, Alain; Fierro, Vanessa; Muñoz, Vinicio Torres; Davila, Alejandro Camacho; Lubian, José Román Torres; Sánchez, Guillermo González

2011-01-01

We have prepared all-biopolymer nanocomposite films using lignin as a filler and cellulose triacetate (CTA) as a polymer matrix, and characterized them by several analytical methods. Three types of lignin were tested: organosolv, hydrolytic and kraft, with or without acetylation. They were used in the form of nanoparticles incorporated at 1 wt% in CTA. Self-supported films were prepared by vapor-induced phase separation at controlled temperature (35–55 °C) and relative humidity (10–70%). The efficiency of acetylation of each type of lignin was studied and discussed, as well as its effects on film structure, homogeneity and mechanical properties. The obtained results are explained in terms of intermolecular filler-matrix interaction at the nanometer scale, for which the highest mechanical resistance was reached using hydrolytic lignin in the nanocomposite. PMID:27877425

Mechanical and solubility properties of bio-nanocomposite film of semi refined kappa carrageenan/ZnO nanoparticles

NASA Astrophysics Data System (ADS)

Saputri, Apriliana Eka; Praseptiangga, Danar; Rochima, Emma; Panatarani, Camellia; Joni, I. Made

2018-02-01

The aim of this present work is to develop semi refined kappa carrageenan based bio-nanocomposite film as an alternative to synthetic petroleum based food packaging materials. Among natural polymers, carrageenan is one of the most promising material, since it is a renewable bioresource. The ZnO nanoparticles (0.5%; 1.0%; 1.5% w/w carrageenan) was incorporated into carrageenan polymer to prepare bio-nanocomposite films, where ZnO acts as reinforcement for carrageenan matrix. The mechanical and solubility properties of the prepared films were investigated as a function of ZnO concentration. The results indicated that the addition of ZnO exhibits greater solubility compared to the neat film. The elongation at break is insignificantly different on the films with and without addition ZnO. The tensile strength of the film was highest for the sample with 0.5% ZnO. These mechanical and solubility properties suggest that bio-nanocomposite film of semi refined kappa carrageenan and nanoparticle ZnO can be effectively used as food packaging material.

Optical studies of CdSe/PVA nanocomposite films

NASA Astrophysics Data System (ADS)

Kushwaha, Kamal Kumar; Ramrakhaini, Meera

2018-05-01

The nanocomposite films of CdSe nanocrystals in polyvinyl alcohol (PVA) matrix were synthesized by environmental friendly chemical method. These composites were characterized by X-ray diffraction which indicates the hexagonal crystalline structure of CdSe with crystal size up to a few nm. The crystal size is found to decrease by increasing PVA Concentration. The photoluminescence (PL) characteristics of these composite films with varying concentration of PVA as well as Cd2+ content have been investigated. The PL peak of CdSe was observed at 510 nm and higher intensity is observed by increasing PVA concentration without any change in position of PL peak. Due to proper passivation of surface states non-radiative transition are reduced which enhance the PL intensity. By increasing concentration of Cd2+ content in the CdSe/PVA nanocomposite films, smaller CdSe nanocrystals were obtained giving higher intensity and blue shift in the PL peak due to enhanced oscillator strength and quantum confinement effect. The PL peak in green and blue region makes these composite films promising materials for optical display devices. The Refractive index of these composites was also measured at sodium line with the help of Abee's refractometer and was found in the range of 2.20-2.45. It is seen that refractive index varies with polymer concentration. This may be useful for their potential application in anti-reflection coating, display devices and optical sensors.

Rheological and thermal properties of polylactide/silicate nanocomposites films.

PubMed

Ahmed, Jasim; Varshney, Sunil K; Auras, Rafeal

2010-03-01

Polylactide (DL)/polyethylene glycol/silicate nanocomposite blended biodegradable films have been prepared by solvent casting method. Rheological and thermal properties were investigated for both neat amorphous polylactide (PLA-DL form) and blend of montmorillonite (clay) and poly (ethylene glycol) (PEG). Melt rheology of the PLA individually and blends (PLA/clay; PLA/PEG; PLA/PEG/clay) were performed by small amplitude oscillation shear (SAOS) measurement. Individually, PLA showed an improvement in the viscoelastic properties in the temperature range from 180 to 190 degrees C. Incorporation of nanoclay (3% to 9% wt) was attributed by significant improvements in the elastic modulus (G') of PLA/clay blend due to intercalation at higher temperature. Both dynamic modulii of PLA/PEG blend were significantly reduced with addition of 10% PEG. Rheometric measurement could not be conducted while PLA/PEG blends containing 25% PEG. A blend of PLA/PEG/clay (68/23/9) showed liquid-like properties with excellent flexibility. Thermal analysis of different clay loading films indicated that the glass transition temperatures (T(g)) remained unaffected irrespective of clay concentration due to immobilization of polymer chain in the clay nanocomposite. PEG incorporation reduced the T(g) of the blend (PLA/PEG and PLA/PEG/clay) significantly. Both rheological and thermal analysis data supported plasticization and flexibility of the blended films. It is also interesting to study competition between PLA and PEG for the intercalation into the interlayer spacing of the clay. This study indicates that PLA/montmorillonite blend could serve as effective nano-composite for packaging and other applications.

Development of an antimicrobial material based on a nanocomposite cellulose acetate film for active food packaging.

PubMed

Rodríguez, Francisco J; Torres, Alejandra; Peñaloza, Ángela; Sepúlveda, Hugo; Galotto, María J; Guarda, Abel; Bruna, Julio

2014-01-01

Nanocomposites based on biopolymers have been recognised as potential materials for the development of new ecofriendly food packaging. In addition, if these materials incorporate active substances in their structure, the potential applications are much higher. Therefore, this work was oriented to develop nanocomposites with antimicrobial activity based on cellulose acetate (CA), a commercial organoclay Cloisite30B (C30B), thymol (T) as natural antimicrobial component and tri-ethyl citrate (TEC) as plasticiser. Nanocomposites were prepared by a solvent casting method and consisted of 5% (w/w) of C30B, 5% (w/w) of TEC and variable content of T (0%, 0.5% and 2% w/w). To evaluate the effect of C30B into the CA matrix, CA films without this organoclay but with T were also prepared. All nanocomposites showed the intercalation of CA into the organoclay structure; furthermore this intercalation was favoured when 2% (w/w) of T was added to the nanocomposite. In spite of the observed intercalation, the presence of C30B inside the CA matrices increased the opacity of the films significantly. On the other hand, T showed a plasticiser effect on the thermal properties of CA nanocomposites decreasing glass transition, melting temperature and melting enthalpy. The presence of T in CA nanocomposites also allowed the control de Listeria innocua growth when these materials were placed in contact with this Gram-positive bacterium. Interestingly, antimicrobial activity was increased with the presence of C30B. Finally, studies on T release showed that the clay structure inside the CA matrix did not affect its release rate; however, this nanofiller affected the partition coefficient KP/FS which was higher to CA nanocomposites films than in CA films without organoclay. The results obtained in the present study are really promising to be applied in the manufacture of food packaging materials.

Storage stability of banana chips in polypropylene based nanocomposite packaging films.

PubMed

Manikantan, M R; Sharma, Rajiv; Kasturi, R; Varadharaju, N

2014-11-01

In this study, polypropylene (PP) based nanocomposite films of 15 different compositions of nanoclay, compatibilizer and thickness were developed and used for packaging and storage of banana chips. The effect of nanocomposite films on the quality characteristics viz. moisture content (MC), water activity (WA), total color difference(TCD), breaking force (BF), free fatty acid (FFA), peroxide value(PV), total plate count (TPC) and overall acceptability score of banana chips under ambient condition at every 15 days interval were studied for 120 days. All quality parameters of stored banana chips increased whereas overall acceptability scores decreased during storage. The elevation in FFA, BF and TCD of stored banana chips increased with elapse of storage period as well as with increased proportion of both nanoclay and compatibilizer but decreased by reducing the thickness of film. Among all the packaging materials, the WA of banana chips remained lower than 0.60 i.e. critical limit for microbial growth up to 90 days of storage. The PV of banana chips packaged also remained within the safe limit of 25 meq oxygen kg(-1) throughout the storage period. Among all the nanocomposite films, packaging material having 5 % compatibilizer, 2 % nanoclay & 100 μm thickness (treatment E) and 10 % compatibilizer, 4 % nanoclay & 120 μm thickness (treatment N) showed better stability of measured quality characteristics of banana chips than any other treatment.

Investigation on sodium benzoate release from poly(butylene adipate-co-terephthalate)/organoclay/sodium benzoate based nanocomposite film and their antimicrobial activity.

PubMed

Mondal, Dibyendu; Bhowmick, Biplab; Maity, Dipanwita; Mollick, Md Masud R; Rana, Dipak; Rangarajan, Vivek; Sen, Ramkrishna; Chattopadhyay, Dipankar

2015-03-01

Polymeric nanocomposites embedded with nontoxic antimicrobial agents have recently gained potential industrial significance, mainly for their applicability to preserve food quality and ensure safety. In this study, a poly(butylene adipate-co-terephthalate) (PBAT)/organoclay (CMMT) based nanocomposite film doped with sodium benzoate (SB) as antimicrobial agent was prepared by a solution mixing process. A homogenous dispersion of organoclay (cetyltrimethylammonium-modified montmorillonite [CMMT]) in PBAT matrix was observed by X-ray diffraction and transmission electron microscopy. PBAT/CMMT nanocomposite film showed higher barrier properties against water and methanol vapor compared to the PBAT film. The release of SB from PBAT and its nanocomposite film was measured and the relevant data were fitted to the Weibull model. The higher values of Weibull's shape factor and scale parameter as corroborated by experimental findings indicated faster rate of SB release from PBAT/CMMT/SB nanocomposite film, when compared to the pristine PBAT film. Bacterial inhibition studies were accomplished against 2 food pathogenic bacteria, Bacillus subtilis and Staphylococcus aureus, by determining the zone of inhibition and corresponding growth profiles. Both bacterial inhibition studies and growth profiles established that PBAT/CMMT/SB demonstrated better antimicrobial activity than PBAT/SB film. Therefore, PBAT/CMMT/SB nanocomposite film can be used for food packaging application as it showed good barrier properties and antimicrobial activity against food pathogenic bacteria. © 2015 Institute of Food Technologists®

Biodegradation and cytotoxicity of ciprofloxacin-loaded hydroxyapatite-polycaprolactone nanocomposite film for sustainable bone implants.

PubMed

Nithya, Rajendran; Meenakshi Sundaram, Nachiappan

2015-01-01

In recent years there has been a steep increase in the number of orthopedic patients for many reasons. One major reason is osteomyelitis, caused by pyrogenic bacteria, with progressive infection of the bone or bone marrow and surrounding tissues. So antibiotics must be introduced during bone implantation to avoid prolonged infection. The objective of the study reported here was to prepare a composite film of nanocrystalline hydroxyapatite (HAp) and polycaprolactone (PCL) polymer loaded with ciprofloxacin, a frequently used antibiotic agent for bone infections. Nanocrystalline HAp was synthesized by precipitation method using the precursor obtained from eggshell. The nanocomposite film (HAp-PCL-ciprofloxacin) was prepared by solvent evaporation. Drug-release and biodegradation studies were undertaken by immersing the composite film in phosphate-buffered saline solution, while a cytotoxicity test was performed using the fibroblast cell line NIH-3T3 and osteoblast cell line MG-63. The pure PCL film had quite a low dissolution rate after an initial sharp weight loss, whereas the ciprofloxacin-loaded HAp-PCL nanocomposite film had a large weight loss due to its fast drug release. The composite film had higher water absorption than the pure PCL, and increasing the concentration of the HAp increased the water absorption. The in vitro cell-line study showed a good biocompatibility and bioactivity of the developed nanocomposite film. The prepared film will act as a sustainable bone implant in addition to controlled drug delivery.

Resistive switching in ZnO/ZnO:In nanocomposite

NASA Astrophysics Data System (ADS)

Khakhulin, D. A.; Vakulov, Z. E.; Smirnov, V. A.; Tominov, R. V.; Yoon, Jong-Gul; Ageev, O. A.

2017-11-01

A lot of effort nowadays is put into development of new approaches to processing and storage of information in integrated circuits due to limitations in miniaturisation. Our research is dedicated to one of actively developed concepts - oxide based resistive memory devices. A material that draws interest due to its promising technological properties is ZnO but pure ZnO lacks in performance in comparison with some other transition metal oxides. Thus our work is focused on improvement of resistive switching parameters in ZnO films by creation of complex nanocomposites. In this work we report characterisation of a nanocomposite based on PLD grown ZnO films with inclusions of In. Such solution allows us to achieve improvements of main parameters that are critical for ReRAM device: RHRS/RLRS ratio, endurance and retention.

Nanocomposite fibers and film containing polyolefin and surface-modified carbon nanotubes

DOEpatents

Chu,Benjamin; Hsiao, Benjamin S.

2010-01-26

Methods for modifying carbon nanotubes with organic compounds are disclosed. The modified carbon nanotubes have enhanced compatibility with polyolefins. Nanocomposites of the organo-modified carbon nanotubes and polyolefins can be used to produce both fibers and films having enhanced mechanical and electrical properties, especially the elongation-to-break ratio and the toughness of the fibers and/or films.

Spin reorientations in Tb-Fe films grown on polyimide substrates

NASA Astrophysics Data System (ADS)

Maneesh, K. Sai; Arout Chelvane, J.; Talapatra, A.; Basumatary, Himalay; Mohanty, J.; Kamat, S. V.

2018-02-01

This paper reports the effect of film thickness and rapid thermal annealing on the spin reorientations in Tb-Fe films grown on flexible polyimide substrates. Magnetization studies indicated that the spins reorient from in-plane to out-of-plane direction with increase in film thicknesses. This was confirmed by magnetic force microscopy studies which showed weak featureless contrast for films deposited with lower thickness and a strong out-of-plane contrast for films grown with higher thicknesses. On subsequent rapid thermal annealing all the Tb-Fe films exhibited in-plane magnetic anisotropy. The results were explained based on competition between uniaxial and shape anisotropies, nature of residual stresses as well as nucleation of crystalline Fe phase in an amorphous Tb-Fe matrix on rapid thermal annealing.

Hydrothermal Synthesis Au-Bi2Te3 Nanocomposite Thermoelectric Film with a Hierarchical Sub-Micron Antireflection Quasi-Periodic Structure.

PubMed

Tian, Junlong; Zhang, Wang; Zhang, Yuan; Xue, Ruiyang; Wang, Yuhua; Zhang, Zhijian; Zhang, Di

2015-06-03

In this work, Au-Bi(2)Te(3) nanocomposite thermoelectric film with a hierarchical sub-micron antireflection quasi-periodic structure was synthesized via a low-temperature chemical route using Troides helena (Linnaeus) forewing (T_FW) as the biomimetic template. This method combines chemosynthesis with biomimetic techniques, without the requirement of expensive equipment and energy intensive processes. The microstructure and the morphology of the Au-Bi(2)Te(3) nanocomposite thermoelectric film was analyzed by X-ray diffraction (XRD), field-emission scanning-electron microscopy (FESEM), and transmission electron microscopy (TEM). Coupled the plasmon resonances of the Au nanoparticles with the hierarchical sub-micron antireflection quasi-periodic structure, the Au-Bi(2)Te(3) nanocomposite thermoelectric film possesses an effective infrared absorption and infrared photothermal conversion performance. Based on the finite difference time domain method and the Joule effect, the heat generation and the heat source density distribution of the Au-Bi(2)Te(3) nanocomposite thermoelectric film were studied. The heterogeneity of heat source density distribution of the Au-Bi(2)Te(3) nanocomposite thermoelectric film opens up a novel promising technique for generating thermoelectric power under illumination.

Giant room temperature magnetoelectric response in strain controlled nanocomposites

NASA Astrophysics Data System (ADS)

Rafique, Mohsin; Herklotz, Andreas; Dörr, Kathrin; Manzoor, Sadia

2017-05-01

We report giant magnetoelectric coupling at room temperature in a self-assembled nanocomposite of BiFeO3-CoFe2O4 (BFO-CFO) grown on a BaTiO3 (BTO) crystal. The nanocomposite consisting of CFO nanopillars embedded in a BFO matrix exhibits weak perpendicular magnetic anisotropy due to a small out-of-plane compression (˜0.3%) of the magnetostrictive (CFO) phase, enabling magnetization rotation under moderate in-plane compression. Temperature dependent magnetization measurements demonstrate strong magnetoelastic coupling between the BaTiO3 substrate and the nanocomposite film, which has been exploited to produce a large magnetoelectric response in the sample. The reorientation of ferroelectric domains in the BTO crystal upon the application of an electric field (E) alters the strain state of the nanocomposite film, thus enabling control of its magnetic anisotropy. The strain mediated magnetoelectric coupling coefficient α = μ o d M / d E calculated from remnant magnetization at room temperature is 2.6 × 10-7 s m-1 and 1.5 × 10-7 s m-1 for the out-of-plane and in-plane orientations, respectively.

Atomically flat platinum films grown on synthetic mica

NASA Astrophysics Data System (ADS)

Tanaka, Hiroyuki; Taniguchi, Masateru

2018-04-01

Atomically flat platinum thin films were heteroepitaxially grown on synthetic fluorophlogopite mica [KMg3(AlSi3O10)F2] by van der Waals epitaxy. Platinum films deposited on a fluorophlogopite mica substrate by inductively coupled plasma-assisted sputtering with oxygen introduction on a synthetic mica substrate resulted in the growth of twin single-crystalline epitaxial Pt(111) films.

Carbon nanotubes/fluorinated polymers nanocomposite thin films for electrical contacts lubrication

NASA Astrophysics Data System (ADS)

Benedetto, A.; Viel, P.; Noël, S.; Izard, N.; Chenevier, P.; Palacin, S.

2007-09-01

The need to operate in extreme environmental conditions (ultra high vacuum, high temperatures, aerospatial environment, …) and the miniaturization toward micro electromechanical systems is demanding new materials in the field of low-level electrical contacts lubrication. Dry and chemically immobilized lubrication is expected to be an alternative to the traditional wet lubricants oils. With the goal to conciliate electrical conductivity and lubricant properties we designed nanocomposite thin films composed of a 2D carbon nanotubes network embedded in an organic matrix. The nanotubes networks were deposited on gold surfaces modified by electrochemical cathodic grafting of poly(acrylonitrile). The same substrate served for covalently bonding the low-friction organic matrix. Three different matrixes were tested: a perfluorinated oligomer chemically grafted and two different polyfluorinated acrylates electrochemically grafted. The nanocomposite thin films have been characterized by ATR FT-IR, XPS and Raman spectroscopy. We measured the effects of the different matrixes and the nanotubes addition on the tribological properties and on the contact resistances of the films.

The Development of Non-Enzymatic Glucose Biosensors Based on Electrochemically Prepared Polypyrrole-Chitosan-Titanium Dioxide Nanocomposite Films.

PubMed

Al-Mokaram, Ali M A Abdul Amir; Yahya, Rosiyah; Abdi, Mahnaz M; Mahmud, Habibun Nabi Muhammad Ekramul

2017-05-31

The performance of a modified electrode of nanocomposite films consisting of polypyrrole-chitosan-titanium dioxide (Ppy-CS-TiO₂) has been explored for the developing a non-enzymatic glucose biosensors. The synergy effect of TiO₂ nanoparticles (NPs) and conducting polymer on the current responses of the electrode resulted in greater sensitivity. The incorporation of TiO₂ NPs in the nanocomposite films was confirmed by X-ray photoelectron spectroscopy (XPS) spectra. FE-SEM and HR-TEM provided more evidence for the presence of TiO₂ in the Ppy-CS structure. Glucose biosensing properties were determined by amperommetry and cyclic voltammetry (CV). The interfacial properties of nanocomposite electrodes were studied by electrochemical impedance spectroscopy (EIS). The developed biosensors showed good sensitivity over a linear range of 1-14 mM with a detection limit of 614 μM for glucose. The modified electrode with Ppy-CS nanocomposite also exhibited good selectivity and long-term stability with no interference effect. The Ppy-CS-TiO₂ nanocomposites films presented high electron transfer kinetics. This work shows the role of nanomaterials in electrochemical biosensors and describes the process of their homogeneous distribution in composite films by a one-step electrochemical process, where all components are taken in a single solution in the electrochemical cell.

Effect of Surfactant Type and Sonication Energy on the Electrical Conductivity Properties of Nanocellulose-CNT Nanocomposite Films.

PubMed

Siljander, Sanna; Keinänen, Pasi; Räty, Anna; Ramakrishnan, Karthik Ram; Tuukkanen, Sampo; Kunnari, Vesa; Harlin, Ali; Vuorinen, Jyrki; Kanerva, Mikko

2018-06-20

We present a detailed study on the influence of sonication energy and surfactant type on the electrical conductivity of nanocellulose-carbon nanotube (NFC-CNT) nanocomposite films. The study was made using a minimum amount of processing steps, chemicals and materials, to optimize the conductivity properties of free-standing flexible nanocomposite films. In general, the NFC-CNT film preparation process is sensitive concerning the dispersing phase of CNTs into a solution with NFC. In our study, we used sonication to carry out the dispersing phase of processing in the presence of surfactant. In the final phase, the films were prepared from the dispersion using centrifugal cast molding. The solid films were analyzed regarding their electrical conductivity using a four-probe measuring technique. We also characterized how conductivity properties were enhanced when surfactant was removed from nanocomposite films; to our knowledge this has not been reported previously. The results of our study indicated that the optimization of the surfactant type clearly affected the formation of freestanding films. The effect of sonication energy was significant in terms of conductivity. Using a relatively low 16 wt. % concentration of multiwall carbon nanotubes we achieved the highest conductivity value of 8.4 S/cm for nanocellulose-CNT films ever published in the current literature. This was achieved by optimizing the surfactant type and sonication energy per dry mass. Additionally, to further increase the conductivity, we defined a preparation step to remove the used surfactant from the final nanocomposite structure.

Fabrication and characterization of polyvinyl alcohol/metal (Ca, Mg, Ti) doped zirconium phosphate nanocomposite films for scaffold-guided tissue engineering application.

PubMed

Kalita, Himani; Pal, Pallabi; Dhara, Santanu; Pathak, Amita

2017-02-01

Nanocomposite films of polyvinyl alcohol (PVA) and zirconium phosphate (ZrP)/doped ZrP (doped with Ca, Mg, Ti) nanoparticles have been developed by solvent casting method to assess their potential as matrix material in scaffold-guided tissue engineering application. The prepared ZrP and doped ZrP nanoparticles as well as the nanocomposite films were characterized by various spectroscopic and microscopic techniques. Nanoindentation studies revealed improved nanomechanical properties in the PVA/doped ZrP nanocomposite films (highest for PVA/Ti doped ZrP: hardness=262.4MPa; elastic modulus=5800MPa) as compared to the PVA/ZrP and neat PVA films. In-vitro cell culture experiments carried out to access the cellular viability, attachment, proliferation, and migration on the substrates, using mouse fibroblast (3T3) cell lines, inferred enhanced bioactivity in the PVA/doped ZrP nanocomposite films (highest for PVA/Ca doped ZrP) in contrast to PVA/ZrP and neat PVA films. Controlled biodegradability as well as swelling behavior, superior bioactivity and improved mechanical properties of the PVA/doped ZrP nanocomposite films make them promising matrix materials for scaffold-guided tissue engineering application. Copyright © 2016 Elsevier B.V. All rights reserved.

Self-assembled Co-BaZrO 3 nanocomposite thin films with ultra-fine vertically aligned Co nanopillars

DOE PAGES

Huang, Jijie; Li, Leigang; Lu, Ping; ...

2017-05-11

A simple one-step pulsed laser deposition (PLD) method has been applied to grow self-assembled metal-oxide nanocomposite thin films. The as-deposited Co-BaZrO 3 films show high epitaxial quality with ultra-fine vertically aligned Co nanopillars (diameter <5 nm) embeded in BZO matrix. The diameter of the nanopillars can be further tuned by varying the deposition frequency. The metal and oxide phases grow separately without inter-diffusion or mixing. Taking advantage of this unique structure, a high saturation magnetization of ~1375 emu/cm 3 in the Co- BaZrO 3 nanocomposites has been achieved and further confirmed by Lorentz microscopy imaging in TEM. Furthermore, the coercivitymore » values of this nanocomposite thin films range from 600 Oe (20 Hz) to 1020 Oe (2 Hz), which makes the nanocomposite an ideal candidate for high-density perpendicular recording media.« less

Dielectric property study of poly(4-vinylphenol)-graphene oxide nanocomposite thin film

NASA Astrophysics Data System (ADS)

Roy, Dhrubojyoti

2018-05-01

Thin film capacitor device having a sandwich structure of indium tin oxide (ITO)-coated glass/polymer or polymer nanocomposite /silver has been fabricated and their dielectric and leakage current properties has been studied. The dielectric properties of the capacitors were characterized for frequencies ranging from 1 KHz to 1 MHz. 5 wt% Poly(4-vinylphenol)(PVPh)-Graphene (GO) nanocomposite exhibited an increase in dielectric constant to 5.6 and small rise in dielectric loss to around˜0.05 at 10 KHz w.r.t polymer. The DC conductivity measurements reveal rise of leakage current in nanocomposite.

Optical and structural studies of films grown thermally on zirconium surfaces

NASA Astrophysics Data System (ADS)

Morgan, J. M.; McNatt, J. S.; Shepard, M. J.; Farkas, N.; Ramsier, R. D.

2002-06-01

Variable angle IR reflection spectroscopy and atomic force microscopy are used to determine the thickness and morphology of films grown thermally on Zr surfaces in air. The density and homogeneity of these films increases with temperature in the range studied (773-873 K) and growth at the highest temperature follows cubic rate law kinetics. We demonstrate a structure-property relationship for these thermally grown films and suggest the application of IR reflectivity as an inspection method during the growth of environmentally passive films on industrial Zr components.

Analysis of ultraviolet exposure effects on the surface properties of epoxy/graphene nanocomposite films on Mylar substrate

NASA Astrophysics Data System (ADS)

Clausi, Marialaura; Santonicola, M. Gabriella; Schirone, Luigi; Laurenzi, Susanna

2017-05-01

In this paper, we present a study of the effects generated by exposure to UV-C radiation on nanocomposite films made of graphene nanoplatelets dispersed in an epoxy matrix. The nanocomposite films, at different nanoparticle size and concentration, were fabricated on Mylar substrate using the spin coating process. The effects of UV-C irradiation on the surface hydrophobicity and on the electrical properties of the epoxy/graphene films were investigated using contact angle measurements and electrical impedance spectroscopy, respectively. According to our results, the UV-C irradiation selectively degrades the polymer matrix of the nanocomposite films, giving rise to more conductive and hydrophobic layers due to exposure of the graphene component of the composite material. The results presented here have important implications in the design of spacecraft components and structures destined for long-term space missions.

Pd-Ni-MWCNT nanocomposite thin films: preparation and structure

NASA Astrophysics Data System (ADS)

Kozłowski, Mirosław; Czerwosz, ElŻbieta; Sobczak, Kamil

2017-08-01

The properties of nanocomposite palladium-nickel-multi-walled (Pd-Ni-MWCNT) films deposited on aluminum oxide (Al2O3) substrate have been prepared and investigated. These films were obtained by 3 step process consisted of PVD/CVD/PVD methods. The morphology and structure of the obtained films were characterized by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) techniques at various stages of the film formation. EDX spectrometer was used to measurements of elements segregation in the obtained film. TEM and STEM (Scanning Transmission Electron Microscopy) observations showed MWCNTs decorated with palladium nanoparticles in the film obtained in the last step of film formation (final PVD process). The average size of the palladium nanoparticles observed both on MWCNTs and carbonaceous matrix does not exceed 5 nm. The research was conducted on the use of the obtained films as potential sensors of gases (e.g. H2, NH3, CO2) and bio-sensors or optical sensors.

Characterization of an Olive Flounder Bone Gelatin-Zinc Oxide Nanocomposite Film and Evaluation of Its Potential Application in Spinach Packaging.

PubMed

Beak, Songee; Kim, Hyeri; Song, Kyung Bin

2017-11-01

Olive flounder bone gelatin (OBG) was used for a film base material in this study. In addition, zinc oxide nanoparticles (ZnO) were incorporated into the OBG film to prepare a nanocomposite film and to impart antimicrobial activity to it. The tensile strength of the OBG film increased by 6.62 MPa, and water vapor permeability and water solubility decreased by 0.93 × 10 -9 g/m s Pa and 13.79%, respectively, by the addition of ZnO to the OBG film. In particular, the OBG-ZnO film exhibited antimicrobial activity against Listeria monocytogenes. To investigate the applicability of the OBG-ZnO packaging film, fresh spinach was wrapped in this film and stored for a week. The results indicated that the OBG-ZnO film showed antimicrobial activity against L. monocytogenes inoculated on spinach without affecting the quality of spinach, such as vitamin C content and color. Thus, the OBG-ZnO nanocomposite film can be applied as an efficient antimicrobial food packaging material. As a base material of edible films, gelatin was extracted from olive flounder bone, which is fish processing by-product. Olive flounder bone gelatin (OBG) nanocomposite films were prepared with zinc oxide nanoparticles (ZnO). For an application to antimicrobial packaging, spinach was wrapped with the OBG-ZnO nanocomposite film. © 2017 Institute of Food Technologists®.

L-Arginine modified multi-walled carbon nanotube/sulfonated poly(ether ether ketone) nanocomposite films for biomedical applications

NASA Astrophysics Data System (ADS)

Kaya, Hatice; Bulut, Osman; Kamali, Ali Reza; Ege, Duygu

2018-06-01

Favorable implant-tissue interactions are crucial to achieve successful osseointegration of the implants. Poly(ether ether ketone) (PEEK) is an interesting alternative to titanium in orthopedics because of its low cost, high biocompatibility and comparable mechanical properties with cancellous bone. Despite these advantages; however, the untreated surface of PEEK fails to osseointegrate due to its bioinert and hydrophobic behavior. This paper deals with the surface modification of PEEK with a novel method. For this, PEEK was first treated with concentrated sulfuric acid to prepare sulfonated PEEK (SPEEK) films using a solvent casting method. Then, 1 and 2 wt% multi-walled carbon nanotube was incorporated into SPEEK to form nanocomposite films. The samples were characterized with Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy. After successful preparation of the nanocomposite films, L-arginine was covalently conjugated on the nanocomposite films to further improve their surface properties. Subsequently, the samples were characterized using X-ray Photoemission Spectroscopy (XPS), water contact angle measurements and Atomic Force Microscopy (AFM) and Dynamic Mechanical Thermal Analysis (DMTA). Finally, cell culture studies were carried out by using Alamar Blue assay to evaluate the biocompatibility of the films. The results obtained indicate the successful preparation of L-arginine-conjugated MWCNT/SPEEK nanocomposite films. The modified surface shows potential to improve implants' mechanical and biological performances.

Thermomechanical properties of polymer nanocomposites: Exploring a unified relationship with planar polymer films

NASA Astrophysics Data System (ADS)

Bansal, Amitabh

The thermal and mechanical response of polymers, which provide limitations to their practical use, are greatly improved by the addition of a small fraction of an inorganic nanofiller. However, the resulting changes in polymer properties are poorly understood, primarily due to the non-uniform spatial distribution of nanoparticles. This research explores the properties of polystyrene filed with silica nanoparticles and illustrates for the first time that the thermodynamic properties of "polymer nanocomposites" are quantitatively equivalent to the well-understood case of planar polymer films with a uniform thickness. These ideas are quantified by drawing a direct analogy between thin film thickness and an appropriate average ligament thickness measured using electron microscopy. The change in polymer glass transition temperatures with decreasing ligament thickness were found to be quantitatively equivalent to the corresponding thin film data. In combination with viscoelastic properties of the nanocomposites that are in quantitative agreement with data from thin films, these conclusions provide a facile means of understanding and predicting the thermomechanical properties and, potentially, the engineering properties of practically relevant polymer nanocomposites. Grafting of high molecular weight polystyrene onto the silica nanoparticles greatly improves the dispersion quality of nanofillers and also provides a means to tailor the thermo-mechanical properties in nanocomposites. It is concluded that the grafted polystyrene is akin to polymer brushes on flat surfaces. The mobility and stiffness of these grafted chains are expected to be low as compared to the free polymer. In this context a mechanism for the increase in glass transition is proposed: (1) the stiff grafted chains will tend to decrease mobility and thus increase glass transition, (2) the extent of interdigitation of the grafted polystyrene into the matrix will determine the extent to which the nanocomposite

Development of LLDPE based active nanocomposite films with nanoclays impregnated with volatile compounds.

PubMed

Tornuk, Fatih; Sagdic, Osman; Hancer, Mehmet; Yetim, Hasan

2018-05-01

In this study, a novel procedure was performed for grafting of nanoclays (montmorillonite (MMT) and halloysite (HNT)) with essential oil constituents (thymol (THY), eugenol (EUG) and carvacrol (CRV)) using Tween 80 as surfactant and then the nanoclay particles were incorporated into LLDPE pellets (5 wt%) to produce active nanocomposite films using a twin screw extruder. The resulting nanocomposite films were analyzed for antimicrobial and antioxidant capacity as well as thickness, mechanical, color, barrier, thermal properties and surface morphology and molecular composition. Release of the active compounds from the films at the refrigerated and room temperature conditions were also tested. The results showed that the films had strong in vitro antibacterial activity against pathogenic bacteria (Salmonella Typhimurium, Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus and Bacillus cereus) while their effect against lactic acid bacteria (Lactobacillus rhamnosus and Lb. casei) was limited. The lowest and highest DPPH scavenging ability levels were 65.59% and % 87.92, belonged to THY-MMT and EUG-MMT, respectively. Release of active compounds at 24 °C was much more rapid than at 4 °C. CRV-HNT and THY-HNT provided slower release than the other films. SEM results showed that nanoclays were uniformly dispersed in the polymer matrix with exceptional agglomerates. Incorporation of the active nanoclays significantly (P > 0.05) improved tensile strength and elongation of the films. The results confirmed that LLDPE based active nanocomposite films could be successfully produced due to its good interaction with MMT and HNT, activated with THY, EUG and CRV. Copyright © 2018 Elsevier Ltd. All rights reserved.

Migration of nanosized layered double hydroxide platelets from polylactide nanocomposite films.

PubMed

Schmidt, B; Katiyar, V; Plackett, D; Larsen, E H; Gerds, N; Koch, C Bender; Petersen, J H

2011-01-01

Melt-extruded L-polylactide (PLA) nanocomposite films were prepared from commercially available PLA and laurate-modified Mg-Al layered double hydroxide (LDH-C12). Three films were tested for total migration as well as specific migration of LDH, tin, laurate and low molecular weight PLA oligomers (OLLA). This is the first reported investigation on the migration properties of PLA-LDH nanocomposite films. The tests were carried out as part of an overall assessment of the suitability of such films for use as food contact materials (FCM). Total migration was determined according to a European standard method. All three films showed migration of nanosized LDH, which was quantified using acid digestion followed by inductively coupled plasma mass spectrometric (ICP-MS) detection of (26)Mg. Migration of LDH from the films was also confirmed by examining migrates using transmission electron microscopy (TEM) and was attributed indirectly to the significant PLA molecular weight reduction observed in extruded PLA-LDH-C12 films. Migration of tin was detected in two of the film samples prepared by dispersion of LDH-C12 using a masterbatch technique and migration of the laurate organomodifier took place from all three film types. The results indicate that the material properties are in compliance with the migration limits for total migration and specific lauric acid migration as set down by the EU legislation for FCM, at least if a reduction factor for fresh meat is taken into consideration. The tin detected arises from the use of organotin catalysts in the manufacture of PLA.

Interpreting Neutron Reflectivity Profiles of Diblock Copolymer Nanocomposite Thin Films Using Hybrid Particle-Field Simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahalik, Jyoti P.; Dugger, Jason W.; Sides, Scott W.

Mixtures of block copolymers and nanoparticles (block copolymer nanocomposites) are known to microphase separate into a plethora of microstructures, depending on the composition, length scale and nature of interactions among its different constituents. Theoretical and experimental works on this class of nanocomposites have already high-lighted intricate relations among chemical details of the polymers, nanoparticles, and various microstructures. Confining these nanocomposites in thin films yields an even larger array of structures, which are not normally observed in the bulk. In contrast to the bulk, exploring various microstructures in thin films by the experimental route remains a challenging task. Here in thismore » work, we construct a model for the thin films of lamellar forming diblock copolymers containing spherical nanoparticles based on a hybrid particle-field approach. The model is benchmarked by comparison with the depth profiles obtained from the neutron reflectivity experiments for symmetric poly(deuterated styrene-b-n butyl methacrylate) copolymers blended with spherical magnetite nanoparticles covered with hydrogenated poly(styrene) corona. We show that the model based on a hybrid particle-field approach provides details of the underlying microphase separation in the presence of the nanoparticles through a direct comparison to the neutron reflectivity data. This work benchmarks the application of the hybrid particle-field model to extract the interaction parameters for exploring different microstructures in thin films containing block copolymers and nanocomposites.« less

Interpreting Neutron Reflectivity Profiles of Diblock Copolymer Nanocomposite Thin Films Using Hybrid Particle-Field Simulations

DOE PAGES

Mahalik, Jyoti P.; Dugger, Jason W.; Sides, Scott W.; ...

2018-04-10

Mixtures of block copolymers and nanoparticles (block copolymer nanocomposites) are known to microphase separate into a plethora of microstructures, depending on the composition, length scale and nature of interactions among its different constituents. Theoretical and experimental works on this class of nanocomposites have already high-lighted intricate relations among chemical details of the polymers, nanoparticles, and various microstructures. Confining these nanocomposites in thin films yields an even larger array of structures, which are not normally observed in the bulk. In contrast to the bulk, exploring various microstructures in thin films by the experimental route remains a challenging task. Here in thismore » work, we construct a model for the thin films of lamellar forming diblock copolymers containing spherical nanoparticles based on a hybrid particle-field approach. The model is benchmarked by comparison with the depth profiles obtained from the neutron reflectivity experiments for symmetric poly(deuterated styrene-b-n butyl methacrylate) copolymers blended with spherical magnetite nanoparticles covered with hydrogenated poly(styrene) corona. We show that the model based on a hybrid particle-field approach provides details of the underlying microphase separation in the presence of the nanoparticles through a direct comparison to the neutron reflectivity data. This work benchmarks the application of the hybrid particle-field model to extract the interaction parameters for exploring different microstructures in thin films containing block copolymers and nanocomposites.« less

Effects of preparation methods on the structure and mechanical properties of wet conditioned starch/montmorillonite nanocomposite films.

PubMed

Müller, Péter; Kapin, Éva; Fekete, Erika

2014-11-26

TPS/Na-montmorillonite nanocomposite films were prepared by solution and melt blending. Clay content changed between 0 and 25 wt% based on the amount of dry starch. Structure, tensile properties, and water content of wet conditioned films were determined as a function of clay content. Intercalated structure and VH-type crystallinity of starch were found for all the nanocomposites independently of clay and plasticizer content or preparation method, but at larger than 10 wt% clay content nanocomposites prepared by melt intercalation contained aggregated particles as well. In spite of the incomplete exfoliation clay reinforces TPS considerably. Preparation method has a strong influence on mechanical properties of wet conditioned films. Mechanical properties of the conditioned samples prepared by solution homogenization are much better than those of nanocomposites prepared by melt blending. Water, which was either adsorbed or bonded in the composites in conditioning or solution mixing process, respectively, has different effect on mechanical properties. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Development of Non-Enzymatic Glucose Biosensors Based on Electrochemically Prepared Polypyrrole–Chitosan–Titanium Dioxide Nanocomposite Films

PubMed Central

AL-Mokaram, Ali M. A. Abdul Amir; Yahya, Rosiyah; Abdi, Mahnaz M.; Mahmud, Habibun Nabi Muhammad Ekramul

2017-01-01

The performance of a modified electrode of nanocomposite films consisting of polypyrrole–chitosan–titanium dioxide (Ppy-CS-TiO2) has been explored for the developing a non-enzymatic glucose biosensors. The synergy effect of TiO2 nanoparticles (NPs) and conducting polymer on the current responses of the electrode resulted in greater sensitivity. The incorporation of TiO2 NPs in the nanocomposite films was confirmed by X-ray photoelectron spectroscopy (XPS) spectra. FE-SEM and HR-TEM provided more evidence for the presence of TiO2 in the Ppy-CS structure. Glucose biosensing properties were determined by amperommetry and cyclic voltammetry (CV). The interfacial properties of nanocomposite electrodes were studied by electrochemical impedance spectroscopy (EIS). The developed biosensors showed good sensitivity over a linear range of 1–14 mM with a detection limit of 614 μM for glucose. The modified electrode with Ppy-CS nanocomposite also exhibited good selectivity and long-term stability with no interference effect. The Ppy-CS-TiO2 nanocomposites films presented high electron transfer kinetics. This work shows the role of nanomaterials in electrochemical biosensors and describes the process of their homogeneous distribution in composite films by a one-step electrochemical process, where all components are taken in a single solution in the electrochemical cell. PMID:28561760

Production and characterization of a new biodegradable fenugreek seed gum based active nanocomposite film reinforced with nanoclays.

PubMed

Memiş, Saliha; Tornuk, Fatih; Bozkurt, Fatih; Durak, M Zeki

2017-10-01

In the present work, fenugreek seed gum (FSG)/clay nanocomposite films were prepared with nanoclays (Na + montmorillonite [MMT], halloysite [HNT] and Nanomer ® I.44 P [NM]) at different amounts (0, 2.5, 5.0 and 7.5g clay/100g FSG) by solution casting method and characterized. Increasing amount of nanoclay significantly (P<0.05) improved oxygen barrier and thermal properties of the biodegradable films. Agar diffusion tests revealed that FSG based nanocomposite films exhibited strong antimicrobial properties against foodborne pathogens namely Listeria monocytogenes, Escherichia coli O157:H7, Staphylococcus aureus and Bacillus cereus independently of clay type and concentration. In the case of mechanical properties, nanoclay incorporation up to 5% provided higher (P<0.05) tensile strength (TS) properties while elongation at break (EB) values of the films significantly (P<0.05) decreased in the presence of clay in the film matrix. SEM micrographs showed that especially lower levels (up to 5%) of nanoclay reinforcements provided a homogeneous and smooth film structure. In conclusion, FSG based nanocomposite films reinforced with nanoclays up to 5% showed a precious potential to be used in antimicrobial food packaging applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Thickness dependent optical properties of PEMA and (PEMA){sub 0.85}/(ZnO){sub 0.15} nanocomposite films deposited by spray pyrolysis technique on ITO substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thakur, Anjna, E-mail: anjna56@gmail.com; Thakur, Priya; Yadav, Kamlesh, E-mail: kamlesh.yadav001@gmail.com

2016-05-06

In this paper, poly (ethyl methacrylate) (PEMA) and (PEMA){sub 0.85}/(ZnO){sub 0.15} nanocomposite films for 2, 3, 4 and 5 minutes have been deposited by spray pyrolysis technique on indium tin oxide (ITO) coated substrate. The effect of thickness of the film on the morphological and optical properties of PEMA and (PEMA){sub 0.85}/(ZnO){sub 0.15} nanocomposite films are studied. The morphological and optical properties of pure PEMA and (PEMA){sub 0.85}/(ZnO){sub 0.15} nanocomposite films are compared. The field emission scanning electron microscopy (FESEM) shows that as the thickness of film increases, uniformity of films increases. It is found from UV-Visible spectra that themore » energy band gap decreases with increasing the deposition time and refractive index increases with increasing the thickness of the film. The band gap of the nanocomposites is found less than the pure polymer film and opposite trend is observed for refractive index. The optical absorption of PEMA/ZnO nanocomposite films is higher than pure PEMA film. The thickness of the nanocomposite film plays a significant role in the tunability of the optical properties.« less

Characterization of the new biodegradable WPI/clay nanocomposite films based on kefiran exopolysaccharide.

PubMed

Zolfi, Mohsen; Khodaiyan, Faramarz; Mousavi, Mohammad; Hashemi, Maryam

2015-06-01

Physico-mechanical, thermal and structural characteristics of nanocomposite film composed of kefiran-whey protein isolate (WPI)-montmorillonite (MMT; 1, 3 and 5 % w/w) were studied. Incorporation of MMT significantly affected the mechanical attributes of the kefiran-WPI films. The tensile strength and Young's modulus increased and the percentage of elongation at break decreased as the MMT content increased. Moisture content, moisture absorption and water solubility decreased as the MMT concentration increased. Differential scanning calorimetry indicated that the glass transition temperature for kefiran-WPI film was -12.5 °C and was noticeably affected by an increase in MMT. X-ray diffraction analysis showed formation of an exfoliated structure with the addition of small amounts of MMT to the kefiran-WPI matrix. Intercalation and some exfoliation occurred up to 5 % (wt) increase in MMT. Scanning electron microscopy demonstrated ideal dispersion for MMT nanoparticles into the structure of the bio-nanocomposite films.

Carbon Nanotube/Conductive Additive/Space Durable Polymer Nanocomposite Films for Electrostatic Charge Dissipation

NASA Technical Reports Server (NTRS)

Smith, Joseph G., Jr.; Watson, Kent A.; Delozier, Donavon M.; Connell, John W.

2003-01-01

Thin film membranes of space environmentally stable polymeric materials possessing low color/solar absorptivity (alpha) are of interest for potential applications on Gossamer spacecraft. In addition to these properties, sufficient electrical conductivity is required in order to dissipate electrostatic charge (ESC) build-up brought about by the charged orbital environment. One approach to achieve sufficient electrical conductivity for ESC mitigation is the incorporation of single wall carbon nanotubes (SWNTs). However, when the SWNTs are dispersed throughout the polymer matrix, the nanocomposite films tend to be significantly darker than the pristine material resulting in a higher alpha. The incorporation of conductive additives in combination with a decreased loading level of SWNTs is one approach for improving alpha while retaining conductivity. Taken individually, the low loading level of conductive additives and SWNTs is insufficient in achieving the percolation level necessary for electrical conductivity. When added simultaneously to the film, conductivity is achieved through a synergistic effect. The chemistry, physical, and mechanical properties of the nanocomposite films will be presented.

Preparation of mesoporous carbon nitride structure by the dealloying of Ni/a-CN nanocomposite films

NASA Astrophysics Data System (ADS)

Zhou, Han; Shen, Yongqing; Huang, Jie; Liao, Bin; Wu, Xianying; Zhang, Xu

2018-05-01

The preparation of mesoporous carbon nitride (p-CN) structure by the selective dealloying process of Ni/a-CN nanocomposite films is investigated. The composition and structure of the Ni/a-CN nanocomposite films and porous carbon nitride (p-CN) films are determined by scan electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Phase separated structure including nickel carbide phase and the surrounding amorphous carbon nitride (a-CN) matrix are detected for the as-deposited films. Though the bulk diffusion is introduced in the film during the annealing process, the grain sizes for the post-annealed films are around 10 nm and change little comparing with the ones of the as-deposited films, which is associated with the thermostability of the CN surrounding in the film. The p-CN skeleton with its pore size around 12.5 nm is formed by etching the post-annealed films, indicative of the stability of the phase separated structure during the annealing process.

Antibacterial effect of visible light reactive TiO2/Ag nanocomposite thin film on the orthodontic appliances.

PubMed

Yun, Kwidug; Oh, Gyejeong; Vang, Mongsook; Yang, Hongso; Lim, Hyunpil; Koh, Jeongtae; Jeong, Woonjo; Yoon, Dongjoo; Lee, Kyungku; Lee, Kwangmin; Park, Sangwon

2011-08-01

This study evaluated the antibacterial effect of a visible light reactive TiO2/Ag nanocomposite thin film on dental orthodontic wire (STS 304 wire). The growth of S. mutans and A. actinomycetemcomitans was suppressed on the specimens coated with TiO2/Ag compared to the uncoated specimens. The antibacterial effect of the TiO2/Ag nanocomposite thin film was improved under visible light irradiation.

Microstructure of thermally grown and deposited alumina films probed with positrons

NASA Astrophysics Data System (ADS)

Somieski, Bertram; Hulett, Lester D.; Xu, Jun; Pint, Bruce A.; Tortorelli, Peter F.; Nielsen, Bent; Asoka-Kumar, Palakkal; Suzuki, Ryoichi; Ohdaira, Toshiyuki

1999-03-01

Aluminum oxide films used for corrosion protection of iron and nickel aluminides were generated by substrate oxidation as well as plasma and physical vapor depositions. The films grown by oxidation were crystalline. The others were amorphous. Defect structures of the films were studied by positron spectroscopy techniques. Lifetimes of the positrons, and Doppler broadening of the γ photons generated by their annihilation, were measured as functions of the energies with which they were injected. In this manner, densities and sizes of the defects were determined as functions of depths from the outer surfaces of the films. Alumina films generated by oxidation had high densities of open volume defects, mainly consisting of a few aggregated vacancies. In the outer regions of the films the structures of the defects did not depend on substrate compositions. Positron lifetime measurements, and the S and W parameters extracted from Doppler broadening spectra, showed uniform distributions of defects in the crystalline Al2O3 films grown on nickel aluminide substrates, but these data indicated intermediate layers of higher defect contents at the film/substrate interfaces of oxides grown on iron aluminide substrates. Amorphous films generated by plasma and physical vapor deposition had much larger open volume defects, which caused the average lifetimes of the injected positrons to be significantly longer. The plasma deposited film exhibited a high density of large cavities.

Exchange-coupled hard magnetic Fe-Co/CoPt nanocomposite films fabricated by electro-infiltration

NASA Astrophysics Data System (ADS)

Wen, Xiao; Andrew, Jennifer S.; Arnold, David P.

2017-05-01

This paper introduces a potentially scalable electro-infiltration process to produce exchange-coupled hard magnetic nanocomposite thin films. Fe-Co/CoPt nanocomposite films are fabricated by deposition of CoFe2O4 nanoparticles onto Si substrate, followed by electroplating of CoPt. Samples are subsequently annealed under H2 to reduce the CoFe2O4 to magnetically soft Fe-Co and also induce L10 ordering in the CoPt. Resultant films exhibit 0.97 T saturation magnetization, 0.70 T remanent magnetization, 127 kA/m coercivity and 21.8 kJ/m3 maximum energy density. First order reversal curve (FORC) analysis and δM plot are used to prove the exchange coupling between soft and hard magnetic phases.

Fabrication of gelatin-TiO2 nanocomposite film and its structural, antibacterial and physical properties.

PubMed

He, Qingyan; Zhang, Yuchen; Cai, Xixi; Wang, Shaoyun

2016-03-01

Biodegradable fish skin gelatin-titanium dioxide (TiO2) nanocomposite films were fabricated and characterized as a function of incorporating amount of TiO2 nanoparticles (gelatin/TiO2 ratio of 30:1, 20:1 and 10:1). A uniform distribution of TiO2 nanoparticles into gelatin matrix was observed using atomic force microscopy (AFM) micrographs. The data of intrinsic fluorescence spectra, Fourier transform infrared spectra (FTIR) and X-ray diffraction confirmed the interaction between protein and nanoparticles through hydrogen bonding. The TiO2-incorporated gelatin nanocomposite films exhibited more effective antibacterial activity for Escherichia coli after irradiating 120 min by UV light (365 nm), which were 54.38% for E. coli and 44.89% for Staphylococcus aureus, respectively. The analysis of physical properties revealed that addition of TiO2 nanoparticles to gelatin films significantly increased the tensile strength and elongation at break, while decreased its water vapor permeability. The light barrier measurements indicated that these films were highly transparent, and they had excellent barrier properties against UVC light at the same time. The results demonstrated the feasibility of incorporating nanoparticles to improve the properties of gelatin films, and it is of significance in utilizing the gelatin and titanium dioxide to produce biodegradable nanocomposite film as packaging material in food industry. Copyright © 2015 Elsevier B.V. All rights reserved.

Dispersion of Cobalt Nanoparticles on Nanowires Grown on Silicon Carbide-Alumina Nanocomposites.

PubMed

Kim, Inho; Seo, Kyeong Won; Ahn, Byoung Sung; Moon, Dong Ju; Kim, Sang Woo

2017-04-01

Silicon carbide-alumina nanocomposite supports including a nanowire architecture for a high dispersion of cobalt nanocatalysts were fabricated using a modified sol–gel process and paste extrusion process to form cylindrical shape beads, followed by thermal treatment. Well-developed aluminosilicate nanowires were formed on a nanoporous support, which are grown from a catalytic metal seed at the nanowire growth tips during heat treatment at 1,100 °C for 1 h under nitrogen gas flow. Cobalt oxide precursors were highly dispersed on the nanowires grown on the surface of the nanoporous bodies through a supercritical carbon dioxide fluid-assisted wet-impregnation process. The highly-dispersed Co nanoparticles with size of less than 10 nm were finally obtained on the nanowires via phase transitions from Co₃O₄ to CoO and from CoO to Co during the thermal reduction.

Microstructural studies by TEM of diamond films grown by combustion flame

NASA Astrophysics Data System (ADS)

Ma, G.-H. M.; Hirose, Y.; Amanuma, S.; McClure, M.; Prater, J. T.; Glass, J. T.

Microstructures of diamond films grown in an oxygen-acetylene combustion flame were studied by TEM. The O2/C2H2 gas ratio was fixed and the substrate materials and temperature were varied. High quality diamond films were grown by this method at high growth rates of about 30 micron/hr. A rough surface and high density of secondary nucleation sites and microtwins were observed in the diamond grains grown on molybdenum (Mo) at a substrate temperature of 500 C. When the substrate temperature wass raised to between 500 and 870 C, the defect density was greatly reduced, revealing a low density of stacking faults and dislocations. Diamond films grown on Si substrates did not show the same substrate temperature dependence on defect density, at least not over the same temperature range. However, the same correlation between defect density, secondary nucleation, and surface morphology was observed.

Room temperature magneto-transport properties of nanocomposite Fe-In2O3 thin films

NASA Astrophysics Data System (ADS)

Tambasov, Igor A.; Gornakov, Kirill O.; Myagkov, Victor G.; Bykova, Liudmila E.; Zhigalov, Victor S.; Matsynin, Alexey A.; Yozhikova, Ekaterina V.

2015-12-01

A ferromagnetic Fe-In2O3 nanocomposite thin film has been synthesized by the thermite reaction Fe2O3+In→Fe-In2O3. Measurements of the Hall carrier concentration, Hall mobility and magnetoresistance have been conducted at room temperature. The nanocomposite Fe-In2O3 thin film had n=1.94·1020 cm-3, μ=6.45 cm2/Vs and negative magnetoresistance. The magnetoresistance for 8.8 kOe was ~-0.22%.The negative magnetoresistance was well described by the weak localization and model proposed by Khosla and Fischer.

W:Al 2O 3 nanocomposite thin films with tunable optical properties prepared by atomic layer deposition

DOE PAGES

Babar, Shaista; Mane, Anil U.; Yanguas-Gil, Angel; ...

2016-06-17

Here, a systematic alteration in the optical properties of W:Al 2O 3 nanocomposite films is demonstrated by precisely varying the W cycle percentage (W%) from 0 to 100% in Al 2O 3 during atomic layer deposition. The direct and indirect band energies of the nanocomposite materials decrease from 5.2 to 4.2 eV and from 3.3 to 1.8 eV, respectively, by increasing the W% from 10 to 40. X-ray absorption spectroscopy reveals that, for W% < 50, W is present in both metallic and suboxide states, whereas, for W% ≥ 50, only metallic W is seen. This transition from dielectric tomore » metallic character at W% ~ 50 is accompanied by an increase in the electrical and thermal conductivity and the disappearance of a clear band gap in the absorption spectrum. The density of the films increases monotonically from 3.1 g/cm 3 for pure Al 2O 3 to 17.1 g/cm 3 for pure W, whereas the surface roughness is greatest for the W% = 50 films. The W:Al 2O 3 nanocomposite films are thermally stable and show little change in optical properties upon annealing in air at 500 °C. These W:Al 2O 3 nanocomposite films show promise as selective solar absorption coatings for concentrated solar power applications.« less

Size dependent nonlinear optical properties of spin coated zinc oxide-polystyrene nanocomposite films

NASA Astrophysics Data System (ADS)

Jeeju, Pullarkat P.; Jayalekshmi, S.; Chandrasekharan, K.; Sudheesh, P.

2012-11-01

Using simple wet chemical method at room temperature, zinc oxide (ZnO) nanoparticles embedded in polystyrene (PS) matrix were synthesized. The size of the ZnO nanoparticles could be varied by varying the precursor concentration, reaction time and stirring speed. Transparent films of ZnO/PS nanocomposites of thickness around 1 μm were coated on ultrasonically cleaned glass substrates by spin coating. The optical absorptive nonlinearity in ZnO/PS nanocomposite films was investigated using open aperture Z-scan technique with nanosecond laser pulses at 532 nm. The results indicate optical limiting type nonlinearity in the films due to two-photon absorption in ZnO. These films also show a self-defocusing type negative nonlinear refraction in closed aperture Z-scan experiment. The observed nonlinear absorption is strongly dependent on particle size and the normalized transmittance could be reduced to as low as 0.43 by the suitable choice of the ZnO nanoparticle size. These composite films can hence be used as efficient optical limiters for sensor protection. The much-pronounced nonlinear response of these composite films, compared to pure ZnO, combined with the improved stability of ZnO nanoparticles in the PS matrix offer prospects of application of these composite films in the fabrication of stable non-linear optical devices.

Ti 3 C 2 T x (MXene)–polyacrylamide nanocomposite films

DOE PAGES

Naguib, Michael; Saito, Tomonori; Lai, Sophia; ...

2016-07-20

Polymer nanocomposite films are of great interest due to their enhanced properties over base polymers. By incorporating 2D titanium carbide a representative of a new family of 2D materials, MXenes, as nanofillers into a water soluble polyacrylamide (PAM) matrix, the resulting films benefit from the flexibility, robustness, and processability of PAM, as well as the conductivity and mechanical properties of MXene fillers. We report on manufacturing and characterization of MXene-PAM nanocomposite films. Dimethylsulfoxide (DMSO) intercalation in-between the Ti 3C 2-based MXene layers led to full delamination of the MXene layers and hence a uniform dispersion of hydrophilic MXene nanosheets inmore » aqueous PAM solutions was achieved. Moreover, the polymer composite solutions of up to 75 wt.% MXene loading were sonicated and cast onto large Teflon trays and dried at room temperature to produce shiny black films. The observation of reduced 0002 peaks of Ti 3C 2T x phase in X-ray diffraction patterns and TEM images indicate the presence of well dispersed nanoflakes. The as-prepared composite films are flexible and the conductivity was increased significantly to 3 x 10 -3 S cm -1 for 6 wt. % MXene-PAM films. With high MXene loading, some non-uniformity between the top and bottom surfaces was observed. This could be due to the segregation of MXene layers in composite films during drying. Finally, the power law dependence of conductivity above the percolation threshold is presented through detailed conductivity measurements.« less

Processing and properties of eco-friendly bio-nanocomposite films filled with cellulose nanocrystals from sugarcane bagasse.

PubMed

El Achaby, Mounir; El Miri, Nassima; Aboulkas, Adil; Zahouily, Mohamed; Bilal, Essaid; Barakat, Abdellatif; Solhy, Abderrahim

2017-03-01

Novel synthesis strategy of eco-friendly bio-nanocomposite films have been exploited using cellulose nanocrystals (CNC) and polyvinyl alcohol/carboxymethyl cellulose (PVA/CMC) blend matrix as a potential in food packaging application. The CNC were extracted from sugarcane bagasse using sulfuric acid hydrolysis, and they were successfully characterized regarding their morphology, size, crystallinity and thermal stability. Thereafter, PVA/CMC-CNC bio-nanocomposite films, at various CNC contents (0.5-10wt%), were fabricated by the solvent casting method, and their properties were investigated. It was found that the addition of 5wt% CNC within a PVA/CMC increased the tensile modulus and strength by 141% and 83% respectively, and the water vapor permeability was reduced by 87%. Additionally, the bio-nanocomposites maintained the same transparency level of the PVA/CMC blend film (transmittance of ∼90% in the visible region), suggesting that the CNC were dispersed at the nanoscale. In these bio-nanocomposites, the adhesion properties and the large number of functional groups that are present in the CNC's surface and the macromolecular chains of the PVA/CMC blend are exploited to improve the interfacial interactions between the CNC and the blend. Consequently, these eco-friendly structured bio-nanocomposites with superior properties are expected to be useful in food packaging applications. Copyright © 2016. Published by Elsevier B.V.

Preparation and characterization of polymeric nanocomposite films for application as protective coatings

NASA Astrophysics Data System (ADS)

Gagliardi, S.; Rondino, F.; D'Erme, C.; Persia, F.; Menchini, F.; Santarelli, M. L.; Paulke, B.-R.; Enayati, A. L.; Falconieri, M.

2017-08-01

Addiction of ceramic nanoparticles to acrylic polymers provides a simple and effective means to produce paints with important properties, such as mechanical resistance and tailored wettability, even though for optimal performances, an engineered nanoparticle distribution would be desirable. In this paper we report on the realization and on the morphological and functional characterization of nanocomposites where the nanophase is distributed on the surface of acrylic polymer films, in order to enhance the expression of surface-related properties. To this aim, commercial titanium oxide and silicon oxide nanopowders were dispersed in water and the suspensions were air-sprayed on polymeric films prepared by paint brushing, thus producing a nanostructured ceramic surface coating. Control of the pH of suspensions and acrylic acid functionalization of the surface of titania were used together with high power ultrasonic treatments in order to control dimension of the aggregates in the sprayed suspensions. Optical microscopy, mechanical profilometry, and atomic force microscopy were used to characterize the nanocomposite surface morphology and correlate it to the coating functional properties, evaluated through mechanical abrasion tests and contact angle measurements; also, colorimetry on coated stones was performed in order to test the impact of the coatings on the aesthetical appearance and their photostability under UV irradiation. Results show that the nanostructured ceramic layer slightly improves the resistance of coatings to mechanical abrasion in case of polymer films prepared from latexes. The nanocomposite surface layer does not affect the wettability of the polymer, which remained slightly hydrophilic; this behavior is likely due to inadequate distribution of the nanophase. On the other hand UV-induced superhydrophilicity was observed when the concentration of surface titania nanoparticles is about 0.6 mg/cm2. Colorimetric analysis on historical and Carrara

Improvement of food packaging related properties in whey protein isolate‑based nanocomposite films and coatings by addition of montmorillonite nanoplatelets

NASA Astrophysics Data System (ADS)

Schmid, Markus; Merzbacher, Sarah; Brzoska, Nicola; Müller, Kerstin; Jesdinszki, Marius

2017-11-01

In the present study the effects of the addition of montmorillonite (MMT) nanoplatelets on whey protein isolate (WPI)-based nanocomposite films and coatings were investigated. The main objective was the development of WPI-based MMT-nanocomposites with enhanced barrier and mechanical properties. WPI-based nanocomposite cast-films and coatings were prepared by dispersing 0 % (reference sample), 3 %, 6 %, 9 % (w/w protein) MMT, or, depending on the protein concentration, also 12 % and 15 % (w/w protein) MMT into native WPI-based dispersions, followed by subsequent denaturation during the drying and curing process. The natural MMT nanofillers could be randomly dispersed into film-forming WPI-based nanodispersions, displaying good compatibility with the hydrophilic biopolymer matrix. As a result, by addition of 15 % (w/w protein) MMT into 10 % (w/w dispersion) WPI-based cast-films or coatings, the oxygen permeability (OP) was reduced by 91 % for glycerol-plasticized and 84 % for sorbitol-plasticized coatings, water vapor transmission rate (WVTR) was reduced by 58 % for sorbitol-plasticized cast-films. Due to the addition of MMT- nanofillers the Young’s modulus and tensile strength improved by 315 % and 129 %, respectively, whereas elongation at break declined by 77 % for glycerol-plasticized cast-films. In addition, comparison of plasticizer type revealed that sorbitol-plasticized cast-films were generally stiffer and stronger, but less flexible compared glycerol-plasticized cast-films. Viscosity measurements demonstrated good processability and suitability for up-scaled industrial processes of native WPI-based nanocomposite dispersions, even at high nanofiller-loadings. These results suggest that the addition of natural MMT- nanofillers into native WPI-based matrices to form nanocomposite films and coatings holds great potential to replace well-established, fossil-based packaging materials for at least certain applications such as oxygen barriers as part of

Thermally tunable VO2-SiO2 nanocomposite thin-film capacitors

NASA Astrophysics Data System (ADS)

Sun, Yifei; Narayanachari, K. V. L. V.; Wan, Chenghao; Sun, Xing; Wang, Haiyan; Cooley, Kayla A.; Mohney, Suzanne E.; White, Doug; Duwel, Amy; Kats, Mikhail A.; Ramanathan, Shriram

2018-03-01

We present a study of co-sputtered VO2-SiO2 nanocomposite dielectric thin-film media possessing continuous temperature tunability of the dielectric constant. The smooth thermal tunability is a result of the insulator-metal transition in the VO2 inclusions dispersed within an insulating matrix. We present a detailed comparison of the dielectric characteristics of this nanocomposite with those of a VO2 control layer and of VO2/SiO2 laminate multilayers of comparable overall thickness. We demonstrated a nanocomposite capacitor that has a thermal capacitance tunability of ˜60% between 25 °C and 100 °C at 1 MHz, with low leakage current. Such thermally tunable capacitors could find potential use in applications such as sensing, thermal cloaks, and phase-change energy storage devices.

Thin-film transistors with a graphene oxide nanocomposite channel.

PubMed

Jilani, S Mahaboob; Gamot, Tanesh D; Banerji, P

2012-12-04

Graphene oxide (GO) and graphene oxide-zinc oxide nanocomposites (GO-ZnO) were used as channel materials on SiO(2)/Si to fabricate thin-film transistors (TFT) with an aluminum source and drain. Pure GO-based TFT showed poor field-effect characteristics. However, GO-ZnO-nanocomposite-based TFT showed better field-effect performance because of the anchoring of ZnO nanostructures in the GO matrix, which causes a partial reduction in GO as is found from X-ray photoelectron spectroscopic data. The field-effect mobility of charge carriers at a drain voltage of 1 V was found to be 1.94 cm(2)/(V s). The transport of charge carriers in GO-ZnO was explained by a fluctuation-induced tunneling mechanism.

Optical properties of PbS/PVP nanocomposites films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patel, Mitesh H., E-mail: miteshpatel7204@gmail.com; Chaudhuri, Tapas K.; Patel, Vaibhav K.

2016-05-06

PbS/Polyvinylpyrrolidone (PVP) nanocomposites films with different volume fraction of PbS have been deposited from single molecular precursors. X-ray diffraction patterns conforms the formation of PbS nanocrystals in PVP matrix. The transmission spectra of the films in the wavelength range of 300 to 2400 nm show the absorption edges are blue shifted due to formation of PbS Nanoparticles. The band gap determined are 2.4, 1.5 and 1.25 eV for PbS volume fraction of 8.5, 16, 27%, respectively. The corresponding refractive indices, n determined from Fresnel relation are 1.8, 2, and 2.35 which are in between that of PbS (4.2) and PVP (1.48).

Single-crystalline BaTiO3 films grown by gas-source molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Matsubara, Yuya; Takahashi, Kei S.; Tokura, Yoshinori; Kawasaki, Masashi

2014-12-01

Thin BaTiO3 films were grown on GdScO3 (110) substrates by metalorganic gas-source molecular beam epitaxy. Titanium tetra-isopropoxide (TTIP) was used as a volatile precursor that provides a wide growth window of the supplied TTIP/Ba ratio for automatic adjustment of the film composition. Within the growth window, compressively strained films can be grown with excellent crystalline quality, whereas films grown outside of the growth window are relaxed with inferior crystallinity. This growth method will provide a way to study the intrinsic properties of ferroelectric BaTiO3 films and their heterostructures by precise control of the stoichiometry, structure, and purity.

Ag+12 ion induced modifications of structural and optical properties of ZnO-PMMA nanocomposite films

NASA Astrophysics Data System (ADS)

Sharma, Sarla; Vyas, Rishi; Vijay, Y. K.

2013-02-01

The influence of swift heavy ion (SHI) irradiation on structural and photoluminescence (PL) properties of ZnO-PMMA nanocomposite films, prepared by solution casting method, was studied. The ZnO-PMMA nanocomposite films were irradiated using 120 MeV Ag+12 ions at different fluences varying from 1×1011 to 1×1013 ions/cm2. The intensity of the X-ray diffraction peaks is increased at the high fluence, without evolution of any new peak. A shift in absorption edge (i.e. shift in optical band gap) towards higher wavelength was observed after irradiation and PL from ZnO-PMMA nanocomposite films is found to increase up to a critical fluence and then found to be suppressed for higher fluence (1×1012 ion/cm2). The change in photoluminescence after irradiation can be attributed to the change in microstructure of PMMA matrix as well as the agglomeration of ZnO nanoparticles.

Inorganic nanocomposite films with polymer nanofillers made by the concurrent multi-beam multi-target pulsed laser deposition

NASA Astrophysics Data System (ADS)

Darwish, Abdalla M.; Sarkisov, Sergey S.; Mele, Paolo; Saini, Shrikant; Moore, Shaelynn; Bastian, Tyler; Dorlus, Wydglif; Zhang, Xiaodong; Koplitz, Brent

2017-08-01

We report on the new class of inorganic nanocomposite films with the inorganic phase hosting the polymer nanofillers made by the concurrent multi-beam multi-target pulsed laser deposition of the inorganic target material and matrix assisted pulsed laser evaporation of the polymer (MBMT-PLD/MAPLE). We used the exemplary nanocomposite thermoelectric films of aluminum-doped ZnO known as AZO with the nanofillers made of poly(methyl methacrylate) known as PMMA on various substrates such as SrTiO3, sapphire, fused silica, and polyimide. The AZO target was ablated with the second harmonic (532 nm) of the Nd:YAG Q-switched laser while PMMA was evaporated from its solution in chlorobenzene frozen in liquid nitrogen with the fundamental harmonic (1064 nm) of the same laser (50 Hz pulse repetition rate). The introduction of the polymer nanofillers increased the electrical conductivity of the nanocomposite films (possibly due to the carbonization of PMMA and the creation of additional channels of electric current) three times and reduced the thermal conductivity by 1.25 times as compared to the pure AZO films. Accordingly, the increase of the thermoelectric figure-of merit ZT would be 4 times. The best performance was observed for the sapphire substrates where the films were the most uniform. The results point to a huge potential of the optimization of a broad variety of optical, opto-electronic, and solar-power nanocomposite inorganic films by the controllable introduction of the polymer nanofillers using the MBMT-PLD/MAPLE method.

BiVO4 thin film photoanodes grown by chemical vapor deposition.

PubMed

Alarcón-Lladó, Esther; Chen, Le; Hettick, Mark; Mashouf, Neeka; Lin, Yongjing; Javey, Ali; Ager, Joel W

2014-01-28

BiVO4 thin film photoanodes were grown by vapor transport chemical deposition on FTO/glass substrates. By controlling the flow rate, the temperatures of the Bi and V sources (Bi metal and V2O5 powder, respectively), and the temperature of the deposition zone in a two-zone furnace, single-phase monoclinic BiVO4 thin films can be obtained. The CVD-grown films produce global AM1.5 photocurrent densities up to 1 mA cm(-2) in aqueous conditions in the presence of a sacrificial reagent. Front illuminated photocatalytic performance can be improved by inserting either a SnO2 hole blocking layer and/or a thin, extrinsically Mo doped BiVO4 layer between the FTO and the CVD-grown layer. The incident photon to current efficiency (IPCE), measured under front illumination, for BiVO4 grown directly on FTO/glass is about 10% for wavelengths below 450 nm at a bias of +0.6 V vs. Ag/AgCl. For BiVO4 grown on a 40 nm SnO2/20 nm Mo-doped BiVO4 back contact, the IPCE is increased to over 40% at wavelengths below 420 nm.

Influence of growth temperature on properties of zirconium dioxide films grown by atomic layer deposition

NASA Astrophysics Data System (ADS)

Kukli, Kaupo; Ritala, Mikko; Aarik, Jaan; Uustare, Teet; Leskela, Markku

2002-08-01

ZrO2 films were grown by atomic layer deposition from ZrCl4 and H2O or a mixture of H2O and H2O2 on Si(100) substrates in the temperature range of 180-600 degC. The films were evaluated in the as-deposited state, in order to follow the effect of deposition temperature on the film quality. The rate of crystal growth increased and the content of residual impurities decreased with increasing temperature. The zirconium-to-oxygen atomic ratio, determined by ion-beam analysis, corresponded to the stoichiometric dioxide regardless of the growth temperature. The effective permittivity of ZrO2 in Al/ZrO2/Si capacitor structures increased from 13-15 in the films grown at 180 degC to 19 in the films grown at 300-600 degC, measured at 100 kHz. The permittivity was relatively high in the crystallized films, compared to the amorphous ones, but rather insensitive to the crystal structure. The permittivity was higher in the films grown using water. The leakage current density tended to be lower and the breakdown field higher in the films grown using hydrogen peroxide.

A sulphonated carbon dot-chitosan hybrid hydrogel nanocomposite as an efficient ion-exchange film for Ca2+ and Mg2+ removal

NASA Astrophysics Data System (ADS)

Baruah, Upama; Konwar, Achyut; Chowdhury, Devasish

2016-04-01

We have developed a hybrid hydrogel nanocomposite film via conjugation of oxidised carbon dots synthesized from 11-mercaptoundecanoic acid with chitosan. The potential applicability of the film was then successfully tested for the removal of Ca2+ and Mg2+ ions from solution.We have developed a hybrid hydrogel nanocomposite film via conjugation of oxidised carbon dots synthesized from 11-mercaptoundecanoic acid with chitosan. The potential applicability of the film was then successfully tested for the removal of Ca2+ and Mg2+ ions from solution. Electronic supplementary information (ESI) available: The ESI includes the detailed synthesis and characterization of carbon dots both before and after oxidation and of the carbon dot-chitosan nanocomposite films viz. DLS, SEM, UV-visible, FTIR, PL spectroscopy and TGA. See DOI: 10.1039/c6nr01129b

Photoelectrochemical response and corrosion behavior of CdS/TiO2 nanocomposite films in an aerated 0.5 M NaCl solution

NASA Astrophysics Data System (ADS)

Boonserm, Aleena; Kruehong, Chaiyaput; Seithtanabutara, Varinrumpai; Artnaseaw, Apichart; Kwakhong, Panomkorn

2017-10-01

This research aimed to investigate the photoelectrochemical response and corrosion behavior of CdS/TiO2 nanocomposite films using electrochemical measurements in an aerated 0.5 M NaCl solution under white light illumination. The CdS/TiO2 nanocomposite films were prepared by chemical bath deposition technique in a solution of cadmium and sulfide ions. The high resolution images of CdS/TiO2 nanocomposite films were provided by field emission scanning electron microscope. Theirs chemical identification and quantitative compositional information, crystallinity and actual chemical compounds formed were determined by energy dispersive spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy, respectively. The results indicated that the photoelectrochemical activity of the films depended strongly on CdS content. From the preparation of CdS/TiO2 nanocomposite films by 5, 10 and 15 dipping cycles in the chemical solutions, the best photoelectrochemical response was revealed by the 10 dipping cycles-prepared film. Galvanic couple testing demonstrated that the photoelectrochemical response of the film decreased continuously compared to that of anodized nanoporous TiO2 substrate which described by photocorrosion of CdS nanoparticles. In addition, chloride-ion attack also induced pitting corrosion leading to fluctuation and deterioration of photoelectrochemical response. CdO2 and Cd(OH)2 depositions were found as the main photocorrosion products on collapsed nanostructured-surface. The relevance between photoelectrochemical response and corrosion behavior of CdS/TiO2 nanocomposite film was discussed in detail.

Group III-nitride thin films grown using MBE and bismuth

DOEpatents

Kisielowski, Christian K.; Rubin, Michael

2002-01-01

The present invention comprises growing gallium nitride films in the presence of bismuth using MBE at temperatures of about 1000 K or less. The present invention further comprises the gallium nitride films fabricated using the inventive fabrication method. The inventive films may be doped with magnesium or other dopants. The gallium nitride films were grown on sapphire substrates using a hollow anode Constricted Glow Discharge nitrogen plasma source. When bismuth was used as a surfactant, two-dimensional gallium nitride crystal sizes ranging between 10 .mu.m and 20 .mu.m were observed. This is 20 to 40 times larger than crystal sizes observed when GaN films were grown under similar circumstances but without bismuth. It is thought that the observed increase in crystal size is due bismuth inducing an increased surface diffusion coefficient for gallium. The calculated value of 4.7.times.10.sup.-7 cm.sup.2 /sec. reveals a virtual substrate temperature of 1258 K which is 260 degrees higher than the actual one.

Group III-nitride thin films grown using MBE and bismuth

DOEpatents

Kisielowski, Christian K.; Rubin, Michael

2000-01-01

The present invention comprises growing gallium nitride films in the presence of bismuth using MBE at temperatures of about 1000 K or less. The present invention further comprises the gallium nitride films fabricated using the inventive fabrication method. The inventive films may be doped with magnesium or other dopants. The gallium nitride films were grown on sapphire substrates using a hollow anode Constricted Glow Discharge nitrogen plasma source. When bismuth was used as a surfactant, two-dimensional gallium nitride crystal sizes ranging between 10 .mu.m and 20 .mu.m were observed. This is 20 to 40 times larger than crystal sizes observed when GaN films were grown under similar circumstances but without bismuth. It is thought that the observed increase in crystal size is due bismuth inducing an increased surface diffusion coefficient for gallium. The calculated value of 4.7.times.10.sup.-7 cm.sup.2 /sec. reveals a virtual substrate temperature of 1258 K which is 260 degrees higher than the actual one.

Graphene Oxide/Poly(3-hexylthiophene) Nanocomposite Thin-Film Phototransistor for Logic Circuit Applications

NASA Astrophysics Data System (ADS)

Mansouri, S.; Coskun, B.; El Mir, L.; Al-Sehemi, Abdullah G.; Al-Ghamdi, Ahmed; Yakuphanoglu, F.

2018-04-01

Graphene is a sheet-structured material that lacks a forbidden band, being a good candidate for use in radiofrequency applications. We have elaborated graphene-oxide-doped poly(3-hexylthiophene) nanocomposite to increase the interlayer distance and thereby open a large bandgap for use in the field of logic circuits. Graphene oxide/poly(3-hexylthiophene) (GO/P3HT) nanocomposite thin-film transistors (TFTs) were fabricated on silicon oxide substrate by spin coating method. The current-voltage ( I- V) characteristics of TFTs with various P3HT compositions were studied in the dark and under light illumination. The photocurrent, charge carrier mobility, subthreshold voltage, density of interface states, density of occupied states, and I ON/ I OFF ratio of the devices strongly depended on the P3HT weight ratio in the composite. The effects of white-light illumination on the electrical parameters of the transistors were investigated. The results indicated that GO/P3HT nanocomposite thin-film transistors have high potential for use in radiofrequency applications, and their feasibility for use in digital applications has been demonstrated.

Mechanical comparison of a polymer nanocomposite to a ceramic thin-film anti-reflective filter.

PubMed

Druffel, Thad; Geng, Kebin; Grulke, Eric

2006-07-28

Thin-film filters on optical components have been in use for decades and, for those industries utilizing a polymer substrate, the mismatch in mechanical behaviour has caused problems. Surface damage including scratches and cracks induces haze on the optical filter, reducing the transmission of the optical article. An in-mold anti-reflective (AR) filter incorporating 1/4-wavelength thin films based on a polymer nanocomposite is outlined here and compared with a traditional vacuum deposition AR coating. Nanoindentation and nanoscratch techniques are used to evaluate the mechanical properties of the thin films. Scanning electron microscopy (SEM) images of the resulting indentations and scratches are then compared to the force deflection curves to further explain the phenomena. The traditional coatings fractured by brittle mechanisms during testing, increasing the area of failure, whereas the polymer nanocomposite gave ductile failure with less surface damage.

Preparation and characterization of bio-nanocomposite films based on soy protein isolate and montmorillonite using melt extrusion

USDA-ARS?s Scientific Manuscript database

The non-biodegradable and non-renewable nature of plastic packaging has led to a renewed interest in packaging materials based on bio-nanocomposites (biopolymer matrix reinforced with nanoparticles such as layered silicates). Bio-nanocomposite films based on soy protein isolate (SPI) and montmorillo...

Thermal hydrogen reduction for preservation of mesoporous silica film nanocomposites with a hexagonal structure containing amphiphilic triphenylene

NASA Astrophysics Data System (ADS)

Lintang, Hendrik O.; Jalani, Mohamad Azani; Yuliati, Leny

2017-11-01

We highlight that columnar assembly of self-assembled templates was successfully utilized using sol-gel technique of mesostructured silica for the quality improvement of transparent mesoporous film nanocomposites with a hexagonal structure through appropriate heat treatment methods and self-assembled templates in the removal of organic components. In contrast to the reported mesostructured silica film nanocomposites containing columnar assembly of trinuclear gold(I) pyrazolate complex ([Au3Pz3]C10TEG/silicahex) with calcination at 450 °C, mesostructured silica film nanocomposites from self-assembled template of triphenylene bearing amphiphilic decoxy triethylene glycol side chains (TPC10TEG/silicahex) can be completely collapsed upon calcination at 450 °C. This hexagonal structure can be only preserved with calcination at 250 °C although intensity of its main diffraction peak of d100 at 2θ of 3.70° was significantly decreased. On the other hands, thermal hydrogen reduction at the same temperature was found to be the best heat treatment to preserve the quality of mesoporous silica film nanocomposites with decreasing in intensity of diffraction peak up to 30%. Such phenomenon might be caused by slow decomposition of organic components with the presence of hydrogen gas upon heating to shrinkage the silica wall from interpenetration of ethylene glycol segments of the side chains and to open bonding of benzene ring from the core.

Chemical synthesis and characterization of chitosan/silver nanocomposites films and their potential antibacterial activity.

PubMed

Shah, Aamna; Hussain, Izhar; Murtaza, Ghulam

2018-05-12

This study provides the optimum preparation parameters for functional chitosan silver nanocomposite (CSN) films with promising antibacterial efficacy though prepared with very low silver nitrate (AgNO 3 ) concentration. Chitosan nano‑silver composites were fabricated by In-situ chemical method utilizing the reducing ability of sodium borohydride (NaBH 4 ) and afterward casted into films. Utilization of response surface methodology, NCSS, and SigmaPlot for the optimization of CSN and their predicted antibacterial efficacy assessment of the selected bacterial strains (standard and clinical) was the essential part of the study. The cumulative silver ions released from the CSN films was examined by AAS and was found pH dependent. The developed nanocomposite films exhibited strong antibacterial activity against ATCC strains of Gram-positive Staphylococcus aureus, Gram-negative bacteria (Pseudomonas aeruginosa) and clinically isolated strains of MRSA. The antibacterial activity CSN films were compared with three commercially available dressings (Aquacel Ag®, Bactigras®, and Kaltostat®) and Quench cream. Statistical analysis of the results indicated that the developed CSN films were equally or even more effective than commercial products. Thus the fabricated CSN films may act as a potential candidate to overcome the emerging antibiotic resistance particularly in hospital-acquired skin infections caused by MRSA. Copyright © 2018. Published by Elsevier B.V.

Optical, structural and electrochromic behavior studies on nanocomposite thin film of aniline, o-toluidine and WO3

NASA Astrophysics Data System (ADS)

Najafi-Ashtiani, Hamed; Bahari, Ali

2016-08-01

In the field of materials for electrochromic (EC) applications much attention was paid to the derivatives of aniline. We report on the optical, structural and electrochromic properties of electrochromic thin film based on composite of WO3 nanoparticles and copolymer of aniline and o-toluidine prepared by electrochemical polymerization method on fluorine doped tin oxide (FTO) coated glass. The thin film was studied by X-ray diffraction (XRD) and Fourier transforms infrared (FTIR) spectroscopy. The morphology of prepared thin film was characterized by field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and the thermal gravimetric analysis (TGA) as well. The optical spectra of nanocomposite thin film were characterized in the 200-900 nm wavelength range and EC properties of nanocomposite thin film were studied by cyclic voltammetry (CV). The calculation of optical band gaps of thin film exhibited that the thin film has directly allowed transition with the values of 2.63 eV on first region and 3.80 eV on second region. Dispersion parameters were calculated based on the single oscillator model. Finally, important parameters such as dispersion energy, oscillator energy and lattice dielectric constant were determined and compared with the data from other researchers. The nonlinear optical properties such as nonlinear optical susceptibility, nonlinear absorption coefficient and nonlinear refractive index were extracted. The obtained results of nanocomposite thin film can be useful for the optoelectronic applications.

Fabrication of antibacterial PVA nanocomposite films containing dendritic polymer functionalized multi-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Sapalidis, Andreas; Sideratou, Zili; Panagiotaki, Katerina N.; Sakellis, Elias; Kouvelos, Evangelos P.; Papageorgiou, Sergios; Katsaros, Fotios

2018-03-01

A series of Poly(vinyl alcohol) (PVA) nanocomposite films containing quaternized hyperbranched polyethyleneimine (PEI) functionalized multi-walled carbon nanotubes (ox-CNTs@QPEI) are prepared by solvent casting technique. The modified carbon based material exhibits high aqueous solubility, due to the hydrophilic character of the functionalized hyperbranched dendritic polymer. The quaternized PEI successfully wraps around nanotube walls, as polycations provide electrostatic repulsion. Various contents of ox-CNTs@QPEI ranging from 0.05 to 1.0 % w/w were employed to prepare functionalized PVA nanocomposites. The developed films exhibit adequate optical transparency, improved mechanical properties and extremely high antibacterial behavior due to the excellent dispersion of the functionalized carbon nanotubes into the PVA matrix.

Characterization of PLD grown WO3 thin films for gas sensing

NASA Astrophysics Data System (ADS)

Boyadjiev, Stefan I.; Georgieva, Velichka; Stefan, Nicolaie; Stan, George E.; Mihailescu, Natalia; Visan, Anita; Mihailescu, Ion N.; Besleaga, Cristina; Szilágyi, Imre M.

2017-09-01

Tungsten trioxide (WO3) thin films were grown by pulsed laser deposition (PLD) with the aim to be applied in gas sensors. The films were studied by atomic force microscopy (AFM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and profilometry. To study the gas sensing behavior of these WO3 films, they were deposited on quartz resonators and the quartz crystal microbalance (QCM) method was applied to analyze their gas sensitivity. Synthesis of tetragonal-WO3 films starting from a target with predominantly monoclinic WO3 phase was observed. The films deposited at 300 °C presented a surface topology favorable for the sorption properties, consisting of a film matrix with protruding craters/cavities. QCM prototype sensors with such films were tested for NO2 sensing. The PLD grown WO3 thin films show good sensitivity and fast reaction at room temperature, even in as-deposited state. With the presented technology, the manufacturing of QCM gas sensors is simple, fast and cost-effective, and it is also suitable for energy-effective portable equipment for on-line monitoring of environmental changes.

Flexible and conductive MXene films and nanocomposites with high capacitance

DOE PAGES

Ling, Zheng; Ren, Chang E.; Zhao, Meng-Qiang; ...

2014-11-11

MXenes, a new family of 2D materials, combine hydrophilic surfaces with metallic conductivity. Delamination of MXene produces single-layer nanosheets with thickness of about a nanometer and lateral size of the order of micrometers. The high aspect ratio of delaminated MXene renders it promising nanofiller in multifunctional polymer nanocomposites. In this study, Ti 3C 2T x MXene was mixed with either a charged polydiallyldimethylammonium chloride (PDDA) or an electrically neutral polyvinyl alcohol (PVA) to produce Ti 3C 2T x/polymer composites. The as-fabricated composites are flexible and have electrical conductivities as high as 2.2 × 10 4 S/m in the case ofmore » the Ti 3C 2T x/PVA composite film and 2.4 × 10 5 S/m for pure Ti 3C 2T x films. The tensile strength of the Ti 3C 2T x/PVA composites was significantly enhanced compared with pure Ti 3C 2T x or PVA films. The intercalation and confinement of the polymer between the MXene flakes not only increased flexibility but also enhanced cationic intercalation, offering an impressive volumetric capacitance of ~530 F/cm 3 for MXene/PVA-KOH composite film at 2 mV/s. Finally, to our knowledge, this study is a first, but crucial, step in exploring the potential of using MXenes in polymer-based multifunctional nanocomposites for a host of applications, such as structural components, energy storage devices, wearable electronics, electrochemical actuators, and radiofrequency shielding, to name a few.« less

Optimization of nanocomposite Au/TiO2 thin films towards LSPR optical-sensing

NASA Astrophysics Data System (ADS)

Rodrigues, M. S.; Costa, D.; Domingues, R. P.; Apreutesei, M.; Pedrosa, P.; Martin, N.; Correlo, V. M.; Reis, R. L.; Alves, E.; Barradas, N. P.; Sampaio, P.; Borges, J.; Vaz, F.

2018-04-01

Nanomaterials based on Localized Surface Plasmon Resonance (LSPR) phenomena are revealing to be an important solution for several applications, namely those of optical biosensing. The main reasons are mostly related to their high sensitivity, with label-free detection, and to the simplified optical systems that can be implemented. For the present work, the optical sensing capabilities were tailored by optimizing LSPR absorption bands of nanocomposite Au/TiO2 thin films. These were grown by reactive DC magnetron sputtering. The main deposition parameters changed were the number of Au pellets placed in the Ti target, the deposition time, and DC current applied to the Ti-Au target. Furthermore, the Au NPs clustering, a key feature to have biosensing responses, was induced by several post-deposition in-air annealing treatments at different temperatures, and investigated via SEM analysis. Results showed that the Au/TiO2 thin films with a relatively low thickness (∼100 nm), revealing concentrations of Au close to 13 at.%, and annealed at temperatures above 600 °C, had the most well-defined LSPR absorption band and thus, the most promising characteristics to be explored as optical sensors. The NPs formation studies revealed an incomplete aggregation at 300 and 500 ⁰C and well-defined spheroidal NPs for higher temperatures. Plasma treatment with Ar led to a gradual blue-shift of the LSPR absorption band, which demonstrates the sensitivity of the films to changes in the dielectric environment surrounding the NPs (essential for optical sensing applications) and the exposure of the Au nanoparticles (crucial for a higher sensitivity).

Thin film lithium-based batteries and electrochromic devices fabricated with nanocomposite electrode materials

DOEpatents

Gillaspie, Dane T; Lee, Se-Hee; Tracy, C. Edwin; Pitts, John Roland

2014-02-04

Thin-film lithium-based batteries and electrochromic devices (10) are fabricated with positive electrodes (12) comprising a nanocomposite material composed of lithiated metal oxide nanoparticles (40) dispersed in a matrix composed of lithium tungsten oxide.

Nanocomposite thin films for triggerable drug delivery.

PubMed

Vannozzi, Lorenzo; Iacovacci, Veronica; Menciassi, Arianna; Ricotti, Leonardo

2018-05-01

Traditional drug release systems normally rely on a passive delivery of therapeutic compounds, which can be partially programmed, prior to injection or implantation, through variations in the material composition. With this strategy, the drug release kinetics cannot be remotely modified and thus adapted to changing therapeutic needs. To overcome this issue, drug delivery systems able to respond to external stimuli are highly desirable, as they allow a high level of temporal and spatial control over drug release kinetics, in an operator-dependent fashion. Areas covered: On-demand drug delivery systems actually represent a frontier in this field and are attracting an increasing interest at both research and industrial level. Stimuli-responsive thin films, enabled by nanofillers, hold a tremendous potential in the field of triggerable drug delivery systems. The inclusion of responsive elements in homogeneous or heterogeneous thin film-shaped polymeric matrices strengthens and/or adds intriguing properties to conventional (bare) materials in film shape. Expert opinion: This Expert Opinion review aims to discuss the approaches currently pursued to achieve an effective on-demand drug delivery, through nanocomposite thin films. Different triggering mechanisms allowing a fine control on drug delivery are described, together with current challenges and possible future applications in therapy and surgery.

Effect of type and content of modified montmorillonite on the structure and properties of bio-nanocomposite films based on soy protein isolate and montmorillonite.

PubMed

Kumar, P; Sandeep, K P; Alavi, S; Truong, V D; Gorga, R E

2010-06-01

The nonbiodegradable and nonrenewable nature of plastic packaging has led to a renewed interest in packaging materials based on bio-nanocomposites (biopolymer matrix reinforced with nanoparticles such as layered silicates). Bio-nanocomposite films based on soy protein isolate (SPI) and modified montmorillonite (MMT) were prepared using melt extrusion. The effect of different type (Cloisite 20A and Cloisite 30B) and content (0% to 15%) of modified MMT on the structure (degree of intercalation and exfoliation) and properties (color, mechanical, dynamic mechanical, thermal stability, and water vapor permeability) of SPI-MMT bio-nanocomposite films were investigated. Extrusion of SPI and modified MMTs resulted in bio-nanocomposites with exfoliated structures at lower MMT content (5%). At higher MMT content (15%), the structure of bio-nanocomposites ranged from intercalated for Cloisite 20A to disordered intercalated for Cloisite 30B. At an MMT content of 5%, bio-nanocomposite films based on modified MMTs (Cloisite 20A and Cloisite 30B) had better mechanical (tensile strength and percent elongation at break), dynamic mechanical (glass transition temperature and storage modulus), and water barrier properties as compared to those based on natural MMT (Cloisite Na(+)). Bio-nanocomposite films based on 10% Cloisite 30B had mechanical properties comparable to those of some of the plastics that are currently used in food packaging applications. However, much higher WVP values of these films as compared to those of existing plastics might limit the application of these films to packaging of high moisture foods such as fresh fruits and vegetables.

Synthesis and characterization of HDPE/N-MWNT nanocomposite films.

PubMed

Chouit, Fairouz; Guellati, Ounassa; Boukhezar, Skander; Harat, Aicha; Guerioune, Mohamed; Badi, Nacer

2014-01-01

In this work, a series of nitrogen-doped multi-walled carbon nanotubes (N-MWCNTs) with several weight percentages (0.1, 0.4, 0.8, and 1.0 wt.%) were synthesized by catalytic chemical vapor deposition (CCVD) technique. The N-MWCNTs were first characterized and then dispersed in high-density polyethylene (HDPE) polymer matrix to form a nanocomposite. The HDPE/N-MWCNT nanocomposite films were prepared by melt mixing and hot pressing; a good dispersion in the matrix and a good N-MWCNT-polymer interfacial adhesion have been verified by scanning electron microscopy (SEM). Raman spectroscopy measurements have been performed on prepared samples to confirm the presence and nature of N-MWNTs in HDPE matrix. The X-ray diffraction (XRD) analysis demonstrated that the crystalline structure of HDPE matrix was not affected by the incorporation of the N-MWNTs.

Synthesis and characterization of HDPE/N-MWNT nanocomposite films

PubMed Central

2014-01-01

In this work, a series of nitrogen-doped multi-walled carbon nanotubes (N-MWCNTs) with several weight percentages (0.1, 0.4, 0.8, and 1.0 wt.%) were synthesized by catalytic chemical vapor deposition (CCVD) technique. The N-MWCNTs were first characterized and then dispersed in high-density polyethylene (HDPE) polymer matrix to form a nanocomposite. The HDPE/N-MWCNT nanocomposite films were prepared by melt mixing and hot pressing; a good dispersion in the matrix and a good N-MWCNT-polymer interfacial adhesion have been verified by scanning electron microscopy (SEM). Raman spectroscopy measurements have been performed on prepared samples to confirm the presence and nature of N-MWNTs in HDPE matrix. The X-ray diffraction (XRD) analysis demonstrated that the crystalline structure of HDPE matrix was not affected by the incorporation of the N-MWNTs. PMID:25024676

Thermal and rheological properties of L-polylactide/polyethylene glycol/silicate nanocomposites films.

PubMed

Ahmed, Jasim; Varshney, Sunil K; Auras, Rafael; Hwang, Sung W

2010-10-01

The melt rheology and thermal properties of polylactide (PLA)-based nanocomposite films that were prepared by solvent casting method with L-PLA, polyethylene glycol (PEG), and montmorillonite clay were studied. The neat PLA showed predominantly solid-like behavior (G' > G″) and the complex viscosity (η*) decreased systematically as the temperature increased from 184 to 196 °C. The elastic modulus (G') of PLA/clay blend showed a significant improvement in the magnitude in the melt, while clay concentration was at 6% wt or higher. At similar condition, PEG dramatically reduced dynamic modulii and complex viscosity of PLA/PEG blend as function of concentration. A nanocomposite blend of PLA/PEG/clay (74/20/6) when compared to the neat polymer and PLA/PEG blend exhibited intermediate values of elastic modulus (G') and complex viscosity (η*) with excellent flexibility. Thermal analysis of different clay loading blends indicated that the melting temperature (T(m)) and glass transition temperature (T(g)) remained unaffected irrespective of clay concentration due to immobilization of polymer chain in the clay nanocomposite. PEG incorporation reduced the T(g) and the T(m) of the blends (PLA/PEG and PLA/PEG/clay) significantly, however, crystallinity increased in the similar condition. The transmission electron microscopy (TEM) image of nanocomposite films indicated good compatibility between PLA and PEG, whereas clay was not thoroughly distributed in the PLA matrix and remained as clusters. The percent crystallinity obtained by X-ray was significantly higher than that of differential scanning calorimeter (DSC) data for PLA.

Structure and physical properties of starch/poly vinyl alcohol/sodium montmorillonite nanocomposite films.

PubMed

Ali, Samer S; Tang, Xiaozhi; Alavi, Sajid; Faubion, Jon

2011-12-14

Nanocomposites of starch, poly vinyl alcohol (PVOH), and sodium montmorillonite (Na(+)MMT) were produced by solution mixing and cast into films. Tensile strength (TS) and elongation at the break (E%) of the films ranged from 11.60 to 22.35 MPa and 28.93-211.40%, respectively, while water vapor permeability (WVP) ranged from 0.718 to 1.430 g·mm/kPa·h·m(2). In general, an increase in Na(+)MMT content (0-20%) enhanced TS and decreased E% and WVP. Use of higher molecular weight PVOH increased both TS and E% and also decreased WVP. Mechanical properties were negatively affected, but water vapor barrier properties improved with increasing starch content (0-80%). X-ray diffraction and transmission electron microscopy were used to analyze the nanostructure, and molecular conformations and interactions in the multicomponent nanocomposites were inferred from glass transition behavior. Interactions between starch and PVOH were strongest, followed by polymer/clay interactions. On the basis of this insight, a conceptual model was presented to explain the phenomena of intercalation and exfoliation in the starch/PVOH/Na(+)MMT nanocomposites.

Mechanical, structural and thermal properties of Ag-Cu and ZnO reinforced polylactide nanocomposite films.

PubMed

Ahmed, Jasim; Arfat, Yasir Ali; Castro-Aguirre, Edgar; Auras, Rafael

2016-05-01

Plasticized polylactic acid (PLA) based nanocomposite films were prepared by incorporating polyethylene glycol (PEG) and two selected nanoparticles (NPs) [silver-copper (Ag-Cu) alloy (<100 nm) and zinc oxide (ZnO) (<50 and <100 nm)] through solvent casting method. Incorporation of Ag-Cu alloy into the PLA/PEG matrix increased the glass transition temperature (Tg) significantly. The crystallinity of the nanocomposites (NCs) was significantly influenced by NP incorporation as evidenced from differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis. The PLA nanocomposite reinforced with NPs exhibited much higher tensile strength than that of PLA/PEG blend. Melt rheology of NCs exhibited a shear-thinning behavior. The mechanical property drastically reduced with a loading of NPs, which is associated with degradation of PLA. SEM micrographs exhibited that both Ag-Cu alloy and ZnO NPs were dispersed well in the PLA film matrix. Copyright © 2016 Elsevier B.V. All rights reserved.

Field emission from amorphous carbon films grown by electrochemical deposition using methanol liquid

NASA Astrophysics Data System (ADS)

Kiyota, H.; Higashi, M.; Kurosu, T.; Iida, M.

2006-05-01

The field emission from an amorphous carbon (a-C) film grown by electrochemical deposition has been studied. The deposition of the a-C film was accomplished by applying a direct-current potential to a substrate that was immersed in methanol. Both scanning electron microscopy and Raman results indicate that smooth and homogeneous a-C films are grown on specific substrates such as Ti and Al. Field emission measurements demonstrate excellent emission properties such as threshold fields as low as 5 V/μm. Enhancement factors are estimated to be in the range of 1300-1500; these are attributed to local field enhancements around sp2 carbon clusters that are embedded in the a-C films. Emission properties of a-C films grown on Si exhibit a current saturation under higher applied fields. These saturation characteristics are explained by effects of a potential barrier at the interface between the a-C film and the substrate. The interface barrier is reduced by formation of the Ti interfacial layer, suggesting that the formation of TiC decreases the contact resistance between the substrate and the a-C film. Therefore, an approach to use carbide formation at the interface is verified as useful to improve the emission properties of a-C films.

Nanocomposites biodegradable coating on BOPET films to enhance hot seal strength properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barbaro, G., E-mail: giovannibarbaro@email.it; Galdi, M. R., E-mail: mrgaldi@unisa.it; Di Maio, L., E-mail: ldimaio@unisa.it

2015-12-17

The coating technology is a strategic solution to improve the properties of flexible packaging films. Indeed, additional functional layers are often designed and added as coating on the substrate, in order to improve the characteristic of the flexible packaging and to meet the requirements for the desired gas or vapour barrier, for adhesion and sealing, or for improving the film printability, its aesthetics and durability. Moreover, this technology allows to functionalize a polymeric substrate applying materials with different chemistry, rheology, thermal and structural characteristics. BOPET films are widely used for food packaging applications thanks to their good gas barrier andmore » mechanical properties, high transparency and for the excellent printability. In regard to sealing performance, BOPET films show poor sealing properties so they are mostly submitted to lamination processes with polyethylene. Nevertheless, this solution compromises the PET recyclability and influences the gas permeability of the multilayer PET based structures. The aim of this work is to investigate on the effect of nanocomposite biodegradable coatings for BOPET substrates in enhancing the heat sealing strength of eco-compatible PET/PLA films. At this regards, different percentages of Cloisite C30B (0%, 2% and 4%{sub wt/wt}) have been added to PLA by solution intercalation technique and the nanocomposite biodegradable materials produced have been applied on BOPET commercial films by casting. The BOPET coated films have been characterized in order to evaluate the heat sealing strength and the mechanical, gas permeability and surface properties. The results have shown that the addition of nanoclay in PLA coating significantly enhance the hot tack properties of the PET/PLA system produced, while the oxygen and water vapour permeability are slightly increased if compared to pure BOPET films.« less

Nanocomposites biodegradable coating on BOPET films to enhance hot seal strength properties

NASA Astrophysics Data System (ADS)

Barbaro, G.; Galdi, M. R.; Di Maio, L.; Incarnato, L.

2015-12-01

The coating technology is a strategic solution to improve the properties of flexible packaging films. Indeed, additional functional layers are often designed and added as coating on the substrate, in order to improve the characteristic of the flexible packaging and to meet the requirements for the desired gas or vapour barrier, for adhesion and sealing, or for improving the film printability, its aesthetics and durability. Moreover, this technology allows to functionalize a polymeric substrate applying materials with different chemistry, rheology, thermal and structural characteristics. BOPET films are widely used for food packaging applications thanks to their good gas barrier and mechanical properties, high transparency and for the excellent printability. In regard to sealing performance, BOPET films show poor sealing properties so they are mostly submitted to lamination processes with polyethylene. Nevertheless, this solution compromises the PET recyclability and influences the gas permeability of the multilayer PET based structures. The aim of this work is to investigate on the effect of nanocomposite biodegradable coatings for BOPET substrates in enhancing the heat sealing strength of eco-compatible PET/PLA films. At this regards, different percentages of Cloisite C30B (0%, 2% and 4%wt/wt) have been added to PLA by solution intercalation technique and the nanocomposite biodegradable materials produced have been applied on BOPET commercial films by casting. The BOPET coated films have been characterized in order to evaluate the heat sealing strength and the mechanical, gas permeability and surface properties. The results have shown that the addition of nanoclay in PLA coating significantly enhance the hot tack properties of the PET/PLA system produced, while the oxygen and water vapour permeability are slightly increased if compared to pure BOPET films.

Highly Sensitive Detection and Removal of Lead Ions in Water Using Cysteine-Functionalized Graphene Oxide/Polypyrrole Nanocomposite Film Electrode.

PubMed

Seenivasan, Rajesh; Chang, Woo-Jin; Gunasekaran, Sundaram

2015-07-29

We synthesized cysteine-functionalized graphene oxide (sGO) using carbonyldiimidazole as a cross-linker via amide and carbamate linkages. The sGO/polypyrrole (PPy) nanocomposite film was grown on the working electrode surface of a screen-printed electrode (SPE) via controlled one-step electrochemical deposition. The sGO/PPy-SPE was used to detect lead ions (Pb(2+)) in water by first depositing Pb(2+) on the working electrode surface for 10 min at -1.2 V, and then anodic stripping by differential pulse voltammetry (DPV). The DPV signals were linear in the ranges of 1.4-28 ppb (R(2) = 0.994), 28-280 ppb (R(2) = 0.997), and 280-14 000 ppb (R(2) = 0.990) Pb(2+). The measurable detection limit of the sensor is 0.07 ppb (S/N = 3), which is more than 2 orders of magnitude below the 10 ppb threshold for drinking water set by the World Health Organization. The average removal efficiency of Pb(2+) deposited on the electrode was 99.2% (S/N = 3), with relative standard deviation (RSD) of 3.8%. Our results indicate good affinity of sGO/PPy nanocomposite to Pb(2+), which can be used to effectively adsorb and remove Pb(2+) in water samples. Therefore, sGO/PPy nanocomposite we synthesized is useful for highly sensitive on-site and real-time monitoring of heavy metal ions and water treatment.

Synthesis of Nm-PHB (nanomelanin-polyhydroxy butyrate) nanocomposite film and its protective effect against biofilm-forming multi drug resistant Staphylococcus aureus.

PubMed

Kiran, George Seghal; Jackson, Stephen A; Priyadharsini, Sethu; Dobson, Alan D W; Selvin, Joseph

2017-08-22

Melanin is a dark brown ubiquitous photosynthetic pigment which have many varied and ever expanding applications in fabrication of radio-protective materials, food packaging, cosmetics and in medicine. In this study, melanin production in a Pseudomonas sp. which was isolated from the marine sponge Tetyrina citirna was optimized employing one-factor at a time experiments and characterized for chemical nature and stability. Following sonication nucleated nanomelanin (Nm) particles were formed and evaluated for antibacterial and antioxidant properties. Nanocomposite film was fabricated using combinations (% w/v) of polyhydroxy butyrate-nanomelanin (PHB:Nm) blended with 1% glycerol. The Nm was found to be spherical in shape with a diameter of 100-140 nm and showed strong antimicrobial activity against both Gram positive and Gram negative bacteria. The Nm-PHB nanocomposite film was homogeneous, smooth, without any cracks, and flexible. XRD and DSC data indicated that the film was crystalline in nature, and was thermostable up to 281.87 °C. This study represents the first report on the synthesis of Nm and fabrication of Nm-PHB nanocomposite film which show strong protective effect against multidrug resistant Staphyloccoccus aureus. Thus this Nm-PHB nanocomposite film may find utility as packaging material for food products by protecting the food products from oxidation and bacterial contamination.

Swift heavy ion induced modification in morphological and physico-chemical properties of tin oxide nanocomposites

NASA Astrophysics Data System (ADS)

Jaiswal, Manoj Kumar; Kanjilal, D.; Kumar, Rajesh

2013-11-01

Nanocomposite thin films of tin oxide (SnO2)/titanium oxide (TiO2) were grown on silicon (1 0 0) substrates by electron beam evaporation deposition technique using sintered nanocomposite pellet of SnO2/TiO2 in the percentage ratio of 95:5. Sintering of the nanocomposite pellet was done at 1300 °C for 24 h. The thicknesses of these films were measured to be 100 nm during deposition using piezo-sensor attached to the deposition chamber. TiO2 doped SnO2 nanocomposite films were irradiated by 100 MeV Au8+ ion beam at fluence range varying from 1 × 1011 ions/cm2 to 5 × 1013 ions/cm2 at Inter University Accelerator Center (IUAC), New Delhi, India. Chemical properties of pristine and ion irradiation modified thin films were characterized by Fourier Transform Infrared (FTIR) spectroscopy. FTIR peak at 610 cm-1 confirms the presence of O-Sn-O bridge of tin (IV) oxide signifying the composite nature of pristine and irradiated thin films. Atomic Force Microscope (AFM) in tapping mode was used to study the surface morphology and grain growth due to swift heavy ion irradiation at different fluencies. Grain size calculations obtained from sectional analysis of AFM images were compared with results obtained from Glancing Angle X-ray Diffraction (GAXRD) measurements using Scherrer’s formulae. Phase transformation due to irradiation was observed from Glancing Angle X-ray Diffraction (GAXRD) results. The prominent 2θ peaks observed in GAXRD spectrum are at 30.67°, 32.08°, 43.91°, 44.91° and 52.35° in the irradiated films.

Room temperature direct band gap emission characteristics of surfactant mediated grown compressively strained Ge films

NASA Astrophysics Data System (ADS)

Katiyar, Ajit K.; Grimm, Andreas; Bar, R.; Schmidt, Jan; Wietler, Tobias; Joerg Osten, H.; Ray, Samit K.

2016-10-01

Compressively strained Ge films have been grown on relaxed Si0.45Ge0.55 virtual substrates using molecular beam epitaxy in the presence of Sb as a surfactant. Structural characterization has shown that films grown in the presence of surfactant exhibit very smooth surfaces with a relatively higher strain value in comparison to those grown without any surfactant. The variation of strain with increasing Ge layer thickness was analyzed using Raman spectroscopy. The strain is found to be reduced with increasing film thickness due to the onset of island nucleation following Stranski-Krastanov growth mechanism. No phonon assisted direct band gap photoluminescence from compressively strained Ge films grown on relaxed Si0.45Ge0.55 has been achieved up to room temperature. Excitation power and temperature dependent photoluminescence have been studied in details to investigate the origin of different emission sub-bands.

Room temperature synthesis and optical studies on Ag and Au mixed nanocomposite polyvinylpyrrolidone polymer films.

PubMed

Udayabhaskar, R; Mangalaraja, R V; Manikandan, D; Arjunan, V; Karthikeyan, B

2012-12-01

Optical properties of silver, gold and bimetallic (Au:Ag) nanocomposite polymer films which are prepared by chemical method have been reported. The experimental data was correlated with the theoretical calculations using Mie theory. We adopt small change in the theoretical calculations of bimetallic/mixed particle nanocomposite and the theory agrees well with the experimental data. Polyvinylpyrrolidone (PVP) was used as reducing and capping agent. Fourier transform infrared spectroscopy (FTIR) study reveals the presence of different functional groups, the possible mechanism that leads to the formation of nanoparticles by using PVP alone as reducing agent. Optical absorption spectra of Ag and Au nanocomposite polymers show a surface plasmon resonance (SPR) band around 430 and 532 nm, respectively. Thermal annealing effect on the prepared samples at 60 °C for different time durations result in shift of SPR band maximum and varies the full width at half maximum (FWHM). Absorption spectra of Au:Ag bimetallic films show bands at 412 and 547 nm confirms the presence of Ag and Au nanoparticles in the composite. Copyright © 2012 Elsevier B.V. All rights reserved.

Nanocomposite synthesis and photoluminescence properties of MeV Au-ion beam modified Ni thin films

NASA Astrophysics Data System (ADS)

Siva, Vantari; Datta, Debi P.; Singh, Avanendra; Som, T.; Sahoo, Pratap K.

2016-01-01

We report on the synthesis and properties of nano-composites from thin Ni films on Silica matrix using Au-ion beam. When 2.2 MeV Au-ions are irradiated on 5 nm Ni film on Silica, the surface morphology changes drastically with ion fluence. In fact, within a fluence range of 5 × 1014-1 × 1016 ions/cm2, a sharp increase in surface roughness follows after an initial surface smoothening. The depth profiles extracted from Rutherford backscattering spectra demonstrates the diffusion of Ni and Au into the silica matrix. The photoluminescence spectra of the irradiated samples reveal the development of two bands centered at 3.3 eV and 2.66 eV, respectively. Deconvolution of those bands shows five different emission peaks, corresponding to different luminescence centers, which confirms the existence of Ni-Au nanocomposites in silica matrix. The optical and structural modifications are understood in terms of ion induced local heating and mass transport due to thermal spikes, which leads to nanocomposite formation in silica.

Magnetic anisotropy and transport properties of 70 nm SrRuO3 films grown on different substrates

NASA Astrophysics Data System (ADS)

Wang, X. W.; Zhang, Y. Q.; Meng, H.; Wang, Z. J.; Li, D.; Zhang, Z. D.

2011-04-01

Magnetic and transport properties of 70 nm SrRuO3 films grown on (001) SrTiO3, (001) LaAlO3 and (001) MgO have been investigated. A perpendicular magnetic anisotropy is observed in compressive strained films grown on SrTiO3. A weaker perpendicular magnetic anisotropy and a weak in-plane magnetic anisotropy are found in strain-free films grown on MgO and LAO, respectively, possibly due to different growth mechanisms. In addition, metallic behavior is observed in all the as-grown films and the resistivity of the film grown on MgO is lowest (230 μΩ cm at 300 K), which is close to that of bulk single crystal SrRuO3 (about 195 μΩ cm). The relation between structure and properties indicates that the magnetic anisotropy, as well as the magnitude of resistivity of SrRuO3 films, can be effectively tailored by taking advantage of different strains and growth mechanisms induced by growth on different substrates.

Carbon Nanotube/Space Durable Polymer Nanocomposite Films for Electrostatic Charge Dissipation

NASA Technical Reports Server (NTRS)

Smith, J. G., Jr.; Watson, K. A.; Thompson, C. M.; Connell, J. W.

2002-01-01

Low solar absorptivity, space environmentally stable polymeric materials possessing sufficient electrical conductivity for electrostatic charge dissipation (ESD) are of interest for potential applications on spacecraft as thin film membranes on antennas, solar sails, large lightweight space optics, and second surface mirrors. One method of imparting electrical conductivity while maintaining low solar absorptivity is through the use of single wall carbon nanotubes (SWNTs). However, SWNTs are difficult to disperse. Several preparative methods were employed to disperse SWNTs into the polymer matrix. Several examples possessed electrical conductivity sufficient for ESD. The chemistry, physical, and mechanical properties of the nanocomposite films will be presented.

Dimensional effects on the tunneling conductivity of gold-implanted nanocomposite films

NASA Astrophysics Data System (ADS)

Grimaldi, C.; Cattani, M.; Salvadori, M. C.

2015-03-01

We study the dependence of the electrical conductivity on the gold concentration of Au-implanted polymethylmethacrylate (PMMA) and alumina nanocomposite thin films. For Au contents larger than a critical concentration, the conductivity of Au-PMMA and Au-alumina is well described by percolation in two dimensions, indicating that the critical correlation length for percolation is larger than the thickness of the films. Below the critical loading, the conductivity is dominated by tunneling processes between isolated Au particles dispersed in PMMA or alumina continuous matrices. Using an effective medium analysis of the tunneling conductivity, we show that Au-PMMA behaves as a tunneling system in two dimensions, as the film thickness is comparable to the mean Au particle size. On the contrary, the conductivity of Au-alumina films is best described by tunneling in three dimensions, although the film thickness is only a few times larger than the particle size. We interpret the enhancement of the effective dimensionality of Au-alumina films in the tunneling regime as due to the larger film thickness as compared to the mean interparticle distances.

Large-Strain Transparent Magnetoactive Polymer Nanocomposites

NASA Technical Reports Server (NTRS)

Meador, Michael A.

2012-01-01

A document discusses polymer nano - composite superparamagnetic actuators that were prepared by the addition of organically modified superparamagnetic nanoparticles to the polymer matrix. The nanocomposite films exhibited large deformations under a magnetostatic field with a low loading level of 0.1 wt% in a thermoplastic polyurethane elastomer (TPU) matrix. The maximum actuation deformation of the nanocomposite films increased exponentially with increasing nanoparticle concentration. The cyclic deformation actuation of a high-loading magnetic nanocomposite film was examined in a low magnetic field, and it exhibited excellent reproducibility and controllability. Low-loading TPU nanocomposite films (0.1-2 wt%) were transparent to semitransparent in the visible wavelength range, owing to good dispersion of the magnetic nanoparticles. Magnetoactuation phenomena were also demonstrated in a high-modulus, high-temperature polyimide resin with less mechanical deformation.

Fabrication, characterization and in-vitro cytotoxicity of magnetic nanocomposite polymeric film for multi-functional medical application

NASA Astrophysics Data System (ADS)

Zhao, Lingyun; Xu, Xiaoyu; Wang, Xiaowen; Zhang, Xiaodong; Gao, Fuping; Tang, Jintian

2009-07-01

Cancer comprehensive treatment has been fully acknowledged as it can provide an effective multimodality approach for fighting cancers. In this study, various innovative technologies for cancer treatment including cancer nanotechnology, chemotherapy by sustainable release, as well as magnetic induction hyperthermia (MIH) have been integrated for the purpose of cancer comprehensive treatment. Briefly, such kind of treatment can be realized by applying of the tailored magnetic nanoparticles (MNPs) composite polymeric film. Fe3O4 MNPs acting as the agent for MIH, and anti-cancer drug docetaxel as chemotherapeutic agent were incorporated within the biodegradable polymeric film. Physiochemical characterizations on MNPs and the film have been systematically carried out by various instrumental analyses. Our results demonstrated that the film has been successfully fabricated by the solvent cast method. Hyperthermia could be induced by stimulating the nanocomposite film under an alternative magnetic field (AMF). The incorporation of MNPs, as well as hyperthermia would facilitate the drug release from the polymeric film. The in-vitro cytotoxicity results indicated the bi-modal cancer treatment approach for combined MIH and chemotherapy is more effective than the mono-modal treatment by docetaxel treatment. The magnetic nanocomposite film can realize cancer comprehensive treatment thus has great potential in clinical application.

Method of fabricating low-dislocation-density epitaxially-grown films with textured surfaces

DOEpatents

Li, Qiming; Wang, George T

2015-01-13

A method for forming a surface-textured single-crystal film layer by growing the film atop a layer of microparticles on a substrate and subsequently selectively etching away the microparticles to release the surface-textured single-crystal film layer from the substrate. This method is applicable to a very wide variety of substrates and films. In some embodiments, the film is an epitaxial film that has been grown in crystallographic alignment with respect to a crystalline substrate.

Surface structure analysis of BaSi2(100) epitaxial film grown on Si(111) using CAICISS

NASA Astrophysics Data System (ADS)

Okasaka, Shouta; Kubo, Osamu; Tamba, Daiki; Ohashi, Tomohiro; Tabata, Hiroshi; Katayama, Mitsuhiro

2015-05-01

Geometry and surface structure of a BaSi2(100) film on Si(111) formed by reactive deposition epitaxy (RDE) have been investigated using coaxial impact-collision ion scattering spectroscopy and atomic force microscopy. BaSi2(100) film can be grown only when the Ba deposition rate is sufficiently fast. It is revealed that a BaSi2(100) film grown at 600 °C has better crystallinity than a film grown at 750 °C owing to the mixture of planes other than (100) in the RDE process at higher temperatures. The azimuth angle dependence of the scattering intensity from Ba shows sixfold symmetry, indicating that the minimum height of surface steps on BaSi2(100) is half of the length of unit cell. By comparing the simulated azimuth angle dependences for more than ten surface models with experimental one, it is strongly indicated that the surface of a BaSi2(100) film grown on Si(111) is terminated by Si tetrahedra.

Dynamic Mechanical Characterization of Thin Film Polymer Nanocomposites

NASA Technical Reports Server (NTRS)

Herring, Helen M.; Gates, Thomas S. (Technical Monitor)

2003-01-01

Many new materials are being produced for aerospace applications with the objective of maximizing certain ideal properties without sacrificing others. Polymer composites in various forms and configurations are being developed in an effort to provide lighter weight construction and better thermal and electrical properties and still maintain adequate strength and stability. To this end, thin film polymer nanocomposites, synthesized for the purpose of influencing electrical conductivity using metal oxide particles as filler without incurring losses in mechanical properties, were examined to determine elastic modulus and degree of dispersion of particles. The effects of various metal oxides on these properties will be discussed.

High quality TmIG films with perpendicular magnetic anisotropy grown by sputtering

NASA Astrophysics Data System (ADS)

Wu, C. N.; Tseng, C. C.; Yeh, S. L.; Lin, K. Y.; Cheng, C. K.; Fanchiang, Y. T.; Hong, M.; Kwo, J.

Ferrimagnetic thulium iron garnet (TmIG) films grown on gadolinium gallium garnet substrates recently showed stress-induced perpendicular magnetic anisotropy (PMA), attractive for realization of quantum anomalous Hall effect (QAHE) of topological insulator (TI) films via the proximity effect. Moreover, current induced magnetization switching of Pt/TmIG has been demonstrated for the development of room temperature (RT) spintronic devices. In this work, high quality TmIG films (about 25nm) were grown by sputtering at RT followed by post-annealing. We showed that the film composition is tunable by varying the growth parameters. The XRD results showed excellent crystallinity of stoichiometric TmIG films with an out-of-plane lattice constant of 1.2322nm, a narrow film rocking curve of 0.017 degree, and a film roughness of 0.2 nm. The stoichiometric films exhibited PMA and the saturation magnetization at RT was 109 emu/cm3 (RT bulk value 110 emu/cm3) with a coercive field of 2.7 Oe. In contrast, TmIG films of Fe deficiency showed in-plane magnetic anisotropy. The high quality sputtered TmIG films will be applied to heterostructures with TIs or metals with strong spin-orbit coupling for novel spintronics.

Influence of deposition temperature and amorphous carbon on microstructure and oxidation resistance of magnetron sputtered nanocomposite Crsbnd C films

NASA Astrophysics Data System (ADS)

Nygren, Kristian; Andersson, Matilda; Högström, Jonas; Fredriksson, Wendy; Edström, Kristina; Nyholm, Leif; Jansson, Ulf

2014-06-01

It is known that mechanical and tribological properties of transition metal carbide films can be tailored by adding an amorphous carbon (a-C) phase, thus making them nanocomposites. This paper addresses deposition, microstructure, and for the first time oxidation resistance of magnetron sputtered nanocomposite Crsbnd C/a-C films with emphasis on studies of both phases. By varying the deposition temperature between 20 and 700 °C and alternating the film composition, it was possible to deposit amorphous, nanocomposite, and crystalline Crsbnd C films containing about 70% C and 30% Cr, or 40% C and 60% Cr. The films deposited at temperatures below 300 °C were X-ray amorphous and 500 °C was required to grow crystalline phases. Chronoamperometric polarization at +0.6 V vs. Ag/AgCl (sat. KCl) in hot 1 mM H2SO4 resulted in oxidation of Crsbnd C, yielding Cr2O3 and C, as well as oxidation of C. The oxidation resistance is shown to depend on the deposition temperature and the presence of the a-C phase. Physical characterization of film surfaces show that very thin C/Cr2O3/Crsbnd C layers develop on the present material, which can be used to improve the oxidation resistance of, e.g. stainless steel electrodes.

MEMS sensor material based on polypyrrole carbon nanotube nanocomposite: film deposition and characterization

NASA Astrophysics Data System (ADS)

Teh, Kwok-Siong; Lin, Liwei

2005-11-01

Conductive polymer-based nanocomposite has been utilized as a MEMS sensing material via a one-step, selective on-chip deposition process at room temperature. A doped polypyrrole (PPy) variant synthesized by incorporating multi-walled carbon nanotube (MWCNT) into electropolymerized PPy has been shown to improve the sensing performance utilizing a two-terminal, micro-gap chemiresistor architecture. The dodecylbenzenesulfonate (DBS)-doped PPy-MWCNT nanocomposites are found to be responsive to oxidants, such as hydrogen peroxide (H2O2), and this effect can be extended to glucose detection using H2O2 as a proxy material. The oxidant sensing effect is demonstrated by subjecting a glucose oxidase (GOx)-laden PPy-MWCNT nanocomposite film to various concentrations of glucose solution. Such PPy-MWCNT nanocomposite, when applied in a chemiresistor configuration, obviates the need for reference electrode and electron mediators, by measuring the direct and reversible, oxidation-reduction induced conductivity change. Experimentally, GOx-laden, doped PPy-MWCNT is tested to be sensitive to glucose concentration up to 20 mM, which covers the physiologically important range for diabetics of 0-20 mM.

Transparent 'solution' of ultrathin magnesium hydroxide nanocrystals for flexible and transparent nanocomposite films.

PubMed

Wang, Jie-Xin; Sun, Qian; Chen, Bo; Wu, Xi; Zeng, Xiao-Fei; Zhang, Cong; Zou, Hai-Kui; Chen, Jian-Feng

2015-05-15

Transparent solutions of nanocrystals exhibit many unique properties, and are thus attractive materials for numerous applications. However, the synthesis of transparent nanocrystal solutions of magnesium hydroxide (MH) with wide applications is yet to be realized. Here, we report a facile two-step process, which includes a direct reactive precipitation in alcohol phase instead of aqueous phase combined with a successive surface modification, to prepare transparent alcohol solutions containing lamellar MH nanocrystals with an average size of 52 nm and an ultrathin thickness of 1-2 nm, which is the thinnest MH nanoplatelet reported in the literatures. Further, highly flexible and transparent nanocomposite films are fabricated with a solution mixing method by adding the transparent MH nanocrystal solutions into PVB solution. Considering the simplicity of the fabrication process, high transparency and good flexibility, this MH/polymer nanocomposite film is promising for flame-resistant applications in plastic electronics and optical devices with high transparency, such as flexible displays, optical filters, and flexible solar cells.

Stress-induced magnetic properties of PLD-grown high-quality ultrathin YIG films

NASA Astrophysics Data System (ADS)

Bhoi, Biswanath; Kim, Bosung; Kim, Yongsub; Kim, Min-Kwan; Lee, Jae-Hyeok; Kim, Sang-Koog

2018-05-01

Yttrium iron garnet (YIG:Y3Fe5O12) thin films were grown on (111) gadolinium gallium garnet (Gd3Ga5O12, GGG) substrates using pulsed-laser deposition under several different deposition and annealing conditions. X-ray diffraction measurements revealed that the crystallographical orientation of the YIG films is pseudomorphic to and the same as that of the GGG substrate, with a slight rhombohedral distortion along the surface normal. Furthermore, X-ray reciprocal space mapping evidenced that in-situ annealed YIG films during film growth are under compressive strain, whereas ex-situ annealed films have two different regions under compressive and tensile strain. The saturation magnetization ( 4 π M S ) of the films was found to vary, according to the deposition conditions, within the range of 1350 to 1740 G, with a very low coercivity of H C < 5 Oe. From ferromagnetic resonance (FMR) measurements, we estimated the effective saturation magnetization ( 4 π M e f f ) to be 1810 to 2530 G, which are larger than that of single crystalline bulk YIG (˜1750 G). Such high values of 4 π M e f f are attributable to the negative anisotropy field ( H U ) that increases in size with increasing compressive in-plane strain induced in YIG films. The damping constant ( α G ) of the grown YIG films was found to be quite sensitive to the strain employed. The lowest value of α G obtained was 2.8 × 10-4 for the case of negligible strain. These results suggest a means of tailoring H U and α G in the grown YIG films by the engineering of strain for applications in spintronics and magneto-optical devices.

Acetylene Gas-Sensing Properties of Layer-by-Layer Self-Assembled Ag-Decorated Tin Dioxide/Graphene Nanocomposite Film

PubMed Central

Jiang, Chuanxing; Yin, Nailiang; Yao, Yao; Shaymurat, Talgar; Zhou, Xiaoyan

2017-01-01

This paper demonstrates an acetylene gas sensor based on an Ag-decorated tin dioxide/reduced graphene oxide (Ag–SnO2/rGO) nanocomposite film, prepared by layer-by-layer (LbL) self-assembly technology. The as-prepared Ag–SnO2/rGO nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectrum. The acetylene sensing properties were investigated using different working temperatures and gas concentrations. An optimal temperature of 90 °C was determined, and the Ag–SnO2/rGO nanocomposite sensor exhibited excellent sensing behaviors towards acetylene, in terms of response, repeatability, stability and response/recovery characteristics, which were superior to the pure SnO2 and SnO2/rGO film sensors. The sensing mechanism of the Ag–SnO2/rGO sensor was attributed to the synergistic effect of the ternary nanomaterials, and the heterojunctions created at the interfaces between SnO2 and rGO. This work indicates that the Ag–SnO2/rGO nanocomposite is a good candidate for constructing a low-temperature acetylene sensor. PMID:28927021

The Enhancement Of UV Sensor Response By Zinc Oxide Nanorods / Reduced Graphene Oxide Bilayer Nanocomposites Film

NASA Astrophysics Data System (ADS)

Mohammed, Ali A. A.; Suriani, AB; Jabur, Akram R.

2018-05-01

Zinc oxide nanorods (ZnO NRs) / reduced graphene oxide (rGO) nanocomposites assisted by sodium dodecyl sulfate surfactant (ZnO NRs/rGO-SDS) showed a good response for UV sensor application that has sensitivity of around ∼32.54. Whereas, the UV sensor response on pristine ZnO NRs showed almost 15 times lower response than the ZnO NRs/rGO-SDS nanocomposites. The pristine ZnO NRs were prepared by sol-gel immersion method before rGO solution was sprayed on the ZnO films using spraying method. The GO solution was produced via electrochemical exfoliation method at 0.1 M SDS electrolyte then the solution was reduced using hydrazine hydrate under 24 hours magnetic stirring at a temperature of around ∼100 °C. The samples were characterized using energy dispersive X-ray, field emission scanning electron microscope, micro-Raman, ultraviolet visible, X-ray diffraction, UV lamp and four-point probe measurement. The aim of this study was to improve the UV sensor response based on ZnO/rGO-SDS nanocomposites. In conclusion, the fabricated ZnO NRs/rGO-SDS nanocomposites assisted with SDS is a good candidate for the use in UV sensor applications as compared to pristine ZnO NRs films.

PET based nanocomposite films for microwave packaging applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galdi, M. R., E-mail: mrgaldi@unisa.it; Olivieri, R.; Liguori, L.

In recent years, changes in life standards have promoted the diffusion of Ready to Cook (RTC) and Ready to Eat (RTE) products for microwave ovens. However, the main limits in microwave (MW) ovens usage are often related to the proper choice of packaging materials suitable for such technology. In fact, packages for microwaveable RTC and RTE foods should ensure adequate preservation of the product before cooking/heating such as high barriers to gases and aromas and adequate control of water vapor transmission. In addition, microwaveable packaging material must be transparent to MW, thermally stable and resistant to the mechanical stress inducedmore » by the accumulation in the head space of volatile substances produced during the cooking. Polymeric materials are good candidates for microwaveable packaging thanks to their transparency to MW. In the last years a great interest is devoted to developing innovative solution based on the use of additives or systems that act as susceptors or heating enhancers for improving the characteristics of polymers in cooking/heating in MW ovens. The present work was focused on the production and characterization of nanocomposite copolyester based films suitable for microwaveable food packaging applications. The matrices selected consist in two PET copolymers modified with carbon black (ULTRA STD) and with titanium oxide (ULTRA NA). Nanocomposite co-extruded multilayer films were produced using different percentages (0%, 2% and 4%wt/wt) of Cloisite 20A (C20A). Films were analyzed for evaluating the effect of nanofiller on the morphology and barrier properties. Moreover, to verify the effectiveness of the designed systems in reducing the cooking times of meat products, MW heating tests were carried out on pork meat hamburgers in MW oven at varying supplied powers. The cooking tests have pointed out that the selected matrices are efficient in reducing cooking times and that even low concentration of C20A acts as heating enhancers of

PET based nanocomposite films for microwave packaging applications

NASA Astrophysics Data System (ADS)

Galdi, M. R.; Olivieri, R.; Liguori, L.; Albanese, D.; Di Matteo, M.; Di Maio, L.

2015-12-01

In recent years, changes in life standards have promoted the diffusion of Ready to Cook (RTC) and Ready to Eat (RTE) products for microwave ovens. However, the main limits in microwave (MW) ovens usage are often related to the proper choice of packaging materials suitable for such technology. In fact, packages for microwaveable RTC and RTE foods should ensure adequate preservation of the product before cooking/heating such as high barriers to gases and aromas and adequate control of water vapor transmission. In addition, microwaveable packaging material must be transparent to MW, thermally stable and resistant to the mechanical stress induced by the accumulation in the head space of volatile substances produced during the cooking. Polymeric materials are good candidates for microwaveable packaging thanks to their transparency to MW. In the last years a great interest is devoted to developing innovative solution based on the use of additives or systems that act as susceptors or heating enhancers for improving the characteristics of polymers in cooking/heating in MW ovens. The present work was focused on the production and characterization of nanocomposite copolyester based films suitable for microwaveable food packaging applications. The matrices selected consist in two PET copolymers modified with carbon black (ULTRA STD) and with titanium oxide (ULTRA NA). Nanocomposite co-extruded multilayer films were produced using different percentages (0%, 2% and 4%wt/wt) of Cloisite 20A (C20A). Films were analyzed for evaluating the effect of nanofiller on the morphology and barrier properties. Moreover, to verify the effectiveness of the designed systems in reducing the cooking times of meat products, MW heating tests were carried out on pork meat hamburgers in MW oven at varying supplied powers. The cooking tests have pointed out that the selected matrices are efficient in reducing cooking times and that even low concentration of C20A acts as heating enhancers of PET.

Enhanced mechanical, thermal and antimicrobial properties of poly(vinyl alcohol)/graphene oxide/starch/silver nanocomposites films.

PubMed

Usman, Adil; Hussain, Zakir; Riaz, Asim; Khan, Ahmad Nawaz

2016-11-20

In the present work, synthesis of poly(vinyl alcohol)/graphene oxide/starch/silver (PVA/GO/Starch/Ag) nanocomposites films is reported. Such films have been characterized and investigated for their mechanical, thermal and antimicrobial properties. The exfoliation of GO in the PVA matrix occurs owing to the non-covalent interactions of the polymer chains of PVA and hydrophilic surface of the GO layers. Presence of GO in PVA and PVA/starch blends were found to enhance the tensile strength of the nanocomposites system. It was found that the thermal stability of PVA as well as PVA/starch blend systems increased by the incorporation of GO where strong physical bonding between GO layers and PVA/starch blends is assumed to cause thermal barrier effects. Antimicrobial properties of the prepared films were investigated against Escherichia coli and Staphylococcus aureus. Our results show enhanced antimicrobial properties of the prepared films where PVA-GO, PVA-Ag, PVA-GO-Ag and PVA-GO-Ag-Starch showed antimicrobial activity in ascending order. Copyright © 2016 Elsevier Ltd. All rights reserved.

Local electrical properties of thermally grown oxide films formed on duplex stainless steel surfaces

NASA Astrophysics Data System (ADS)

Guo, L. Q.; Yang, B. J.; He, J. Y.; Qiao, L. J.

2018-06-01

The local electrical properties of thermally grown oxide films formed on ferrite and austenite surfaces of duplex stainless steel at different temperatures were investigated by Current sensing atomic force microscopy, X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). The current maps and XPS/AES analyses show that the oxide films covering austenite and ferrite surfaces formed at different temperatures exhibit different local electrical characteristics, thickness and composition. The dependence of electrical conductivity of oxide films covering austenite and ferrite surface on the formation temperature is attributed to the film thickness and semiconducting structures, which is intrinsically related to thermodynamics and kinetics process of film grown at different temperature. This is well elucidated by corresponding semiconductor band structures of oxide films formed on austenite and ferrite phases at different temperature.

High barrier multilayer packaging by the coextrusion method: The effect of nanocomposites and biodegradable polymers on flexible film properties

NASA Astrophysics Data System (ADS)

Thellen, Christopher T.

The objective of this research was to investigate the use of nanocomposite and multilayer co-extrusion technologies for the development of high gas barrier packaging that is more environmentally friendly than many current packaging system. Co-extruded bio-based and biodegradable polymers that could be composted in a municipal landfill were one direction that this research was aimed. Down-gauging of high performance barrier films using nanocomposite technology and co-extrusion was also investigated in order to reduce the amount of solid waste being generated by the packaging. Although the research is focused on military ration packaging, the technologies could easily be introduced into the commercial flexible packaging market. Multilayer packaging consisting of poly(m-xylylene adipamide) nanocomposite layers along with adhesive and tie layers was co-extruded using both laboratory and pilot-scale film extrusion equipment. Co-extrusion of biodegradable polyhydroxyalkanoates (PHA) along with polyvinyl alcohol (PVOH) and tie layers was also accomplished using similar co-extrusion technology. All multilayer films were characterized for gas barrier, mechanical, and thermal properties. The biodegradability of the PVOH and PHA materials in a marine environment was also investigated. The research has shown that co-extrusion of these materials is possible at a research and pilot level. The use of nanocomposite poly(m-xylylene adipamide) was effective in down-gauging the un-filled barrier film to thinner structures. Bio-based PHA/PVOH films required the use of a malefic anhydride grafted PHA tie layer to improve layer to layer adhesion in the structure to avoid delamination. The PHA polymer demonstrated a high rate of biodegradability/mineralization in the marine environment while the rate of biodegradation of the PVOH polymer was slower.

Thermoluminescence of the Films, Nanocomposites, and Solutions of the Silicon Organic Polymer Poly(di- n-hexyl silane)

NASA Astrophysics Data System (ADS)

Ostapenko, N. I.; Kerita, O. A.; Ostapenko, Yu. V.

2018-03-01

A comparative study of low-temperature thermoluminescence (5-120 K) of silicon organic polymer poly(di-n-hexyl silane) films, nanocomposites (when the polymer is introduced into nanopores of silica MCM-41 and SBA-15 with diameter of pores 2.8 and 10 nm) as well as solutions of polymer in tetrahydrofuran with different concentrations from 10-3 to 10-5 mol/L was carried out. It was shown that it is possible to control the number of charge carrier traps, as well as their energy distribution by changing the diameter of silica nanopores. It is established that maxima and FWHMs of the thermoluminescence curves of nanocomposites significantly depend on the pore diameter of the nanoporous silica. This result agrees with the data obtained in the investigation of polymer solutions. In the nanocomposite with a minimum pore diameter (2.8 nm), the number and depth of the traps as well as dispersion of their energy are significantly reduced compared to their values in the polymer film.

Study of the structure of 3D-ordered macroporous GaN-ZnS:Mn nanocomposite films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kurdyukov, D. A., E-mail: kurd@gvg.ioffe.ru; Shishkin, I. I.; Grudinkin, S. A.

A film-type 3D-ordered macroporous GaN-ZnS:Mn nanocomposite with the structure of an inverted opal is fabricated. Structural studies of the nanocomposite are performed, and it is shown that GaN and ZnS:Mn introduced into the pores of the silica opal are nanocrystallites misoriented with respect to each other. It is shown that the nanocomposite is a structurally perfect 3D photonic crystal. The efficiency of using a buffer of GaN crystallites to preclude interaction between the surface of the spherical a-SiO{sub 2} particles forming the opal matrix and chemically active substances introduced into the pores is demonstrated.

Laser Deposition of Polymer Nanocomposite Thin Films and Hard Materials and Their Optical Characterization

DTIC Science & Technology

2013-12-05

visible light on instruments such as microscope tips and micro- surgical tools. Hard carbon known as diamond-like carbon films produced by pulsed laser ...visible (610 nm) LED source and a supplemental infra-red 980-nm laser diode (for the studies of the upconversion fluorescence). The basic package...5/2013 Final Performance Report 15 Sep 2012- 14 Sep 2013 LASER DEPOSITION OF POLYMER NANOCOMPOSITE THIN FILMS AND HARD MATERIALS AND THEIR OPTICAL

Structural and optical characteristics of GaAs films grown on Si/Ge substrates

NASA Astrophysics Data System (ADS)

Rykov, A. V.; Dorokhin, M. V.; Vergeles, P. S.; Baidus, N. V.; Kovalskiy, V. A.; Yakimov, E. B.; Soltanovich, O. A.

2018-03-01

A GaAs/AlAs heterostructure and a GaAs film grown on Si/Ge substrates have been fabricated and studied. A Ge buffer on a silicon substrate was fabricated using the MBE process. A3B5 films were grown by MOCVD at low pressures. Photoluminescence spectroscopy was used to define the optical quality of A3B5 films. Structural properties were investigated using the electron beam induced current method. It was established that despite a rather high density of dislocations on the epitaxial layers, the detected photoluminescence radiation of layers indicates the acceptable crystalline quality of the top GaAs layer.

Epitaxial titanium diboride films grown by pulsed-laser deposition

NASA Astrophysics Data System (ADS)

Zhai, H. Y.; Christen, H. M.; Cantoni, C.; Goyal, A.; Lowndes, D. H.

2002-03-01

Epitaxial, smooth, and low-resistivity titanium diboride (TiB2) films have been grown on SiC substrates using pulsed-laser deposition. Combined studies from ex situ x-ray diffraction and in situ reflection high-energy electron diffraction indicate the crystallographic alignment between TiB2 and SiC both parallel and normal to the substrate. Atomic force microscopy and scanning electron microscopy studies show that these epitaxial films have a smooth surface, and the resistivity of these films is comparable to that of single-crystal TiB2. Growth of these films is motivated by this material's structural and chemical similarity and lattice match to the newly discovered superconductor MgB2, both to gain further insight into the physical mechanisms of diborides in general and, more specifically, as a component of MgB2-based thin-film heterostructures.

Dielectric tunability of vertically aligned ferroelectric-metal oxide nanocomposite films controlled by out-of-plane misfit strain

NASA Astrophysics Data System (ADS)

Wu, Huaping; Ma, Xuefu; Zhang, Zheng; Zhu, Jun; Wang, Jie; Chai, Guozhong

2016-04-01

A nonlinear thermodynamic model based on the vertically aligned nanocomposite (VAN) thin films of ferroelectric-metal oxide system has been developed to investigate the physical properties of the epitaxial Ba0.6Sr0.4TiO3 (BST) films containing vertical Sm2O3 (SmO) nanopillar arrays on the SrTiO3 substrate. The phase diagrams of out-of-plane lattice mismatch vs. volume fraction of SmO are calculated by minimizing the total free energy. It is found that the phase transformation and dielectric response of BST-SmO VAN systems are extremely dependent on the in-plane misfit strain, the out-of-plane lattice mismatch, the volume fraction of SmO phase, and the external electric field applied to the nanocomposite films at room temperature. In particular, the BST-SmO VAN systems exhibit higher dielectric properties than pure BST films. Giant dielectric response and maximum tunability are obtained near the lattice mismatch where the phase transition occurs. Under the in-plane misfit strain of umf=0.3 % and the out-of-plane lattice mismatch of u3=0.002 , the dielectric tunability can be dramatically enhanced to 90% with the increase of SmO volume fraction, which is well consistent with previous experimental results. This work represents an approach to further understand the dependence of physical properties on the lattice mismatch (in-plane and out-of-plane) and volume fraction, and to manipulate or optimize functionalities in the nanocomposite oxide thin films.

Nucleant layer effect on nanocolumnar ZnO films grown by electrodeposition

NASA Astrophysics Data System (ADS)

Tolosa, Maria D. Reyes; Damonte, Laura C.; Brine, Hicham; Bolink, Henk J.; Hernández-Fenollosa, María A.

2013-03-01

Different ZnO nanostructured films were electrochemically grown, using an aqueous solution based on ZnCl2, on three types of transparent conductive oxides grow on commercial ITO (In2O3:Sn)-covered glass substrates: (1) ZnO prepared by spin coating, (2) ZnO prepared by direct current magnetron sputtering, and (3) commercial ITO-covered glass substrates. Although thin, these primary oxide layers play an important role on the properties of the nanostructured films grown on top of them. Additionally, these primary oxide layers prevent direct hole combination when used in optoelectronic devices. Structural and optical characterizations were carried out by scanning electron microscopy, atomic force microscopy, and optical transmission spectroscopy. We show that the properties of the ZnO nanostructured films depend strongly on the type of primary oxide-covered substrate used. Previous studies on different electrodeposition methods for nucleation and growth are considered in the final discussion.

Nucleant layer effect on nanocolumnar ZnO films grown by electrodeposition.

PubMed

Tolosa, Maria D Reyes; Damonte, Laura C; Brine, Hicham; Bolink, Henk J; Hernández-Fenollosa, María A

2013-03-23

Different ZnO nanostructured films were electrochemically grown, using an aqueous solution based on ZnCl2, on three types of transparent conductive oxides grow on commercial ITO (In2O3:Sn)-covered glass substrates: (1) ZnO prepared by spin coating, (2) ZnO prepared by direct current magnetron sputtering, and (3) commercial ITO-covered glass substrates. Although thin, these primary oxide layers play an important role on the properties of the nanostructured films grown on top of them. Additionally, these primary oxide layers prevent direct hole combination when used in optoelectronic devices. Structural and optical characterizations were carried out by scanning electron microscopy, atomic force microscopy, and optical transmission spectroscopy. We show that the properties of the ZnO nanostructured films depend strongly on the type of primary oxide-covered substrate used. Previous studies on different electrodeposition methods for nucleation and growth are considered in the final discussion.

Pulsed photoinitiated fabrication of inkjet printed titanium dioxide/reduced graphene oxide nanocomposite thin films.

PubMed

Bourgeois, Briley; Luo, Sijun; Riggs, Brian; Ji, Yaping; Adireddy, Shiva; Schroder, Kurt; Farnsworth, Stan; Chrisey, Douglas; Escarra, Matthew

2018-08-03

This work reports a new technique for scalable and low-temperature processing of nanostructured TiO 2 thin films, allowing for practical manufacturing of TiO 2 -based devices such as perovskite solar cells at low-temperature or on flexible substrates. Dual layers of dense and mesoporous TiO 2 /graphitic oxide nanocomposite films are synthesized simultaneously using inkjet printing and pulsed photonic irradiation. Investigation of process parameters including precursor concentration (10-20 wt%) and exposure fluence (4.5-8.5 J cm -2 ) reveals control over crystalline quality, graphitic oxide phase, film thickness, dendrite density, and optical properties. Raman spectroscopy shows the E g peak, characteristic of anatase phase titania, increases in intensity with higher photonic irradiation fluence, suggesting increased crystallinity through higher fluence processing. Film thickness and dendrite density is shown to increase with precursor concentration in the printed ink. The dense base layer thickness was controlled between 20 and 80 nm. The refractive index of the films is determined by ellipsometry to be 1.92 ± 0.08 at 650 nm. Films exhibit an energy weighted optical transparency of 91.1%, in comparison to 91.3% of a thermally processed film, when in situ carbon materials were removed. Transmission and diffuse reflectance are used to determine optical band gaps of the films ranging from 2.98 to 3.38 eV in accordance with the photonic irradiation fluence and suggests tunability of TiO 2 phase composition. The sheet resistance of the synthesized films is measured to be 14.54 ± 1.11 Ω/□ and 28.90 ± 2.24 Ω/□ for films as-processed and after carbon removal, respectively, which is comparable to high temperature processed TiO 2 thin films. The studied electrical and optical properties of the light processed films show comparable results to traditionally processed TiO 2 while offering the distinct advantages of scalable manufacturing, low-temperature processing

Positronium formation in SiO2 films grown on Si substrates studied by monoenergetic positron beams

NASA Astrophysics Data System (ADS)

Uedono, A.; Wei, L.; Tanigawa, S.; Suzuki, R.; Ohgaki, H.; Mikado, T.; Kawano, T.; Ohji, Y.

1994-04-01

The annihilation characteristics of positrons in SiO2 films grown on Si substrates were studied by using monoenergetic positron beams. Doppler broadening profiles of the annihilation radiation and lifetime spectra of positrons were measured as a function of incident positron energy for SiO2 (166 nm)/Si specimens fabricated by thermal oxidation. From the measurements, it was found that about 90% of positrons implanted into the SiO2 film annihilate from positronium (Ps) states. This fact was due to the trapping of positrons by open-space defects and a resultant enhanced formation of Ps in such regions. For the SiO2 film grown at 650 °C, the lifetime of ortho-Ps was found to be shorter than that in the film grown at 1000 °C. This result suggests that the volume of open-space defects in the SiO2 film decreased with decreasing the growth rate of the SiO2 film.

Structural and optical characterization of NiSe film grown by screen-printing method

NASA Astrophysics Data System (ADS)

Sharma, Kapil; Sharma, D. K.; Dwivedi, D. K.; Kumar, Vipin

2018-05-01

In present investigation NiSe films were grown by economical screen-printing method. Optimum conditions for growing good quality screen-printed films were found. The films were characterized for their structural and optical properties. The polycrystalline nature of films with hexagonal structure was confirmed through XRD analysis. Direct type of optical band gap of 1.75 eV for the NiSe film was confirmed by optical characterization.

Chitosan nanocomposite films: enhanced electrical conductivity, thermal stability, and mechanical properties.

PubMed

Marroquin, Jason B; Rhee, K Y; Park, S J

2013-02-15

A novel, high-performance Fe(3)O(4)/MWNT/Chitosan nanocomposite has been prepared by a simple solution evaporation method. A significant synergistic effect of Fe(3)O(4) and MWNT provided enhanced electrical conductivity, mechanical properties, and thermal stability on the nanocomposites. A 5% (wt) loading of Fe(3)O(4)/MWNT in the nanocomposite increased conductivity from 5.34×10(-5) S/m to 1.49×10(-2) S/m compared to 5% (wt) MWNT loadings. The Fe(3)O(4)/MWNT/Chitosan films also exhibited increases in tensile strength and modulus of 70% and 155%, respectively. The integral procedure decomposition temperature (IPDT) was enhanced from 501 °C to 568 °C. These effects resulted from a number of factors: generation of a greater number of conductive channels through interactions between MWNT and Fe(3)O(4) surfaces, a higher relative crystallinity, the antiplasticizing effects of Fe(3)O(4), a restricted mobility and hindrance of depolymerization of the Chitosan chain segments, as well as uniform distribution, improved dispersion, and strong interfacial adhesion between the MWNT and Chitosan matrix. Copyright © 2012 Elsevier Ltd. All rights reserved.

Metal-insulator transition characteristics of VO2 thin films grown on Ge(100) single crystals

NASA Astrophysics Data System (ADS)

Yang, Z.; Ko, C.; Ramanathan, S.

2010-10-01

Phase transitions exhibited by correlated oxides could be of potential relevance to the emerging field of oxide electronics. We report on the synthesis of high-quality VO2 thin films grown on single crystal Ge(100) substrates by physical vapor deposition and their metal-insulator transition (MIT) properties. Thermally triggered MIT is demonstrated with nearly three orders of magnitude resistance change across the MIT with transition temperatures of 67 °C (heating) and 61 °C (cooling). Voltage-triggered hysteretic MIT is observed at room temperature at threshold voltage of ˜2.1 V for ˜100 nm thickness VO2 films. Activation energies for electron transport in the insulating and conducting states are obtained from variable temperature resistance measurements. We further compare the properties of VO2 thin films grown under identical conditions on Si(100) single crystals. The VO2 thin films grown on Ge substrate show higher degree of crystallinity, slightly reduced compressive strain, larger resistance change across MIT compared to those grown on Si. Depth-dependent x-ray photoelectron spectroscopy measurements were performed to provide information on compositional variation trends in the two cases. These results suggest Ge could be a suitable substrate for further explorations of switching phenomena and devices for thin film functional oxides.

Superconducting properties of Nb-Cu nano-composites and nano-alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parab, Pradnya, E-mail: pradnyaprb@gmail.com; Kumar, Sanjeev; Bhui, Prabhjyot

The evolution of the superconducting transition temperature (T{sub c}) in nano-composite and nano-alloys of Nb-Cu, grown by DC magnetron co-sputtering are investigated. Microstructure of these films depends less strongly on the ratio of Nb:Cu but more on the growth temperature. At higher growth temperature, phase separated granular films of Nb and Cu were formed which showed superconducting transition temperatures (T{sub c}) of ~ 7.2±0.5 K, irrespective of the composition. Our results show that this is primarily influenced by the microstructure of the films determined during growth which rules out the superconducting proximity effect expected in these systems. At room temperaturemore » growth, films with nano-scale alloying were obtained at the optimal compositional range of 45-70 atomic% (At%) of Nb. These were also superconducting with a T{sub c} of 3.2 K.« less

Innovative Linear Low Density Polyethylene Nanocomposite Films Reinforced with Organophilic Layered Double Hydroxides: Fabrication, Morphology and Enhanced Multifunctional Properties.

PubMed

Xie, Jiazhuo; Wang, Haijun; Wang, Zhou; Zhao, Qinghua; Yang, Yuechao; Waterhouse, Geoffrey I N; Hao, Lei; Xiao, Zihao; Xu, Jing

2018-01-08

Herein, we reported the successful development of novel nanocomposite films based on linear low density polyethylene (LLDPE) with enhanced anti-drop, optical, mechanical, thermal and water vapor barrier properties by introducing organophilic layered double hydroxides (OLDHs) nanosheets. OLDHs loadings were varied from 0-6 wt.%. Structural analyses using the Fourier transform infrared spectrum (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) indicated that the OLDHs nanosheets were homogeneously dispersed with an ordered alignment in the LLDPE matrix. The LLDPE film containing 2 wt.% OLDHs (denoted as OLDHs-2) showed the optimal mechanical, thermal and water vapor barrier properties, whilst the anti-drop and optical performance of the films improved with increasing OLDHs content. The enhanced antidrop properties of the composite films relative to pristine LLDPE can be expected to effectively reduce agricultural losses to disease when the films are applied as agricultural films, whilst the superior light transmittance and water-retaining properties of the composite films will boost agricultural production. Results presented suggest that multifunctional LLDPE/OLDHs nanocomposites show great promise as low cost agricultural plastic films.

Nanocrystal-polymer nanocomposite electrochromic device

DOEpatents

Milliron, Delia; Runnerstrom, Evan; Helms, Brett; Llordes, Anna; Buonsanti, Raffaella; Garcia, Guillermo

2015-12-08

Described is an electrochromic nanocomposite film comprising a solid matrix of an oxide based material, the solid matrix comprising a plurality of transparent conducting oxide (TCO) nanostructures dispersed in the solid matrix and a lithium salt dispersed in the solid matrix. Also described is a near infrared nanostructured electrochromic device having a functional layer comprising the electrochromic nanocomposite film.

Effect of Hydrogen in Zinc Oxide Thin-Film Transistor Grown by Metal Organic Chemical Vapor Deposition

NASA Astrophysics Data System (ADS)

Jo, Jungyol; Seo, Ogweon; Jeong, Euihyuk; Seo, Hyunseok; Lee, Byeongon; Choi, Yearn-Ik

2007-04-01

We studied the transport characteristics of ZnO grown by metal organic chemical vapor deposition (MOCVD) at temperatures between 200 and 500 °C. The crystal quality, measured by X-ray diffraction, improved as the growth temperature increased. However, the mobility measured in the thin-film transistor (TFT) decreased in films grown at higher temperatures. In our experiments, a ZnO TFT grown at 250 °C showed good electrical characteristics, with a 13 cm2 V-1 s-1 mobility and a 103 on/off ratio. We conclude that hydrogen incorporated during MOCVD growth plays an important role in determining the transistor characteristics. This was supported by results of secondary ion mass spectroscopy (SIMS), where a higher hydrogen concentration was observed in films grown at lower temperatures.

Development of silane grafted ZnO core shell nanoparticles loaded diglycidyl epoxy nanocomposites film for antimicrobial applications.

PubMed

Suresh, S; Saravanan, P; Jayamoorthy, K; Ananda Kumar, S; Karthikeyan, S

2016-07-01

In this article a series of epoxy nanocomposites film were developed using amine functionalized (ZnO-APTES) core shell nanoparticles as the dispersed phase and a commercially available epoxy resin as the matrix phase. The functional group of the samples was characterized using FT-IR spectra. The most prominent peaks of epoxy resin were found in bare epoxy and in all the functionalized ZnO dispersed epoxy nanocomposites (ZnO-APTES-DGEBA). The XRD analysis of all the samples exhibits considerable shift in 2θ, intensity and d-spacing values but the best and optimum concentration is found to be 3% ZnO-APTES core shell nanoparticles loaded epoxy nanocomposites supported by FT-IR results. From TGA measurements, 100wt% residue is obtained in bare ZnO nanoparticles whereas in ZnO core shell nanoparticles grafted DGEBA residue percentages are 37, 41, 45, 46 and 52% for 0, 1, 3, 5 and 7% ZnO-APTES-DGEBA respectively, which is confirmed with ICP-OES analysis. From antimicrobial activity test, it was notable that antimicrobial activity of 7% ZnO-APTES core shell nanoparticles loaded epoxy nanocomposite film has best inhibition zone effect against all pathogens under study. Copyright © 2016 Elsevier B.V. All rights reserved.

Plasma - enhanced dispersion of metal and ceramic nanoparticles in polymer nanocomposite films

NASA Astrophysics Data System (ADS)

Maguire, Paul; Liu, Yazi; Askari, Sadegh; Patel, Jenish; Macia-Montero, Manuel; Mitra, Somak; Zhang, Richao; Sun, Dan; Mariotti, Davide

2015-09-01

In this work we demonstrate a facile method to synthesize a nanoparticle/PEDOT:PSS hybrid nanocomposite material in aqueous solution through atmospheric pressure direct current (DC) plasma processing at room temperature. Both metal (Au) and ceramic (TiO2) nanoparticle composite films have been fabricated. Nanoparticle dispersion is enhanced considerable and remains stable. TiO2/polymer hybrid nanoparticles with a distinct core shell structure have been obtained. Increased nanoparticle/PEDOT:PSS nanocomposite electrical conductivity has been observed. The improvement in nanocomposite properties is due to the enhanced dispersion and stability in liquid polymer of microplasma processed Au or TiO2 nanoparticles. Both plasma induced surface charge and nanoparticle surface termination with specific plasma chemical species are thought to provide an enhanced barrier to nanoparticle agglomeration and promote nanoparticle-polymer bonding. This is expected to have a significant benefit in materials processing with inorganic nanoparticles for applications in energy storage, photocatalysis and biomedical sensors. Engineering and Physical Sciences Research Council (EPSRC: EP/K006088/1, EP/K006142, Nos. EP/K022237/1).

BaTiO3/PVDF Nanocomposite Film with High Energy Storage Density

NASA Astrophysics Data System (ADS)

Wang, Xiaohui

2016-03-01

A gradated multilayer BaTiO3/poly(vinylidenefluoride) thin film structure is presented to achieve both a higher breakdown strength and a superior energy-storage capability. Key to the process is the sequential deposition of uniform dispersions of the single component source, which generate a blended PVDF-BTO-PVDF structure prior to full evaporation of solvent, and thermal treatment of the dielectric. The result is like sandwich structure with partial 0-3 character. The central layer designed to provide the high electric displacement, is composed of high volume fraction 6-10 nm BTO nanocrystals produced by a TEG-sol method. The outer layers of the structure are predominantly PVDF, with a significantly lower volume fraction of BTO, taking advantage of the higher dielectric strength for pure PVDF at the electrode-nanocomposite interface. The film is mechanically flexible, and can be removed from the substrate, with total thicknesses in the range 1.2 - 1.5 μm. Parallel plate capacitance devices improved dielectric performances, compared to reported values for BTO-PVDF 0-3 nanocomposites, with a maximal discharged energy density of 19.4J/cm3 and dielectric breakdown strengths of up to 495 kV/mm.

Epitaxial YBa2Cu3O7-x nanocomposite films and coated conductors from BaMO3 (M = Zr, Hf) colloidal solutions

NASA Astrophysics Data System (ADS)

Obradors, X.; Puig, T.; Li, Z.; Pop, C.; Mundet, B.; Chamorro, N.; Vallés, F.; Coll, M.; Ricart, S.; Vallejo, B.; Pino, F.; Palau, A.; Gázquez, J.; Ros, J.; Usoskin, A.

2018-04-01

Superconducting nanocomposites are the best material choice to address the performance required in power applications and magnets working under high magnetic fields. However, it is still challenging to sort out how to achieve the highest superconducting performance using attractive and competitive manufacturing processes. Colloidal solutions have been recently developed as a novel and very promising low cost route to manufacture nanocomposite coated conductors. Well dispersed and stabilized preformance nanoparticle solutions are first prepared with high concentrations and then mixed with the YBa2Cu3O7 metalorganic precursor solutions to generate colloidal solutions to grow the nanocomposite films. Here we demonstrate, for the first time, that non-reactive BaZrO3 and BaHfO3 perovskite preformed nanoparticles are suitable for growing high quality thin and thick films, and coated conductors with a homogeneous distribution and controlled particle size using this fabrication method. Additionally, we extend the nanoparticle content of the nanocomposites up to 20%-25% mol without any degradation of the superconducting properties. Thick nanocomposite films, up to 0.8 μm, have been prepared with a single deposition of low-fluorine solutions using an ink jet printing dispenser and we demonstrate that the preformed nanoparticles display only a very limited coarsening during the growth process and so high critical current densities J c (B) under high magnetic fields. These films show the highest critical currents achieved so far based on the colloidal solution approach, I c = 220 A/cm-w at 77 K and self-field, and they still have a high potential for further increase in the film thickness. Finally, we also show that nanocomposite YBa2Cu3O7-BaZrO3 coated conductors based on an alternating beam assisted deposited YSZ buffer layer on stainless steel metallic substrates can be developed based on these novel colloidal solutions. Non-reactive preformed oxide perovskite

Nucleant layer effect on nanocolumnar ZnO films grown by electrodeposition

PubMed Central

2013-01-01

Different ZnO nanostructured films were electrochemically grown, using an aqueous solution based on ZnCl2, on three types of transparent conductive oxides grow on commercial ITO (In2O3:Sn)-covered glass substrates: (1) ZnO prepared by spin coating, (2) ZnO prepared by direct current magnetron sputtering, and (3) commercial ITO-covered glass substrates. Although thin, these primary oxide layers play an important role on the properties of the nanostructured films grown on top of them. Additionally, these primary oxide layers prevent direct hole combination when used in optoelectronic devices. Structural and optical characterizations were carried out by scanning electron microscopy, atomic force microscopy, and optical transmission spectroscopy. We show that the properties of the ZnO nanostructured films depend strongly on the type of primary oxide-covered substrate used. Previous studies on different electrodeposition methods for nucleation and growth are considered in the final discussion. PMID:23522332

Bio-active nanocomposite films based on nanocrystalline cellulose reinforced styrylquinoxalin-grafted-chitosan: Antibacterial and mechanical properties.

PubMed

Fardioui, Meriem; Meftah Kadmiri, Issam; Qaiss, Abou El Kacem; Bouhfid, Rachid

2018-07-15

In this study, active nanocomposite films based on cellulose nanocrystalline (NCC) reinforced styrylquinoxalin-grafted-chitosan are prepared by solvent-casting process. The structures of the two styrylquinoxaline derivatives were confirmed by FT-IR, 1 H, 13 C NMR spectral data and the study of the antibacterial activity against Escherichia coli (EC), Staphylococcus aureus (SA), Bacillus subtilis (BS) and Pseudomonas Aeruginosa (PA) exhibits that they have a good antibacterial activity against (PA). On their side, the styrylquinoxalin-g-chitosan films are able to inhibit the growth of (PA) through their contact area without being damaged by the antibacterial test conditions. The addition of 5wt% of NCCs as nano-reinforcements revealed no change at the level of antibacterial activity but led to an important improvement of the mechanical properties (more than 60% and 90% improvement in Young's modulus and tensile strength, respectively) of the modified-chitosan films. Thereby, the present nanocomposite films are prepared by a simple way and featured by good mechanical and antibacterial properties which enhance the possibility to use them as bio-based products for biomedical and food packaging. Copyright © 2018 Elsevier B.V. All rights reserved.

Chemical Synthesis and Optical Properties of CdS Poly(Lactic Acid) Nanocomposites and Their Transparent Fluorescent Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Cai-Feng; Cheng, Yu-Peng; Xie, He-Yi

2011-01-01

This paper describes the chemical synthesis of cadmium sulfide (CdS) polymer nanocomposites by covalently grafting poly(lactic acid) (PLA) onto the surfaces of CdS nanocrystals (NCs). Synthesis of the nanocomposites involved two steps. Lactic acid (LA) capped CdS NCs were first prepared by reacting cadmium chloride (CdCl2) with sodium sulfide (Na2S) using LA as the organic ligand in H2O/N,N-dimethylformamide (DMF) solution. Next CdS PLA nanocomposites were formed by in situ ring-opening polymerization of lactide on the surface of modified CdS NCs. Transparent fluorescent films were then successfully prepared by blending as-prepared CdS PLA nanocomposites with high-molecular-weight PLA. The as-prepared CdS NCsmore » and their nanocomposites were studied by transmission electron microscopic imaging, thermogravimetric analyses, and spectroscopic measurements (ultraviolet-visible absorption and photoluminescence). The spectroscopic studies revealed that the CdS polymer nanocomposites exhibited good optical properties in terms of their photoluminescence and transparency.« less

Active nanocomposite films based on soy proteins-montmorillonite- clove essential oil for the preservation of refrigerated bluefin tuna (Thunnus thynnus) fillets.

PubMed

Echeverría, Ignacio; López-Caballero, María Elvira; Gómez-Guillén, María Carmen; Mauri, Adriana Noemi; Montero, María Pilar

2018-02-02

This manuscript evaluates the potential application of active nanocomposite films based on soy protein isolate (SPI)-montmorillonite (MMT)-clove essential oil (CEO) to the preservation of muscle fillets of bluefin tuna (Thunnus thynnus) during refrigerated storage, and furthermore analyzes whether the clay diffuses from the package to food. SPI films with: CEO (SPI-CEO), MMT (SPI-MMT), or both CEO and MMT (SPI-MMT-CEO), were prepared and used to cover tuna fillets during 17days of storage at 2°C. Polyethylene films were also used as control. Protein films nanoreinforced with 10g MMT/100g SPI and activated with CEO were able to decrease microbial growth (evaluated by TVBN and microorganism counts) and lipid autooxidation (evaluated according to the TBA index, FTIR and color parameters) of tuna fillets during the storage period studied. The presence of clay seemed to favor the release of the active principles of clove oil by prolonging its antimicrobial (especially effective to inhibit Pseudomonas spp.) and antioxidant activity over time without observing the diffusion of the clay's own metals (Si and Al) from the nanocomposite materials to the muscle of fish. These results are encouraging for the use of nanocomposite films in food packaging. Copyright © 2017 Elsevier B.V. All rights reserved.

Characteristics of Fluorine-doped tin oxide thin films grown by Streaming process for Electrodeless Electrochemical Deposition

NASA Astrophysics Data System (ADS)

Yusuf, Gbadebo; Khalilzadeh-Rezaie, Farnood; Cleary, Justin W.; Oladeji, Isaiah O.; Suu, Koukou; Schoenfeld, Winston V.; Peale, Robert E.; Awodugba, Ayodeji O.

2015-04-01

This work investigated the characteristics of SnO2: F films grown by Streaming Process for Electrodeless Electrochemical Deposition (SPEED). Stannic chloride (SnCl4) and ammonium fluoride (NH4 F) was dissolved in a mixture of deionized water and organic solvents. The preheated substrate temperature was varied between 450 and 530° C. High quality SnO2: F films were grown at all the substrate temperatures studied. The typical film thickness was 250 nm. XRD shows that the grown films are polycrystalline SnO2 with a tetragonal crystal structure. The average optical transmission of the films was around 93% throughout the wavelength of 400 to 1000 nm. The lowest electrical resistivity achieved was 6 x 10-4 Ω cm. The Hall measurements showed that the film is an n-type semiconductor, with the highest carrier mobility of 8.3 cm2/V.s, and concentration of 1 x 1021 cm-3. The direct band gap was determined to be 4 eV from the transmittance spectrum.

Chitosan nanocomposite films based on Ag-NP and Au-NP biosynthesis by Bacillus Subtilis as packaging materials.

PubMed

Youssef, Ahmed M; Abdel-Aziz, Mohamed S; El-Sayed, Samah M

2014-08-01

Chitosan-silver (CS-Ag) and Chitosan-gold (CS-Au) nanocomposites films were synthesized by a simple chemical method. A local bacterial isolate identified as Bacillus subtilis ss subtilis was found to be capable to synthesize both silver nanoparticles (Ag-NP) and gold nanoparticles (Au-NP) from silver nitrate (AgNO3) and chloroauric acid (AuCl(4-)) solutions, respectively. The biosynthesis of both Ag-NP and Au-NP characterize using UV/vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD), and then added to chitosan by different ratios (0.5, 1 and 2%). The prepared chitosan nanocomposites films were characterize using UV, XRD, SEM and TEM. Moreover, the antibacterial activity of the prepared films was evaluated against gram positive (Staphylococcus aureus) and gram negative bacteria (Pseudomonas aerugenosa), fungi (Aspergillus niger) and yeast (Candida albicans). Therefore, these materials can be potential used as antimicrobial agents in packaging applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Oxide Ceramic Films Grown on 60 Nitinol for NASA and Department of Defense Applications

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa; Street, Kenneth W.; Lukco, Dorothy; Cytron, Sheldon J.

2005-01-01

Both the NASA Glenn Research Center and the U.S. Army Research Laboratory, Development and Engineering Center (ARDEC) have worked to develop oxide ceramic films grown on 60 nitinol (60-wt% nickel and 40-wt% titanium) to decrease friction and increase wear resistance under unlubricated conditions. In general, oxide and nonoxide ceramic films have unique capabilities as mechanical-, chemical-, and thermal-barrier materials in diverse applications, including high-temperature bearings and gas bearings requiring low friction, wear resistance, and chemical stability. All oxide ceramic films grown on 60 nitinol were furnished by ARDEC, and materials and surface characterization and tribological experiments were conducted at Glenn.

Effects of nanoclay type on the physical and antimicrobial properties of PVOH-based nanocomposite films

USDA-ARS?s Scientific Manuscript database

Polyvinyl alcohols-based nanocomposite films were fabricated with four types of montmorillonite (MMT) nanoclay, including 18-amino stearic acid (I.24TL), methyl, bis hydroxyethyl, octadecyl ammonium (I.34TCN), di-methyl, di-hydrogenated tallow ammonium/siloxane (I.44PSS) organically modified MMT, an...

AC/DC electrical conduction and dielectric properties of PMMA/PVAc/C60 down-shifting nanocomposite films

NASA Astrophysics Data System (ADS)

El-Bashir, S. M.; Alwadai, N. M.; AlZayed, N.

2018-02-01

Polymer nanocomposite films were prepared by doping fullerene C60 in polymer blend composed of polymethacrylate/polyvinyl acetate blends (PMMA/PVAc) using solution cast technique. The films were characterized by differential scanning calorimeter (DSC), Transmission electron microscope (TEM), DC/AC electrical conductivity and dielectric measurements in the frequency range (100 Hz- 1 MHz). The glass transition temperature, Tg, was increased by increasing the concentration of fullerene C60; this property reflects the increase of thermal stability by increasing the nanofiller content. The DC and AC electrical conductivities were enhanced by increasing C60 concentration due to the electron hopping or tunneling between filled and empty localized states above Tg. The relaxation time was determined from the αβ -relaxations and found to be attenuated by increasing the temperature as a typical behavior of amorphous polymers. The calculated values of thermodynamic parameters revealed the increase of molecular stability by increasing the doping concentration; this feature supports the application of PMMA/PVAc/C60 nanocomposite films in a wide scale of solar energy conversion applications such as luminescent down-shifting (LDS) coatings for photovoltaic cells.

New strain states and radical property tuning of metal oxides using a nanocomposite thin film approach

DOE PAGES

MacManus-Driscoll, Judith; Suwardi, Ady; Kursumovic, Ahmed; ...

2015-05-05

Auxetic-like strain states were generated in self-assembled nanocomposite thin films of (Ba 0.6Sr 0.4TiO 3) 1–x – (Sm 2O 3) x(BSTO – SmO). A switch from auxetic-like to elastic-like strain behavior was observed for x > 0.50, when the SmO switched from being nanopillars in the BSTO matrix to being the matrix with BSTO nanopillars embedded in it. A simple model was adopted to explain how in-plane strain varies with x. At high x (0.75), strongly enhanced ferroelectric properties were obtained compared to pure BSTO films. Furthermore, the nanocomposite method represents a powerful new way to tune the properties ofmore » a wide range of strongly correlated metal oxides whose properties are very sensitive to strain.« less

Electric Transport Phenomena of Nanocomposite Organic Polymer Thin Films

NASA Astrophysics Data System (ADS)

Jira, Nicholas C.; Sabirianov, Ildar; Ilie, Carolina C.

We discuss herein the nanocomposite organic thin film diodes for the use of plasmonic solar cells. This experimental work follows the theoretical calculations done for plasmonic solar cells using the MNPBEM toolbox for MatLab. These calculations include dispersion curves and amount of light scattering cross sections for different metallic nanoparticles. This study gives us clear ideas on what to expect from different metals, allowing us to make the best choice on what to use to obtain the best results. One specific technique for light trapping in thin films solar cells utilizes metal nanoparticles on the surface of the semiconductor. The characteristics of the metal, semiconductor interface allows for light to be guided in between them causing it to be scattered, allowing for more chances of absorption. The samples were fabricated using organic thin films made from polymers and metallic nanoparticles, more specifically Poly(1-vinylpyrrolidone-co-2-dimethylaminoethyl methacrylate) copolymer and silver or gold nanoparticles. The two fabrication methods applied include spin coating and Langmuir-Blodgett technique. The transport properties are obtained by analyzing the I-V curves. We will also discuss the resistance, resistivity, conductance, density of charge carriers. SUNY Oswego SCAC Grant.

Manipulation of ZnO composition affecting electrical properties of MEH-PPV: ZnO nanocomposite thin film via spin coating for OLEDs application

NASA Astrophysics Data System (ADS)

Azhar, N. E. A.; Shariffudin, S. S.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

2018-05-01

Recent investigations of the promising materials for optoelectronic have been demonstrated by introducing n-type inorganic material into conjugated polymer. Morphology, optical and electrical of nanocomposites thin films based on poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) and zinc oxide (ZnO) nanotetrapods with various ZnO composition (0 wt% to 0.4 wt%) have been investigated. The MEH-PPV: ZnO nanocomposite thin film was deposited using spin-coating method. Surface morphology was characterized using field emission scanning electron microscopy and shows the uniform dispersion of MEH-PPV and ZnO phases for sample deposited at 0.2 wt%. The photoluminescence (PL) spectra shows the visible emission intensities increased when the ZnO composition increased. The current-voltage (I-V) measurement shows the highest conductivity of nanocomposite thin film deposited at 0.2 wt% of ZnO is 7.40 × 10-1 S. cm-1. This study will provide better performance and suitable for optoelectronic device especially OLEDs application.

High frequency capacitance-voltage characteristics of thermally grown SiO2 films on beta-SiC

NASA Technical Reports Server (NTRS)

Tang, S. M.; Berry, W. B.; Kwor, R.; Zeller, M. V.; Matus, L. G.

1990-01-01

Silicon dioxide films grown under dry and wet oxidation environment on beta-SiC films have been studied. The beta-SiC films had been heteroepitaxially grown on both on-axis and 2-deg off-axis (001) Si substrates. Capacitance-voltage and conductance-voltage characteristics of metal-oxide-semiconductor structures were measured in a frequency range of 10 kHz to 1 MHz. From these measurements, the interface trap density and the effective fixed oxide charge density were observed to be generally lower for off-axis samples.

Au-C allotrope nano-composite films at extreme conditions generated by intense ultra-short laser

NASA Astrophysics Data System (ADS)

Khan, Saif A.; Saravanan, K.; Tayyab, M.; Bagchi, S.; Avasthi, D. K.

2016-07-01

Structural evolution of gold-carbon allotrope nano-composite films under relativistically intense, ultra-short laser pulse irradiation is studied in this work. Au-C nano-composite films, having 4 and 10 at.% of Au, were deposited by co-sputtering technique on silicon substrates. Au-C60 NC films with 2.5 at.% Au were deposited on 12 μm thick Al foil using co-evaporation technique. These samples were radiated with single pulse from 45 fs, 10 TW Ti:Sapphire Laser at RRCAT at an intensity of 3 × 1018 W cm-2. The morphological and compositional changes were investigated using scanning electron microscopy (SEM) and Rutherford back-scattering spectrometry (RBS) techniques. Laser pulse created three morphologically distinct zones around the point of impact on samples with silicon substrates. The gold content in 600 μm circular region around a point of impact is found to reduce by a factor of five. Annular rings of ∼70 nm in diameter were observed in case of Au-C NC film after irradiation. Laser pulse created a hole of about 400 μm in the sample with Al foil as substrate and wavy structures of 6 μm wavelength are found to be created around this hole. The study shows radial variation in nano-structure formation with varying local intensity of laser pulse.

Structure-processing-property correlations in thin films of conjugated polymer nanocomposites and blends

NASA Astrophysics Data System (ADS)

Sreeram, Arvind

(IL) could be obtained in a single step reaction. The incorporation of IL in the film, not only greatly improved its mechanical properties, by acting as a plasticizer, but also imparted a dual mechanism of charge transport. The segments of conjugated double bonds imparted electronic conductivity to the films, and the IL resulted in ionic conductivity. The presence of both electronic and ionic conduction pathways in the films was confirmed by electrochemical impedance spectroscopy (EIS). These IL-imbibed conjugated polymer films are promising as materials for electrochemical energy conversion and storage. In the third part of this work, conjugated polymer films containing multiwalled carbon nanotubes (MWNT) and graphene nanoplatelets (GNP) were synthesized and characterized. PPV--MWNT nanocomposite films and PA--GNP nanocomposite films were characterized using a variety of analytical techniques including transmission electron microscopy, quasistatic and dynamic nanoindentaiton, electrochemical impedance spectroscopy, and cyclic voltammetry. Potential application of these films is in electrochemical supercapacitors.

QCM gas sensor characterization of ALD-grown very thin TiO2 films

NASA Astrophysics Data System (ADS)

Boyadjiev, S.; Georgieva, V.; Vergov, L.; Szilágyi, I. M.

2018-03-01

The paper presents a technology for preparation and characterization of titanium dioxide (TiO2) thin films suitable for gas sensor applications. Applying atomic layer deposition (ALD), very thin TiO2 films were deposited on quartz resonators, and their gas sensing properties were studied using the quartz crystal microbalance (QCM) method. The TiO2 thin films were grown using Ti(iOPr)4 and water as precursors. The surface of the films was observed by scanning electron microscopy (SEM), coupled with energy dispersive X-ray analysis (EDX) used for a composition study. The research was focused on the gas-sensing properties of the films. Films of 10-nm thickness were deposited on quartz resonators with Au electrodes and the QCMs were used to build highly sensitive gas sensors, which were tested for detecting NO2. Although very thin, these ALD-grown TiO2 films were sensitive to NO2 already at room temperature and could register as low concentrations as 50 ppm, while the sorption was fully reversible, and the sensors could be fully recovered. With the technology presented, the manufacturing of gas sensors is simple, fast and cost-effective, and suitable for energy-effective portable equipment for real-time environmental monitoring of NO2.

Stress transfer and matrix-cohesive fracture mechanism in microfibrillated cellulose-gelatin nanocomposite films.

PubMed

Quero, Franck; Padilla, Cristina; Campos, Vanessa; Luengo, Jorge; Caballero, Leonardo; Melo, Francisco; Li, Qiang; Eichhorn, Stephen J; Enrione, Javier

2018-09-01

Microfibrillated cellulose (MFC) obtained from eucalyptus was embedded in gelatin from two sources; namely bovine and salmon gelatin. Raman spectroscopy revealed that stress is transferred more efficiently from bovine gelatin to the MFC when compared to salmon gelatin. Young's modulus, tensile strength, strain at failure and work of fracture of the nanocomposite films were improved by ∼67, 131, 43 y 243% respectively when using salmon gelatin as matrix material instead of bovine gelatin. Imaging of the tensile fracture surface of the MFC-gelatin nanocomposites revealed that crack formation occurs predominantly within bovine and salmon gelatin matrices rather than within the MFC or at the MFC/gelatin interface. This suggests that the mechanical failure mechanism in these nanocomposite materials is predominantly governed by a matrix-cohesive fracture mechanism. Both strength and flexibility are desirable properties for composite coatings made from gelatin-based materials, and so the findings of this study could assist in their utilization in the food and pharmaceutical industry. Copyright © 2018 Elsevier Ltd. All rights reserved.

Influence of Content of Al2O3 on Structure and Properties of Nanocomposite Nb-B-Al-O films

NASA Astrophysics Data System (ADS)

Liu, Na; Dong, Lei; Dong, Lei; Yu, Jiangang; Pan, Yupeng; Wan, Rongxin; Gu, Hanqing; Li, Dejun

2015-11-01

Nb-B-Al-O nanocomposite films with different power of Al2O3 were successfully deposited on the Si substrate via multi-target magnetron co-sputtering method. The influences of Al2O3's content on structure and properties of obtained nanocomposite films through controlling Al2O3's power were investigated. Increasing the power of Al2O3 can influence the bombarding energy and cause the momentum transfer of NbB2. This can lead to the decreasing content of Al2O3. Furthermore, the whole films showed monocrystalline NbB2's (100) phase, and Al2O3 shaded from amorphous to weak cubic-crystalline when decreasing content of Al2O3. This structure and content changes were proof by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). When NbB2 grains were far from each other in lower power of Al2O3, the whole films showed a typical nanocomposite microstructure with crystalline NbB2 grains embedded in a matrix of an amorphous Al2O3 phase. Continuing increasing the power of Al2O3, the less content of Al2O3 tended to cause crystalline of cubic-Al2O3 between the close distances of different crystalline NbB2 grains. The appearance of cubic-crystallization Al2O3 can help to raise the nanocomposite films' mechanical properties to some extent. The maximum hardness and elastic modulus were up to 21.60 and 332.78 GPa, which were higher than the NbB2 and amorphous Al2O3 monolithic films. Furthermore, this structure change made the chemistry bond of O atom change from the existence of O-Nb, O-B, and O-Al bonds to single O-Al bond and increased the specific value of Al and O. It also influenced the hardness in higher temperature, which made the hardness variation of different Al2O3 content reduced. These results revealed that it can enhance the films' oxidation resistance properties and keep the mechanical properties at high temperature. The study highlighted the importance of controlling the Al2O3's content to prepare

Evaluation of the optical characteristics of c-axis oriented zinc oxide thin films grown by sol gel spin coating technique

NASA Astrophysics Data System (ADS)

Baisakh, K.; Behera, S.; Pati, S.

2018-03-01

In this work we have systematically studied the optical characteristics of synthesized wurzite zinc oxide thin films exhibiting (002) orientation. Using sol gel spin coating technique zinc oxide thin films are grown on pre cleaned fused quartz substrates. Structural properties of the films are studied using X-ray diffraction analysis. Micro structural analysis and thickness of the grown samples are analyzed using field emission scanning electron microscopy. With an aim to investigate the optical characteristics of the grown zinc oxide thin films the transmission and reflection spectra are evaluated in the ultraviolet-visible (UV-VIS) range. Using envelope method, the refractive index, extinction coefficient, absorption coefficient, band gap energy and the thickness of the synthesized films are estimated from the recorded UV-VIS spectra. An attempt has also been made to study the influence of crystallographic orientation on the optical characteristics of the grown films.

Elastic properties of nc-TiN /a-Si3N4 and nc-TiN /a-BN nanocomposite films by surface Brillouin scattering

NASA Astrophysics Data System (ADS)

Manghnani, Murli H.; Tkachev, Sergey N.; Zinin, Pavel V.; Glorieoux, Christ; Karvankova, Pavla; Veprek, Stan

2005-03-01

The hardness of nanocomposite (nc) films developed recently appears to reach the hardness of diamond. High hardness is commonly attributed to the granular structure of nanocomposites (Hall-Petch effect) [E. O. Hall, Proc. Phys. Soc. Lond. B 64, 747 (1951); N. J. Petch, J. Iron Steel Inst. 174, 25 (1953)]. However, grain size in nanocomposites is generally small (5-15nm) and falls in the region where the Hall-Petch effect does not apply. The objective of the present study is to report the elastic properties of the superhard nanocomposites determined by means of surface Brillouin scattering (SBS), and to compare the results with those obtained by nanoindentation. Two types of nanocomposite films were studied: nc-TiN /a-Si3N4 and nc-TiN /a-BN. The SBS measurements presented yield values of Young's modulus significantly larger than those obtained from the slope of unloading indentation curve. This discrepancy is attributed to the lack of the validity of the assumptions behind the Sneddon's derivation of the formula used for the calculation of the Young's modulus from the indentation data.

Use of Nanocomposites for Flexible Pressure Sensors =

NASA Astrophysics Data System (ADS)

Sepulveda, Alexandra Conceicao Teixeira

Polymer nanocomposites (PNCs) are defined as polymers bonded with nanoparticles to create materiais with improved properties. The development of this type of material is rapidly emerging as a multidisciplinary research activity, since their final properties can benefit many different fields of application, namely in the development of electrical devices as studied herein. A fabrication technique to produce conductive PNCs was developed in this work and used to fabricate flexible capacitive pressure sensors. The process is based on vertically aligned-carbon nanotubes (A-CNTs) embedded in a flexible and biocompatible matrix of polydimethylsiloxane (PDMS). Thin A-CNTs/PDMS nanocomposite films ( 400 mum) were produced using wetting of as-grown A-CNTs with uncured PDMS and the resulting nanocomposites were used to fabricate flexible pressure sensors. The sensing capability of this A-CNTs/PDMS nanocomposite is attributed to the distinctive combination of mechanical flexibility and electrical properties. The fabricated nanocomposites were characterized and mechanical and electrical properties evaluated. The PDMS is significantly modified by the reinforcing A-CNT fibers, demonstrating non-isotropic (as opposed to the isotropic neat PDMS) elastic properties ali different than the PDMS (Young's modulus of 0.8 MPa), including an anisotropy ratio of 4.8 and increases in the modulus of A-CNTs/PDMS nanocomposites over PDMS by more than 900 % and 100 %, in the CNTs longitudinal and transverse directions, respectively. Regarding the electrical measurements, A-CNTs/PDMS nanocomposites presented an electrical conductivity of 0.35 Sim. The rather low conductivity does not compromise the developed capacitive sensor, but since passive telemetry is required to measure and power the sensor, solutions to overcome this problem were also studied. The configuration of the developed flexible sensor is similar to typical silicon-based capacitive pressure sensors. It is composed of three thin

Device level optimization of poly(vinylidene fluoride-trifluoroethylene)–zinc oxide polymer nanocomposite thin films for ferroelectric applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

C K, Subash, E-mail: cksubash08@gmail.com; Valiyaneerilakkal, Uvais; Varghese, Soney

Polymer nanocomposite was prepared using poly(vinylidene fluoride-trifluoroethylene) and zinc oxide (ZnO) nanopowder, which are ferroelectric in nature. Nanocomposite was prepared in various concentrations(0.2, 0.4, 0.8, and 1 wt. %) using probe ultra-sonication, followed by spin coating and annealing at 120 °C for 2 h to improve the formation of β-phase. Metal-ferroelectric-metal capacitor was fabricated using this optimized thin film as a ferroelectric layer. Device level optimization was carried out by polarization-electric field (P-E) hysteresis studies of this film, which shows polarization enhancement of composite. Various characterization techniques like atomic force microscopy, Fourier transform infra-red spectroscopy (FT-IR), Differential scanning calorimetry, and X-ray diffractionmore » were used to study the β-phase formation of nancomposite. The capacitance–voltage (C-V) and current-voltage (I-V) characteristics were studied through varying frequency and temperature. C-V measurements show an increase of 79% in the capacitance of polymer nanocomposite, which can be used for the fabrication of ferroelectric devices.« less

Electron field emission from phase pure nanotube films grown in a methane/hydrogen plasma

NASA Astrophysics Data System (ADS)

Küttel, Olivier M.; Groening, Oliver; Emmenegger, Christoph; Schlapbach, Louis

1998-10-01

Phase pure nanotube films were grown on silicon substrates by a microwave plasma under conditions which normally are used for the growth of chemical vapor deposited diamond films. However, instead of using any pretreatment leading to diamond nucleation we deposited metal clusters on the silicon substrate. The resulting films contain only nanotubes and also onion-like structures. However, no other carbon allotropes like graphite or amorphous clustered material could be found. The nanotubes adhere very well to the substrates and do not need any further purification step. Electron field emission was observed at fields above 1.5 V/μm and we observed an emission site density up to 104/cm2 at 3 V/μm. Alternatively, we have grown nanotube films by the hot filament technique, which allows to uniformly cover a two inch wafer.

Poly(vinylidene fluoride) Flexible Nanocomposite Films with Dopamine-Coated Giant Dielectric Ceramic Nanopowders, Ba(Fe0.5Ta0.5)O3, for High Energy-Storage Density at Low Electric Field.

PubMed

Wang, Zhuo; Wang, Tian; Wang, Chun; Xiao, Yujia; Jing, Panpan; Cui, Yongfei; Pu, Yongping

2017-08-30

Ba(Fe 0.5 Ta 0.5 )O 3 /poly(vinylidene fluoride) (BFT/PVDF) flexible nanocomposite films are fabricated by tape casting using dopamine (DA)-modified BFT nanopowders and PVDF as a matrix polymer. After a surface modification of installing a DA layer with a thickness of 5 nm, the interfacial couple interaction between BFT and PVDF is enhanced, resulting in less hole defects at the interface. Then the dielectric constant (ε'), loss tangent (tan δ), and AC conductivity of nanocomposite films are reduced. Meanwhile, the value of the reduced dielectric constant (Δε') and the strength of interfacial polarization (k) are introduced to illustrate the effect of DA on the dielectric behavior of nanocomposite films. Δε' can be used to calculate the magnitude of interfacial polarization, and the strength of the dielectric constant contributed by the interface can be expressed as k. Most importantly, the energy-storage density and energy-storage efficiency of nanocomposite films with a small BFT@DA filler content of 1 vol % at a low electric field of 150 MV/m are enhanced by about 15% and 120%, respectively, after DA modification. The high energy-storage density of 1.81 J/cm 3 is obtained in the sample. This value is much larger than the reported polymer-based nanocomposite films. In addition, the outstanding cycle and bending stability of the nanocomposite films make it a promising candidate for future flexible portable energy devices.

Resistive switching effect of N-doped MoS2-PVP nanocomposites films for nonvolatile memory devices

NASA Astrophysics Data System (ADS)

Wu, Zijin; Wang, Tongtong; Sun, Changqi; Liu, Peitao; Xia, Baorui; Zhang, Jingyan; Liu, Yonggang; Gao, Daqiang

2017-12-01

Resistive memory technology is very promising in the field of semiconductor memory devices. According to Liu et al, MoS2-PVP nanocomposite can be used as an active layer material for resistive memory devices due to its bipolar resistive switching behavior. Recent studies have also indicated that the doping of N element can reduce the band gap of MoS2 nanosheets, which is conducive to improving the conductivity of the material. Therefore, in this paper, we prepared N-doped MoS2 nanosheets and then fabricated N-doped MoS2-PVP nanocomposite films by spin coating. Finally, the resistive memory [C. Tan et al., Chem. Soc. Rev. 44, 2615 (2015)], device with ITO/N-doped MoS2-PVP/Pt structure was fabricated. Study on the I-V characteristics shows that the device has excellent resistance switching effect. It is worth mentioning that our device possesses a threshold voltage of 0.75 V, which is much better than 3.5 V reported previously for the undoped counterparts. The above research shows that N-doped MoS2-PVP nanocomposite films can be used as the active layer of resistive switching memory devices, and will make the devices have better performance.

Synthesis and characterization of new nanocomposites films using alanine-Cu-functionalized graphene oxide as nanofiller and PVA as polymeric matrix for improving of their properties

NASA Astrophysics Data System (ADS)

Abdolmaleki, Amir; Mallakpour, Shadpour; Karshenas, Azam

2017-09-01

In the synthesis of polymer-graphene nanocomposites, for improving properties of nanocomposites, two factors dispersion and strong interfacial interactions between graphene and the polymer, are essential. In the present work, poly(vinyl alcohol) PVA/GO-Cu-alanine nanocomposite films were manufactured using concentrations 0, 1, 3 and 5 wt% of GO-Cu-alanine in water solution. For this purpose, L-alanine amino acid was located on the surface and edges of GO through copper(II) ion as a coordinating function. Then, flexible PVA/GO-Cu-alanine nanocomposite films were fabricated using GO-Cu-alanine as filler and PVA as matrix. Due to the existence of affective interaction between GO-Cu-alanine and PVA matrix, the acquired PVA/GO-Cu-alanine nanocomposites demonstrated great thermal and mechanical properties. Properties of manufactured materials were characterized by Fourier transform infrared, X-ray photoelectron spectroscopies (XPS), X-ray diffraction (XRD), Thermal gravimetric analysis, elemental analysis, field emission scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy (EDX).

Role of silver nanotube on conductivity, dielectric permittivity and current voltage characteristics of polyvinyl alcohol-silver nanocomposite film

NASA Astrophysics Data System (ADS)

Mukherjee, P. S.; Das, A. K.; Dutta, B.; Meikap, A. K.

2017-12-01

A comprehensive study on the prevailing conduction mechanism, dielectric relaxation and current voltage behaviour of Polyvinyl alcohol (PVA) - Silver (Ag) nanotube composite film has been reported. Introduction of Ag nanotubes enhances the conductivity and dielectric permittivity of film. Film shows semiconducting behaviour with two activation energies. The dc conductivity of the nanocomposite film obeys the adiabatic small polaron model. The dielectric permittivity can be analysed by modified Cole-Cole model. A non-Debye type asymmetric behaviour has been observed in the sample. The back to back Schottky diode concept has been used to describe the current-voltage characteristic of the composite film.

Structure and magnetic properties of spinel-perovskite nanocomposite thin films on SrTiO3 (111) substrates

NASA Astrophysics Data System (ADS)

Kim, Dong Hun; Yang, Junho; Kim, Min Seok; Kim, Tae Cheol

2016-09-01

Epitaxial CoFe2O4-BiFeO3 nanocomposite thin films were synthesized on perovskite structured SrTiO3 (001) and (111) substrates by combinatorial pulsed laser deposition and characterized using scanning electron microscopy, x-ray diffraction, and vibrating sample magnetometer. Triangular BiFeO3 nanopillars were formed in a CoFe2O4 matrix on (111) oriented SrTiO3 substrates, while CoFe2O4 nanopillars with rectangular or square top surfaces grew in a BiFeO3 matrix on (001) substrates. The magnetic hysteresis loops of nanocomposites on (111) oriented SrTiO3 substrates showed isotropic properties due to the strain relaxation while those of films on SrTiO3 (001) substrates exhibited a strong out-of-plane anisotropy originated from shape and strain effects.

Properties of CsI, CsBr and GaAs thin films grown by pulsed laser deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brendel, V M; Garnov, S V; Yagafarov, T F

2014-09-30

CsI, CsBr and GaAs thin films have been grown by pulsed laser deposition on glass substrates. The morphology and structure of the films have been studied using X-ray diffraction and scanning electron microscopy. The CsI and CsBr films were identical in stoichiometry to the respective targets and had a polycrystalline structure. Increasing the substrate temperature led to an increase in the density of the films. All the GaAs films differed in stoichiometry from the target. An explanation was proposed for this fact. The present results demonstrate that, when the congruent transport condition is not fulfilled, films identical in stoichiometry tomore » targets can be grown by pulsed laser deposition in the case of materials with a low melting point and thermal conductivity. (interaction of laser radiation with matter)« less

Supported porous carbon and carbon-CNT nanocomposites for supercapacitor applications

NASA Astrophysics Data System (ADS)

Schopf, Dimitri; Es-Souni, Mohammed

2016-03-01

Supported porous carbon and porous carbon-MWCNT-nanocomposite films are produced by pyrolysis of porous polyvinylidene fluoride (PVDF) or porous PVDF-MWCNT-nanocomposite films on thermally resistant substrates. All films are characterized by SEM, RAMAN and XRD. The application of these films as supercapacitors is explored with outstanding supercapacitance values ranging from 80 to 120 F g-1 (up to 70 mF cm-2) in a three-electrode set-up in 1 M KOH, depending on microstructure. Additionally, the implementation of porous nanocarbon-MWCNT-nanocomposite films as electrodes in a symmetrical supercapacitor device is investigated. In all cases, long-term charge-discharge stability is demonstrated.

Nano-Crystalline Diamond Films with Pineapple-Like Morphology Grown by the DC Arcjet vapor Deposition Method

NASA Astrophysics Data System (ADS)

Li, Bin; Zhang, Qin-Jian; Shi, Yan-Chao; Li, Jia-Jun; Li, Hong; Lu, Fan-Xiu; Chen, Guang-Chao

2014-08-01

A nano-crystlline diamond film is grown by the dc arcjet chemical vapor deposition method. The film is characterized by scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM), x-ray diffraction (XRD) and Raman spectra, respectively. The nanocrystalline grains are averagely with 80 nm in the size measured by XRD, and further proven by Raman and HRTEM. The observed novel morphology of the growth surface, pineapple-like morphology, is constructed by cubo-octahedral growth zones with a smooth faceted top surface and coarse side surfaces. The as-grown film possesses (100) dominant surface containing a little amorphous sp2 component, which is far different from the nano-crystalline film with the usual cauliflower-like morphology.

Influence of PA6 nanocomposite films on the stability of vacuum-aged beef loins during storage in modified atmospheres.

PubMed

Picouet, P A; Fernandez, A; Realini, C E; Lloret, E

2014-01-01

A masterbatch of polyamide 6 (PA6) containing dispersed nanoclays, was used to fabricate a novel multilayer film for vacuum packed meat. Performance of the nanocomposite was compared to a control PA6 multilayer and a high barrier commercial film. Addition of nanoclays improved oxygen barrier properties, UV-blocking capability and stiffness. Beef loins were vacuum-aged using the three films for 0 7, 14 and 21 days at 2°C. After each ageing time, beef steaks were packaged in commercial trays and high oxygen atmosphere and stored at 4°C for 9 days. Beef quality parameters and gas content were studied during display time in MAP (1, 3, 6 and 9 d). Beef quality parameters were not influenced by the packaging materials used during ageing and the performance of nanocomposites was comparable to high barrier films. Ageing had a positive impact on the stabilization of redness up to day 6 in MAP. Thereafter, oxymyoglobin content and oxidation levels were negatively influenced by ageing. © 2013.

Transparent and Electrically Conductive Carbon Nanotube-Polymer Nanocomposite Materials for Electrostatic Charge Dissipation

NASA Technical Reports Server (NTRS)

Dervishi, E.; Biris, A. S.; Biris, A. R.; Lupu, D.; Trigwell, S.; Miller, D. W.; Schmitt, T.; Buzatu, D. A.; Wilkes, J. G.

2006-01-01

In recent years, nanocomposite materials have been extensively studied because of their superior electrical, magnetic, and optical properties and large number of possible applications that range from nano-electronics, specialty coatings, electromagnetic shielding, and drug delivery. The aim of the present work is to study the electrical and optical properties of carbon nanotube(CNT)-polymer nanocomposite materials for electrostatic charge dissipation. Single and multi-wall carbon nanotubes were grown by catalytic chemical vapor deposition (CCVD) on metal/metal oxide catalytic systems using acetylene or other hydrocarbon feedstocks. After the purification process, in which amorphous carbon and non-carbon impurities were removed, the nanotubes were functionalized with carboxylic acid groups in order to achieve a good dispersion in water and various other solvents. The carbon nanostructures were analyzed, both before and after functionalization by several analytical techniques, including microscopy, Raman spectroscopy, and X-Ray photoelectron spectroscopy. Solvent dispersed nanotubes were mixed (1 to 7 wt %) into acrylic polymers by sonication and allowed to dry into 25 micron thick films. The electrical and optical properties of the films were analyzed as a function of the nanotubes' concentration. A reduction in electrical resistivity, up to six orders of magnitude, was measured as the nanotubes' concentration in the polymeric films increased, while optical transparency remained 85 % or higher relative to acrylic films without nanotubes.

Photocatalytic degradation of metronidazole and methylene blue by PVA-assisted Bi2WO6-CdS nanocomposite film under visible light irradiation

NASA Astrophysics Data System (ADS)

Rajendran, Ranjith; Varadharajan, Krishnakumar; Jayaraman, Venkatesan; Singaram, Boobas; Jeyaram, Jayaprakash

2018-02-01

The enhanced photocatalytic performance of nanocomposite is synthesized via the hydrothermal method and characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FT-IR), UV-visible diffuse reflectance spectroscopy (UV-Vis DRS) and photoluminescence spectroscopy (PL). Under visible light irradiation, PVA assisted Bi2WO6-CdS nanocomposite film displayed enhanced photocatalytic efficiency and inhibition of photocorrosion as compared with pure CdS, pure Bi2WO6 and Bi2WO6-CdS composite. The PVA assisted Bi2WO6-CdS composite film catalyst showed stable catalytic performance until seven successive runs with 92% of methylene blue(MB) degradation, and easy to recover after degradation of organic pollutant. PVA assisted Bi2WO6-CdS nanocomposite film has optimal band edge position for superior photocatalytic degradation. Furthermore, the trapping experiment was carried out using different scavenger for active species. Among the active species, OH· are the most responsive species which play a vital role in the degradation of metronidazole and MB.

Structural and magnetic properties of hexagonal Cr1-δTe films grown on CdTe(001) by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Kanazawa, Ken; Yamawaki, Kazuma; Sekita, Naoya; Nishio, Yôtarô; Kuroda, Shinji; Mitome, Masanori; Bando, Yoshio

2015-04-01

We investigated the structural and magnetic properties of Cr1-δTe thin films grown on CdTe(001) layers by molecular beam epitaxy (MBE) with systematic variations of the ratio between Cr and Te fluxes and the substrate temperature Ts during the growth. Cr1-δTe of the hexagonal structure (hex-Cr1-δTe) was always formed irrespective of the growth conditions, but the growth orientation was different depending on the Cr/Te flux ratio and Ts. Hex-Cr1-δTe was grown in the [0001] axis in the range of small Cr/Te ratios and high Ts while it was also grown in the direction normal to the (1-102) plane at larger Cr/Te ratios or lower Ts. Hex-Cr1-δTe films grown in the both orientations show ferromagnetism, but they exhibit a clear contrast in the field dependence of perpendicular magnetization at 2 K; a square hysteretic loop in the film grown in the [0001] axis versus a round-shape loop in the film grown in the direction normal to the (1-102) plane. Moreover, the films grown in the [0001] axis at the smallest Cr/Te ratio show variations of ferromagnetic properties with Curie temperature (Tc) and the coercivity (Hc) varying according to the value of Ts.

Smart Nacre-inspired Nanocomposites.

PubMed

Peng, Jingsong; Cheng, Qunfeng

2018-03-15

Nacre-inspired nanocomposites with excellent mechanical properties have achieved remarkable attention in the past decades. The high performance of nacre-inspired nanocomposites is a good basis for the further application of smart devices. Recently, some smart nanocomposites inspired by nacre have demonstrated good mechanical properties as well as effective and stable stimuli-responsive functions. In this Concept, we summarize the recent development of smart nacre-inspired nanocomposites, including 1D fibers, 2D films and 3D bulk nanocomposites, in response to temperature, moisture, light, strain, and so on. We show that diverse smart nanocomposites could be designed by combining various conventional fabrication methods of nacre-inspired nanocomposites with responsive building blocks and interface interactions. The nacre-inspired strategy is versatile for different kinds of smart nanocomposites in extensive applications, such as strain sensors, displays, artificial muscles, robotics, and so on, and may act as an effective roadmap for designing smart nanocomposites in the future. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterization of single-crystalline Al films grown on Si(111)

NASA Astrophysics Data System (ADS)

Fortuin, A. W.; Alkemade, P. F. A.; Verbruggen, A. H.; Steinfort, A. J.; Zandbergen, H.; Radelaar, S.

1996-10-01

Single-crystalline Al films have been grown by molecular beam epitaxy on a (7 × 7) reconstructed Si(111) surface at 50°C. The 100 nm thick Al films were extensively characterized by X-ray diffraction, transmission electron diffraction and microscopy, SIMS, and RBS in combination with ion channeling. The orientational relationship found was Al(111) t' | Si(111) and Al[11¯0] t'| Si[11¯0]. The film is single-crystalline over the entire 4″ Si wafer. TED and TEM showed that the lattice mismatch of 25.3% at room temperature is accommodated at the interface by alignment of every three Si atoms to four Al atoms. Annealing of the film at 400°C for 30 min led to a reduction of defects in the film and an increase at the interface. Furthermore, it increased the Si concentration in the Al film slightly. We regard this deposition method as the most appropriate one among the various techniques for epitaxial growth of Al on Si explored so far.

RHEED oscillations in spinel ferrite epitaxial films grown by conventional planar magnetron sputtering

NASA Astrophysics Data System (ADS)

Ojima, T.; Tainosho, T.; Sharmin, S.; Yanagihara, H.

2018-04-01

Real-time in situ reflection high energy electron diffraction (RHEED) observations of Fe3O4, γ-Fe2O3, and (Co,Fe)3O4 films on MgO(001) substrates grown by a conventional planar magnetron sputtering was studied. The change in periodical intensity of the specular reflection spot in the RHEED images of three different spinel ferrite compounds grown by two different sputtering systems was examined. The oscillation period was found to correspond to the 1/4 unit cell of each spinel ferrite, similar to that observed in molecular beam epitaxy (MBE) and pulsed laser deposition (PLD) experiments. This suggests that the layer-by-layer growth of spinel ferrite (001) films is general in most physical vapor deposition (PVD) processes. The surfaces of the films were as flat as the surface of the substrate, consistent with the observed layer-by-layer growth process. The observed RHEED oscillation indicates that even a conventional sputtering method can be used to control film thickness during atomic layer depositions.

An Amperometric Immunosensor Based on Multi-Walled Carbon Nanotubes-Thionine-Chitosan Nanocomposite Film for Chlorpyrifos Detection

PubMed Central

Sun, Xia; Cao, Yaoyao; Gong, Zhili; Wang, Xiangyou; Zhang, Yan; Gao, Jinmei

2012-01-01

In this work, a novel amperometric immunosensor based on multi-walled carbon nanotubes-thionine-chitosan (MWCNTs-THI-CHIT) nanocomposite film as electrode modified material was developed for the detection of chlorpyrifos residues. The nanocomposite film was dropped onto a glassy carbon electrode (GCE), and then the anti-chlorpyrifos monoclonal antibody was covalently immobilized onto the surface of MWCNTs-THI-CHIT/GCE using the crosslinking agent glutaraldehyde (GA). The modification procedure was characterized by using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under the optimized conditions, a linear relationship between the relative change in peak current of different pulse voltammetry (DPV) and the logarithm of chlorpyrifos solution concentration was obtained in the range from 0.1 to 1.0 × 105 ng/mL with a detection limit of 0.046 ng/mL. The proposed chlorpyrifos immunosensor exhibited high reproducibility, stability, and good selectivity and regeneration, making it a potential alternative tool for ultrasensitive detection of chlorpyrifos residues in vegetables and fruits. PMID:23443396

Characteristic time scales of coalescence of silver nanocomposite and nanoparticle films induced by continuous wave laser irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paeng, Dongwoo; Grigoropoulos, Costas P., E-mail: cgrigoro@berkeley.edu; Lee, Daeho

2014-08-18

In-situ optical probing has been performed to analyze and compare the characteristic coalescence time scales of silver ion-doped polyvinylalcohol nanocomposite (Ag-PVA NC) and polyvinylpyrrolidone-capped silver nanoparticle (Ag-PVP NP) films subjected to continuous wave laser irradiation. The Ag-PVA NC yielded conductive metallic patterns by photothermal reduction of PVA, formation of nanoparticles from silver ions and their subsequent coalescence. On the other hand, Ag-PVP NP thin films produced conductive patterns through only coalescence of nanoparticles. Upon laser irradiation, Ag-PVA NC and Ag-PVP NP films exhibited different coalescence characteristics.

Effect of type and content of modified montmorillonite on the structure and properties of bio-nanocomposite films based on soy protein isolate and montmorillonite

USDA-ARS?s Scientific Manuscript database

The non-biodegradable and non-renewable nature of plastic packaging has led to a renewed interest in packaging materials based on bio-nanocomposites (biopolymer matrix reinforced with nanoparticles such as layered silicates). Bio-nanocomposite films based on soy protein isolate (SPI) and modified mo...

Zinc Oxide Grown by CVD Process as Transparent Contact for Thin Film Solar Cell Applications

NASA Astrophysics Data System (ADS)

Faÿ, S.; Shah, A.

Metalorganic chemical vapor deposition of ZnO films (MOCVD) [1] started to be comprehensively investigated in the 1980s, when thin film industries were looking for ZnO deposition processes especially useful for large-scale coatings at high growth rates. Later on, when TCO for thin film solar cells started to be developed, another advantage of growing TCO films by the CVD process has been highlighted: the surface roughness. Indeed, a large number of studies on CVD ZnO revealed that an as-grown rough surface cn be obtained with this deposition process [2-4]. A rough surface induces a light scattering effect, which can significantly improve light trapping (and therefore current photo-generation) within thin film silicon solar cells. The CVD process, indeed, directly leads to as-grown rough ZnO films without any post-etching step (the latter is often introduced to obtain a rough surface, when working with as-deposited flat sputtered ZnO). This fact could turn out to be a significant advantage when upscaling the manufacturing process for actual commercial production of thin film solar modules. The zinc and oxygen sources for CVD growth of ZnO films are given in Table 6.1.

Ionic Conductivity Increased by Two Orders of Magnitude in Micrometer-Thick Vertical Yttria-Stabilized ZrO 2 Nanocomposite Films

DOE PAGES

Lee, Shinbuhm; Zhang, Wenrui; Khatkhatay, Fauzia; ...

2015-09-03

We design and create a unique cell geometry of templated micrometer-thick epitaxial nanocomposite films which contain ~20 nm diameter yttria-stabilized ZrO 2 (YSZ) nanocolumns, strain coupled to a SrTiO 3 matrix. We also enhanced the ionic conductivity of these nanocolumnsby over 2 orders of magnitude compared to plain YSZ films. Concomitant with the higher ionic conduction is the finding that the YSZ nanocolumns in the films have much higher crystallinity and orientation, compared to plain YSZ films. Hence, “oxygen migration highways” are formed in the desired out-of-plane direction. This improved structure is shown to originate from the epitaxial coupling ofmore » the YSZ nanocolumns to the SrTiO 3 film matrix and from nucleation of the YSZ nanocolumns on an intermediate nanocomposite base layer of highly aligned Sm-doped CeO 2 nanocolumns within the SrTiO 3 matrix. Furthermore, this intermediate layer reduces the lattice mismatch between the YSZ nanocolumns and the substrate. Vertical ionic conduction values as high as 10 –2 Ω –1 cm –1 were demonstrated at 360 °C (300 °C lower than plain YSZ films), showing the strong practical potential of these nanostructured films for use in much lower operation temperature ionic devices.« less

Polymer Nanocomposite Film with Metal Rich Surface Prepared by In Situ Single-Step Formation of Palladium Nanoparticles: An Interesting Way to Combine Specific Functional Properties.

PubMed

Thompson, David; Kranbuehl, David; Espuche, Eliane

2016-10-18

This paper presents a continuous single-step route that permits preparation of a thermostable polymer/metal nanocomposite film and to combine different functional properties in a unique material. More precisely, palladium nanoparticles are in situ generated in a polyimide matrix thanks to a designed curing cycle which is applied to a polyamic acid/metal precursor solution cast on a glass plate. A metal-rich surface layer which is strongly bonded to the bulk film is formed in addition to homogeneously dispersed metal nanoparticles. This specific morphology leads to obtaining an optically reflective film. The metal nanoparticles act as gas diffusion barriers for helium, oxygen, and carbon dioxide; they induce a tortuosity effect which allows dividing the gas permeation coefficients by a factor near to 2 with respect to the neat polyimide matrix. Moreover, the ability of the in situ synthesized palladium nanoparticles to entrap hydrogen is evidenced. The nanocomposite film properties can be modulated as a function of the location of the film metal-rich surface with respect to the hydrogen feed. The synthesized nanocomposite could represent a major interest for a wide variety of applications, from specific coatings for aerospace or automotive industry, to catalysis applications or sensors.

Thickness dependence of crystal and optical characterization on ZnO thin film grown by atomic layer deposition

NASA Astrophysics Data System (ADS)

Baek, Seung-Hye; Lee, Hyun-Jin; Lee, Sung-Nam

2018-06-01

We studied the thickness dependence of the crystallographic and optical properties of ZnO thin films grown on c-plane sapphire substrate using atomic layer deposition. High-resolution X-ray diffraction (HR-XRD) revealed two peaks at 34.5° and 36.2° in the initial growth stage of ZnO on the sapphire substrate, corresponding to the (002) and (101) ZnO planes, respectively. However, as the thickness of the ZnO film increased, the XRD intensity of the (002) ZnO peak increased drastically, compared with that of the (101) ZnO peak. This indicated that (002) and (101) ZnO were simultaneously grown on the c-plane sapphire substrate in the initial growth stage, and that (002) ZnO was predominantly grown with the increase in the thickness of ZnO film. The ZnO thin film presented an anisotropic surface structure at the initial stage, whereas the isotropic surface morphology was developed with an increase in the film thickness of ZnO. These observations were consistent with the HR-XRD results.

C-Axis-Oriented Hydroxyapatite Film Grown Using ZnO Buffer Layer

NASA Astrophysics Data System (ADS)

Sakoishi, Yasuhiro; Iguchi, Ryo; Nishikawa, Hiroaki; Hontsu, Shigeki; Hayami, Takashi; Kusunoki, Masanobu

2013-11-01

A method of fabricating c-axis-oriented hydroxyapatite film on a quartz crystal microbalance (QCM) sensor was investigated. ZnO was used as a template to obtain a hexagonal hydroxyapatite crystal of uniaxial orientation. The ZnO was grown as a c-axis film on a Au/quartz with the surface structure of a QCM sensor. Under optimized conditions, hydroxyapatite was deposited by pulsed laser deposition. X-ray diffraction showed the hydroxyapatite film to be oriented along the c-axis. Because Au and ZnO are applied to many devices, the anisotropic properties of hydroxyapatite may be incorporated into these devices as well as QCM sensors.

The preparation of γ-crystalline non-electrically poled photoluminescant ZnO-PVDF nanocomposite film for wearable nanogenerators

NASA Astrophysics Data System (ADS)

Jana, Santanu; Garain, Samiran; Ghosh, Sujoy Kumar; Sen, Shrabanee; Mandal, Dipankar

2016-11-01

Polyvinylidene fluoride (PVDF) films are filled with various mass fractions (wt%) of zinc oxide nanoparticles (ZnO-NPs) to fabricate the high performance of a wearable polymer composite nanogenerator (PCNG). The ZnO-NPs can induced a fully γ-crystalline phase in PVDF, where traditional electrical poling is not necessary for the generation of piezoelectric properties. The PCNG delivers up to 28 V of open circuit voltage and 450 nA of short circuit current by simple repeated human finger imparting (under a pressure amplitude of 8.43 kPa) that generates sufficient power to turn on at least 48 commercial blue light emitting diodes (LEDs) instantly. Furthermore, it also successfully charged the capacitors, signifying practical applicability as a piezoelectric based nanogenerator for self-powering devices. The applicability of PCNG by wearable means is clarified when it gives rise to a sensible response, say up to 400 mV of output voltage synchronized with the PCNG embedded human finger in a bending and releasing gesture. UV-visible absorption spectral analysis revealed the possibility of estimating a change in the optical band gap value (E g), refractive index (n) and optical activation energy (E a) in different concentrations of ZnO-NP incorporated PVDF nanocomposite films, and it possesses a useful methodology where ZnO-NPs can be used as an optical probe. Near blue light emission is observed from photoluminescence spectra, which are clearly shown from a Commission Internationale de L’Eclairage (CIE) diagram. The piezoelectric charge coefficient of the nanocomposite film is estimated to be -6.4 pC/N, where even electrical poling treatment is not employed. In addition, dielectric properties have been studied to understand the role of molecular kinetic and interfacial polarization occurring in nanocomposite films at different applied frequencies.

Synthesis of PDLLA/PLLA-bentonite nanocomposite through sonication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sitompul, Johnner, E-mail: sitompul@che.itb.ac.id; Setyawan, Daru, E-mail: daru.setyawan@gmail.com; Kim, Daniel Young Joon, E-mail: daniel.kim12321@gmail.com

2016-04-19

This paper concerns the synthesis of poly(D,L-lactic acid)/poly(L-lactic acid) bentonite nanocomposites. Poly (D,L-lactic acid) (PDLLA) was synthesized using lactic acid through the ZnO-catalyzed direct polycondensation method at vacuum pressure and poly(L-lactic acid) (PLLA) was synthesized with L-lactide by ring-opening polymerization method. The PDLLA/PLLA-bentonite nanocomposite films were synthesized using the solvent casting method. The nanoclay, bentonite, was prepared using the solution-intercalation method by dissolving the nanoparticles into chloroform before sonication. In this study, PDLLA/PLLA-bentonite nanocomposite films were produced using variable amounts of nanoclay and sonication times during the mixing of PDLLA/PLLA and bentonite. The properties of the PDLLA/PLLA nanocomposites were thenmore » characterized using the X-ray Diffraction (XRD), Universal Testing Machine (UTM), Water Vapor Permeability (WVP) tests, and the enzymatic biodegradability test. The XRD test was used to measure the intercalation of nanoclay layers in the PDLLA/PLLA matrix and the PDLLA/PLLA-bentonite intercalated nanocomposite films. It was found through these various tests that adding bentonite to the PDLLA/PLLA increases tensile strength to 56.76 MP. Furthermore, the biodegradability increases as well as the barrier properties of the polymers The different sonication time used during the mixing of the polymer solution with bentonite also affected the properties of the PDLLA/PLLA-bentonite nanocomposite films.« less

Investigation on the compensation effect of residual carbon impurities in low temperature grown Mg doped GaN films

NASA Astrophysics Data System (ADS)

Yang, J.; Zhao, D. G.; Jiang, D. S.; Chen, P.; Liu, Z. S.; Le, L. C.; Li, X. J.; He, X. G.; Liu, J. P.; Zhang, S. M.; Wang, H.; Zhu, J. J.; Yang, H.

2014-04-01

The influence of unintentionally doped carbon impurities on electrical resistivity and yellow luminescence (YL) of low-temperature (LT) grown Mg doped GaN films is investigated. It is found that the resistivity of Mg doped GaN films are closely related to the residual carbon impurity concentration, which may be attributed to the compensation effect of carbon impurities. The carbon impurity may preferentially form deep donor complex CN-ON resulting from its relatively low formation energy. This complex is an effective compensate center for MgGa acceptors as well as inducing YL in photoluminescence spectra. Thus, the low resistivity LT grown p-type GaN films can be obtained only when the residual carbon impurity concentration is sufficiently low, which can explain why LT P-GaN films with lower resistivity were obtained more easily when relatively higher pressure, temperature, or NH3/TMGa flow rate ratio were used in the LT grown Mg doped GaN films reported in earlier reports.

Ferroelectric PLZT thick films grown by poly(1-vinylpyrrolidone-co-vinyl acetate) (PVP/VA)-modified sol-gel process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Zhongqiang; Ma, Beihai; Li, Meiya

2016-03-01

We report the growth of ferroelectric Pb0.92La0.08Zr0.52Ti0.48O3 (PLZT) thick films using a poly(1-vinylpyrrolidone-co-vinyl acetate) (PVP/VA)-modified sol–gel process. A per-coating thickness of ≈0.66 μm has been demonstrated using PVP/VA-modified solution, which is more than doubled that of the PLZT films grown by PVP-modified method, and nearly 6 times the per-coating thickness of films prepared by conventional sol–gel process. PLZT thick films grown on LNO/Ni substrates exhibited denser microstructure, higher remanent polarization (11 μC/cm 2) and dielectric tunability (45%), lower leakage current density (≈1.2 × 10 -8 A/cm 2), and higher breakdown strength (≈1.6 MV/cm) than those for the samples grown onmore » PtSi substrates. These results demonstrated great potential of using PVP/VA-modified sol–gel process for high power film capacitor applications.« less

Polyimide Nanocomposites Prepared from High-Temperature, Reduced Charge Organoclays

NASA Technical Reports Server (NTRS)

Delozier, D. M.; Orwoll, R. A.; Cahoon, J. F.; Ladislaw, J. S.; Smith, J. G., Jr.; Connell, J. W.

2003-01-01

Montmorillonite clays modified with the dihydrochloride salt of 1,3-bis(3-aminophenoxy)benzene (APB) were used in the preparation of polyimide/organoclay hybrid films. Organoclays with varying surface charge based upon APB were prepared and examined for their dispersion behavior in the polymer matrix. High molecular weight poly(amide acid) solutions were prepared in the presence of the organoclays. Films were cast and subsequently heated to 300C to cause imidization. The resulting nanocomposite films, containing 3 wt% of organoclay, were characterized by transmission electron microscopy and X-ray diffraction. The clay's cation exchange capacity (CEC) played a key role in determining the extent of dispersion in the polyimide matrix. Considerable dispersion was observed in some of the nanocomposite films. The most effective organoclay was found to have a CEC of 0.70 meq/g. Nanocomposite films prepared with 3-8 wt% of this organoclay were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and thin-film tensile testing. High levels of clay dispersion could be achieved even at the higher clay loadings. Results from mechanical testing revealed that while the moduli of the nanocomposites increased with increasing clay loadings, both strength and elongation decreased.

Active packaging from chitosan-titanium dioxide nanocomposite film for prolonging storage life of tomato fruit.

PubMed

Kaewklin, Patinya; Siripatrawan, Ubonrat; Suwanagul, Anawat; Lee, Youn Suk

2018-06-01

The feasibility of active packaging from chitosan (CS) and chitosan containing nanosized titanium dioxide (CT) to maintain quality and extend storage life of climacteric fruit was investigated. The CT nanocomposite film and CS film were fabricated using a solution casting method and used as active packaging to delay ripening process of cherry tomatoes. Changes in firmness, weight loss, a*/b* color, lycopene content, total soluble solid, ascorbic acid, and concentration of ethylene and carbon dioxide of the tomatoes packaged in CT film, CS film, and control (without CT or CS films) were monitored during storage at 20°C. Classification of fruit quality as a function of different packaging treatments was visualized using linear discriminant analysis. Tomatoes packaged in the CT film evolved lower quality changes than those in the CS film and control. The results suggested that the CT film exhibited ethylene photodegradation activity when exposed to UV light and consequently delayed the ripening process and changes in the quality of the tomatoes. Copyright © 2018 Elsevier B.V. All rights reserved.

RBS and PIXE analysis of chlorine contamination in ALD-Grown TiN films on silicon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meersschaut, J.; Witters, T.; Kaeyhkoe, M.

2013-04-19

The performance, strengths and limitations of RBS and PIXE for the characterization of trace amounts of Cl in TiN thin films are critically compared. The chlorine atomic concentration in ALD grown TiN thin films on Si is determined for samples grown at temperatures ranging from 350 Degree-Sign C to 550 Degree-Sign C. We show that routine Rutherford backscattering spectrometry measurements (1.5 MeV He{sup +}) and PIXE measurements (1.5 MeV H{sup +}) on 20 nm thick TiN films allow one to determine the Cl content down to 0.3 at% with an absolute statistical accuracy reaching 0.03 at%. Possible improvements to pushmore » the sensitivity limit for both approaches are proposed.« less

Nanocomposite films

DOEpatents

Mitlin, David; , Ophus, Colin; Evoy, Stephane; Radmilovic, Velimir; Mohammadi, Reza; Westra, Ken; Nelson-Fitzpatrick, Nathaniel; Lee, Zonghoon

2010-07-20

A thin-film composition of nanocrystal molybdenum in an amorphous metallic matrix may be formed by co-sputtering Mo with aluminum or nickel. NEMS cantilevers may be formed from the film. The films exhibit high nanoindentation hardness and a reduction in roughness and intrinsic stress, while maintaining resistivity in the metallic range.

Zinc oxide films chemically grown onto rigid and flexible substrates for TFT applications

NASA Astrophysics Data System (ADS)

Suchea, M.; Kornilios, N.; Koudoumas, E.

2010-10-01

This contribution presents some preliminary results regarding the use of a chemical route for the growth of good quality ZnO thin films that can be used for the fabrication of thin film transistors (TFTs). The films were grown at rather low temperature (60 °C) on glass and PET substrates using non-aqueous (zinc acetate dihydrate in methanol) precursor solution and their surface morphology, crystalline structure, optical transmittance and electrical characteristics were studied. The study indicated that good quality films with desirable ZnO structure onto rigid and flexible substrates can be obtained, using a simple, cheap, low temperature chemical growth method.

Structural and morphological properties of ITO thin films grown by magnetron sputtering

NASA Astrophysics Data System (ADS)

Ghorannevis, Z.; Akbarnejad, E.; Ghoranneviss, M.

2015-10-01

Physical properties of transparent and conducting indium tin oxide (ITO) thin films grown by radiofrequency (RF) magnetron sputtering are studied systematically by changing deposition time. The X-ray diffraction (XRD) data indicate polycrystalline thin films with grain orientations predominantly along the (2 2 2) and (4 0 0) directions. From atomic force microscopy (AFM) it is found that by increasing the deposition time, the roughness of the film increases. Scanning electron microscopy (SEM) images show a network of a high-porosity interconnected nanoparticles, which approximately have a pore size ranging between 20 and 30 nm. Optical measurements suggest an average transmission of 80 % for the ITO films. Sheet resistances are investigated using four-point probes, which imply that by increasing the film thickness the resistivities of the films decrease to 2.43 × 10-5 Ω cm.

The {alpha}-particle excited scintillation response of the liquid phase epitaxy grown LuAG:Ce thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prusa, P.; Cechak, T.; Mares, J. A.

2008-01-28

Liquid phase epitaxy grown Lu{sub 3}Al{sub 5}O{sub 12}:Ce (LuAG:Ce) 20 {mu}m thick films and plate cut from the bulk Czochralski-grown LuAG:Ce crystal were prepared for comparison of photoelectron yield (PhY) and PhY dependence on shaping time (0.5-10 {mu}s). {sup 241}Am ({alpha} particles) was used for excitation. At the 0.5 {mu}s shaping time, the best film shows comparable PhY with the bulk sample. PhY of bulk material increases noticeably more with shaping time than that of the films. Energy resolution of films is better. Influence of Pb{sup 2+} contamination in the films (from the flux) and antisite Lu{sub Al} defect inmore » bulk material is discussed.« less

Magnetization enhancement due to incorporation of non-magnetic nitrogen content in (Co{sub 84}Zr{sub 16})N{sub x} nano-composite films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Jitendra, E-mail: jitendra@ceeri.ernet.in; Akhtar, Jamil; Academy of Scientific and Innovative Research, New Delhi 110001

We report the magnetic, electronic, and structural properties of nano-composite (Co{sub 84}Zr{sub 16})N{sub x} or CZN films prepared by reactive co-sputter deposition method. As-deposited CZN films have shown enhancement in magnetization (M{sub s}) with incorporation of nitrogen content, which is related to the evolution of nano-composite phase. X-ray diffraction study has confirmed poly-crystalline growth of CZN films with fcc(331) and fcc(422) phases. High-resolution transmission electron microscope study reveals that CZN films are composed of ordered and crystalline ferromagnetic Co nano-clusters, which are embedded in the nano-composite matrix. Photoemission measurements show the change in the intensity near the Fermi level mostmore » likely due to defects and shift in the core-levels binding energy with nitrogen concentration. Raman spectroscopy data show an increase in the intensity of the Raman lines with nitrogen concentration upto 20%. However, the intensity is significantly lower for 30% sample. This indicates that less nitrogen or defect states are being substituted into the lattice above 20% and is consistent with the observed magnetic behavior. Our studies indicate that defects induced due to the incorporation of non-magnetic nitrogen content play a key role to enhance the magnetization.« less

Peeling off effects in vertically aligned Fe3C filled carbon nanotubes films grown by pyrolysis of ferrocene

NASA Astrophysics Data System (ADS)

Boi, Filippo S.; Medranda, Daniel; Ivaturi, Sameera; Wang, Jiayu; Guo, Jian; Lan, Mu; Wen, Jiqiu; Wang, Shanling; He, Yi; Mountjoy, Gavin; Willis, Maureen A. C.; Xiang, Gang

2017-06-01

We report the observation of an unusual self-peeling effect which allows the synthesis of free standing vertically aligned carbon nanotube films filled with large quantities of Fe3C and small quantities of γ-Fe crystals. We demonstrate that this effect depends on the interplay of three main factors: (1) the physical interactions between the chosen substrate surface and grown carbon nanotubes (CNTs), which is fixed by the composition of the used substrate (111 SiO2/Si or quartz), (2) the CNT-CNT Van der Waals interactions, and (3) the differential thermal contraction between the grown CNT film and the used substrate, which is fixed by the cooling rate differences between the grown film and the used quartz or Si/SiO2 substrates. The width and stability of these films are then further increased to cm-scale by addition of small quantities of toluene to the ferrocene precursor.

Electrochemical detection of nitrite on poly(pyronin Y)/graphene nanocomposites modified ITO substrate

NASA Astrophysics Data System (ADS)

Şinoforoğlu, Mehmet; Dağcı, Kader; Alanyalıoğlu, Murat; Meral, Kadem

2016-06-01

The present study reports on an easy preparation of poly(pyronin Y)/graphene (poly(PyY)/graphene) nanocomposites thin films on indium tin oxide coated glass substrates (ITO). The thin films of poly(PyY)/graphene nanocomposites are prepared by a novel method consisting of three steps; (i) preparation of graphene oxide (GO) thin films on ITO by spin-coating method, (ii) self-assembly of PyY molecules from aqueous solution onto the GO thin film, (iii) surface-confined electropolymerization (SCEP) of the adsorbed PyY molecules on the GO thin film. The as-prepared poly(PyY)/graphene nanocomposites thin films are characterized by using electroanalytical and spectroscopic techniques. Afterwards, the graphene-based polymeric dye thin film on ITO is used as an electrode in an electrochemical cell. Its performance is tested for electrochemical detection of nitrite. Under optimized conditions, the electrocatalytical effect of the nanocomposites thin film through electrochemical oxidation of nitrite is better than that of GO coated ITO.

Nanocomposite films based on CMC, okra mucilage and ZnO nanoparticles: Physico mechanical and antibacterial properties.

PubMed

Mohammadi, Hamid; Kamkar, Abolfazl; Misaghi, Ali

2018-02-01

This work examined the physico mechanical parameters and antibacterial activity of CMC/okra mucilage (OM) blend films containing ZnO nanoparticles (NPs). Different proportions of CMC and okra mucilage (100/0; 70/30; 60/40 and 50/50 respectively), were mixed and casted to posterior analysis of formed films. The more colored films were obtained by higher contents of okra mucilage and adding ZnO nanoparticles. The incorporation of ZnO NPs into CMC film decreased the elongation at the break (EB) value of the films and increased the tensile strength (TS) value of the film. With increase in CMC concentration in the films, higher water vapor permeability and higher solubility in water were achieved. Microstructure analysis using SEM showed a smooth and compact surface morphology, homogeneous structure, and a rough surface for CMC, CMC+ZnO, and CMC/OM30%+ZnO, respectively. Nanocomposite films presented antibacterial activity against tested bacteria. Films contained okra mucilage showed more antibacterial activity. The inhibitory activities of resultant films were stronger against S. aureus than E. coli. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hole-dominated transport in InSb nanowires grown on high-quality InSb films

NASA Astrophysics Data System (ADS)

Algarni, Zaina; George, David; Singh, Abhay; Lin, Yuankun; Philipose, U.

2016-12-01

We have developed an effective strategy for synthesizing p-type indium antimonide (InSb) nanowires on a thin film of InSb grown on glass substrate. The InSb films were grown by a chemical reaction between S b 2 S 3 and I n and were characterized by structural, compositional, and optical studies. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies reveal that the surface of the substrate is covered with a polycrystalline InSb film comprised of sub-micron sized InSb islands. Energy dispersive X-ray (EDX) results show that the film is stoichiometric InSb. The optical constants of the InSb film, characterized using a variable-angle spectroscopic ellipsometer (VASE) shows a maximum value for refractive index at 3.7 near 1.8 eV, and the extinction coefficient (k) shows a maximum value 3.3 near 4.1 eV. InSb nanowires were subsequently grown on the InSb film with 20 nm sized Au nanoparticles functioning as the metal catalyst initiating nanowire growth. The InSb nanowires with diameters in the range of 40-60 nm exhibit good crystallinity and were found to be rich in Sb. High concentrations of anions in binary semiconductors are known to introduce acceptor levels within the band gap. This un-intentional doping of the InSb nanowire resulting in hole-dominated transport in the nanowires is demonstrated by the fabrication of a p-channel nanowire field effect transistor. The hole concentration and field effect mobility are estimated to be ≈1.3 × 1017 cm-3 and 1000 cm2 V-1 s-1, respectively, at room temperature, values that are particularly attractive for the technological implications of utilizing p-InSb nanowires in CMOS electronics.

Preparation and properties of hybrid monodispersed magnetic α-Fe2O3 based chitosan nanocomposite film for industrial and biomedical applications.

PubMed

Singh, Jay; Srivastava, M; Dutta, Joydeep; Dutta, P K

2011-01-01

In this study, hydrothermally prepared magnetic α-Fe2O3 nanoparticles were dispersed in chitosan (CH) solution to fabricate nanocomposite film. X-ray diffraction (XRD) patterns indicated that the α-Fe2O3 nanoparticles were pure α-Fe2O3 with rhombohedral structures, and the fabrication of CH did not result in a phase change. The scanning electron microscopy (SEM) and transmission electron microscope (TEM) results showed that the hexagonal and spherical monodispersed α-Fe2O3 nanoparticles were encapsulated into the spherical dumb shaped CH-α-Fe2O3 nanocomposite film with a mean diameter of ∼87 and ∼110 nm respectively. The α-Fe2O3 nanoparticles and CH-α-Fe2O3 nanocomposite film were also characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM). Magnetic measurements revealed that the saturated magnetization (Ms) and remanent magnetization (Mr) of the pure α-Fe2O3 nanoparticles reached 0.573 emu/g and 0.100 emu/g respectively and the nanoparticles showed the characteristics of weak ferromagnetic before and after coating with CH. Copyright © 2010 Elsevier B.V. All rights reserved.

Sustainable Energy-Storage Materials from Lignin-Graphene Nanocomposite-Derived Porous Carbon Film

DOE PAGES

Tran, Chau D.; Ho, Hoi Chun; Keum, Jong K.; ...

2017-05-30

We present a simple, green approach to fabricating porous free-standing carbon films. An alkaline solution of low-cost, renewable lignin and graphene oxide (GO) is cast, followed by simultaneous carbonization and activation. Lignin, which is the least valued product from several biomass processing industries, is an efficient source of carbon when used as an intercalating agent to separate graphene sheets derived from homogeneous GO/lignin nanocomposite films prepared from an aqueous alkaline (KOH) solution. After thermal treatment the GO/lignin films show complete dispersion of reduced GO sheets within amorphous lignin-derived carbon. Furthermore, the presence of KOH in the film produces activated carbon.more » The resulting activated carbon films display a specific surface area of up to 1744 m2 g 1 and consist of a balance of pore volumes with pore sizes below and above 1 nm. A two-electrode supercapacitor composed of these films in an aqueous electrolyte exhibits near-ideal capacitive behavior at an ultrahigh scan rate of 1 V s 1, while maintaining an excellent specific capacitance of 162 F g 1. Such outstanding performance of renewable carbon as a supercapacitor, in addition to the ease of electrode fabrication from a precursor containing 85 % lignin, offers a novel method for valorization of lignin-rich byproduct streams from biomass processing industries.« less

Sustainable Energy-Storage Materials from Lignin-Graphene Nanocomposite-Derived Porous Carbon Film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tran, Chau D.; Ho, Hoi Chun; Keum, Jong K.

We present a simple, green approach to fabricating porous free-standing carbon films. An alkaline solution of low-cost, renewable lignin and graphene oxide (GO) is cast, followed by simultaneous carbonization and activation. Lignin, which is the least valued product from several biomass processing industries, is an efficient source of carbon when used as an intercalating agent to separate graphene sheets derived from homogeneous GO/lignin nanocomposite films prepared from an aqueous alkaline (KOH) solution. After thermal treatment the GO/lignin films show complete dispersion of reduced GO sheets within amorphous lignin-derived carbon. Furthermore, the presence of KOH in the film produces activated carbon.more » The resulting activated carbon films display a specific surface area of up to 1744 m2 g 1 and consist of a balance of pore volumes with pore sizes below and above 1 nm. A two-electrode supercapacitor composed of these films in an aqueous electrolyte exhibits near-ideal capacitive behavior at an ultrahigh scan rate of 1 V s 1, while maintaining an excellent specific capacitance of 162 F g 1. Such outstanding performance of renewable carbon as a supercapacitor, in addition to the ease of electrode fabrication from a precursor containing 85 % lignin, offers a novel method for valorization of lignin-rich byproduct streams from biomass processing industries.« less

Preparation and Characterization of Space Durable Polymer Nanocomposite Films from Functionalized Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Delozier, D. M.; Connell, J. W.; Smith, J. G.; Watson, K. A.

2003-01-01

Low color, flexible, space durable polyimide films with inherent, robust electrical conductivity have been under investigation as part of a continuing materials development activity for future NASA space missions involving Gossamer structures. Electrical conductivity is needed in these films to dissipate electrostatic charge build-up that occurs due to the orbital environment. One method of imparting conductivity is through the use of single walled carbon nanotubes (SWNTs). However, the incompatibility and insolubility of the SWNTs severely hampers their dispersion in polymeric matrices. In an attempt to improve their dispersability, SWNTs were functionalized by the reaction with an alkyl hydrazone. After this functionalization, the SWNTs were soluble in select solvents and dispersed more readily in the polymer matrix. The functionalized SWNTs were characterized by Raman spectroscopy and thermogravimetric analysis (TGA). The functionalized nanotubes were dispersed in the bulk of the films using a solution technique. The functionalized nanotubes were also applied to the surface of polyimide films using a spray coating technique. The resultant polyimide nanocomposite films were evaluated for nanotube dispersion, electrical conductivity, mechanical, and optical properties and compared with previously prepared polyimide-SWNT samples to assess the effects of SWNT functionalization.

Two-phase nc-TiN/a-(C,CN{sub x}) nanocomposite films: A HRTEM and MC simulation study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, J.; Lu, Y. H.; Hu, X. J.

2013-06-18

The grain growth in two-phase nanocomposite Ti-C{sub x}-N{sub y} thin films grown by reactive close-field unbalanced magnetron sputtering in an Ar-N{sub 2} gas mixture with microstructures comprising of nanocrystalline (nc-) Ti(N,C) phase surrounded by amorphous (a-) (C,CN{sub x}) phase was investigated by a combination of high-resolution transmission electron microscopy (HRTEM) and Monte Carlo (MC) simulations. The HRTEM results revealed that amorphous-free solid solution Ti(C,N) thin films exhibited polycrystallites with different sizes, orientations and irregular shapes. The grain size varied in the range between several nanometers and several decade nanometers. Further increase of C content (up to {approx}19 at.% C) mademore » the amorphous phase wet nanocrystallites, which strongly hindered the growth of nanocrystallites. As a result, more regular Ti(C,N) nanocrystallites with an average size of {approx}5 nm were found to be separated by {approx}0.5-nm amorphous phases. When C content was further increased (up to {approx}48 at.% in this study), thicker amorphous matrices were produced and followed by the formation of smaller sized grains with lognormal distribution. Our MC analysis indicated that with increasing amorphous volume fraction (i.e. increasing C content), the transformation from nc/nc grain boundary (GB)-curvature-driven growth to a/nc GB-curvature-driven growth is directly responsible for the observed grain growth from great inhomogeneity to homogeneity process.« less

Electronic excitation induced modifications of structural, electrical and optical properties of Cu-C60 nanocomposite thin films

NASA Astrophysics Data System (ADS)

Inani, H.; Singhal, R.; Sharma, P.; Vishnoi, R.; Ojha, S.; Chand, S.; Sharma, G. D.

2017-09-01

High energy ion irradiation significantly affects the size and shape of nanoparticles in composites. Low concentration metal fraction embedded in fullerene matrix in form of nanocomposites was synthesized by thermal co-evaporation method. Swift heavy ion irradiation was performed with 120 MeV Au ion beam on Cu-C60 nanocomposites at different fluences 1 × 1012, 3 × 1012, 6 × 1012, 1 × 1013 and 3 × 1013 ions/cm2. Absorption spectra demonstrated that absorption intensity of nanocomposite thin film was increased whereas absorption modes of fullerene C60 were diminished with fluence. Rutherford backscattering spectroscopy was also performed to estimate the thickness of the film and atomic metal fraction in matrix and found to be 45 nm and 3%, respectively. Transmission electron microscopy was performed for structural and particle size evaluation of Cu nanoparticles (NPs) in fullerene C60 matrix. A growth of Cu nanoparticles is observed at a fluence of 3 × 1013 ions/cm2 with a bi-modal distribution in fullerene C60. Structural evolution of fullerene C60 matrix with increasing fluence of 120 MeV Au ion beam is studied by Raman spectroscopy which shows the amorphization of matrix (fullerene C60) at lower fluence. The growth of Cu nanoparticles is explained using the phenomena of Ostwald ripening.

Effect of precursor on epitaxially grown of ZnO thin film on p-GaN/sapphire (0 0 0 1) substrate by hydrothermal technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sahoo, Trilochan; Ju, Jin-Woo; Kannan, V.

2008-03-04

Single crystalline ZnO thin film on p-GaN/sapphire (0 0 0 1) substrate, using two different precursors by hydrothermal route at a temperature of 90 deg. C were successfully grown. The effect of starting precursor on crystalline nature, surface morphology and optical emission of the films were studied. ZnO thin films were grown in aqueous solution of zinc acetate and zinc nitrate. X-ray diffraction analysis revealed that all the thin films were single crystalline in nature and exhibited wurtzite symmetry and c-axis orientation. The thin films obtained with zinc nitrate had a more pitted rough surface morphology compared to the filmmore » grown in zinc acetate. However the thickness of the films remained unaffected by the nature of the starting precursor. Sharp luminescence peaks were observed from the thin films almost at identical energies but deep level emission was slightly prominent for the thin film grown in zinc nitrate.« less

Impact of Sweet Potato Starch-Based Nanocomposite Films Activated With Thyme Essential Oil on the Shelf-Life of Baby Spinach Leaves

PubMed Central

Issa, Aseel; Ibrahim, Salam A.; Tahergorabi, Reza

2017-01-01

Salmonella Typhimurium (S. Typhi) and Escherichia coli (E. coli) have been responsible for an increasing number of outbreaks linked to fresh produce, such as baby spinach leaves, in the last two decades. More recently, antimicrobial biodegradable packaging systems have been attracting much attention in the food packaging industry as eco-friendly alternatives to conventional plastic packaging. The objective of this study was to evaluate the effect of antibacterial nanocomposite films on inoculated spinach leaves and on the sensory properties of these leaves during eight days of refrigerated storage. In this study, an antibacterial film comprised of sweet potato starch (SPS), montmorillonite (MMT) nanoclays and thyme essential oil (TEO) as a natural antimicrobial agent was developed. Our results showed that the incorporation of TEO in the film significantly (p < 0.05) reduced the population of E. coli and S. Typhi on fresh baby spinach leaves to below detectable levels within five days, whereas the control samples without essential oil maintained approximately 4.5 Log colony forming unit (CFU)/g. The sensory scores for spinach samples wrapped in films containing TEO were higher than those of the control. This study thus suggests that TEO has the potential to be directly incorporated into a SPS film to prepare antimicrobial nanocomposite films for food packaging applications. PMID:28587199

Synthesis and characterization of MoB{sub 2−x} thin films grown by nonreactive DC magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malinovskis, Paulius, E-mail: paulius.malinovskis@kemi.uu.se; Lewin, Erik; Jansson, Ulf

2016-05-15

DC magnetron sputtering was used to deposit molybdenum boride thin films for potential low-friction applications. The films exhibit a nanocomposite structure with ∼10 nm large MoB{sub 2−x} (x > 0.4) grains surrounded by a boron-rich tissue phase. The preferred formation of the metastable and substoichiometric hP3-MoB{sub 2} structure (AlB{sub 2}-type) is explained with kinetic constraints to form the thermodynamically stable hR18-MoB{sub 2} phase with a very complex crystal structure. Nanoindentation revealed a relatively high hardness of (29 ± 2) GPa, which is higher than bulk samples. The high hardness can be explained by a hardening effect associated with the nanocomposite microstructure where the surrounding tissuemore » phase restricts dislocation movement. A tribological study confirmed a significant formation of a tribofilm consisting of molybdenum oxide and boron oxide, however, without any lubricating effects at room temperature.« less

Magnetic Hysteresis in Nanocomposite Films Consisting of a Ferromagnetic AuCo Alloy and Ultrafine Co Particles

PubMed Central

Chinni, Federico; Spizzo, Federico; Montoncello, Federico; Mattarello, Valentina; Maurizio, Chiara; Mattei, Giovanni; Del Bianco, Lucia

2017-01-01

One fundamental requirement in the search for novel magnetic materials is the possibility of predicting and controlling their magnetic anisotropy and hence the overall hysteretic behavior. We have studied the magnetism of Au:Co films (~30 nm thick) with concentration ratios of 2:1, 1:1, and 1:2, grown by magnetron sputtering co-deposition on natively oxidized Si substrates. They consist of a AuCo ferromagnetic alloy in which segregated ultrafine Co particles are dispersed (the fractions of Co in the AuCo alloy and of segregated Co increase with decreasing the Au:Co ratio). We have observed an unexpected hysteretic behavior characterized by in-plane anisotropy and crossed branches in the loops measured along the hard magnetization direction. To elucidate this phenomenon, micromagnetic calculations have been performed for a simplified system composed of two exchange-coupled phases: a AuCo matrix surrounding a Co cluster, which represents an aggregate of particles. The hysteretic features are qualitatively well reproduced provided that the two phases have almost orthogonal anisotropy axes. This requirement can be plausibly fulfilled assuming a dominant magnetoelastic character of the anisotropy in both phases. The achieved conclusions expand the fundamental knowledge on nanocomposite magnetic materials, offering general guidelines for tuning the hysteretic properties of future engineered systems. PMID:28773075

Control of Defects in Aluminum Gallium Nitride ((Al)GaN) Films on Grown Aluminum Nitride (AlN) Substrates

DTIC Science & Technology

2013-02-01

Nord, J.; Albe, K.; Erhart, P.; Nordlund, K. Modelling of Compound Semiconductors: Analytical Bond-order Potential for Gallium , Nitrogen and Gallium ...Control of Defects in Aluminum Gallium Nitride ((Al)GaN) Films on Grown Aluminum Nitride (AlN) Substrates by Iskander G. Batyrev, Chi-Chin Wu...Aluminum Gallium Nitride ((Al)GaN) Films on Grown Aluminum Nitride (AlN) Substrates Iskander G. Batyrev and N. Scott Weingarten Weapons and

In situ diazonium-modified flexible ITO-coated PEN substrates for the deposition of adherent silver-polypyrrole nanocomposite films.

PubMed

Samanta, Soumen; Bakas, Idriss; Singh, Ajay; Aswal, Dinesh K; Chehimi, Mohamed M

2014-08-12

In this paper, we report a simple and versatile process of electrografting the aryl multilayers onto indium tin oxide (ITO)-coated flexible poly(ethylene naphthalate) (PEN) substrates using a diazonium salt (4-pyrrolylphenyldiazonium) solution, which was generated in situ from a reaction between the 4-(1H-pyrrol-1-yl)aniline precursor and sodium nitrite in an acidic medium. The first aryl layer bonds with the ITO surface through In-O-C and Sn-O-C bonds which facilitate the formation of a uniform aryl multilayer that is ∼8 nm thick. The presence of the aryl multilayer has been confirmed by impedance spectroscopy as well as by electron-transfer blocking measurements. These in situ diazonium-modified ITO-coated PEN substrates may find applications in flexible organic electronics and sensor industries. Here we demonstrate the application of diazonium-modified flexible substrates for the growth of adherent silver/polpyrrole nanocomposite films using surface-confined UV photopolymerization. These nanocomposite films have platelet morphology owing to the template effect of the pyrrole-terminated aryl multilayers. In addition, the films are highly doped (32%). This work opens new areas in the design of flexible ITO-conductive polymer hybrids.

P-doped strontium titanate grown using two target pulsed laser deposition for thin film solar cells

NASA Astrophysics Data System (ADS)

Man, Hamdi

Thin-film solar cells made of Mg-doped SrTiO3 p-type absorbers are promising candidates for clean energy generation. This material shows p-type conductivity and also demonstrates reasonable absorption of light. In addition, p-type SrTiO3 can be deposited as thin films so that the cost can be lower than the competing methods. In this work, Mg-doped SrTiO3 (STO) thin-films were synthesized and analyzed in order to observe their potential to be employed as the base semiconductor in photovoltaic applications. Mg-doped STO thin-films were grown by using pulsed laser deposition (PLD) using a frequency quadrupled Yttrium Aluminum Garnet (YAG) laser and with a substrate that was heated by back surface absorption of infrared (IR) laser light. The samples were characterized using X-ray photoelectron spectroscopy (XPS) and it was observed that Mg atoms were doped successfully in the stoichiometry. Reflection high energy electron diffraction (RHEED) spectroscopy proved that the thin films were polycrystalline. Kelvin Probe work function measurements indicated that the work function of the films were 4.167 eV after annealing. UV/Vis Reflection spectroscopy showed that Mg-doped STO thin-films do not reflect significantly except in the ultraviolet region of the spectrum where the reflection percentage increased up to 80%. Self-doped STO thin-films, Indium Tin Oxide (ITO) thin films and stainless steel foil (SSF) were studied in order to observe their characteristics before employing them in Mg-doped STO based solar cells. Self-doped STO thin films were grown using PLD and the results showed that they are capable of serving as the n-type semiconductor in solar cell applications with oxygen vacancies in their structure and low reflectivity. Indium Tin Oxide thin-films grown by PLD system showed low 25-50 ?/square sheet resistance and very low reflection features. Finally, commercially available stainless steel foil substrates were excellent substrates for the inexpensive growth of

Microstructural Characteristics of GeSbTe Thin Films Grown by RF Sputtering

NASA Astrophysics Data System (ADS)

Nelson, M. J.; Inglefield, C. E.; Olson, J. K.; Li, H.; Taylor, P. C.

2004-10-01

Thin films of GeSbTe are of interest due to their potential use in rewritable optical data storage media and reconfigurable electronics. The amorphous and crystalline phases of GeSbTe exhibit very different reflectivity and electrical conductivity. Films of nominally amorphous Ge_2Sb_2Te5 were grown to various thicknesses using RF sputtering on quartz substrates. The surfaces of the films were analyzed using Atomic Force Microscopy (AFM) and surface roughness measurements were taken. The thicker films had a truly isotropic surface while the thinnest films displayed crystalline features, such as angular steps. Conductivity measurements of the films in both coplanar and sandwich geometries correlate with the AFM data and indicate a high degree of crystallinity during the initial stages of growth. This work was supported by the Air Force Research Laboratory under grant number F29601-03-01-0229 and by Weber State University through the Phyllis Crosby Gardner fellowship.

Structural and electromagnetic properties of NiAlxFe2-xO4/SiO2 nanocomposite films deposited using a sol-gel spin-coating method

NASA Astrophysics Data System (ADS)

Wang, Li; Li, Xuejian; Li, Ji; Liu, Mei; Xu, Shichong; Li, Haibo

2017-12-01

NiAlxFe2-xO4/SiO2 (0 ≤ x ≤ 1.0) nanocomposite films deposited on Si(1 0 0) substrates were prepared by a sol-gel spin-coating method. The influences of Al3+ content and annealing temperature on the structural and electromagnetic properties of the nanocomposite films were investigated. The results indicated that NiAlxFe2-xO4 in the nanocomposite films crystallized after annealing at 1073 K and above. When the doping content x increased from 0 to 1.0, the lattice constants and the average crystallite sizes of the NiAlxFe2-xO4 nanoparticles decreased. The saturation magnetization and coercivity of the films were inversely proportional to the Al3+ content. The maximum value of saturation magnetization (361.6 emu/cm3) and the minimum value of coercivity (18.6 kA/m) were obtained for x of 0.2. When the annealing temperature increased from 1073 to 1473 K, the lattice constant and the average crystallite size of the NiAl0.2Fe1.8O4 nanoparticles increased from 0.8322 to 0.8349 nm and 4 to 28 nm, respectively, and the saturation magnetization and coercivity of the films increased from 214.8 to 464.5 emu/cm3 and 8.2 to 26.9 kA/m, respectively. Moreover, the DC resistivity of the films increased with increasing Al3+ content and annealing temperature.

Comparison of stress states in GaN films grown on different substrates: Langasite, sapphire and silicon

NASA Astrophysics Data System (ADS)

Park, Byung-Guon; Saravana Kumar, R.; Moon, Mee-Lim; Kim, Moon-Deock; Kang, Tae-Won; Yang, Woo-Chul; Kim, Song-Gang

2015-09-01

We demonstrate the evolution of GaN films on novel langasite (LGS) substrate by plasma-assisted molecular beam epitaxy, and assessed the quality of grown GaN film by comparing the experimental results obtained using LGS, sapphire and silicon (Si) substrates. To study the substrate effect, X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and photoluminescence (PL) spectra were used to characterize the microstructure and stress states in GaN films. Wet etching of GaN films in KOH solution revealed that the films deposited on GaN/LGS, AlN/sapphire and AlN/Si substrates possess Ga-polarity, while the film deposited on GaN/sapphire possess N-polarity. XRD, Raman and PL analysis demonstrated that a compressive stress exist in the films grown on GaN/LGS, AlN/sapphire, and GaN/sapphire substrates, while a tensile stress appears on AlN/Si substrate. Comparative analysis showed the growth of nearly stress-free GaN films on LGS substrate due to the very small lattice mismatch ( 3.2%) and thermal expansion coefficient difference ( 7.5%). The results presented here will hopefully provide a new framework for the further development of high performance III-nitride-related devices using GaN/LGS heteroepitaxy.

Highly crystalline MoS{sub 2} thin films grown by pulsed laser deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Serrao, Claudy R.; You, Long; Gadgil, Sushant

2015-02-02

Highly crystalline thin films of MoS{sub 2} were prepared over large area by pulsed laser deposition down to a single monolayer on Al{sub 2}O{sub 3} (0001), GaN (0001), and SiC-6H (0001) substrates. X-ray diffraction and selected area electron diffraction studies show that the films are quasi-epitaxial with good out-of-plane texture. In addition, the thin films were observed to be highly crystalline with rocking curve full width half maxima of 0.01°, smooth with a RMS roughness of 0.27 nm, and uniform in thickness based on Raman spectroscopy. From transport measurements, the as-grown films were found to be p-type.

Correlation of process parameters and properties of TiO2 films grown by ion beam sputter deposition from a ceramic target

NASA Astrophysics Data System (ADS)

Bundesmann, Carsten; Lautenschläge, Thomas; Spemann, Daniel; Finzel, Annemarie; Mensing, Michael; Frost, Frank

2017-10-01

The correlation between process parameters and properties of TiO2 films grown by ion beam sputter deposition from a ceramic target was investigated. TiO2 films were grown under systematic variation of ion beam parameters (ion species, ion energy) and geometrical parameters (ion incidence angle, polar emission angle) and characterized with respect to film thickness, growth rate, structural properties, surface topography, composition, optical properties, and mass density. Systematic variations of film properties with the scattering geometry, namely the scattering angle, have been revealed. There are also considerable differences in film properties when changing the process gas from Ar to Xe. Similar systematics were reported for TiO2 films grown by reactive ion beam sputter deposition from a metal target [C. Bundesmann et al., Appl. Surf. Sci. 421, 331 (2017)]. However, there are some deviations from the previously reported data, for instance, in growth rate, mass density and optical properties.

Structure and sublimation of water ice films grown in vacuo at 120-190 K studied by positron and positronium annihilation.

PubMed

Townrow, S; Coleman, P G

2014-03-26

The crystalline structure of ∼ 5-20 μm water ice films grown at 165 and 172 K has been probed by measuring the fraction of positrons forming ortho-positronium (ortho-Ps) and decaying into three gamma photons. It has been established that films grown at slower rates (water vapour pressure ≥ 1 mPa) have lower concentrations of lattice defects and closed pores, which act as Ps traps, than those grown at higher rates (vapour pressure ∼ 100 mPa), evidenced by ortho-Ps diffusion lengths being approximately four times greater in the former. By varying the growth temperature between 162 and 182 K it was found that films become less disordered at temperatures above ∼ 172 K, with the ortho-Ps diffusion length rising by ∼ 60%, in this range. The sublimation energy for water ice films grown on copper has been measured to be 0.462(5) eV using the time dependence of positron annihilation parameters from 165 to 195 K, in agreement with earlier studies and with no measurable dependence on growth rate and thermal history.

Efficient upconversion polymer-inorganic nanocomposite thin film emitters prepared by the double beam matrix assisted pulsed laser evaporation (DB-MAPLE)

NASA Astrophysics Data System (ADS)

Darwish, Abdalla M.; Burkett, Allan; Blackwell, Ashley; Taylor, Keylantra; Walker, Vernell; Sarkisov, Sergey; Koplitz, Brent

2014-09-01

We report on fabrication and investigation of optical and morphological properties of highly efficient (a quantum yield of 1%) upconversion polymer-inorganic nanocomposite thin film emitters prepared by the new technique of double beam matrix assisted pulsed laser evaporation (DB-MAPLE). Polymer poly(methyl methacrylate) (PMMA) host was evaporated on a silicon substrate using a 1064-nm pulsed laser beam using a target made of frozen (to the temperature of liquid nitrogen) solution of PMMA in chlorobenzene. Concurrently, the second 532-nm pulsed beam from the same laser was used to impregnate the polymer host with the inorganic nanoparticulate made of the rare earth upconversion compounds NaYF4: Yb3+, Er3+, NaYF4: Yb3+, Ho3+, and NaYF4: Yb3+, Tm3+. The compounds were initially synthesized using the wet process, baked, and compressed in solid pellet targets. The proposed DB-MAPLE method has the advantage of making highly homogeneous nanocomposite films with precise control of the doping rate due to the optimized overlapping of the plumes produced by the ablation of the organic and inorganic target with the infrared and visible laser beams respectively. X-ray diffraction, electron and atomic force microscopy, and optical fluorescence spectroscopy indicated that the inorganic nanoparticulate preserved its crystalline structure and upconversion properties (strong emission in green, red, and blue bands upon illumination with 980-nm laser diode) after being transferred from the target in the polymer nanocomposite film. The produced films can be used in applications varying from the efficiency enhancement of the photovoltaic cells, optical sensors and biomarkers to anti-counterfeit labels.

Ultra-Smooth ZnS Films Grown on Silicon via Pulsed Laser Deposition

NASA Astrophysics Data System (ADS)

Reidy, Christopher; Tate, Janet

2011-10-01

Ultra-smooth, high quality ZnS films were grown on (100) and (111) oriented Si wafers via pulsed laser deposition with a KrF excimer laser in UHV (10-9 Torr). The resultant films were examined with optical spectroscopy, electron diffraction, and electron probe microanalysis. The films have an rms roughness of ˜1.5 nm, and the film stoichiometry is approximately Zn:S :: 1:0.87. Additionally, each film exhibits an optical interference pattern which is not a function of probing location on the sample, indicating excellent film thickness uniformity. Motivation for high-quality ZnS films comes from a proposed experiment to measure carrier amplification via impact ionization at the boundary between a wide-gap and a narrow-gap semiconductor. If excited charge carriers in a sufficiently wide-gap harvester can be extracted into a narrow-gap host material, impact ionization may occur. We seek near-perfect interfaces between ZnS, with a direct gap between 3.3 and 3.7 eV, and Si, with an indirect gap of 1.1 eV.

Microstructures and growth mechanisms of GaN films epitaxially grown on AlN/Si hetero-structures by pulsed laser deposition at different temperatures.

PubMed

Wang, Wenliang; Yang, Weijia; Lin, Yunhao; Zhou, Shizhong; Li, Guoqiang

2015-11-13

2 inch-diameter GaN films with homogeneous thickness distribution have been grown on AlN/Si(111) hetero-structures by pulsed laser deposition (PLD) with laser rastering technique. The surface morphology, crystalline quality, and interfacial property of as-grown GaN films are characterized in detail. By optimizing the laser rastering program, the ~300 nm-thick GaN films grown at 750 °C show a root-mean-square (RMS) thickness inhomogeneity of 3.0%, very smooth surface with a RMS surface roughness of 3.0 nm, full-width at half-maximums (FWHMs) for GaN(0002) and GaN(102) X-ray rocking curves of 0.7° and 0.8°, respectively, and sharp and abrupt AlN/GaN hetero-interfaces. With the increase in the growth temperature from 550 to 850 °C, the surface morphology, crystalline quality, and interfacial property of as-grown ~300 nm-thick GaN films are gradually improved at first and then decreased. Based on the characterizations, the corresponding growth mechanisms of GaN films grown on AlN/Si hetero-structures by PLD with various growth temperatures are hence proposed. This work would be beneficial to understanding the further insight of the GaN films grown on Si(111) substrates by PLD for the application of GaN-based devices.

Microstructures and growth mechanisms of GaN films epitaxially grown on AlN/Si hetero-structures by pulsed laser deposition at different temperatures

PubMed Central

Wang, Wenliang; Yang, Weijia; Lin, Yunhao; Zhou, Shizhong; Li, Guoqiang

2015-01-01

2 inch-diameter GaN films with homogeneous thickness distribution have been grown on AlN/Si(111) hetero-structures by pulsed laser deposition (PLD) with laser rastering technique. The surface morphology, crystalline quality, and interfacial property of as-grown GaN films are characterized in detail. By optimizing the laser rastering program, the ~300 nm-thick GaN films grown at 750 °C show a root-mean-square (RMS) thickness inhomogeneity of 3.0%, very smooth surface with a RMS surface roughness of 3.0 nm, full-width at half-maximums (FWHMs) for GaN(0002) and GaN(102) X-ray rocking curves of 0.7° and 0.8°, respectively, and sharp and abrupt AlN/GaN hetero-interfaces. With the increase in the growth temperature from 550 to 850 °C, the surface morphology, crystalline quality, and interfacial property of as-grown ~300 nm-thick GaN films are gradually improved at first and then decreased. Based on the characterizations, the corresponding growth mechanisms of GaN films grown on AlN/Si hetero-structures by PLD with various growth temperatures are hence proposed. This work would be beneficial to understanding the further insight of the GaN films grown on Si(111) substrates by PLD for the application of GaN-based devices. PMID:26563573

Effect of growth parameters on crystallinity and properties of ZnO films grown by plasma assisted MOCVD

NASA Astrophysics Data System (ADS)

Losurdo, M.; Giangregorio, M. M.; Sacchetti, A.; Capezzuto, P.; Bruno, G.; Malandrino, G.; Fragalà, I. L.

2007-07-01

Thin films of ZnO have been grown by plasma assisted metal-organic chemical vapour deposition (PA-MOCVD) using a 13.56 MHz O 2 plasma and the Zn(TTA)•tmed (HTTA=2-thenoyltrifluoroacetone, TMED=N,N,N',N'-tetramethylethylendiamine) precursor. The effects of growth parameters such as the plasma activation, the substrate, the surface temperature, and the ratio of fluxes of precursors on the structure, morphology, and optical and electrical properties of ZnO thin films have been studied. Under a very low plasma power of 20 W, c-axis oriented hexagonal ZnO thin films are grown on hexagonal sapphire (0001), cubic Si(001) and amorphous quartz substrates. The substrate temperature mainly controls grain size.

Growth and properties of amorphous silicon films grown using pulsed-flow reactive plasma beam epitaxy

NASA Technical Reports Server (NTRS)

Dalal, Vikram L.; Knox, Ralph; Kandalaft, Nabeeh; Baldwin, Greg

1991-01-01

The growth and properties of a-Si:H films grown using a novel deposition technique, reactive plasma beam epitaxy, are discussed. In this technique, a remote H plasma produced in a microwave-ECR reactor is used to grow a-Si:H films at low pressures. The H ions react with SiH4 introduced near the substrate to produce the film. The flow of SiH4 is pulsed on or off, thereby achieving in-situ annealing of the film during growth by H ions and radicals. The films produced by this technique appear to have good electronic quality, and are more stable than the standard glow discharge films.

Chitosan-Iron Oxide Coated Graphene Oxide Nanocomposite Hydrogel: A Robust and Soft Antimicrobial Biofilm.

PubMed

Konwar, Achyut; Kalita, Sanjeeb; Kotoky, Jibon; Chowdhury, Devasish

2016-08-17

We report a robust biofilm with antimicrobial properties fabricated from chitosan-iron oxide coated graphene oxide nanocomposite hydrogel. For the first time, the coprecipitation method was used for the successful synthesis of iron oxide coated graphene oxide (GIO) nanomaterial. After this, films were fabricated by the gel-casting technique aided by the self-healing ability of the chitosan hydrogel network system. Both the nanomaterial and the nanocomposite films were characterized by techniques such as scanning electron microscopy, FT-IR spectroscopy, X-ray diffraction, and vibrating sample magnetometry. Measurements of the thermodynamic stability and mechanical properties of the films indictaed a significant improvement in their thermal and mechanical properties. Moreover, the stress-strain profile indicated the tough nature of the nanocomposite hydrogel films. These improvements, therefore, indicated an effective interaction and good compatibility of the GIO nanomaterial with the chitosan hydrogel matrix. In addition, it was also possible to fabricate films with tunable surface properties such as hydrophobicity simply by varying the loading percentage of GIO nanomaterial in the hydrogel matrix. Fascinatingly, the chitosan-iron oxide coated graphene oxide nanocomposite hydrogel films displayed significant antimicrobial activities against both Gram-positive and Gram-negative bacterial strains, such as methicillin-resistant Staphylococcus aureus, Staphylococcus aureus, and Escherichia coli, and also against the opportunistic dermatophyte Candida albicans. The antimicrobial activities of the films were tested by agar diffusion assay and antimicrobial testing based on direct contact. A comparison of the antimicrobial activity of the chitosan-GIO nanocomposite hydrogel films with those of individual chitosan-graphene oxide and chitosan-iron oxide nanocomposite films demonstrated a higher antimicrobial activity for the former in both types of tests. In vitro hemolysis

High quality atomically thin PtSe2 films grown by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Yan, Mingzhe; Wang, Eryin; Zhou, Xue; Zhang, Guangqi; Zhang, Hongyun; Zhang, Kenan; Yao, Wei; Lu, Nianpeng; Yang, Shuzhen; Wu, Shilong; Yoshikawa, Tomoki; Miyamoto, Koji; Okuda, Taichi; Wu, Yang; Yu, Pu; Duan, Wenhui; Zhou, Shuyun

2017-12-01

Atomically thin PtSe2 films have attracted extensive research interests for potential applications in high-speed electronics, spintronics and photodetectors. Obtaining high quality thin films with large size and controlled thickness is critical. Here we report the first successful epitaxial growth of high quality PtSe2 films by molecular beam epitaxy. Atomically thin films from 1 ML to 22 ML have been grown and characterized by low-energy electron diffraction, Raman spectroscopy and x-ray photoemission spectroscopy. Moreover, a systematic thickness dependent study of the electronic structure is revealed by angle-resolved photoemission spectroscopy (ARPES), and helical spin texture is revealed by spin-ARPES. Our work provides new opportunities for growing large size single crystalline films to investigate the physical properties and potential applications of PtSe2.

Optical Characterization of Lead Monoxide Films Grown by Laser-Assisted Deposition

NASA Astrophysics Data System (ADS)

Baleva, M.; Tuncheva, V.

1994-05-01

The Raman spectra of PbO films, grown by laser-assisted deposition (LAD) at different substrate temperatures are investigated. The spectra of the films, deposited on amorphous, single crystal quartz and polycrystal PbTe substrates, are compared with the Raman spectra of tetragonal and orthorhombic powder samples. The phonon frequencies determined in our experiment with powder samples coincide fairly well with those obtained by Adams and Stevens, J. Chem. Soc., Dalton Trans., 1096 (1977). Thus the Raman spectra of the powder samples presented in this paper can be considered as unambiguous characteristics of the two different PbO crystal phases. It was concluded that the Raman scattering may serve as a tool for identification of PbO films and their crystal modifications. On the basis of this investigation it was concluded that the film structure changes from orthorhombic to tetragonal with increased substrate temperature, and that the nature of the substrate influences the crystal structure of the films. On the basis of the Raman spectra of the β-PbO films with prevailing (001) orientation of crystallization, an assignment of the modes is proposed.

Thermal-induced structural and optical investigations of Agsbnd ZnO nanocomposite thin films

NASA Astrophysics Data System (ADS)

Singh, S. K.; Singhal, R.

2018-07-01

In the present paper, we have successfully synthesized Agsbnd ZnO nanocomposite thin films by RF-magnetron sputtering technique at room temperature. Systematic investigations of thermal-induced structural and optical modifications in Agsbnd ZnO thin films have been observed and described. The Agsbnd ZnO thin films were annealed at three different temperatures of 300 °C, 400 °C and 500 °C in vacuum to prevent the oxidation of Ag. The presence and formation of Ag nanoparticles were estimated by transmission electron microscopy. X-ray diffraction analysis revealed the structural information about the crystalline quality of ZnO. The crystallinity as well as the crystallite size of the films have been found to be improved with annealing temperatures. The estimated crystallite size was ∼15.8 nm for as-deposited film and 19.0 nm for the film at a higher temperature. The chemical composition and structural analysis of as-deposited film were carried out by X-ray photoelectron spectroscopy. A very sharp absorption band appeared at ∼540 nm for Ag NPs that is associated with the surface plasmon resonance band of Ag. A noticeable red shift of about ∼12 nm has been recorded for films annealed at 500 °C. Atomic force microscopy has been utilized to examine the surface morphology of the as-deposited and annealed films. The grain size was found to be increase with increasing annealing temperature, while no significant changes were observed in the roughness of Agsbnd ZnO thin films. Raman spectroscopy revealed lattice defects and disordering in the films after the thermal annealing.

Novel processing to produce polymer/ceramic nanocomposites by atomic layer deposition

NASA Astrophysics Data System (ADS)

Liang, Xinhua

Polymeric materials can be greatly influenced by nanoscale inclusions of inorganic materials. The main goal of this thesis is to fabricate novel polymer/ceramic composite materials for two different applications using atomic layer deposition (ALD) or molecular layer deposition (MLD) methods. One is to produce well-dispersed polymer/ceramic nanocomposites with improved barrier properties for packaging applications. The other is to produce porous polymer/ceramic composites with improved bioactivity for tissue engineering applications. ALD has been successfully utilized for the conformal and uniform deposition of ultra-thin alumina and titania films on primary micron-sized polymer particles. The mechanism to initiate alumina and titania ALD on polymer particles without chemical functional groups was confirmed. A nucleation period was needed for both alumina and titania ALD on high density polyethylene (HDPE) particles and no nucleation period was needed for alumina ALD on polymethyl methacrylate particles. Titania ALD films deposited at low temperatures had an amorphous structure and showed much weaker photoactivity than common pigment-grade anatase TiO2 particles. Highly uniform and conformal ultra-thin aluminum alkoxide (alucone) polymer films were deposited on primary silica and titania nanoparticles using MLD in a fluidized bed reactor. The deposition chemistry and properties of alucone MLD films were investigated. The photoactivity of pigment-grade TiO2 particles was quenched after 20 cycles of an alucone MLD film, but the films shrank and decomposed in the presence of water, which decreased the passivation effect of the photoactivity of TiO2 particles. Well-dispersed polymer/ceramic nanocomposites were obtained by extruding alumina ALD coated HDPE particles. The diffusion coefficient of the fabricated nanocomposite membranes can be reduced by half with the inclusion of 7.3 vol.% alumina flakes. However, a corresponding increase in permeability was also observed

Biocompatibility of GaSb thin films grown by RF magnetron sputtering

NASA Astrophysics Data System (ADS)

Nishimoto, Naoki; Fujihara, Junko; Yoshino, Katsumi

2017-07-01

GaSb may be suitable for biological applications, such as cellular sensors and bio-medical instrumentation because of its low toxicity compared with As (III) compounds and its band gap energy. Therefore, the biocompatibility and the film properties under physiological conditions were investigated for GaSb thin films with or without a surface coating. GaSb thin films were grown on quartz substrates by RF magnetron sputtering, and then coated with (3-mercaptopropyl) trimethoxysilane (MPT). The electrical properties, surface morphology, and crystal structure of the GaSb thin film were unaffected by the MPT coating. The cell viability assay suggested that MPT-coated GaSb thin films are biocompatible. Bare GaSb was particularly unstable in pH9 buffer. Ga elution was prevented by the MPT coating, although the Ga concentration in the pH 9 buffer was higher than that in the other solutions. The surface morphology and crystal structure were not changed by exposure to the solutions, except for the pH 9 buffer, and the thin film properties of MPT-coated GaSb exposed to distilled water and H2O2 in saline were maintained. These results indicate that MPT-coated GaSb thin films are biocompatible and could be used for temporary biomedical devices.

Hydrothermally synthesized PZT film grown in highly concentrated KOH solution with large electromechanical coupling coefficient for resonator.

PubMed

Feng, Guo-Hua; Lee, Kuan-Yi

2017-12-01

This paper presents a study of lead zirconate titanate (PZT) films hydrothermally grown on a dome-shaped titanium diaphragm. Few articles in the literature address the implementation of hydrothermal PZT films on curved-diaphragm substrates for resonators. In this study, a 50-μm-thick titanium sheet is embossed using balls of designed dimensions to shape a dome-shaped cavity array. Through single-process hydrothermal synthesis, PZT films are grown on both sides of the processed titanium diaphragm with good adhesion and uniformity. The hydrothermal synthesis process involves a high concentration of potassium hydroxide solution and excess amounts of lead acetate and zirconium oxychloride octahydrate. Varied deposition times and temperatures of PZT films are investigated. The grown films are characterized by X-ray diffraction and scanning electron microscopy. The 10-μm-thick PZT dome-shaped resonators with 60- and 20-μm-thick supporting layers are implemented and further tested. Results for both resonators indicate that large electromechanical coupling coefficients and a series resonance of 95 MHz from 14 MHz can be attained. The device is connected to a complementary metal-oxide-semiconductor integrated circuit for analysis of oscillator applications. The oscillator reaches a Q value of 6300 in air. The resonator exhibits a better sensing stability when loaded with water when compared with air.

Hydrothermally synthesized PZT film grown in highly concentrated KOH solution with large electromechanical coupling coefficient for resonator

PubMed Central

Lee, Kuan-Yi

2017-01-01

This paper presents a study of lead zirconate titanate (PZT) films hydrothermally grown on a dome-shaped titanium diaphragm. Few articles in the literature address the implementation of hydrothermal PZT films on curved-diaphragm substrates for resonators. In this study, a 50-μm-thick titanium sheet is embossed using balls of designed dimensions to shape a dome-shaped cavity array. Through single-process hydrothermal synthesis, PZT films are grown on both sides of the processed titanium diaphragm with good adhesion and uniformity. The hydrothermal synthesis process involves a high concentration of potassium hydroxide solution and excess amounts of lead acetate and zirconium oxychloride octahydrate. Varied deposition times and temperatures of PZT films are investigated. The grown films are characterized by X-ray diffraction and scanning electron microscopy. The 10-μm-thick PZT dome-shaped resonators with 60- and 20-μm-thick supporting layers are implemented and further tested. Results for both resonators indicate that large electromechanical coupling coefficients and a series resonance of 95 MHz from 14 MHz can be attained. The device is connected to a complementary metal–oxide–semiconductor integrated circuit for analysis of oscillator applications. The oscillator reaches a Q value of 6300 in air. The resonator exhibits a better sensing stability when loaded with water when compared with air. PMID:29308260

Hydrothermally synthesized PZT film grown in highly concentrated KOH solution with large electromechanical coupling coefficient for resonator

NASA Astrophysics Data System (ADS)

Feng, Guo-Hua; Lee, Kuan-Yi

2017-12-01

This paper presents a study of lead zirconate titanate (PZT) films hydrothermally grown on a dome-shaped titanium diaphragm. Few articles in the literature address the implementation of hydrothermal PZT films on curved-diaphragm substrates for resonators. In this study, a 50-μm-thick titanium sheet is embossed using balls of designed dimensions to shape a dome-shaped cavity array. Through single-process hydrothermal synthesis, PZT films are grown on both sides of the processed titanium diaphragm with good adhesion and uniformity. The hydrothermal synthesis process involves a high concentration of potassium hydroxide solution and excess amounts of lead acetate and zirconium oxychloride octahydrate. Varied deposition times and temperatures of PZT films are investigated. The grown films are characterized by X-ray diffraction and scanning electron microscopy. The 10-μm-thick PZT dome-shaped resonators with 60- and 20-μm-thick supporting layers are implemented and further tested. Results for both resonators indicate that large electromechanical coupling coefficients and a series resonance of 95 MHz from 14 MHz can be attained. The device is connected to a complementary metal-oxide-semiconductor integrated circuit for analysis of oscillator applications. The oscillator reaches a Q value of 6300 in air. The resonator exhibits a better sensing stability when loaded with water when compared with air.

Anomalous Drag Reduction and Hydrodynamic Interactions of Nanoparticles in Polymer Nanocomposite Thin Films

NASA Astrophysics Data System (ADS)

Basu, Jaydeep; Begam, Nafisa; Chandran, Sivasurender; Sprung, Michael

2015-03-01

One of the central dogma of fluid physics is the no-slip boundary condition whose validity has come under intense scrutiny, especially in the fields of micro and nanofluidics. Although various studies show the violation of the no-slip condition its effect on flow of colloidal particles in viscous media has been rarely explored. Here we report unusually large reduction of effective drag experienced by polymer grafted nanoparticles moving through a highly viscous film of polymer, well above its glass transition temperature. The extent of drag reduction increases with decreasing temperature and polymer film thickness. We also observe apparent divergence of the wave vector dependent hydrodynamic interaction function of these nanoparticles with an anomalous power law exponent of ~ 2 at the lowest temperatures and film thickness. Such strong hydrodynamic interactions are not expected in polymer melts where these interactions are known to be screened to molecular dimensions. We provide evidence for the presence of large hydrodynamic slip at the nanoparticle-polymer interface and demonstrate its tunability with temperature and confinement. Our study suggests novel physics emerging in dynamics nanoparticles due to confinement and interface wettability in thin films of polymer nanocomposites.

Influence of Food with High Moisture Content on Oxygen Barrier Property of Polyvinyl Alcohol (PVA)/Vermiculite Nanocomposite Coated Multilayer Packaging Film.

PubMed

Kim, Jung Min; Lee, Min Hyeock; Ko, Jung A; Kang, Dong Ho; Bae, Hojae; Park, Hyun Jin

2018-02-01

This study investigates the potential complications in applying nanoclay-based waterborne coating to packaging films for food with high moisture content. Multilayer packaging films were prepared by dry laminating commercially available polyvinyl alcohol (PVA)/vermiculite nanocomposite coating films and linear low-density polyethylene film, and the changes in oxygen barrier properties were investigated according to different relative humidity using 3 types of food simulants. When the relative humidity was above 60%, the oxygen permeability increased sharply, but this was reversible. Deionized water and 3% acetic acid did not cause any large structural change in the PVA/vermiculite nanocomposite but caused a reversible deterioration of the oxygen barrier properties. In contrast, 50% ethanol, a simulant for the semifatty food, induced irreversible structural changes with deterioration of the oxygen barrier property. These changes are due to the characteristics of PVA rather than vermiculite. We believe this manuscript would be of interest to the wide group of researchers, organizations, and companies in the field of developing nanoclay-based gas barrier packaging for foods with high moisture content. Hence, we wish to diffuse our knowledge to the scientific community. © 2018 Institute of Food Technologists®.

Effects of substrate conductivity on cell morphogenesis and proliferation using tailored, atomic layer deposition-grown ZnO thin films

PubMed Central

Choi, Won Jin; Jung, Jongjin; Lee, Sujin; Chung, Yoon Jang; Yang, Cheol-Soo; Lee, Young Kuk; Lee, You-Seop; Park, Joung Kyu; Ko, Hyuk Wan; Lee, Jeong-O

2015-01-01

We demonstrate that ZnO films grown by atomic layer deposition (ALD) can be employed as a substrate to explore the effects of electrical conductivity on cell adhesion, proliferation, and morphogenesis. ZnO substrates with precisely tunable electrical conductivity were fabricated on glass substrates using ALD deposition. The electrical conductivity of the film increased linearly with increasing duration of the ZnO deposition cycle (thickness), whereas other physical characteristics, such as surface energy and roughness, tended to saturate at a certain value. Differences in conductivity dramatically affected the behavior of SF295 glioblastoma cells grown on ZnO films, with high conductivity (thick) ZnO films causing growth arrest and producing SF295 cell morphologies distinct from those cultured on insulating substrates. Based on simple electrostatic calculations, we propose that cells grown on highly conductive substrates may strongly adhere to the substrate without focal-adhesion complex formation, owing to the enhanced electrostatic interaction between cells and the substrate. Thus, the inactivation of focal adhesions leads to cell proliferation arrest. Taken together, the work presented here confirms that substrates with high conductivity disturb the cell-substrate interaction, producing cascading effects on cellular morphogenesis and disrupting proliferation, and suggests that ALD-grown ZnO offers a single-variable method for uniquely tailoring conductivity. PMID:25897486

Amorphous indium gallium zinc oxide thin film grown by pulse laser deposition technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mistry, Bhaumik V., E-mail: bhaumik-phy@yahoo.co.in; Joshi, U. S.

Highly electrically conducting and transparent in visible light IGZO thin film were grown on glass substrate at substrate temperature of 400 C by a pulse laser deposition techniques. Structural, surface, electrical, and optical properties of IGZO thin films were investigated at room temperature. Smooth surface morphology and amorphous nature of the film has been confirmed from the AFM and GIXRD analysis. A resistivity down to 7.7×10{sup −3} V cm was reproducibly obtained while maintaining optical transmission exceeding 70% at wavelengths from 340 to 780 nm. The carrier densities of the film was obtain to the value 1.9×10{sup 18} cm{sup 3},more » while the Hall mobility of the IGZO thin film was 16 cm{sup 2} V{sup −1}S{sup −1}.« less

Molecular beam epitaxially grown copper indium diselenide and copper gallium diselenide films

NASA Astrophysics Data System (ADS)

Yoon, Seokhyun

2005-12-01

To eliminate the influence of grain boundaries, CuInSe2 (CIS) and CuGaSe2 (CGS) films were grown on (100) GaAs wafers. The effects of Cu to III metal ratio and dosing with Na on the growth mode and defect properties were studied at two growth temperatures. The impact of post-annealing in Se on the defect structure of CGS film was also studied. Two-dimensional simulations were used to better understand the role of grain boundary on cell performance. For growth at 360°C, the In-rich CIS films were polycrystalline, whereas the Cu-rich CIS films were epitaxial exhibiting a Stranski-Krastanov (S-K) growth mode. It is proposed that a Cu-Se secondary phase enhances the mobility of adatoms, allowing epitaxial growth to a critical thickness, at which point segregation at the nucleation sites became faster the rate of growth. Island structures, embedded in a matrix region, were oriented along the [01-1] directed edges with surface undulations apparent on the matrix surface with dominant {112} crystal planes. At the higher growth temperature of 464°C, the CIS films grew epitaxially without the need of a Cu-Se phase. Both CIS films grown at low and high temperatures were nearly relaxed. The segregation of epitaxial Cu1.5Se was also observed in the Cu-rich, Na-dosed CIS film, which is attributed to a surfactant effect of Na. At a growth temperature of 438°C, CGS films showed a S-K growth mode and nearly pseudomorphic growth. Hemispherical islands with twins were observed in the Ga-rich CGS films and epitaxial Cu1.5Se phase were identified in the top region of the island structure. From the PL analysis of Cu-rich, Na-dosed CGS film after Se-annealing, a new defect level located 20 meV above the valence band edge was identified as NaGa acceptor state. Two-dimensional simulation of the impact of grain boundaries on device performance showed that the short circuit current decreases sharply along with the other device parameters below a critical grain size due to the complete

Solution-processable alumina: PVP nanocomposite dielectric layer for high-performance organic thin-film transistors

NASA Astrophysics Data System (ADS)

Lin, Hui; Kong, Xiao; Li, Yiran; Kuang, Peng; Tao, Silu

2018-03-01

In this article, we have investigated the effect of nanocomposite gate dielectric layer built by alumina (Al2O3) and poly(4-vinyphenol) (PVP) with solution method which could enhance the dielectric capability and decrease the surface polarity. Then, we used modify layer to optimize the surface morphology of dielectric layer to further improve the insulation capability, and finally we fabricated the high-performance and low-voltage organic thin-film transistors by using this nanocomposite dielectric layer. The result shows that the devices with Al2O3:10%PVP dielectric layer with a modified layer exhibited a mobility of 0.49 cm2/Vs, I on/Ioff ratio of 7.8 × 104, threshold voltage of - 1.2 V, sub-threshold swing of 0.3 V/dec, and operating voltage as low as - 4 V. The improvement of devices performance was owing to the good insulation capability, appropriate capacitance of dielectric layer, and preferable interface contact, smaller crystalline size of active layer.

Heterojunction oxide thin-film transistors with unprecedented electron mobility grown from solution.

PubMed

Faber, Hendrik; Das, Satyajit; Lin, Yen-Hung; Pliatsikas, Nikos; Zhao, Kui; Kehagias, Thomas; Dimitrakopulos, George; Amassian, Aram; Patsalas, Panos A; Anthopoulos, Thomas D

2017-03-01

Thin-film transistors made of solution-processed metal oxide semiconductors hold great promise for application in the emerging sector of large-area electronics. However, further advancement of the technology is hindered by limitations associated with the extrinsic electron transport properties of the often defect-prone oxides. We overcome this limitation by replacing the single-layer semiconductor channel with a low-dimensional, solution-grown In 2 O 3 /ZnO heterojunction. We find that In 2 O 3 /ZnO transistors exhibit band-like electron transport, with mobility values significantly higher than single-layer In 2 O 3 and ZnO devices by a factor of 2 to 100. This marked improvement is shown to originate from the presence of free electrons confined on the plane of the atomically sharp heterointerface induced by the large conduction band offset between In 2 O 3 and ZnO. Our finding underscores engineering of solution-grown metal oxide heterointerfaces as an alternative strategy to thin-film transistor development and has the potential for widespread technological applications.

Heterojunction oxide thin-film transistors with unprecedented electron mobility grown from solution

PubMed Central

Faber, Hendrik; Das, Satyajit; Lin, Yen-Hung; Pliatsikas, Nikos; Zhao, Kui; Kehagias, Thomas; Dimitrakopulos, George; Amassian, Aram; Patsalas, Panos A.; Anthopoulos, Thomas D.

2017-01-01

Thin-film transistors made of solution-processed metal oxide semiconductors hold great promise for application in the emerging sector of large-area electronics. However, further advancement of the technology is hindered by limitations associated with the extrinsic electron transport properties of the often defect-prone oxides. We overcome this limitation by replacing the single-layer semiconductor channel with a low-dimensional, solution-grown In2O3/ZnO heterojunction. We find that In2O3/ZnO transistors exhibit band-like electron transport, with mobility values significantly higher than single-layer In2O3 and ZnO devices by a factor of 2 to 100. This marked improvement is shown to originate from the presence of free electrons confined on the plane of the atomically sharp heterointerface induced by the large conduction band offset between In2O3 and ZnO. Our finding underscores engineering of solution-grown metal oxide heterointerfaces as an alternative strategy to thin-film transistor development and has the potential for widespread technological applications. PMID:28435867

Structural Properties Characterized by the Film Thickness and Annealing Temperature for La2O3 Films Grown by Atomic Layer Deposition.

PubMed

Wang, Xing; Liu, Hongxia; Zhao, Lu; Fei, Chenxi; Feng, Xingyao; Chen, Shupeng; Wang, Yongte

2017-12-01

La 2 O 3 films were grown on Si substrates by atomic layer deposition technique with different thickness. Crystallization characteristics of the La 2 O 3 films were analyzed by grazing incidence X-ray diffraction after post-deposition rapid thermal annealing treatments at several annealing temperatures. It was found that the crystallization behaviors of the La 2 O 3 films are affected by the film thickness and annealing temperatures as a relationship with the diffusion of Si substrate. Compared with the amorphous La 2 O 3 films, the crystallized films were observed to be more unstable due to the hygroscopicity of La 2 O 3 . Besides, the impacts of crystallization characteristics on the bandgap and refractive index of the La 2 O 3 films were also investigated by X-ray photoelectron spectroscopy and spectroscopic ellipsometry, respectively.

Polarity control of GaN epitaxial films grown on LiGaO2(001) substrates and its mechanism.

PubMed

Zheng, Yulin; Wang, Wenliang; Li, Xiaochan; Li, Yuan; Huang, Liegen; Li, Guoqiang

2017-08-16

The polarity of GaN epitaxial films grown on LiGaO 2 (001) substrates by pulsed laser deposition has been well controlled. It is experimentally proved that the GaN epitaxial films grown on nitrided LiGaO 2 (001) substrates reveal Ga-polarity, while the GaN epitaxial films grown on non-nitrided LiGaO 2 (001) substrates show N-polarity. The growth mechanisms for these two cases are systematically studied by first-principles calculations based on density functional theory. Theoretical calculation presents that the adsorption of a Ga atom preferentially occurs at the center of three N atoms stacked on the nitrided LiGaO 2 (001) substrates, which leads to the formation of Ga-polarity GaN. Whereas the adsorption of a Ga atom preferentially deposits at the top of a N atom stacked on the non-nitrided LiGaO 2 (001) substrates, which results in the formation of N-polarity GaN. This work of controlling the polarity of GaN epitaxial films is of paramount importance for the fabrication of group-III nitride devices for various applications.

Whey protein isolate/cellulose nanofibre/TiO2 nanoparticle/rosemary essential oil nanocomposite film: Its effect on microbial and sensory quality of lamb meat and growth of common foodborne pathogenic bacteria during refrigeration.

PubMed

Alizadeh Sani, Mahmood; Ehsani, Ali; Hashemi, Mohammad

2017-06-19

The use of biodegradable nanocomposite films in active packaging is of great importance since they can have a controlled release of antimicrobial compounds. This study was conducted to evaluate the efficacy of whey protein isolate (WPI)/cellulose nanofibre (CNF) nanocomposite films containing 1.0% (w/w) titanium dioxide (TiO 2 ) and 2.0% (w/v) rosemary essential oil (REO) in preserving the microbial and sensory quality of lamb meat during the storage at 4±1°C. Initially, the best concentration of each compound to be added to the film was determined by micro-dilution and disc diffusion methods. The microbial and sensory properties of lamb meat were controlled in two groups (control and treatment) over 15days of storage. Then, the samples were analysed for total viable count (TVC), Pseudomonas spp. count, Enterobacteriaceae count, Lactic acid bacteria (LAB) count, inoculated Staphylococcus aureus count, Listeria monocytogenes count, and Escherichia coli O 157 :H 7 count. Microbial analysis and nine-point hedonic scale was applied for the sensory analysis. Results indicated that the use of nanocomposite films significantly reduced the bacterial counts of treatment group. Higher inhibition effect was observed on Gram-positive bacteria than on Gram-negative bacteria (P<0.05). The microbial and sensory evaluations also showed that the use of nanocomposite films significantly increased the shelf life of treated meat (15days) compared to the control meat (6days). Based on the results of this study, the edible nanocomposite films were effective in preserving the microbial and sensory qualities of lamb meat; therefore, this application is recommended in meat especially red meat. Copyright © 2017 Elsevier B.V. All rights reserved.

Preparation and characterization of a poly (1, 4-phenylenevinylene) derivative-based hybrid thin film nanocomposites with enhanced performance

NASA Astrophysics Data System (ADS)

Belhaj, Marwa; Jemmeli, Dhouha; Dridi, Cherif; Ben Salem, Balkiss; Jaballah, Najmeddine; Majdoub, Mustapha; Yatskiv, Roman; Grym, Jan

2018-05-01

In this study, a poly (1, 4-phenylenevinylene) derivative (PPV-C6) was synthesized via Gilch polycondensation, and its electrochemical and optical characteristics were determined by cyclic voltammetry analysis, ultraviolet-visible, and photoluminescence spectroscopy. The polymer exhibited semiconductor behavior with an optical band gap of about 2.02 eV. Thin-film hybrid nanocomposites were prepared based on PPV-C6 with a large range of concentrations of sol-gel synthesized surfactant-free ZnO nanoparticles (n-ZnO). We investigated the photophysical properties of nanocomposites with different weight ratios of n-ZnO. The optical absorption spectra of PPV-C6: n-ZnO nanocomposites exhibited moderate variation in terms of the optical band gap energy with respect to the pristine polymer. Photoluminescence spectra indicated that the optimum n-ZnO concentration was about 50 wt% to achieve photoluminescence quenching, which corresponded to the most homogeneous surface and efficient charge transfer due to optimal exciton dissociation. We established good correlations between the investigated properties.

Probing localized strain in solution-derived YB a2C u3O7 -δ nanocomposite thin films

NASA Astrophysics Data System (ADS)

Guzman, Roger; Gazquez, Jaume; Mundet, Bernat; Coll, Mariona; Obradors, Xavier; Puig, Teresa

2017-07-01

Enhanced pinning due to nanoscale strain is unique to the high-Tc cuprates, where pairing may be modified with lattice distortion. Therefore a comprehensive understanding of the defect landscape is required for a broad range of applications. However, determining the type and distribution of defects and their associated strain constitutes a critical task, and for this aim, real-space techniques for atomic resolution characterization are necessary. Here, we use scanning transmission electron microscopy (STEM) to study the atomic structure of individual defects of solution-derived YB a2C u3O7 (YBCO) nanocomposites, where the inclusion of incoherent secondary phase nanoparticles within the YBCO matrix dramatically increases the density of Y1B a2C u4O8 (Y124) intergrowths, the commonest defect in YBCO thin films. The formation of the Y124 is found to trigger a concatenation of strain-derived interactions with other defects and the concomitant nucleation of intrinsic defects, which weave a web of randomly distributed nanostrained regions that profoundly transform the vortex-pinning landscape of the YBCO nanocomposite thin films.

Anisotropic elasticity of quasi-one-component polymer nanocomposites.

PubMed

Voudouris, Panayiotis; Choi, Jihoon; Gomopoulos, Nikos; Sainidou, Rebecca; Dong, Hongchen; Matyjaszewski, Krzysztof; Bockstaller, Michael R; Fytas, George

2011-07-26

The in-plane and out-of-plane elastic properties of thin films of "quasi-one-component" particle-brush-based nanocomposites are compared to those of "classical" binary particle-polymer nanocomposite systems with near identical overall composition using Brillouin light scattering. Whereas phonon propagation is found to be independent of the propagation direction for the binary particle/polymer blend systems, a pronounced splitting of the phonon propagation velocity along the in-plane and out-of-plane film direction is observed for particle-brush systems. The anisotropic elastic properties of quasi-one-component particle-brush systems are interpreted as a consequence of substrate-induced order formation into layer-type structures and the associated breaking of the symmetry of the film. The results highlight new opportunities to engineer quasi-one-component nanocomposites with advanced control of structural and physical property characteristics based on the assembly of particle-brush materials.

Persistent photocurrent and deep level traps in PLD-grown In-Ga-Zn-O thin films studied by thermally stimulated current spectroscopy

NASA Astrophysics Data System (ADS)

Wang, Buguo; Anders, Jason; Leedy, Kevin; Schuette, Michael; Look, David

2018-02-01

InGaZnO (IGZO) is a promising semiconductor material for thin-film transistors (TFTs) used in DC and RF switching applications, especially since it can be grown at low temperatures on a wide variety of substrates. Enhancement-mode TFTs based on IGZO thin films grown by pulsed laser deposition (PLD) have been recently fabricated and these transistors show excellent performance; however, compositional variations and defects can adversely affect film quality, especially in regard to electrical properties. In this study, we use thermally stimulated current (TSC) spectroscopy to characterize the electrical properties and the deep traps in PLD-grown IGZO thin films. It was found that the as-grown sample has a DC activation energy of 0.62 eV, and two major traps with activation energies at 0.16-0.26 eV and at 0.90 eV. However, a strong persistent photocurrent (PPC) sometimes exists in the as-grown sample, so we carry out post-growth annealing in an attempt to mitigate the effect. It was found that annealing in argon increases the conduction, produces more PPC and also makes more traps observable. Annealing in air makes the film more resistive, and removes PPC and all traps but one. This work demonstrates that current-based trap emission, such as that associated with the TSC, can effectively reveal electronic defects in highlyresistive semiconductor materials, especially those are not amenable to capacitance-based techniques, such as deeplevel transient spectroscopy (DLTS).

Sliding friction of nanocomposite WC1-x/C coatings: transfer film and its influence on tribology.

PubMed

Liu, Y; Gubisch, M; Spiess, L; Schaefer, J A

2009-06-01

The transfer film on steel spheres formed in reciprocating sliding against nanocomposite coatings based on nanocrystalline WC1-x in amorphous carbon matrix is characterized and correlated with the tribological properties measured by a precision microtribometer. With the presence of transfer film, a coefficient of friction approximately 0.13 and a depth wear rate approximately 0.35 x 10(-10) m/N.Pass were obtained. The central zone of the transfer film covering approximately 25% of the Hertz contact area is intact while cracks and wear debris are found in the vast peripheral area. It is also heavily oxidized due to the absence of carbon, which is located at the peripherals and acts as lubricants. We propose that the oxidation of WC and adhesion of the oxides to the surface of sphere is the main mechanism for the buildup of the transfer films. With the thickening of the film, the internal stress increases. Under the shear stress, spalling and cracking of the transfer film take place. The overall tribological performance of the coatings is therefore a competing process of buildup and spalling of transfer films.

High-Temperature Annealing as a Method for the Silicon Nanoclusters Growth in Stoichiometric Silicon Dioxide

NASA Astrophysics Data System (ADS)

Ivanova, E. V.; Dementev, P. A.; Sitnikova, A. A.; Aleksandrov, O. V.; Zamoryanskaya, M. V.

2018-07-01

A method for the growth of nanocomposite layers in stoichiometric amorphous silicon dioxide is proposed. It is shown that, after annealing at a temperature of 1150°C in nitrogen atmosphere, a layer containing silicon nanoclusters is formed. Silicon nanoclusters have a crystal structure and a size of 3-6 nm. In a film grown on a n-type substrate, a layer of silicon nanoclusters with a thickness of about 10 nm is observed. In the case of a film grown on a p-type substrate, a nanocomposite layer with a thickness of about 100 nm is observed. The difference in the formation of a nanocomposite layer in films on various substrates is associated with the doping of silicon dioxide with impurities from the substrate during the growth of the film. The formation of the nanocomposite layer was confirmed by transmission electron microscopy, XPS and local cathodoluminescence studies.

Nanocomposites of rice and banana flours blend with montmorillonite: partial characterization.

PubMed

Rodríguez-Marín, María L; Bello-Pérez, Luis A; Yee-Madeira, Hernani; Zhong, Qixin; González-Soto, Rosalía A

2013-10-01

Rice and banana flours are inexpensive starchy materials that can form films with more improved properties than those made with their starch because flour and starch present different hydrophobicity. Montmorillonite (MMT) can be used to further improve the properties of starch-based films, which has not received much research attention for starchy flours. The aim of this work was to evaluate the mechanical and barrier properties of nanocomposite films of banana and rice flours as matrix material with addition of MMT as a nanofiller. MMT was modified using citric acid to produce intercalated structures, as verified by the X-ray diffraction pattern. The intercalated MMT was blended with flour slurries, and films were prepared by casting. Nanocomposite films of banana and rice flours presented an increase in the tensile at break and elongation percentage, respectively, more than their respective control films without MMT. This study showed that banana and rice flours could be alternative raw materials to use in making nanocomposite films. Copyright © 2013 Elsevier B.V. All rights reserved.

Spin-hall-active platinum thin films grown via atomic layer deposition

NASA Astrophysics Data System (ADS)

Schlitz, Richard; Amusan, Akinwumi Abimbola; Lammel, Michaela; Schlicht, Stefanie; Tynell, Tommi; Bachmann, Julien; Woltersdorf, Georg; Nielsch, Kornelius; Goennenwein, Sebastian T. B.; Thomas, Andy

2018-06-01

We study the magnetoresistance of yttrium iron garnet/Pt heterostructures in which the Pt layer was grown via atomic layer deposition (ALD). Magnetotransport experiments in three orthogonal rotation planes reveal the hallmark features of spin Hall magnetoresistance. To estimate the spin transport parameters, we compare the magnitude of the magnetoresistance in samples with different Pt thicknesses. We check the spin Hall angle and the spin diffusion length of the ALD Pt layers against the values reported for high-quality sputter-deposited Pt films. The spin diffusion length of 1.5 nm agrees well with that of platinum thin films reported in the literature, whereas the spin Hall magnetoresistance Δ ρ / ρ = 2.2 × 10 - 5 is approximately a factor of 20 smaller compared to that of our sputter-deposited films. Our results demonstrate that ALD allows fabricating spin-Hall-active Pt films of suitable quality for use in spin transport structures. This work provides the basis to establish conformal ALD coatings for arbitrary surface geometries with spin-Hall-active metals and could lead to 3D spintronic devices in the future.

Investigation of AgInS2 thin films grown by coevaporation

NASA Astrophysics Data System (ADS)

Arredondo, C. A.; Clavijo, J.; Gordillo, G.

2009-05-01

AgInS2 thin films were grown on soda-lime glass substrates by co-evaporation of the precursors in a two-step process. X-ray diffraction (XRD) measurements indicated that these compounds grow in different phases and with different crystalline structure depending upon the deposition conditions. However, through a parameter study, conditions were found to grow thin films containing only the AgInS2 phase with chalcopyrite type structure. In samples containing a mixture of several phases, the contribution in percentage terms of each phase to the whole compound was estimated with the help of the PowderCell simulation package. It was also found that the AgInS2 films present p-type conductivity, a high absorption coefficient (greater than 104 cm-1) and an energy band gap Eg of about 1.95 eV, indicating that this compound has good properties to perform as absorbent layer in thin film tandem solar cells. The effect of the deposition conditions on the optical and morphological properties was also investigated through spectral transmitance and atomic force microscopy (AFM) measurements.

Nutraceutically inspired pectin-Mg(OH)₂ nanocomposites for bioactive packaging applications.

PubMed

Moreira, Francys K V; De Camargo, Lais A; Marconcini, José M; Mattoso, Luiz H C

2013-07-24

This paper reports on the development of bioactive edible films based on pectin as a dietary matrix and magnesium hydroxide (Mg(OH)2) nanoplates as a reinforcing filler. Nanocomposites of high-methoxyl (HM) and low-methoxyl (LM) pectins were prepared using the casting method at concentrations of Mg(OH)2 ranging from 0.5 to 5 wt %. Atomic force microscopy and FTIR spectroscopy were employed to characterize the nanocomposite structure. The tensile properties and thermal stability of the nanocomposites were also examined to ascertain the effect of Mg(OH)2 inclusion and degree of methoxylation. The results provided evidence that the Mg(OH)2 nanoplates were uniformly dispersed and interacted strongly with the film matrix. The mechanical and thermal properties were significantly improved in the nanocomposite films compared to the control. Mg(OH)2 nanoplates were more effective in improving properties of LM pectin. Preliminary migration studies using arugula leaves confirmed that pectin-Mg(OH)2 nanocomposites can release magnesium hydroxide by contact, demonstrating their potential for magnesium supplementation in bioactive packaging.

Thin film phase diagram of iron nitrides grown by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Gölden, D.; Hildebrandt, E.; Alff, L.

2017-01-01

A low-temperature thin film phase diagram of the iron nitride system is established for the case of thin films grown by molecular beam epitaxy and nitrided by a nitrogen radical source. A fine-tuning of the nitridation conditions allows for growth of α ‧ -Fe8Nx with increasing c / a -ratio and magnetic anisotropy with increasing x until almost phase pure α ‧ -Fe8N1 thin films are obtained. A further increase of nitrogen content below the phase decomposition temperature of α ‧ -Fe8N (180 °C) leads to a mixture of several phases that is also affected by the choice of substrate material and symmetry. At higher temperatures (350 °C), phase pure γ ‧ -Fe4N is the most stable phase.

Sb-related defects in Sb-doped ZnO thin film grown by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Luo, Caiqin; Ho, Lok-Ping; Azad, Fahad; Anwand, Wolfgang; Butterling, Maik; Wagner, Andreas; Kuznetsov, Andrej; Zhu, Hai; Su, Shichen; Ling, Francis Chi-Chung

2018-04-01

Sb-doped ZnO films were fabricated on c-plane sapphire using the pulsed laser deposition method and characterized by Hall effect measurement, X-ray photoelectron spectroscopy, X-ray diffraction, photoluminescence, and positron annihilation spectroscopy. Systematic studies on the growth conditions with different Sb composition, oxygen pressure, and post-growth annealing were conducted. If the Sb doping concentration is lower than the threshold ˜8 × 1020 cm-3, the as-grown films grown with an appropriate oxygen pressure could be n˜4 × 1020 cm-3. The shallow donor was attributed to the SbZn related defect. Annealing these samples led to the formation of the SbZn-2VZn shallow acceptor which subsequently compensated for the free carrier. For samples with Sb concentration exceeding the threshold, the yielded as-grown samples were highly resistive. X-ray diffraction results showed that the Sb dopant occupied the O site rather than the Zn site as the Sb doping exceeded the threshold, whereas the SbO related deep acceptor was responsible for the high resistivity of the samples.

Colorless polyimide/organoclay nanocomposite substrates for flexible organic light-emitting devices.

PubMed

Kim, Jin-Hoe; Choi, Myeon-Chon; Kim, Hwajeong; Kim, Youngkyoo; Chang, Jin-Hae; Han, Mijeong; Kim, Il; Ha, Chang-Sik

2010-01-01

We report the preparation and application of indium tin oxide (ITO) coated fluorine-containing polyimide/organoclay nanocomposite substrate. Fluorine-containing polyimide/organoclay nanocomposite films were prepared through thermal imidization of poly(amic acid)/organoclay mixture films, whilst on which ITO thin films were coated on the films using a radio-frequency planar magnetron sputtering by varying the substrate temperature and the ITO thickness. Finally the ITO coated fluorine-containing polyimide/organoclay nanocomposite substrate was employed to make flexible organic light-emitting devices (OLED). Results showed that the lower sheet resistance was achieved when the substrate temperature was high and the ITO film was thick even though the optical transmittance was slightly lowered as the thickness increased. approximately 10 nm width ITO nanorods were found for all samples but the size of clusters with the nanorods was generally increased with the substrate temperature and the thickness. The flexible OLED made using the present substrate was quite stable even when the device was extremely bended.

Mechanics of graded glass composites and zinc oxide thin films grown at 90 degrees Celsius in water

NASA Astrophysics Data System (ADS)

Fillery, Scott Pierson

2007-06-01

The purpose of this research was to study the mechanical stability of two different material systems. The glass laminate system, exhibiting a threshold strength when placed under an applied load and ZnO thin films grown on GaN buffered Al2O3 substrates, exhibiting variations in film stability with changes to the Lateral Epitaxial Overgrowth architecture. The glass laminates were fabricated to contain periodic thin layers containing biaxial compressive stresses using ion exchange treatments to create residual compressive stresses at the surface of soda lime silicate glass sheets. Wafer direct bonding of the ion exchanged glass sheets resulted in the fabrication of glass laminates with thin layers of compressive stress adjacent to the glass interfaces. The threshold flexural strength of the ion exchanged glass laminates was determined to be 112 MPa after the introduction of indentation cracks with indent loads ranging from 1kg to 5kg and the laminates were found to exhibit a threshold strength, i.e., a stress below which failure will not occur. Contrary to similar ceramic laminates where cracks either propagate across the compressive layer or bifurcate within the compressive layer, the cracks in the glass laminates were deflected along the interface between the bonded sheets. ZnO films were grown on (0001) GaN buffered Al2O3 substrates by aqueous solution routes at 90°C. The films were found to buckle under compressive residual stresses at film thicknesses greater than 4mum. Lateral epitaxial overgrowth techniques using hexagonal hole arrays showed an increasing film stability with larger array spacing, resulting in film thicknesses up to 92mum. Stress determinations using Raman spectroscopy indicated that stress relaxation at the free surface during film growth played a major role in film stability. Investigations using Finite Element Analysis and Raman spectroscopy demonstrated that the strain energy within the film/substrate system decreased with increasing array

Metal (Ag/Ti)-Containing Hydrogenated Amorphous Carbon Nanocomposite Films with Enhanced Nanoscratch Resistance: Hybrid PECVD/PVD System and Microstructural Characteristics.

PubMed

Constantinou, Marios; Nikolaou, Petros; Koutsokeras, Loukas; Avgeropoulos, Apostolos; Moschovas, Dimitrios; Varotsis, Constantinos; Patsalas, Panos; Kelires, Pantelis; Constantinides, Georgios

2018-03-30

This study aimed to develop hydrogenated amorphous carbon thin films with embedded metallic nanoparticles (a-C:H:Me) of controlled size and concentration. Towards this end, a novel hybrid deposition system is presented that uses a combination of Plasma Enhanced Chemical Vapor Deposition (PECVD) and Physical Vapor Deposition (PVD) technologies. The a-C:H matrix was deposited through the acceleration of carbon ions generated through a radio-frequency (RF) plasma source by cracking methane, whereas metallic nanoparticles were generated and deposited using terminated gas condensation (TGC) technology. The resulting material was a hydrogenated amorphous carbon film with controlled physical properties and evenly dispersed metallic nanoparticles (here Ag or Ti). The physical, chemical, morphological and mechanical characteristics of the films were investigated through X-ray reflectivity (XRR), Raman spectroscopy, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM) and nanoscratch testing. The resulting amorphous carbon metal nanocomposite films (a-C:H:Ag and a-C:H:Ti) exhibited enhanced nanoscratch resistance (up to +50%) and low values of friction coefficient (<0.05), properties desirable for protective coatings and/or solid lubricant applications. The ability to form nanocomposite structures with tunable coating performance by potentially controlling the carbon bonding, hydrogen content, and the type/size/percent of metallic nanoparticles opens new avenues for a broad range of applications in which mechanical, physical, biological and/or combinatorial properties are required.

Effect of heterocyclic based organoclays on the properties of polyimide-clay nanocomposites.

PubMed

Krishnan, P Santhana Gopala; Joshi, Mangala; Bhargava, Prachur; Valiyaveettil, Suresh; He, Chaobin

2005-07-01

Polyimide-clay nanocomposites were prepared from their precursor, namely, polyamic acid, by the solution-casting method. Organomodified montmorillonite (MMT) clay was prepared by treating Na+MMT (Kunipia F) with three different intercalating agents, namely, piperazine dihydrochloride, 1,3-bis(4-piperidinylpropane) dihydrochloride and 4,4'-bipiperidine dihydrochloride at 80 degrees C. Polyamic acid solutions containing various weight percentages of organomodified MMT were prepared by reacting 4,4'-(1,1'-biphenyl-4,4'-diyldioxy)dianiline with bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride in N-methyl-2-pyrrolidinone containing dispersed particles of organomodified MMT at 20 degrees C. Nanocomposite films were prepared from these solutions by solution casting and heated subsequently at a programmed heating rate. These films were transparent and brown in color. The extent of layer separation in nanocomposite films depends upon the chemical structure of the organoclay. These films were characterized by inherent viscosity, FT-IR, DSC, TMA, WAXD, TEM, UV, and TGA. The tensile behavior and surface energy studies were also investigated. The nanocomposite films had superior tensile properties, thermal behavior, and solvent resistance. Among the three organoclays, piperazine dihydrochloride was the best modifier.

Development of novel nano-composite membranes as introduction systems for mass spectrometers: Contrasting nano-composite membranes and conventional inlet systems

NASA Astrophysics Data System (ADS)

Miranda, Luis Diego

This dissertation presents the development of novel nano-composite membranes as introduction systems for mass spectrometers. These nano-composite membranes incorporate anodic aluminum oxide (AAO) membranes as templates that can be used by themselves or modified by a variety of chemical deposition processes. Two types of nano-composite membranes are presented. The first nano-composite membrane has carbon deposited within the pores of an AAO membrane. The second nano-composite membrane is made by coating an AAO membrane with a thin polymer film. The following chapters describe the transmission properties these nano-composite membranes and compare them to conventional mass spectrometry introduction systems. The nano- composite membranes were finally coupled to the inlet system of an underwater mass spectrometer revealing their utility in field deployments.

Structural, chemical, and magnetic properties of Fe films grown on InAs(100)

NASA Astrophysics Data System (ADS)

Ruppel, L.; Witte, G.; Wöll, Ch.; Last, T.; Fischer, S. F.; Kunze, U.

2002-12-01

The structure of epitaxial Fe films grown on an InAs(100)-c(8×2)/(4×2) surface has been studied in situ by means of low-energy electron diffraction and x-ray photoelectron spectroscopy, while their magnetic properties were characterized ex situ by superconducting quantum interference device magnetometry at temperatures of 5 300 K. Deposition of iron at room temperature or below leads to the formation of a thin iron arsenide layer that floats on the Fe film upon further deposition. Postdeposition annealing causes no significant improvement of the film structure but activates a further arsenic diffusion through the Fe film. Significant exchange-bias effects were found at low temperatures for insufficiently capped and partially oxidized Fe films, and are attributed to noncollinear spin order at the Ag capping layer/Fe interface. For perfect, nonoxidized Fe films, such a noncollinear spin order at the Fe/InAs interface is excluded as no thermomagnetic irreversibilities were found. This indicates that the spin order at the Fe/InAs interface is suitable for spin injection.

Improvement of laser molecular beam epitaxy grown SrTiO3 thin film properties by temperature gradient modulation growth

NASA Astrophysics Data System (ADS)

Li, Jin Long; Hao, J. H.; Li, Y. R.

2007-09-01

Oxygen diffusion at the SrTiO3/Si interface was analyzed. A method called temperature gradient modulation growth was introduced to control oxygen diffusion at the interface of SrTiO3/Si. Nanoscale multilayers were grown at different temperatures at the initial growing stage of films. Continuous growth of SrTiO3 films was followed to deposit on the grown sacrificial layers. The interface and crystallinity of SrTiO3/Si were investigated by in situ reflection high energy electron diffraction and x-ray diffraction measurements. It has been shown that the modulated multilayers may help suppress the interfacial diffusion, and therefore improve SrTiO3 thin film properties.

Preparation and Characterization of Polyimide/Organoclay Nanocomposites

NASA Technical Reports Server (NTRS)

Delozier, D. M.; Orwoll, R. A.; Cahoon, J. F.; Johnston, N. J.; Smith, J. G., Jr.; Connell, J. W.

2002-01-01

Organically modified montmorrrillonite clay, containing a long chain aliphatic quarternary ammonium cation, was used to prepare polyimide/organoclay hybrids. Several approaches were examined in an attempt to achieve fully exfoliated nanocomposites. These included simple mixing of the clay in a pre-made high molecular weight poly(amide acid) solution; simple mixing followed by sonication of the organoclay/poly(amide acid) solutions; and the preparation of high molecular weight poly(amide acid)s in the presence of the organoclay dispersed in N-methyl-2-pyrrolidinone (NMP). The best results were obtained using the in-situ polymerization approach. The resulting nanocomposite films (both amide acid and imide), containing 3-8% by weight of organoclay, were characterized by differential scanning calorimetry (DSC), dynamic thermogravimetric analysis (TGA), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thin film tensile properties. A significant degree of dispersion was observed in the nanocomposite films of the amide acid and the imide. After thermal treatment of amide acid films to effect imidization, in both air and nitrogen, the films were visually darker than control films without clay and the level of clay dispersion appeared to have decreased. In the latter case, the separation between the layers of the clay decreased to a spacing less than that present in the original organoclay. These observations suggest that thermal degradation of the aliphatic quarternary ammonium cation occurred likely during thermal treatment to effect imidization and solvent removal. These thermal degradation effects were less pronounced when thermal treatment was performed under nitrogen. The polyimide/organoclay hybrid films exhibited higher room temperature tensile moduli and lower strength and elongation to break than the control films.

Ferromagnetism and Ru-Ru distance in SrRuO3 thin film grown on SrTiO3 (111) substrate

PubMed Central

2014-01-01

Epitaxial SrRuO3 thin films were grown on both (100) and (111) SrTiO3 substrates with atomically flat surfaces that are required to grow high-quality films of materials under debate. The following notable differences were observed in the (111)-oriented SrRuO3 films: (1) slightly different growth mode, (2) approximately 10 K higher ferromagnetic transition temperature, and (3) better conducting behavior with higher relative resistivity ratio, than (100)c-oriented SrRuO3 films. Together with the reported results on SrRuO3 thin films grown on (110) SrTiO3 substrate, the different physical properties were discussed newly in terms of the Ru-Ru nearest neighbor distance instead of the famous tolerance factor. PACS 75.70.Ak; 75.60.Ej; 81.15.Fg PMID:24393495

Structural, morphological and mechanical properties of niobium nitride thin films grown by ion and electron beams emanated from plasma

NASA Astrophysics Data System (ADS)

Siddiqui, Jamil; Hussain, Tousif; Ahmad, Riaz; Umar, Zeeshan A.; Abdus Samad, Ubair

2016-05-01

The influence of variation in plasma deposition parameters on the structural, morphological and mechanical characteristics of the niobium nitride films grown by plasma-emanated ion and electron beams are investigated. Crystallographic investigation made by X-ray diffractometer shows that the film synthesized at 10 cm axial distance with 15 plasma focus shots (PFS) exhibits better crystallinity when compared to the other deposition conditions. Morphological analysis made by scanning electron microscope reveals a definite granular pattern composed of homogeneously distributed nano-spheroids grown as clustered particles for the film synthesized at 10 cm axial distance for 15 PFS. Roughness analysis demonstrates higher rms roughness for the films synthesized at shorter axial distance and by greater number of PFS. Maximum niobium atomic percentage (35.8) and maximum average hardness (19.4 ± 0.4 GPa) characterized by energy-dispersive spectroscopy and nano-hardness analyzer respectively are observed for film synthesized at 10 cm axial distance with 15 PFS.

Size-controlled growth and antibacterial mechanism for Cu:C nanocomposite thin films.

PubMed

Javid, Amjed; Kumar, Manish; Yoon, Seokyoung; Lee, Jung Heon; Han, Jeon Geon

2016-12-21

The interdependence of 'size' and 'volume-fraction' hinders the identification of their individual role in the interface properties of metal nanoparticles (NPs) embedded in a matrix. Here, the case of Cu NPs embedded in a C matrix is presented for their profound antibacterial activity. Cu:C nanocomposite thin films with fixed Cu content (≈12 atomic%) are prepared using a plasma process where plasma energy controls the size of Cu NPs (from 9 nm to 16 nm). An inverse relationship between the size-effect on antibacterial activity against Escherichia coli and Staphylococcus aureus bacteria is established through the real time monitoring of an aliquot by inductively coupled plasma mass spectrometry, which confirmed the inverse relationship of Cu ion release from the nanocomposite with varied Cu NP sizes. It was found that enhancing the total power density increases the plasma density as well as effective kinetic energy of the plasma species, which in turn creates a large number of nucleation sites and restricts the island kind of growth of Cu NPs. The mechanism of NP size-control is illustrated on the basis of ion density and nucleation and the growth regime of plasma species. This physical approach to NP size reduction anticipates a contamination-free competitive recipe of size-control to capping based chemical methods.

Optical limiting in gelatin stabilized Cu-PVP nanocomposite colloidal suspension

NASA Astrophysics Data System (ADS)

Tamgadge, Y. S.; Gedam, P. P.; Thakare, N. B.; Talwatkar, S. S.; Sunatkari, A. L.; Muley, G. G.

2018-05-01

This article illustrates investigations on optical limiting properties of Cu-PVP nanocomposite colloidal suspension. Gelatin stabilized Cu nanoparticles have been synthesized using chemical reduction method and thin films in PVP matrix have been obtained using spin coating technique. Thin films have been characterized by X-ray diffraction (XRD), Ultraviolet-visible (UV-vis) spectroscopy, etc. for structural and linear optical studies. Optical limiting properties of Colloidal Cu-PVP nanocomposites have been investigated at 808 nm diode CW laser. Minimum optical limiting threshold was found for GCu3-PVP nanocomposites sample. The strong optical limiting is thermal in origin as CW laser is used and effects are attributed to thermal lensing effect.

Thermal-induced SPR tuning of Ag-ZnO nanocomposite thin film for plasmonic applications

NASA Astrophysics Data System (ADS)

Singh, S. K.; Singhal, R.

2018-05-01

The formation of silver (Ag) nanoparticles in a ZnO matrix were successfully synthesized by RF-magnetron sputtering at room temperature. As prepared Ag-ZnO nanocomposite (NCs) thin films were annealed in vacuum at three different temperatures of 300 °C, 400 °C and 500 °C, respectively. The structural modifications for as-deposited and annealed films were estimated by X-ray diffraction and TEM techniques. The crystalline behavior preferably along the c-axis of the hexagonal wurtzite structure was observed in as-deposited Ag-ZnO film and improved significantly with increasing the annealing temperature. The crystallite size of as-deposited film was measured to be 13.6 nm, and increases up to 28.5 nm at higher temperatures. The chemical composition and surface structure of the as-deposited films were estimated by X-ray photoelectron spectroscopy. The presence of Ag nanoparticles with average size of 8.2 ± 0.2 nm, was confirmed by transmission electron microscopy. The strong surface plasmon resonance (SPR) band was observed at the wavelength of ∼565 nm for as-deposited film and a remarkable red shift of ∼22 nm was recorded after the annealing treatment as confirmed by UV-visible spectroscopy. Atomic force microscopy confirmed the grain growth from 60.38 nm to 79.42 nm for as-deposited and higher temperature annealed film respectively, with no significant change in the surface roughness. Thermal induced modifications such as disordering and lattice defects in Ag-ZnO NCs thin films were carried out by Raman spectroscopy. High quality Ag-ZnO NCs thin films with minimum strain and tunable optical properties could be useful in various plasmonic applications.

Self-assembly of mesoscopically ordered chromatic polydiacetylene/silica nanocomposites

NASA Technical Reports Server (NTRS)

Lu, Y.; Yang, Y.; Sellinger, A.; Lu, M.; Huang, J.; Fan, H.; Haddad, R.; Lopez, G.; Burns, A. R.; Sasaki, D. Y.;

Dielectric properties of thin C r2O3 films grown on elemental and oxide metallic substrates

NASA Astrophysics Data System (ADS)

Mahmood, Ather; Street, Michael; Echtenkamp, Will; Kwan, Chun Pui; Bird, Jonathan P.; Binek, Christian

2018-04-01

In an attempt to optimize leakage characteristics of α-C r2O3 thin films, its dielectric properties were investigated at local and macroscopic scale. The films were grown on Pd(111), Pt(111), and V2O3 (0001), supported on A l2O3 substrate. The local conductivity was measured by conductive atomic force microscopy mapping of C r2O3 surfaces, which revealed the nature of defects that formed conducting paths with the bottom Pd or Pt layer. A strong correlation was found between these electrical defects and the grain boundaries revealed in the corresponding topographic scans. In comparison, the C r2O3 film on V2O3 exhibited no leakage paths at similar tip bias value. Electrical resistance measurements through e-beam patterned top electrodes confirmed the resistivity mismatch between the films grown on different electrodes. The x-ray analysis attributes this difference to the twin free C r2O3 growth on V2O3 seeding.

All-cellulose nanocomposite film made from bagasse cellulose nanofibers for food packaging application.

PubMed

Ghaderi, Moein; Mousavi, Mohammad; Yousefi, Hossein; Labbafi, Mohsen

2014-04-15

All-cellulose nanocomposite (ACNC) film was produced from sugarcane bagasse nanofibers using N,N-dimethylacetamide/lithium chloride solvent. The average diameter of bagasse fibers (14 μm) was downsized to 39 nm after disk grinding process. X-ray diffraction showed that apparent crystallinity and crystallite size decreased relatively to an increased duration of dissolution time. Thermogravimetric analysis confirmed that thermal stability of the ACNC was slightly less than that of the pure cellulose nanofiber sheet. Tensile strength of the fiber sheet, nanofiber sheet and ACNC prepared with 10 min dissolution time were 8, 101 and 140 MPa, respectively. Water vapor permeability (WVP) of the ACNC film increased relatively to an increased duration of dissolution time. ACNC can be considered as a multi-performance material with potential for application in cellulose-based food packaging owing to its promising properties (tough, bio-based, biodegradable and acceptable levels of WVP). Copyright © 2014 Elsevier Ltd. All rights reserved.

Structural, morphological and electronic properties of pulsed laser grown Eu2O3 thin films

NASA Astrophysics Data System (ADS)

Kumar, Sandeep; Prakash, Ram; Choudhary, R. J.; Phase, D. M.

2018-05-01

Herein, we report the growth, structural, morphological and electronic properties of Europium sesquioxide (Eu2O3) thin films on Si [1 0 0] substrate using pulsed laser deposition technique. The films were deposited at ˜750 °C substrate temperature while the oxygen partial pressure (OPP) was varied (vacuum,˜1 mTorr, ˜10 mTorr and ˜300 mTorr). X-ray diffraction results confirm the single phase cubic structure of the film grown at ˜300 mTorr. The XRD results are also supported by the Raman's spectroscopy results. Eu-3d XPS core level spectra confirms the dominant contributions from the "3+" states of Eu in the film.

Optical and mechanical properties of nanocrystalline ZrC thin films grown by pulsed laser deposition.

DOE PAGES

Craciun, D.; Socol, G.; Lambers, E.; ...

2015-01-17

Thin ZrC films (<500 nm) were grown on (100) Si substrates at a substrate temperature of 500 °C by the pulsed laser deposition (PLD) technique using a KrF excimer laser under different CH 4 pressures. Glancing incidence X-ray diffraction showed that films were nanocrystalline, while X-ray reflectivity studies found out films were very dense and exhibited a smooth surface morphology. Optical spectroscopy data shows that the films have high reflectivity (>90%) in the infrared region, characteristic of metallic behavior. Nanoindentation results indicated that films deposited under lower CH 4 pressures exhibited slightly higher nanohardness and Young modulus values than filmsmore » deposited under higher pressures. As a result, tribological characterization revealed that these films exhibited relatively high wear resistance and steady-state friction coefficients on the order of μ = 0.4.« less

Crystal orientation, crystallinity, and thermoelectric properties of Bi0.9Sr0.1CuSeO epitaxial films grown by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Ishizawa, Mamoru; Fujishiro, Hiroyuki; Naito, Tomoyuki; Ito, Akihiko; Goto, Takashi

2018-02-01

We have grown Bi0.9Sr0.1CuSeO epitaxial thin films on MgO and SrTiO3 (STO) single-crystal substrates by pulsed laser deposition (PLD) under various growth conditions, and investigated the crystal orientation, crystallinity, chemical composition, and thermoelectric properties of the films. The optimization of the growth conditions was realized in the film grown on MgO at the temperature T s = 573 K and Ar pressure P Ar = 0.01 Torr in this study, in which there was no misalignment apart from the c-axis and no impurity phase. It was clearly found that the higher crystal orientation of the epitaxial film grown at a higher temperature under a lower Ar pressure mainly enhanced the thermoelectric power factor P (= S 2/ρ), where S is the Seebeck coefficient and ρ is the electrical resistivity. However, the thermoelectric properties of the films were lower than those of polycrystalline bulk because of lattice distortion from lattice mismatch, a low crystallinity caused by a lower T s, and Bi and Cu deficiencies in the films.

Epitaxially grown BaM hexaferrite films having uniaxial axis in the film plane for self-biased devices

PubMed Central

Zhang, Xiaozhi; Meng, Siqin; Song, Dongsheng; Zhang, Yao; Yue, Zhenxing; Harris, Vincent G.

2017-01-01

Barium hexaferrite (BaM) films with in-plane c-axis orientation are promising and technically important materials for self-biased magnetic microwave devices. In this work, highly oriented BaM films with different thickness and an in-plane easy axis (c-axis) of magnetization were grown on a-plane single-crystal sapphire substrates by direct current magnetron sputtering. A procedure involving seed layers, layer-by-layer annealing was adopted to reduce the substrate-induced strains and allow for the growth of thick (~3.44 μm) films. The epitaxial growth of the BaM film on sapphire was revealed by high-resolution transmission electron microscopy with dislocations being observed at the film-substrate interface. The orientation was also verified by X-ray diffraction and more notably, polarized Raman scattering. The magnetic properties and ferromagnetic resonant frequencies were experimentally characterized by a vibrating sample magnetometry and a frequency-swept ferromagnetic resonant flip-chip technique, respectively. The micron-thick BaM films exhibited a large remanence ratio of 0.92 along in-plane easy axis and a small one of 0.09 for the in-plane hard axis loop measurement. The FMR frequency was 50.3 GHz at zero field and reached 57.9 GHz under a magnetic field of 3 kOe, indicating that the epitaxial BaM films with strong self-biased behaviors have good electromagnetic properties in millimeter-wave range. PMID:28276492

Epitaxially grown BaM hexaferrite films having uniaxial axis in the film plane for self-biased devices.

PubMed

Zhang, Xiaozhi; Meng, Siqin; Song, Dongsheng; Zhang, Yao; Yue, Zhenxing; Harris, Vincent G

2017-03-09

Barium hexaferrite (BaM) films with in-plane c-axis orientation are promising and technically important materials for self-biased magnetic microwave devices. In this work, highly oriented BaM films with different thickness and an in-plane easy axis (c-axis) of magnetization were grown on a-plane single-crystal sapphire substrates by direct current magnetron sputtering. A procedure involving seed layers, layer-by-layer annealing was adopted to reduce the substrate-induced strains and allow for the growth of thick (~3.44 μm) films. The epitaxial growth of the BaM film on sapphire was revealed by high-resolution transmission electron microscopy with dislocations being observed at the film-substrate interface. The orientation was also verified by X-ray diffraction and more notably, polarized Raman scattering. The magnetic properties and ferromagnetic resonant frequencies were experimentally characterized by a vibrating sample magnetometry and a frequency-swept ferromagnetic resonant flip-chip technique, respectively. The micron-thick BaM films exhibited a large remanence ratio of 0.92 along in-plane easy axis and a small one of 0.09 for the in-plane hard axis loop measurement. The FMR frequency was 50.3 GHz at zero field and reached 57.9 GHz under a magnetic field of 3 kOe, indicating that the epitaxial BaM films with strong self-biased behaviors have good electromagnetic properties in millimeter-wave range.

Significantly improved surface morphology of N-polar GaN film grown on SiC substrate by the optimization of V/III ratio

NASA Astrophysics Data System (ADS)

Deng, Gaoqiang; Zhang, Yuantao; Yu, Ye; Yan, Long; Li, Pengchong; Han, Xu; Chen, Liang; Zhao, Degang; Du, Guotong

2018-04-01

In this paper, N-polar GaN films with different V/III ratios were grown on vicinal C-face SiC substrates by metalorganic chemical vapor deposition. During the growth of N-polar GaN film, the V/III ratio was controlled by adjusting the molar flow rate of ammonia while keeping the trimethylgallium flow rate unchanged. The influence of the V/III ratio on the surface morphology of N-polar GaN film has been studied. We find that the surface root mean square roughness of N-polar GaN film over an area of 20 × 20 μm2 can be reduced from 8.13 to 2.78 nm by optimization of the V/III ratio. Then, using the same growth conditions, N-polar InGaN/GaN multiple quantum wells (MQWs) light-emitting diodes (LEDs) were grown on the rough and the smooth N-polar GaN templates, respectively. Compared with the LED grown on the rough N-polar GaN template, dramatically improved interface sharpness and luminescence uniformity of the InGaN/GaN MQWs are achieved for the LED grown on the smooth N-polar GaN template.

Photoinduced Br Desorption from CsBr Thin Films Grown on Cu(100)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Halliday, Matthew T.; Joly, Alan G.; Hess, Wayne P.

2015-10-22

Thin films of CsBr deposited onto metals such as copper are potential photocathode materials for light sources and other applications. We investigate desorption dynamics of Br atoms from CsBr films grown on insulator (KBr, LiF) and metal (Cu) substrates induced by sub-bandgap 6.4 eV laser pulses. The experimental results demonstrate that the peak kinetic energy of Br atoms desorbed from CsBr/Cu films is much lower than that for the hyperthermal desorption from CsBr/LiF films. Kelvin probe measurements indicate negative charge at the surface following Br desorption from CsBr/Cu films. Our ab initio calculations of excitons at CsBr surfaces demonstrate thatmore » this behavior can be explained by an exciton model of desorption including electron trapping at the CsBr surface. Trapped negative charges reduce the energy of surface excitons available for Br desorption. We examine the electron-trapping characteristics of low-coordinated sites at the surface, in particular, divacancies and kink sites. We also provide a model of cation desorption caused by Franck-Hertz excitation of F centers at the surface in the course of irradiation of CsBr/Cu films. These results provide new insights into the mechanisms of photoinduced structural evolution of alkali halide films on metal substrates and activation of metal photocathodes coated with CsBr.« less

Barrier and Mechanical Properties of Starch-Clay Nanocomposite Films

USDA-ARS?s Scientific Manuscript database

The poor barrier and mechanical properties of biopolymer-based food packaging can potentially be enhanced by the use of layered silicates (nanoclay) to produce nanocomposites. In this study, starch-clay nano-composites were synthesized by a melt extrusion method. Natural (MMT) and organically modifi...

Process for the preparation of metal-containing nanostructured films

NASA Technical Reports Server (NTRS)

Lu, Yunfeng (Inventor); Wang, Donghai (Inventor)

2006-01-01

Metal-containing nanostructured films are prepared by electrodepositing a metal-containing composition within the pores of a mesoporous silica template to form a metal-containing silica nanocomposite. The nanocomposite is annealed to strengthen the deposited metal-containing composition. The silica is then removed from the nanocomposite, e.g., by dissolving the silica in an etching solution to provide a self-supporting metal-containing nanostructured film. The nanostructured films have a nanowire or nanomesh architecture depending on the pore structure of the mesoporous silica template used to prepare the films.

Martensitic transformation in as-grown and annealed near-stoichiometric epitaxial Ni2MnGa thin films

NASA Astrophysics Data System (ADS)

Machain, P.; Condó, A. M.; Domenichini, P.; Pozo López, G.; Sirena, M.; Correa, V. F.; Haberkorn, N.

2015-08-01

Magnetic shape memory nanostructures have a great potential in the field of the nanoactuators. The relationship between dimensionality, microstructure and magnetism characterizes the materials performance. Here, we study the martensitic transformation in supported and free-standing epitaxial Ni47Mn24Ga29 films grown by sputtering on (0 0 1) MgO using a stoichiometric Ni2MnGa target. The films have a Curie temperature of ~390 K and a martensitic transition temperature of ~120 K. Similar transition temperatures have been observed in films with thicknesses of 1, 3 and 4 μm. Thicker films (with longer deposition time) present a wider martensitic transformation range that can be associated with small gradients in their chemical concentration due to the high vapour pressure of Mn and Ga. The magnetic anisotropy of the films shows a strong change below the martensitic transformation temperature. No features associated with variant reorientation induced by magnetic field have been observed. Annealed films in the presence of a Ni2MnGa bulk reference change their chemical composition to Ni49Mn26Ga25. The change in the chemical composition increases the martensitic transformation temperature, being closer to the stoichiometric compound, and reduces the transformation hysteresis. In addition, sharper transformations are obtained, which indicate that chemical inhomogeneities and defects are removed. Our results indicate that the properties of Ni-Mn-Ga thin films grown by sputtering can be optimized (fixing the chemical concentration and removing crystalline defects) by the annealing process, which is promising for the development of micromagnetic shape memory devices.

Influence of solution viscosity on hydrothermally grown ZnO thin films for DSSC applications

NASA Astrophysics Data System (ADS)

Marimuthu, T.; Anandhan, N.; Thangamuthu, R.; Surya, S.

2016-10-01

Zinc oxide (ZnO) nanowire arrays (NWAs) were grown onto zinc oxide-titanium dioxide (ZnO-TiO2) seeded fluorine doped tin oxide (FTO) conductive substrate by hydrothermal technique. X-ray diffraction (XRD) patterns depict that ZnO thin films are preferentially oriented along the (002) plane with hexagonal wurtzite structure. Viscosity measurements reveal that viscosity of the solutions linearly increases as the concentrations of the polyvinyl alcohol (PVA) increase in the growth solution. Field emission scanning electron microscope (FE-SEM) images show that the NWAs are vertically grown to seeded FTO substrate with hexagonal structure, and the growth of NWAs decreases as the concentration of the PVA increases. Stylus profilometer and atomic force microscopic (AFM) studies predict that the thickness and roughness of the films decrease with increasing the PVA concentrations. The NWAs prepared at 0.1% of PVA exhibits a lower transmittance and higher absorbance than that of the other films. The band gap of the optimized films prepared at 0.0 and 0.1% of PVA is found to be 3.270 and 3.268 eV, respectively. The photo to current conversion efficiency of the DSSC based on photoanodes prepared at 0.0 and 0.1% of PVA exhibits about 0.64 and 0.82%, respectively. Electrochemical impedance spectra reveal that the DSSC based on photoanode prepared at 0.1% of PVA has the highest charge transfer recombination resistance.

Synthesis and applications of MANs/poly(MMA-co-BA) nanocomposite latex by miniemulsion polymerization

PubMed Central

Chen, Huayao; Zhou, Xinhua; Gunasekaran, Sundaram

2017-01-01

We have synthesized core-shell structured 3-methacryloxypropyltrimethoxysilane (MPS) functionalized antimony-doped tin oxide nanoparticles (MANs)–poly(methyl methacrylate-co-butyl acrylate) (PMMA-co-BA, PMB) nanocomposite latex particles via miniemulsion polymerization method. Polymerizable anionic surfactant DNS-86 (allyloxy polyoxyethylene(10) nonyl ammonium sulfate) was first introduced to synthesize core-shell nanocomposite. The morphologies of synthesized MANs and MANs/PMB latex nanocomposite particles were studied with transmission electron microscopy, which revealed particles, on average 70 nm in size, with a core-shell structure. Owing to the uniformity and hydrophobicity of MANs, the MANs-embedded PMB latex nanocomposite can be tailored more precisely than other nanoparticles-embedded nanocomposites. Films incorporating 10 wt% of MANs in the MAN/PMB latex nanocomposite exhibit good transmittance in the visible region, and excellent opacity in the near infrared region. The MANs/PMB nanocomposite film also appears suitable for heat insulation applications. PMID:29291076

Enhanced antibacterial performance of hybrid semiconductor nanomaterials: ZnO/SnO 2 nanocomposite thin films

NASA Astrophysics Data System (ADS)

Talebian, Nasrin; Nilforoushan, Mohammad Reza; Zargar, Elahe Badri

2011-10-01

The nano-sized coupled oxides ZnO/SnO 2 thin films in a molar ratio of 2:1 (Z2S), 1:1 (ZS) and 1:2 (ZS2) were prepared using sol-gel dip coating method and characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis spectroscopy. Escherichia coli ( E. coli, ATCC 25922) was selected as a model for the Gram-negative bacteria to evaluate antibacterial property of composite samples compared with single ZnO (Z) and single SnO 2 (S) films. The antibacterial activity has been studied applying the so-called antibacterial drop test under UV illumination. The bactericidal activity was estimated by relative number of bacteria survived calculated from the number of viable cells which form colonies on the nutrient agar plates. The influence of the SnO 2-ZnO nanocomposite composition on the structural features and on the antibacterial properties of the thin films are reported and discussed. It is found that all coatings exhibited a high antibacterial activity. The coupled oxide photocatalyst Z2S has better photocatalytic activity to bacteria inactivation than ZS, ZS2, Z and S films. Furthermore, nanostructured films were active even in the absence of irradiation.

Tunneling Spectroscopy of MoN and NbxTi1-xN Thin Films Grown by Atomic Layer Deposition

NASA Astrophysics Data System (ADS)

Cao, Chaoyue; Groll, Nickolas; Klug, Jeffrey; Becker, Nicholas; Altin, Serdar; Proslier, Thomas; Zasadzinski, John

2014-03-01

Tunneling I(V) and dI/dV vs. V are reported on superconducting thin films of MoN and NbxTi1-xN using a point contact method with a Au tip. The films are grown by the chemical process of atomic layer deposition (ALD) onto various substrates (Si, quartz, sapphire) held at 450 C. Resistively measured superconducting Tc values up to 12K and 13K are found for the MoN and NbxTi1-xN respectively. Artificial tunnel barriers (1-3 nm thick) of Al2O3, also grown by ALD, are shown to provide much improved tunneling characteristics compared to the native oxides. Relatively high quality gap features are observed with zero-bias conductance values as low as ~ 10% of the high bias values. Gap parameters Δ ~ 2.0meV are found for the MoN and Δ ~ 2.0-2.4 meV for the NbxTi1-xN which follow the BCS temperature dependence and close near the measured film Tc indicating bulk superconductivity at the surface. The suitability of such conformal ALD grown films for potential superconducting devices is discussed. This work was supported by the U.S. Department of Energy, Office of Science under contract No. DE-AC02-06CH11357.

Arsenic doped p-type zinc oxide films grown by radio frequency magnetron sputtering

NASA Astrophysics Data System (ADS)

Fan, J. C.; Zhu, C. Y.; Fung, S.; Zhong, Y. C.; Wong, K. S.; Xie, Z.; Brauer, G.; Anwand, W.; Skorupa, W.; To, C. K.; Yang, B.; Beling, C. D.; Ling, C. C.

2009-10-01

As-doped ZnO films were grown by the radio frequency magnetron sputtering method. As the substrate temperature during growth was raised above ˜400 °C, the films changed from n type to p type. Hole concentration and mobility of ˜6×1017 cm-3 and ˜6 cm2 V-1 s-1 were achieved. The ZnO films were studied by secondary ion mass spectroscopy, x-ray photoelectron spectroscopy (XPS), low temperature photoluminescence (PL), and positron annihilation spectroscopy (PAS). The results were consistent with the AsZn-2VZn shallow acceptor model proposed by Limpijumnong et al. [Phys. Rev. Lett. 92, 155504 (2004)]. The results of the XPS, PL, PAS, and thermal studies lead us to suggest a comprehensive picture of the As-related shallow acceptor formation.

Ferroelectric and reliability properties of metal-organic chemical vapor deposited Pb(Zr0.15Ti0.85)O3 thin films grown in the self-regulation process window

NASA Astrophysics Data System (ADS)

Zhao, Jin Shi; Lee, Hyun Ju; Sim, Joon Seop; Lee, Keun; Hwang, Cheol Seong

2006-04-01

Ferroelectric reliability of Pb(Zr0.15Ti0.85)O3 films grown by metal-organic chemical vapor deposition at 570°C on an Ir electrode in the self-regulation process window [constant Pb concentration irrespective of the precursor input ratio (Pb /(Zr+Ti), PIR)] was studied. Although the Pb composition and crystallinity of the films grown under different PIR were almost identical, the film grown under a PIR which was near the center of the process window showed the best ferroelectric performance. X-ray photoelectron spectroscopy showed that the films grown at lower and higher PIR have residual ZrO2 and metallic Pb, respectively, which resulted in reduced remanent polarization and reliability.

Solution Coating of Pharmaceutical Nanothin Films and Multilayer Nanocomposites with Controlled Morphology and Polymorphism.

PubMed

Horstman, Elizabeth M; Kafle, Prapti; Zhang, Fengjiao; Zhang, Yifu; Kenis, Paul J A; Diao, Ying

2018-03-28

Nanosizing is rapidly emerging as an alternative approach to enhance solubility and thus the bioavailability of poorly aqueous soluble active pharmaceutical ingredients (APIs). Although numerous techniques have been developed to perform nanosizing of API crystals, precise control and modulation of their size in an energy and material efficient manner remains challenging. In this study, we present meniscus-guided solution coating as a new technique to produce pharmaceutical thin films of nanoscale thickness with controlled morphology. We demonstrate control of aspirin film thickness over more than 2 orders of magnitude, from 30 nm to 1.5 μm. By varying simple process parameters such as the coating speed and the solution concentration, the aspirin film morphology can also be modulated by accessing different coating regimes, namely the evaporation regime and the Landau-Levich regime. Using ellipticine-a poorly water-soluble anticancer drug-as another model compound, we discovered a new polymorph kinetically trapped during solution coating. Furthermore, the polymorphic outcome can be controlled by varying coating conditions. We further performed layer-by-layer coating of multilayer nanocomposites, with alternating thin films of ellipticine and a biocompatible polymer, which demonstrate the potential of additive manufacturing of multidrug-personalized dosage forms using this approach.

Fabrication and physical properties of transparent poly (methyl-methacrylate)-layered silicate nanocomposites

NASA Astrophysics Data System (ADS)

Vasiliu, Elena

Transparent polymer nanocomposites have promising potential for protective coating applications with improved surface resistance, higher temperature performance and low gas permeability for containers and films. Extremely thin protective layers are required for improved performance of various electronic devices in aviation, aerospace and medical equipment as well as for lenses and fiber optics in optical communications. This research study developed a method for fabricating optically transparent nanocomposites of poly(methyl-methacrylate)(PMMA) and a commercial organically-modified layered silicate CloisiteRTM 6A (C6A). The nanocomposites were produced by dispersing C6A and PMMA separately in a common solvent xylene followed by mixing the two solutions by mechanical stirring and/or ultrasonic agitation and then removing the solvent by evaporation. Processing conditions such as the mixing methods and times and the rates of solvent removal were investigated in order to achieve a high degree of dispersion and exfoliation of C6A in the polymer matrix and produce a nanocomposite material with high optical transparency. Small-angle x-ray scattering (SAXS) was used to monitor the morphology of the C6A after each processing step. Thin films of PMMA/C6A nanocomposites were produced by casting and spraying. SAXS results suggest that C6A was partially exfoliated in the composite material with an average of 2 to 3 platelets per crystallite. Transmission electron microscopy (TEM) confirmed the existence of both exfoliated and intercalated C6A in PMMA. One mm thick discs were obtained by molding the sprayed films. The optical transmission of the nanocomposite films and discs was measured with an UV/VIS spectrometer. The spectroscopic results served to identify the best process for producing PMMA-C6A films of high optical transparency. Even the nanocomposite films containing up to 20 wt.% C6A prepared by this process exhibited optical transmittance in the range of 80 to 90

Effect of annealing temperature on optical and electrical properties of ZrO2-SnO2 based nanocomposite thin films

NASA Astrophysics Data System (ADS)

Anitha, V. S.; Lekshmy, S. Sujatha; Berlin, I. John; Joy, K.

2014-01-01

Transparent nanocomposite ZrO2-SnO2 thin films were prepared by sol-gel dip-coating technique. Films were annealed at 500°C, 800°C and 1200°C respectively. X-ray diffraction(XRD) spectra showed a mixture of three phases: tetragonal ZrO2 and SnO2 and orthorhombic ZrSnO4. The grain size of all the three phases' increased with annealing temperature. An average transmittance greater than 85%(in UV-Visible region) is observed for all the films. The band gap for the films decreased from 4.79 eV to 4.62 eV with increase in annealing temperature from 500 to 1200 °C. The electrical resistivity increased with increase in annealing temperature. Such composite ZrO2-SnO2 films can be used in many applications and in optoelectronic devices.

Impact of magnetite nanoparticle incorporation on optical and electrical properties of nanocomposite LbL assemblies.

PubMed

Yashchenok, Alexey M; Gorin, Dmitry A; Badylevich, Mikhail; Serdobintsev, Alexey A; Bedard, Matthieu; Fedorenko, Yanina G; Khomutov, Gennady B; Grigoriev, Dmitri O; Möhwald, Helmuth

2010-09-21

Optical and electrical properties of polyelectrolyte/iron oxide nanocomposite planar films on silicon substrates were investigated for different amount of iron oxide nanoparticles incorporated in the films. The nanocomposite assemblies prepared by the layer-by-layer assembly technique were characterized by ellipsometry, atomic force microscopy, and secondary ion mass-spectrometry. Absorption spectra of the films reveal a shift of the optical absorption edge to higher energy when the number of deposited layers decreases. Capacitance-voltage and current-voltage measurements were applied to study the electrical properties of metal-oxide-semiconductor structures prepared by thermal evaporation of gold electrodes on nanocomposite films. The capacitance-voltage measurements show that the dielectric constant of the film increases with the number of deposited layers and the fixed charge and the trapped charge densities have a negative sign.

Thermoelectric properties of epitaxial β-FeSi2 thin films grown on Si(111) substrates with various film qualities

NASA Astrophysics Data System (ADS)

Watanabe, Kentaro; Taniguchi, Tatsuhiko; Sakane, Shunya; Aoki, Shunsuke; Suzuki, Takeyuki; Fujita, Takeshi; Nakamura, Yoshiaki

2017-05-01

Si-based epitaxial β-FeSi2 thin films are attractive as materials for on-chip thermoelectric power generators. We investigated the structure, crystallinity, and thermoelectric properties of β-FeSi2 thin films epitaxially grown on Si(111) substrates by using three different techniques: conventional reactive deposition epitaxy followed by molecular beam epitaxy (RDE+MBE), solid phase epitaxy (SPE) based on codeposition of Fe and Si presented previously, and SPE followed by MBE (SPE+MBE) presented newly by this work. Their epitaxial growth temperatures were fixed at 530 °C for comparison. RDE+MBE thin films exhibited high crystalline quality, but rough surfaces and rugged β-FeSi2/Si(111) interfaces. On the other hand, SPE thin films showed flat surfaces and abrupt β-FeSi2/Si(111) interfaces but low crystallinity. We found that SPE+MBE thin films realized crystallinity higher than SPE thin films, and also had flatter surfaces and sharper interfaces than RDE+MBE thin films. In SPE+MBE thin film growth, due to the initial SPE process with low temperature codeposition, thermal interdiffusion of Fe and Si was suppressed, resulting in the surface flatness and abrupt interface. Second high temperature MBE process improved the crystallinity. We also investigated thermoelectric properties of these β-FeSi2 thin films. Structural factors affecting the thermoelectric properties of RDE+MBE, SPE, and SPE+MBE thin films were investigated.

Formation of self-organized Mn3O4 nanoinclusions in LaMnO3 films

NASA Astrophysics Data System (ADS)

Pomar, Alberto; Konstantinović, Zorica; Bagués, Nuria; Roqueta, Jaume; López-Mir, Laura; Balcells, Lluis; Frontera, Carlos; Mestres, Narcis; Gutiérrez-Llorente, Araceli; Šćepanović, Maja; Lazarević, Nenad; Popović, Zoran; Sandiumenge, Felip; Martínez, Benjamín; Santiso, José

2016-09-01

We present a single-step route to generate ordered nanocomposite thin films of secondary phase inclusions (Mn3O4) in a pristine perovskite matrix (LaMnO3) by taking advantage of the complex phase diagram of manganese oxides. We observed that in samples grown under vacuum growth conditions from a single LaMnO3 stoichiometric target by Pulsed Laser Deposition, the most favourable mechanism to accommodate Mn2+ cations is the spontaneous segregation of self-assembled wedge-like Mn3O4 ferrimagnetic inclusions inside a LaMnO3 matrix that still preserves its orthorhombic structure and its antiferromagnetic bulk-like behaviour. A detailed analysis on the formation of the self-assembled nanocomposite films evidences that Mn3O4 inclusions exhibit an epitaxial relationship with the surrounding matrix that it may be explained in terms of a distorted cubic spinel with slight ( 9º) c-axis tilting. Furthermore, a Ruddlesden-Popper La2MnO4 phase, helping to the stoichiometry balance, has been identified close to the interface with the substrate. We show that ferrimagnetic Mn3O4 columns influence the magnetic and transport properties of the nanocomposite by increasing its coercive field and by creating local areas with enhanced conductivity in the vicinity of the inclusions.

PLGA/Ag nanocomposites: in vitro degradation study and silver ion release.

PubMed

Fortunati, E; Latterini, L; Rinaldi, S; Kenny, J M; Armentano, I

2011-12-01

New nanocomposite films based on a biodegradable poly (DL-Lactide-co-Glycolide) copolymer (PLGA) and different concentration of silver nanoparticles (Ag) were developed by solvent casting. In vitro degradation studies of PLGA/Ag nanocomposites were conducted under physiological conditions, over a 5 week period, and compared to the behaviour of the neat polymer. Furthermore the silver ions (Ag(+)) release upon degradation was monitored to obtain information on the properties of the nanocomposites during the incubation. The obtained results suggest that the PLGA film morphology can be modified introducing a small percentage of silver nanoparticles that do not affect the degradation mechanism of PLGA polymer in the nanocomposite. However results clearly evinced the stabilizing effect of the Ag nanoparticles in the PLGA polymer and the mineralization process induced by the combined effect of silver and nanocomposite surface topography. The Ag(+) release can be controlled by the polymer degradation processes, evidencing a prolonged antibacterial effect.

Self-Assembled Heteroepitaxial Oxide Nanocomposite for Photoelectrochemical Solar Water Oxidation

PubMed Central

2016-01-01

We report on spontaneously phase ordered heteroepitaxial SrTiO3 (STO):ZnFe2O4 (ZFO) nanocomposite films that give rise to strongly enhanced photoelectrochemical solar water oxidation, consistent with enhanced photoinduced charge separation. The STO:ZFO nanocomposite yielded an enhanced photocurrent density of 0.188 mA/cm2 at 1.23 V vs a reversible hydrogen electrode, which was 7.9- and 2.6-fold higher than that of the plain STO film and ZFO film cases under 1-sun illumination, respectively. The photoelectrode also produced stable photocurrent and Faradaic efficiencies of H2 and O2 formation that were more than 90%. Incident-photon-to-current-conversion efficiency measurements, Tauc plots, Mott–Schottky plots, and electrochemical impedance spectroscopy measurements proved that the strongly enhanced photogenerated charge separation resulted from vertically aligned pseudosingle crystalline components, epitaxial heterojunctions, and a staggered band alignment of the components of the nanocomposite films. This study presents a completely new avenue for efficient solar energy conversion applications. PMID:27212792

Vapor phase polymerization deposition of conducting polymer/graphene nanocomposites as high performance electrode materials.

PubMed

Yang, Yajie; Li, Shibin; Zhang, Luning; Xu, Jianhua; Yang, Wenyao; Jiang, Yadong

2013-05-22

In this paper, we report chemical vapor phase polymerization (VPP) deposition of novel poly(3,4-ethylenedioxythiophene) (PEDOT)/graphene nanocomposites as solid tantalum electrolyte capacitor cathode films. The PEDOT/graphene films were successfully prepared on porous tantalum pentoxide surface as cathode films through the VPP procedure. The results indicated that the high conductivity nature of PEDOT/graphene leads to the decrease of cathode films resistance and contact resistance between PEDOT/graphene and carbon paste. This nanocomposite cathode film based capacitor showed ultralow equivalent series resistance (ESR) ca. 12 mΩ and exhibited better capacitance-frequency performance than the PEDOT based capacitor. The leakage current investigation revealed that the device encapsulation process does not influence capacitor leakage current, indicating the excellent mechanical strength of PEDOT-graphene films. The graphene showed a distinct protection effect on the dielectric layer from possible mechanical damage. This high conductivity and mechanical strength graphene based conducting polymer nanocomposites indicated a promising application future for organic electrode materials.

A flexible mesoporous Li4Ti5O12-rGO nanocomposite film as free-standing anode for high rate lithium ion batteries

NASA Astrophysics Data System (ADS)

Zhu, Kunxu; Gao, Hanyang; Hu, Guoxin

2018-01-01

Advanced flexible electrode is crucial in the development of flexible energy storage devices for emerging wearable and portable electronics. Herein, a free-standing flexible mesoporous Li4Ti5O12-rGO (LTO-rGO) nanocomposite film is rationally designed and fabricated for lithium ion batteries (LIBs). This efficient synthesis involves the growth of lithium titanate hydrate (LTH) precursors on the graphene oxide (GO) by a hydrothermal reaction, assembly into LTH-GO film by vacuum filtration with some extra GO added, and subsequent conversion into LTO-rGO nanocomposite film through calcination. When rGO content in the LTO-rGO film is set, the addition sequence of GO is found to affect its textural and mechanical properties. The resultant free-standing LTO-rGO electrode, taking advantages of high Li4Ti5O12 loading of 73.9%, mesoporous layer-stacked channels with good electron/ion conductivity, good mechanical strength, and enlarged electrode/electrolyte contact area, delivers excellent electrochemical performance (e.g., specific capacity of 135.4 mAh g-1 at 40 C) over the electrode of conventional configuration. Moreover, no organic but all inorganic reagents are used in the synthesis, offering an eco-friendly, cost-efficient, and easily scalable way to fabricate binder-free flexible electrode for LIBs.

Semiconductor Film Grown on a Circular Substrate: Predictive Modeling of Lattice-Misfit Stresses

NASA Astrophysics Data System (ADS)

Suhir, E.; Nicolics, J.; Khatibi, G.; Lederer, M.

2016-03-01

An effective and physically meaningful analytical predictive model is developed for the evaluation the lattice-misfit stresses (LMS) in a semiconductor film grown on a circular substrate (wafer). The two-dimensional (plane-stress) theory-of-elasticity approximation (TEA) is employed in the analysis. The addressed stresses include the interfacial shearing stress, responsible for the occurrence and growth of dislocations, as well as for possible delaminations and the cohesive strength of a buffering material, if any. Normal radial and circumferential (tangential) stresses acting in the film cross-sections and responsible for its short- and long-term strength (fracture toughness) are also addressed. The analysis is geared to the GaN technology.

Electrospun PVA/Bentonite Nanocomposites Mats for Drug Delivery

PubMed Central

Ferrández-Rives, Mariola; Gómez Ribelles, José Luis

2017-01-01

Electrospun mats and films of polyvinyl alcohol (PVA) hydrogel are produced for drug delivery. To provide mechanical consistency to the gel a reinforcement by nanoclays is introduced in the polymer matrix. Four different suspensions of nanoparticles in the polymer solution are prepared in an adequate solvent. These suspensions are subjected to an electrospinning process to produce the nanofiber mat, while films are produced by casting. The influence of the process parameters over the nanofibers microstructure is analyzed by scanning electron microscopy (SEM). The effectiveness of nanoclay encapsulation in the nanocomposites is tested by a thermogravimetric analysis. A crosslinking reaction in solution is carried out to prevent the dissolution of the nanocomposites in aqueous media. A model protein (bovine serum albumin, BSA) is absorbed in the nanocomposites to characterize the release kinetics in phosphate-buffered saline (PBS). PMID:29261123

Structural and optical properties of SiC-SiO2 nanocomposite thin films

NASA Astrophysics Data System (ADS)

Bozetine, I.; Keffous, A.; Kaci, S.; Menari, H.; Manseri, A.

2018-03-01

This study deals with the deposition of thin films of a SiC-SiO2nanocomposite deposited on silicon substrates. The deposition is carried out by a co-sputtering RF magnetron 13.56 MHz, using two targets a polycristallin 6H-SiC and sprigs of SiO2. In order to study the influence of the deposition time on the morphology, the structural and optical properties of the thin films produced, two series of samples were prepared, namely a series A with a 30 min deposition time and a series B of one hour duration. The samples were investigated using different characterization techniques such as Scanning Electron Microscope (SEM), X-ray Diffraction (DRX), Fourier Transform Infrared Spectroscopy (FTIR), Secondary Ion Mass Spectrometry (SIMS) and photoluminescence. The results obtained, reveal an optical gap varies between 1.4 and 2.4 eV depending on the thickness of the film; thus depending on the deposition time. The SIMS profile recorded the presence of oxygen (16O) on the surface, which the signal beneath the silicon signal (28Si) and carbon (12C) signals, which confirms that the oxide (SiO2) is the first material deposited at the interface film - substrate with an a-OSiC structure. The photoluminescence (PL) measurement exhibits two peaks, centred at 390 nm due to the oxide and at 416 nm due probably to the nanocrystals of SiC crystals, note that when the deposition time increases, the intensity of the PL drops drastically, result in agreement with dense and smooth film.

Seedless-grown of ZnO thin films for photoelectrochemical water splitting application

NASA Astrophysics Data System (ADS)

Abdullah, Aidahani; Hamid, Muhammad Azmi Abdul; Chiu, W. S.

2018-04-01

We developed a seedless hydrothermal method to grow a flower like ZnO nanorods. Prior to the growth, a layer of Au thin film is sputtered onto the surface of indium tin oxide (ITO) coated glass substrate. The morphological, structural and optical properties of the ZnO nanostructures were characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), and diffuse reflection measurement to understand the growth process of the working thin film. The photoelectrochemical (PEC) results suggest that the deposition of ZnO nanorods on Au nanoparticles plays an important role in enhancing the photoelectrode activity. H2 evolution from photo-splitting of water over Au-incorporated ZnO in the 0.1M NaOH liquid system was enhanced, compared to that over bare ZnO; particularly, the production of 15.5 µL of H2 gas after twenty five minutes exposure of ZnO grown on Au-coated thin film.

STM study of the Ga thin films grown on Si(111) surface

NASA Astrophysics Data System (ADS)

Tao, Min-Long; Tu, Yu-Bing; Sun, Kai; Ye, Juan; Hao, Shao-Jie; Xiao, Hua-Fang; Wang, Ya-Li; Xie, Zheng-Bo; Wang, Jun-Zhong

2017-09-01

Structural evolution of Ga thin films grown on the Si(111)-√{ 3 } × √{ 3 } -Ga template have been investigated with a low-temperature scanning tunneling microscopy (STM). The first Ga layer exhibits a stripe structure along the base vectors of Si(111) lattices. Individual Ga dimers have been directly visualized from the high-resolution STM images of the first Ga layer. The second Ga layer reveals a pseudo 1×1 structure with respect to the Si(111). A new 5×5 phase has been found in the second Ga layer when annealing the sample to 120 ℃. Further annealing to 150 ℃ leads to the formation of 6.3×6.3 phase, which is more stable than the 5×5 phase. The existences of a variety of superstructures of Ga films demonstrates the delicate balance between the interactions of Si(111)-Ga and Ga-Ga. These results shed important light on the epitaxial growth mechanism of Ga films on semiconductor surfaces.

Stencil lithography of superconducting contacts on MBE-grown topological insulator thin films

NASA Astrophysics Data System (ADS)

Schüffelgen, Peter; Rosenbach, Daniel; Neumann, Elmar; Stehno, Martin P.; Lanius, Martin; Zhao, Jialin; Wang, Meng; Sheehan, Brendan; Schmidt, Michael; Gao, Bo; Brinkman, Alexander; Mussler, Gregor; Schäpers, Thomas; Grützmacher, Detlev

2017-11-01

Topological insulator (Bi0.06Sb0.94)2Te3 thin films grown by molecular beam epitaxy have been capped in-situ with a 2 nm Al film to conserve the pristine topological surface states. Subsequently, a shadow mask - structured by means of focus ion beam - was in-situ placed underneath the sample to deposit a thick layer of Al on well-defined microscopically small areas. The 2 nm thin Al layer fully oxidizes after exposure to air and in this way protects the TI surface from degradation. The thick Al layer remains metallic underneath a 3-4 nm thick native oxide layer and therefore serves as (super-) conducting contacts. Superconductor-Topological Insulator-Superconductor junctions with lateral dimensions in the nm range have then been fabricated via an alternative stencil lithography technique. Despite the in-situ deposition, transport measurements and transmission electron microscope analysis indicate a low transparency, due to an intermixed region at the interface between topological insulator thin film and metallic Al.

Carbon Nanotube-Poly(vinylalcohol) Nanocomposite Film Devices: Applications for Femtosecond Fiber Laser Mode Lockers and Optical Amplifier Noise Suppressors

NASA Astrophysics Data System (ADS)

Sakakibara, Youichi; Rozhin, Aleksey G.; Kataura, Hiromichi; Achiba, Yohji; Tokumoto, Madoka

2005-04-01

We fabricated single-wall carbon nanotube (SWNT)/poly(vinylalcohol) (PVA) nanocomposite freestanding films and examined their application in devices in which the saturable absorption of SWNTs at near-infrared optical telecommunication wavelengths can be utilized. In a passively mode-locked fiber laser, we integrated a 30-μm-thick SWNT/PVA film into a fiber connection adaptor with the film sandwiched by a pair of fiber ferrules. A ring fiber laser with a SWNT/PVA saturable absorber was operated very easily in the mode-locked short-pulse mode with a pulse width of about 500 fs. Reproducible stable device performance was confirmed. In examining noise suppression for optical amplifiers, mixed light of semiconductor amplified spontaneous emission (ASE) source and 370 fs laser pulses was passed through a 100-μm-thick SWNT/PVA film. The transmission loss of the femtosecond pulse light was smaller than that of the ASE light. This proved that the SWNT/PVA film has the ability to suppress ASE noise.

Enhanced energy density and thermostability in polyimide nanocomposites containing core-shell structured BaTiO3@SiO2 nanofibers

NASA Astrophysics Data System (ADS)

Wang, Junchuan; Long, Yunchen; Sun, Ying; Zhang, Xueqin; Yang, Hong; Lin, Baoping

2017-12-01

High energy density polymer nanocomposites with high-temperature resistance are quite desirable for film capacitors and many other power electronics. In this study, polyimide-based (PI) nanocomposite films containing the core-shell structured barium titanate@silicon dioxide (BT@SiO2) nanofibers have been successfully synthesized by the solution casting method. In the BT@SiO2/PI nanocomposite films, the dielectric permittivity as well as the breakdown strength increase significantly. The SiO2 shell layers with moderate dielectric permittivity could effectively mitigate the local field concentration induced by the large mismatch between the dielectric permittivity of BT and PI, which contributes to the enhancement of the breakdown strength of the PI nanocomposite films. As a result, the PI nanocomposite film filled with 3 vol% BT@SiO2 nanofibers exhibits a maximal energy density of 2.31 J cm-3 under the field of 346 kV/mm, which is 62% over the pristine PI (1.42 J cm-3 at 308 kV/mm) and about 200% greater than the best commercial polymer, i.e. biaxially oriented polypropylenes (BOPP) (≈1.2 J cm-3). The thermogravimetric analysis results indicate that the BT@SiO2/PI nanocomposite films have good thermal stability below 500 °C.

Ductile all-cellulose nanocomposite films fabricated from core-shell structured cellulose nanofibrils.

PubMed

Larsson, Per A; Berglund, Lars A; Wågberg, Lars

2014-06-09

Cellulosic materials have many desirable properties such as high mechanical strength and low oxygen permeability and will be an important component in a sustainable biomaterial-based society, but unfortunately they often lack the ductility and formability offered by petroleum-based materials. This paper describes the fabrication and characterization of nanocomposite films made of core-shell modified cellulose nanofibrils (CNFs) surrounded by a shell of ductile dialcohol cellulose, created by heterogeneous periodate oxidation followed by borohydride reduction of the native cellulose in the external parts of the individual fibrils. The oxidation with periodate selectively produces dialdehyde cellulose, and the process does not increase the charge density of the material. Yet the modified cellulose fibers could easily be homogenized to CNFs. Prior to film fabrication, the CNF was shown by atomic force microscopy to be 0.5-2 μm long and 4-10 nm wide. The films were fabricated by filtration, and besides uniaxial tensile testing at different relative humidities, they were characterized by scanning electron microscopy and oxygen permeability. The strength-at-break at 23 °C and 50% RH was 175 MPa, and the films could, before rupture, be strained, mainly by plastic deformation, to about 15% and 37% at 50% RH and 90% RH, respectively. This moisture plasticization was further utilized to form a demonstrator consisting of a double-curved structure with a nominal strain of 24% over the curvature. At a relative humidity of 80%, the films still acted as a good oxygen barrier, having an oxygen permeability of 5.5 mL·μL/(m(2)·24 h·kPa). These properties indicate that this new material has a potential for use as a barrier in complex-shaped structures and hence ultimately reduce the need for petroleum-based plastics.

Influence of a TiN interlayer on the microstructure and mechanical properties of hydroxyapatite films grown by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Nelea, Valentin D.; Ristoscu, Carmen; Colis, Silviu; Arens, Simona; Pelletier, Herve; Mihailescu, Ion N.; Mille, Pierre

2001-04-01

Crystalline hydroxyapatite (HA) thin films grown on metallic substrates is the best choice for bone restoration. This is due to the good biological compatibility of the hydroxyapatite material combined with the good mechanical characteristics of the substrates. We deposit HA thin films by Pulsed Laser Deposition (PLD) in vacuum at room temperature using a KrF* excimer laser ((lambda) equals 248 nm, (tau) FWHM >= 20 ns). The depositions were performed directly on Ti-5Al-2.5Fe or on substrates previously coated with a TiN buffer layer. The HA deposited structures were characterized by complementary techniques: GIXRD, SEM, TEM, SAED, EDS and nanoindentation. Properties of the HA films grown with and without the TiN buffer were discussed in term of microstructure and mechanical behavior. The films with interlayer preserve the stoichiometry, are completely recrystallized and present better mechanical characteristics as compared with those without buffer.

Influence of gamma irradiation on structural, thermal and antibacterial properties of HPMC/ZnO nanocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rao, B. Lakshmeesha; Madhukumar, R.; Latha, S.

This work was carried out to evaluate the effect of gamma irradiation on the structural, thermal and antibacterial properties of HPMC/ZnO nanocomposite films exposed to Cobalt-60 (Average energy: 1.25 MeV). The X-ray diffraction study revealed that the crystallite size (L in Å) decreased as irradiation dose increased. The crystallinity (X{sub c}) of the nanocomposites initially increased and at higher doses it was decreased. The thermal stability of the nanocomposites increased up to 50 kGy and after that decreased as the irradiation dose increased. But, HPMC/ZnO nanocomposite films, showed a promising range of antimicrobial activity against tested micro-organisms making nanocomposites suitablemore » for food packing and other biomedical applications.« less

Multiple delta doping of single crystal cubic boron nitride films heteroepitaxially grown on (001)diamonds

NASA Astrophysics Data System (ADS)

Yin, H.; Ziemann, P.

2014-06-01

Phase pure cubic boron nitride (c-BN) films have been epitaxially grown on (001) diamond substrates at 900 °C. The n-type doping of c-BN epitaxial films relies on the sequential growth of nominally undoped (p-) and Si doped (n-) layers with well-controlled thickness (down to several nanometer range) in the concept of multiple delta doping. The existence of nominally undoped c-BN overgrowth separates the Si doped layers, preventing Si dopant segregation that was observed for continuously doped epitaxial c-BN films. This strategy allows doping of c-BN films can be scaled up to multiple numbers of doped layers through atomic level control of the interface in the future electronic devices. Enhanced electronic transport properties with higher hall mobility (102 cm2/V s) have been demonstrated at room temperature as compared to the normally continuously Si doped c-BN films.

Transparent cellulose/polyhedral oligomeric silsesquioxane nanocomposites with enhanced UV-shielding properties.

PubMed

Feng, Ye; Zhang, Jinming; He, Jiasong; Zhang, Jun

2016-08-20

The solubility of eight types of polyhedral oligomeric silsesquioxane (POSS) derivatives in an ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) and the dispersion of POSS in cellulose matrix were examined. Only a special POSS containing both aminophenyl and nitrophenyl groups (POSS-AN, NH2:NO2=2:6) was selected to prepare nanocomposites, because of its good solubility in AmimCl and high stability during the preparation process. POSS-AN nanoparticles were uniformly dispersed in a cellulose matrix with a size of 30-40nm, and so the resultant cellulose/POSS-AN nanocomposite films were transparent. The mechanical properties of the films achieved a maximum tensile strength of 190MPa after addition of 2wt% POSS-AN. Interestingly, all of the cellulose/POSS-AN films exhibited high UV-absorbing capability. For the 15wt% cellulose/POSS-AN film, the transmittance of UVA (315-400nm) and UVB (280-315nm) was only 9.1% and nearly 0, respectively. The UV aging and shielding experiments showed that the transparent cellulose/POSS-AN nanocomposite films possessed anti-UV aging and UV shielding properties. Copyright © 2016 Elsevier Ltd. All rights reserved.

Optical, electrochemical and hydrophilic properties of Y2O3 doped TiO2 nanocomposite films.

PubMed

Zhang, Xiangchao; Yang, Huaming; Tang, Aidong

2008-12-25

The 5% Y2O3 doped TiO2 nanocomposite film (YTF) deposited on ITO glass substrate has been synthesized by the sol-gel dip-coating method. The as-synthesized samples were characterized using X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), voltage-current (V-I), electrochemical impedance spectroscopy (EIS) and ultraviolet-visible (UV-vis) analysis technologies. The crystalline structure, surface morphology and surface chemical composition of YTF sample have been primarily investigated. The results demonstrate that YTF is anatase crystalline phase with thickness of 480 nm and consists of spherical shape particles with a grain size of about 15.8 nm. The binding energy appears as a chemical shift, and relatively more Y and Ti species are present on the surface, indicating that active surfaces of the nanocomposite film have been enhanced with more oxygen vacancies Vö due to doping Y2O3 to TiO2. The absorption edge of YTF has a red shift, and the optical properties of YTF in visible light region have been obviously improved. The water contact angle is about 8 degrees after daylight lamp irradiation 60 min. An equivalent circuit model provided a reliable description for the electrochemical systems. Based on the Mott-Schottky equation, the donor concentration (ND) for YTF is 1.05 x 10(20) cm(-3), which enhances 1 order of magnitude than that for pure TiO2 film (TF), the flat-band potential (V(fb)) and the space charge layer (d(sc)) obviously decreased. With the incorporation of Y2O3 into TiO2, the optical, electrochemical and photoinduced hydrophilic properties of YTF in visible light region have obviously improved, indicating that YTF shows promising applications in solar energy conversion, self-cleaning and other potential fields.

Photonic structures based on hybrid nanocomposites

NASA Astrophysics Data System (ADS)

Husaini, Saima

In this thesis, photonic structures embedded with two types of nanomaterials, (i) quantum dots and (ii) metal nanoparticles are studied. Both of these exhibit optical and electronic properties different from their bulk counterpart due to their nanoscale physical structure. By integrating these nanomaterials into photonic structures, in which the electromagnetic field can be confined and controlled via modification of geometry and composition, we can enhance their linear and nonlinear optical properties to realize functional photonic structures. Before embedding quantum dots into photonic structures, we study the effect of various host matrices and fabrication techniques on the optical properties of the colloidal quantum dots. The two host matrices of interest are SU8 and PMMA. It is shown that the emission properties of the quantum dots are significantly altered in these host matrices (especially SU8) and this is attributed to a high rate of nonradiative quenching of the dots. Furthermore, the effects of fabrication techniques on the optical properties of quantum dots are also investigated. Finally a microdisk resonator embedded with quantum dots is fabricated using soft lithography and luminescence from the quantum dots in the disk is observed. We investigate the absorption and effective index properties of silver nanocomposite films. It is shown that by varying the fill factor of the metal nanoparticles and fabrication parameters such as heating time, we can manipulate the optical properties of the metal nanocomposite. Optimizing these parameters, a silver nanocomposite film with a 7% fill factor is prepared. A one-dimensional photonic crystal consisting of alternating layers of the silver nanocomposite and a polymer (Polymethyl methacrylate) is fabricated using spin coating and its linear and nonlinear optical properties are investigated. Using reflectivity measurements we demonstrate that the one-dimensional silver-nanocomposite-dielectric photonic crystal

Elastic Modulus and Thermal Conductivity of Thiolene/TiO2 Nanocomposites

PubMed Central

2017-01-01

Metal oxide based polymer nanocomposites find diverse applications as functional materials, and in particular thiol-ene/TiO2 nanocomposites are promising candidates for dental restorative materials. The important mechanical and thermal properties of the nanocomposites, however, are still not well understood. In this study, the elastic modulus and thermal conductivity of thiol-ene/TiO2 nanocomposite thin films with varying weight fractions of TiO2 nanoparticles are investigated by using Brillouin light scattering spectroscopy and 3ω measurements, respectively. As the TiO2 weight fraction increases from 0 to 90%, the effective elastic longitudinal modulus of the films increases from 6.2 to 37.5 GPa, and the effective thermal conductivity from 0.04 to 0.76 W/m K. The former increase could be attributed to the covalent cross-linking of the nanocomposite constituents. The latter one could be ascribed to the addition of high thermal conductivity TiO2 nanoparticles and the formation of possible conductive channels at high TiO2 weight fractions. The linear dependence of the thermal conductivity on the sound velocity, reported for amorphous polymers, is not observed in the present nanocomposite system. PMID:29755637

Tantalum films with well-controlled roughness grown by oblique incidence deposition

NASA Astrophysics Data System (ADS)

Rechendorff, K.; Hovgaard, M. B.; Chevallier, J.; Foss, M.; Besenbacher, F.

2005-08-01

We have investigated how tantalum films with well-controlled surface roughness can be grown by e-gun evaporation with oblique angle of incidence between the evaporation flux and the surface normal. Due to a more pronounced shadowing effect the root-mean-square roughness increases from about 2 to 33 nm as grazing incidence is approached. The exponent, characterizing the scaling of the root-mean-square roughness with length scale (α), varies from 0.75 to 0.93, and a clear correlation is found between the angle of incidence and root-mean-square roughness.

Semiconductor-insulator transition in VO{sub 2} (B) thin films grown by pulsed laser deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rúa, Armando; Díaz, Ramón D.; Lysenko, Sergiy

2015-09-28

Thin films of B-phase VO{sub 2} were grown by pulsed-laser deposition on glass and (100)-cut MgO substrates in a temperature range from 375 to 425 °C and at higher gas pressures than usual for this technique. The films were strongly oriented, with ab-planes parallel to the substrate surface. Detailed study of surface morphology through Atomic Force Microscopy images suggest significant differences in evolution as a function of growth temperature for films on the two types of substrates. Measurements of electrical conductivities through cooling-heating cycles from room temperature to 120 K showed changes of five orders of magnitude, with steeper changes between roommore » temperature and ∼150 K, which corresponds with the extended and reversible phase transition known to occur for this material. At lower temperatures conductivities exhibited Arrhenius behavior, indicating that no further structural change was occurring and that conduction is thermally activated. In this lower temperature range, conductivity of the samples can be described by the near-neighbor hopping model. No hysteresis was found between the cooling and heating braches of the cycles, which is at variance with previous results published for VO{sub 2} (B). This apparent lack of hysteresis for thin films grown in the manner described and the large conductivity variation as a function of temperature observed for the samples suggests this material could be of interest for infrared sensing applications.« less

Carbon nanotube-polymer nanocomposite infrared sensor.

PubMed

Pradhan, Basudev; Setyowati, Kristina; Liu, Haiying; Waldeck, David H; Chen, Jian

2008-04-01

The infrared photoresponse in the electrical conductivity of single-walled carbon nanotubes (SWNTs) is dramatically enhanced by embedding SWNTs in an electrically and thermally insulating polymer matrix. The conductivity change in a 5 wt % SWNT-polycarbonate nanocomposite is significant (4.26%) and sharp upon infrared illumination in the air at room temperature. While the thermal effect predominates in the infrared photoresponse of a pure SWNT film, the photoeffect predominates in the infrared photoresponse of SWNT-polycarbonate nanocomposites.

Thermal stability increase in metallic nanoparticles-loaded cellulose nanocrystal nanocomposites.

PubMed

Goikuria, U; Larrañaga, A; Vilas, J L; Lizundia, E

2017-09-01

Due to the potential of CNC-based flexible materials for novel industrial applications, the aim of this work is to improve the thermal stability of cellulose nanocrystals (CNC) films through a straightforward and scalable method. Based of nanocomposite approach, five different metallic nanoparticles (ZnO, SiO 2 , TiO 2 , Al 2 O 3 and Fe 2 O 3 ) have been co-assembled in water with CNCs to obtain free-standing nanocomposite films. Thermogravimetric analysis (TGA) reveals an increased thermal stability upon nanoparticle. This increase in the thermal stability reaches a maximum of 75°C for the nanocomposites having 10wt% of Fe 2 O 3 and ZnO. The activation energies of thermodegradation process (E a ) determined according to Kissinger and Ozawa-Flynn-Wall methods further confirm the delayed degradation of CNC nanocomposites upon heating. Finally, the changes induced in the crystalline structure during thermodegradation were followed by wide angle X-ray diffraction (WAXD). It is also observed that thermal degradation proceeds at higher temperatures for nanocomposites having metallic nanoparticles. Overall, experimental findings here showed make nanocomposite approach a simple low-cost environmentally-friendly strategy to overcome the relatively poor thermal stability of CNCs when extracted via sulfuric acid assisted hydrolysis of cellulose. Copyright © 2017 Elsevier Ltd. All rights reserved.

MnSi nanostructures obtained from epitaxially grown thin films: magnetotransport and Hall effect

NASA Astrophysics Data System (ADS)

Schroeter, D.; Steinki, N.; Schilling, M.; Fernández Scarioni, A.; Krzysteczko, P.; Dziomba, T.; Schumacher, H. W.; Menzel, D.; Süllow, S.

2018-06-01

We present a comparative study of the (magneto)transport properties, including Hall effect, of bulk, epitaxially grown thin film and nanostructured MnSi. In order to set our results in relation to published data we extensively characterize our materials, this way establishing a comparatively good sample quality. Our analysis reveals that in particular for thin film and nanostructured material, there are extrinsic and intrinsic contributions to the electronic transport properties, which by modeling the data we separate out. Finally, we discuss our Hall effect data of nanostructured MnSi under consideration of the extrinsic contributions and with respect to the question of the detection of a topological Hall effect in a skyrmionic lattice.

Structural and electrical properties of large area epitaxial VO2 films grown by electron beam evaporation