Numerical and Experimental Dynamic Characteristics of Thin-Film Membranes

NASA Technical Reports Server (NTRS)

Young, Leyland G.; Ramanathan, Suresh; Hu, Jia-Zhu; Pai, P. Frank

2004-01-01

Presented is a total-Lagrangian displacement-based non-linear finite-element model of thin-film membranes for static and dynamic large-displacement analyses. The membrane theory fully accounts for geometric non-linearities. Fully non-linear static analysis followed by linear modal analysis is performed for an inflated circular cylindrical Kapton membrane tube under different pressures, and for a rectangular membrane under different tension loads at four comers. Finite element results show that shell modes dominate the dynamics of the inflated tube when the inflation pressure is low, and that vibration modes localized along four edges dominate the dynamics of the rectangular membrane. Numerical dynamic characteristics of the two membrane structures were experimentally verified using a Polytec PI PSV-200 scanning laser vibrometer and an EAGLE-500 8-camera motion analysis system.

A review on polyamide thin film nanocomposite (TFN) membranes: History, applications, challenges and approaches.

PubMed

Lau, W J; Gray, Stephen; Matsuura, T; Emadzadeh, D; Chen, J Paul; Ismail, A F

2015-09-01

This review focuses on the development of polyamide (PA) thin film nanocomposite (TFN) membranes for various aqueous media-based separation processes such as nanofiltration, reverse osmosis and forward osmosis since the concept of TFN was introduced in year 2007. Although the total number of published TFN articles falls far short of the articles of the well-known thin film composite (TFC) membranes, its growth rate is significant, particularly since 2012. Generally, by incorporating an appropriate amount of nanofiller into a thin selective PA layer of a composite membrane, one could produce TFN membranes with enhanced separation characteristics as compared to the conventional TFC membrane. For certain cases, the resulting TFN membranes demonstrate not only excellent antifouling resistance and/or greater antibacterial effect, but also possibly overcome the trade-off effect between water permeability and solute selectivity. Furthermore, this review attempts to give the readers insights into the difficulties of incorporating inorganic nanomaterials into the organic PA layer whose thickness usually falls in a range of several-hundred nanometers. It is also intended to show new possible approaches to overcome these challenges in TFN membrane fabrication. Copyright © 2015 Elsevier Ltd. All rights reserved.

Spectroscopic ellipsometry analysis of a thin film composite membrane consisting of polysulfone on a porous α-alumina support.

PubMed

Ogieglo, Wojciech; Wormeester, Herbert; Wessling, Matthias; Benes, Nieck E

2012-02-01

Exposure of a thin polymer film to a fluid can affect properties of the film such as the density and thickness. In particular in membrane technology, these changes can have important implications for membrane performance. Spectroscopic ellipsometry is a convenient technique for in situ studies of thin films, because of its noninvasive character and very high precision. The applicability of spectroscopic ellipsometry is usually limited to samples with well-defined interfacial regions, whereas in typical composite membranes, often substantial and irregular intrusion of the thin film into the pores of a support exists. In this work, we provide a detailed characterization of a polished porous alumina membrane support, using variable-angle spectroscopic ellipsometry in combination with atomic force microscopy and mercury porosimetry. Two Spectroscopic ellipsometry optical models are presented that can adequately describe the surface roughness of the support. These models consider the surface roughness as a distinct layer in which the porosity gradually increases toward the outer ambient interface. The first model considers the porosity profile to be linear; the second model assumes an exponential profile. It is shown that the models can be extended to account for a composite membrane geometry, by deposition of a thin polysulfone film onto the support. The developed method facilitates practicability for in situ spectroscopic ellipsometry studies of nonequilibrium systems, i.e., membranes under actual permeation conditions.

Membrane catalyst layer for fuel cells

DOEpatents

Wilson, Mahlon S.

1993-01-01

A gas reaction fuel cell incorporates a thin catalyst layer between a solid polymer electrolyte (SPE) membrane and a porous electrode backing. The catalyst layer is preferably less than about 10 .mu.m in thickness with a carbon supported platinum catalyst loading less than about 0.35 mgPt/cm.sup.2. The film is formed as an ink that is spread and cured on a film release blank. The cured film is then transferred to the SPE membrane and hot pressed into the surface to form a catalyst layer having a controlled thickness and catalyst distribution. Alternatively, the catalyst layer is formed by applying a Na.sup.+ form of a perfluorosulfonate ionomer directly to the membrane, drying the film at a high temperature, and then converting the film back to the protonated form of the ionomer. The layer has adequate gas permeability so that cell performance is not affected and has a density and particle distribution effective to optimize proton access to the catalyst and electronic continuity for electron flow from the half-cell reaction occurring at the catalyst.

Ultrahigh Flux Thin Film Boiling Heat Transfer Through Nanoporous Membranes.

PubMed

Wang, Qingyang; Chen, Renkun

2018-05-09

Phase change heat transfer is fundamentally important for thermal energy conversion and management, such as in electronics with power density over 1 kW/cm 2 . The critical heat flux (CHF) of phase change heat transfer, either evaporation or boiling, is limited by vapor flux from the liquid-vapor interface, known as the upper limit of heat flux. This limit could in theory be greater than 1 kW/cm 2 on a planar surface, but its experimental realization has remained elusive. Here, we utilized nanoporous membranes to realize a new "thin film boiling" regime that resulted in an unprecedentedly high CHF of over 1.2 kW/cm 2 on a planar surface, which is within a factor of 4 of the theoretical limit, and can be increased to a higher value if mechanical strength of the membranes can be improved (demonstrated with 1.85 kW/cm 2 CHF in this work). The liquid supply is achieved through a simple nanoporous membrane that supports the liquid film where its thickness automatically decreases as heat flux increases. The thin film configuration reduces the conductive thermal resistance, leads to high frequency bubble departure, and provides separate liquid-vapor pathways, therefore significantly enhances the heat transfer. Our work provides a new nanostructuring approach to achieve ultrahigh heat flux in phase change heat transfer and will benefit both theoretical understanding and application in thermal management of high power devices of boiling heat transfer.

Gas Permeation in Thin Glassy Polymer Films

NASA Astrophysics Data System (ADS)

Paul, Donald

2011-03-01

The development of asymmetric and composite membranes with very thin dense ``skins'' needed to achieve high gas fluxes enabled the commercial use of membranes for molecular level separations. It has been generally assumed that these thin skins, with thicknesses of the order of 100 nm, have the same permeation characteristics as films with thicknesses of 25 microns or more. Thick films are easily made in the laboratory and have been used extensively for measuring permeation characteristics to evaluate the potential of new polymers for membrane applications. There is now evidence that this assumption can be in very significant error, and use of thick film data to select membrane materials or predict performance should be done with caution. This presentation will summarize our work on preparing films of glassy polymers as thin as 20 nm and characterizing their behavior by gas permeation, ellipsometry and positron annihilation lifetime spectroscopy. Some of the most important polymers used commercially as gas separation membranes, i.e., Matrimid polyimide, polysulfone (PSF) and poly(2,6-dimethyl-1,4-phenylene oxide) (PPO), have been made into well-defined thin films in our laboratories by spin casting techniques and their properties studied using the techniques we have developed. These thin films densify (or physically age) much faster than thicker films, and, as result, the permeability decreases, sometimes by several-fold over weeks or months for thin films. This means that the properties of these thin films can be very different from bulk films. The techniques, interpretations and implications of these observations will be discussed. In a broader sense, gas permeation measurements can be a powerful way of developing a better understanding of the effects of polymer chain confinement and/or surface mobility on the behavior of thin films.

Amine Enrichment of Thin-Film Composite Membranes via Low Pressure Plasma Polymerization for Antimicrobial Adhesion.

PubMed

Reis, Rackel; Dumée, Ludovic F; He, Li; She, Fenghua; Orbell, John D; Winther-Jensen, Bjorn; Duke, Mikel C

2015-07-15

Thin-film composite membranes, primarily based on poly(amide) (PA) semipermeable materials, are nowadays the dominant technology used in pressure driven water desalination systems. Despite offering superior water permeation and salt selectivity, their surface properties, such as their charge and roughness, cannot be extensively tuned due to the intrinsic fabrication process of the membranes by interfacial polymerization. The alteration of these properties would lead to a better control of the materials surface zeta potential, which is critical to finely tune selectivity and enhance the membrane materials stability when exposed to complex industrial waste streams. Low pressure plasma was employed to introduce amine functionalities onto the PA surface of commercially available thin-film composite (TFC) membranes. Morphological changes after plasma polymerization were analyzed by SEM and AFM, and average surface roughness decreased by 29%. Amine enrichment provided isoelectric point changes from pH 3.7 to 5.2 for 5 to 15 min of plasma polymerization time. Synchrotron FTIR mappings of the amine-modified surface indicated the addition of a discrete 60 nm film to the PA layer. Furthermore, metal affinity was confirmed by the enhanced binding of silver to the modified surface, supported by an increased antimicrobial functionality with demonstrable elimination of E. coli growth. Essential salt rejection was shown minimally compromised for faster polymerization processes. Plasma polymerization is therefore a viable route to producing functional amine enriched thin-film composite PA membrane surfaces.

Triclosan-immobilized polyamide thin film composite membranes with enhanced biofouling resistance

NASA Astrophysics Data System (ADS)

Park, Sang-Hee; Hwang, Seon Oh; Kim, Taek-Seung; Cho, Arah; Kwon, Soon Jin; Kim, Kyoung Taek; Park, Hee-Deung; Lee, Jung-Hyun

2018-06-01

We report on a strategy to improve biofouling resistance of a polyamide (PA) thin-film composite (TFC) reverse osmosis (RO) membrane via chemically immobilizing triclosan (TC), known as a common organic biocide, on its surface. To facilitate covalent attachment of TC on the membrane surface, TC was functionalized with amine moiety to prepare aminopropyl TC. Then, the TC-immobilized TFC (TFC-TC) membranes were fabricated through a one-step amide formation reaction between amine groups of aminopropyl TC and acyl chloride groups present on the PA membrane surface, which was confirmed by high-resolution XPS. Strong stability of the immobilized TC was also confirmed by a hydraulic washing test. Although the TFC-TC membrane showed slightly reduced separation performance compared to the pristine control, it still maintained a satisfactory RO performance level. Importantly, the TFC-TC membrane exhibited excellent antibacterial activity against both gram negative (E. coli and P. aeruginosa) and gram positive (S. aureus) bacteria along with greatly enhanced resistance to biofilm formation. Our immobilization approach offers a robust and relatively benign strategy to control biofouling of functional surfaces, films and membranes.

Incorporation of layered double nanomaterials in thin film nanocomposite nanofiltration membrane for magnesium sulphate removal

NASA Astrophysics Data System (ADS)

Hanis Tajuddin, Muhammad; Yusof, Norhaniza; Salleh, Wan Norharyati Wan; Fauzi Ismail, Ahmad; Hanis Hayati Hairom, Nur; Misdan, Nurasyikin

2018-03-01

Thin film nanocomposite (TFN) membrane with copper-aluminium layered double hydroxides (LDH) incorporated into polyamide (PA) selective layer has been prepared for magnesium sulphate salt removal. 0, 0.05, 0.1, 0.15, 0.2 wt% of LDH were dispersed in the trimesoyl chloride (TMC) in n-hexane as organic solution and embedded into PA layer during interfacial polymerization with piperazine. The fabricated membranes were further characterized to evaluate its morphological structure and membrane surface hydrophilicity. The TFN membranes performance were evaluated with divalent salt magnesium sulphate (MgSO4) removal and compared with thin film composite (TFC). The morphological structures of TFN membranes were altered and the surface hydrophilicity were enhanced with addition of LDH. Incorporation of LDH has improved the permeate water flux by 82.5% compared to that of TFC membrane with satisfactory rejection of MgSO4. This study has experimentally validated the potential of LDH to improve the divalent salt separation performance for TFN membranes.

Absorbing TiOx thin film enabling laser welding of polyurethane membranes and polyamide fibers

PubMed Central

Amberg, Martin; Haag, Alexander; Storchenegger, Raphael; Rupper, Patrick; Lehmeier, Frederike; Rossi, René M; Hegemann, Dirk

2015-01-01

We report on the optical properties of thin titanium suboxide (TiOx) films for applications in laser transmission welding of polymers. Non-absorbing fibers were coated with TiOx coatings by reactive magnetron sputtering. Plasma process parameters influencing the chemical composition and morphology of the deposited thin films were investigated in order to optimize their absorption properties. Optical absorption spectroscopy showed that the oxygen content of the TiOx coatings is the main parameter influencing the optical absorbance. Overtreatment (high power plasma input) of the fiber surface leads to high surface roughness and loss of mechanical stability of the fiber. The study shows that thin substoichiometric TiOx films enable the welding of very thin polyurethane membranes and polyamide fibers with improved adhesion properties. PMID:27877837

Absorbing TiOx thin film enabling laser welding of polyurethane membranes and polyamide fibers

NASA Astrophysics Data System (ADS)

Amberg, Martin; Haag, Alexander; Storchenegger, Raphael; Rupper, Patrick; Lehmeier, Frederike; Rossi, René M.; Hegemann, Dirk

2015-10-01

We report on the optical properties of thin titanium suboxide (TiOx) films for applications in laser transmission welding of polymers. Non-absorbing fibers were coated with TiOx coatings by reactive magnetron sputtering. Plasma process parameters influencing the chemical composition and morphology of the deposited thin films were investigated in order to optimize their absorption properties. Optical absorption spectroscopy showed that the oxygen content of the TiOx coatings is the main parameter influencing the optical absorbance. Overtreatment (high power plasma input) of the fiber surface leads to high surface roughness and loss of mechanical stability of the fiber. The study shows that thin substoichiometric TiOx films enable the welding of very thin polyurethane membranes and polyamide fibers with improved adhesion properties.

Ultra-thin solid oxide fuel cells: Materials and devices

NASA Astrophysics Data System (ADS)

Kerman, Kian

Solid oxide fuel cells are electrochemical energy conversion devices utilizing solid electrolytes transporting O2- that typically operate in the 800 -- 1000 °C temperature range due to the large activation barrier for ionic transport. Reducing electrolyte thickness or increasing ionic conductivity can enable lower temperature operation for both stationary and portable applications. This thesis is focused on the fabrication of free standing ultrathin (<100 nm) oxide membranes of prototypical O 2- conducting electrolytes, namely Y2O3-doped ZrO2 and Gd2O3-doped CeO2. Fabrication of such membranes requires an understanding of thin plate mechanics coupled with controllable thin film deposition processes. Integration of free standing membranes into proof-of-concept fuel cell devices necessitates ideal electrode assemblies as well as creative processing schemes to experimentally test devices in a high temperature dual environment chamber. We present a simple elastic model to determine stable buckling configurations for free standing oxide membranes. This guides the experimental methodology for Y 2O3-doped ZrO2 film processing, which enables tunable internal stress in the films. Using these criteria, we fabricate robust Y2O3-doped ZrO2 membranes on Si and composite polymeric substrates by semiconductor and micro-machining processes, respectively. Fuel cell devices integrating these membranes with metallic electrodes are demonstrated to operate in the 300 -- 500 °C range, exhibiting record performance at such temperatures. A model combining physical transport of electronic carriers in an insulating film and electrochemical aspects of transport is developed to determine the limits of performance enhancement expected via electrolyte thickness reduction. Free standing oxide heterostructures, i.e. electrolyte membrane and oxide electrodes, are demonstrated. Lastly, using Y2O3-doped ZrO2 and Gd2O 3-doped CeO2, novel electrolyte fabrication schemes are explored to develop oxide

Electrochemical impedance spectroscopy analysis of a thin polymer film-based micro-direct methanol fuel cell

NASA Astrophysics Data System (ADS)

Schulz, Tobias; Weinmüller, Christian; Nabavi, Majid; Poulikakos, Dimos

A single cell micro-direct methanol fuel cell (micro-DMFC) was investigated using electrochemical impedance spectroscopy. The electrodes consisted of thin, flexible polymer (SU8) film microchannel structures fabricated in-house using microfabrication techniques. AC impedance spectroscopy was used to separate contributions to the overall cell polarization from the anode, cathode and membrane. A clear distinction between the different electrochemical phenomena occurring in the micro-DMFC, especially the distinction between double layer charging and Faradaic reactions was shown. The effect of fuel flow rate, temperature, and anode flow channel structure on the impedance of the electrode reactions and membrane/electrode double layer charging were investigated. Analysis of impedance data revealed that the performance of the test cell was largely limited by the presence of intermediate carbon monoxide in the anode reaction. Higher temperatures increase cell performance by enabling intermediate CO to be oxidized at much higher rates. The results also revealed that serpentine anode flow microchannels show a lower tendency to intermediate CO coverage and a more stable cell behavior than parallel microchannels.

Absorbing TiO x thin film enabling laser welding of polyurethane membranes and polyamide fibers.

PubMed

Amberg, Martin; Haag, Alexander; Storchenegger, Raphael; Rupper, Patrick; Lehmeier, Frederike; Rossi, René M; Hegemann, Dirk

2015-10-01

We report on the optical properties of thin titanium suboxide (TiO x ) films for applications in laser transmission welding of polymers. Non-absorbing fibers were coated with TiO x coatings by reactive magnetron sputtering. Plasma process parameters influencing the chemical composition and morphology of the deposited thin films were investigated in order to optimize their absorption properties. Optical absorption spectroscopy showed that the oxygen content of the TiO x coatings is the main parameter influencing the optical absorbance. Overtreatment (high power plasma input) of the fiber surface leads to high surface roughness and loss of mechanical stability of the fiber. The study shows that thin substoichiometric TiO x films enable the welding of very thin polyurethane membranes and polyamide fibers with improved adhesion properties.

Development of an ultra-thin film comprised of a graphene membrane and carbon nanotube vein support.

PubMed

Lin, Xiaoyang; Liu, Peng; Wei, Yang; Li, Qunqing; Wang, Jiaping; Wu, Yang; Feng, Chen; Zhang, Lina; Fan, Shoushan; Jiang, Kaili

2013-01-01

Graphene, exhibiting superior mechanical, thermal, optical and electronic properties, has attracted great interest. Considering it being one-atom-thick, and the reduced mechanical strength at grain boundaries, the fabrication of large-area suspended chemical vapour deposition graphene remains a challenge. Here we report the fabrication of an ultra-thin free-standing carbon nanotube/graphene hybrid film, inspired by the vein-membrane structure found in nature. Such a square-centimetre-sized hybrid film can realize the overlaying of large-area single-layer chemical vapour deposition graphene on to a porous vein-like carbon nanotube network. The vein-membrane-like hybrid film, with graphene suspended on the carbon nanotube meshes, possesses excellent mechanical performance, optical transparency and good electrical conductivity. The ultra-thin hybrid film features an electron transparency close to 90%, which makes it an ideal gate electrode in vacuum electronics and a high-performance sample support in transmission electron microscopy.

Slurry spin coating of thin film yttria stabilized zirconia/gadolinia doped ceria bi-layer electrolytes for solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Kim, Hyun Joong; Kim, Manjin; Neoh, Ke Chean; Han, Gwon Deok; Bae, Kiho; Shin, Jong Mok; Kim, Gyu-Tae; Shim, Joon Hyung

2016-09-01

Thin ceramic bi-layered membrane comprising yttria-stabilized zirconia (YSZ) and gadolinia-doped ceria (GDC) is fabricated by the cost-effective slurry spin coating technique, and it is evaluated as an electrolyte of solid oxide fuel cells (SOFCs). It is demonstrated that the slurry spin coating method is capable of fabricating porous ceramic films by adjusting the content of ethyl-cellulose binders in the source slurry. The porous GDC layer deposited by spin coating under an optimal condition functions satisfactorily as a cathode-electrolyte interlayer in the test SOFC stack. A 2-μm-thick electrolyte membrane of the spin-coated YSZ/GDC bi-layer is successfully deposited as a dense and stable film directly on a porous NiO-YSZ anode support without any interlayers, and the SOFC produces power output over 200 mW cm-2 at 600 °C, with an open circuit voltage close to 1 V. Electrochemical impedance spectra analysis is conducted to evaluate the performance of the fuel cell components in relation with the microstructure of the spin-coated layers.

Thin-Film Nanocomposite Membrane with the Minimum Amount of MOF by the Langmuir-Schaefer Technique for Nanofiltration.

PubMed

Navarro, Marta; Benito, Javier; Paseta, Lorena; Gascón, Ignacio; Coronas, Joaquín; Téllez, Carlos

2018-01-10

An innovative procedure for positioning a monolayer of hydrophilic metal organic framework (MOF) MIL-101(Cr) (MIL, Materials of Institute Lavoisier) nanoparticles (NPs) in thin-film nanocomposite (TFN) membranes has been implemented by transferring a Langmuir-Schaefer (LS) film of the MOF in between the polyamide thin layer at the top and the cross-linked asymmetric polyimide (P84) support at the bottom. The presence and layout of the LS-MIL-101(Cr) monolayer in the TFN membrane was confirmed by scanning transmission electron microscopy imaging with a high-angle annular dark-field detector images and X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, electron energy loss spectroscopy, and atomic force microscopy analyses. This methodology requires the smallest amount of MOF reported to date, 3.8 μg cm -2 , and promotes the formation of a defect-free ultrathin MOF film. Although conventional TFN membranes tend to show MOF agglomerates that could contribute to the formation of unselective defects, LS-TFN membranes, characterized by a homogeneous and continuous MOF coating, exhibit an optimal membrane performance, without a significant decrease in selectivity. Outstanding methanol permeances, one of the best results reported to date, of 10.1 ± 0.5 L m -2 h -1 bar -1 when filtering sunset yellow and of 9.5 ± 2.1 L m -2 h -1 bar -1 when filtering rose bengal have been achieved in LS-TFN membranes with a rejection higher than 90% in all cases. Methanol permeates through the polyamide and the LS-MIL-101(Cr) monolayer, greatly enhanced by the MOF pore system, in comparison to thin-film composite and conventional TFN membranes (7.5 ± 0.7 and 7.7 ± 1.1 L m -2 h -1 bar -1 when filtering sunset yellow), respectively, in which polyamide areas free of MOF NPs are present.

Surface modification of thin film composite reverse osmosis membrane by glycerol assisted oxidation with sodium hypochlorite

NASA Astrophysics Data System (ADS)

Raval, Hiren D.; Samnani, Mohit D.; Gauswami, Maulik V.

2018-01-01

Need for improvement in water flux of thin film composite (TFC) RO membrane has been appreciated by researchers world over and surface modification approach is found promising to achieve higher water flux and solute rejection. Thin film composite RO membrane was exposed to 2000 mg/l sodium hypochlorite solution with varying concentrations of glycerol ranging from 1 to 10%. It was found that there was a drop in concentration of sodium hypochlorite after the addition of glycerol because of a new compound resulted from the oxidation of glycerol with sodium hypochlorite. The water flux of the membrane treated with 1% glycerol with 2000 mg/l sodium hypochlorite for 1 h was about 22% more and salt rejection was 1.36% greater than that of only sodium hypochlorite treated membrane for the same concentration and time. There was an increase in salt rejection of membrane with increase in concentration of glycerol from 1% to 5%, however, increasing glycerol concentration further up to 10%, the salt rejection declined. The water flux was found declining from 1% glycerol solution to 10% glycerol solution. The membrane samples were characterized to understand the change in chemical structure and morphology of the membrane.

High performance direct methanol fuel cell with thin electrolyte membrane

NASA Astrophysics Data System (ADS)

Wan, Nianfang

2017-06-01

A high performance direct methanol fuel cell is achieved with thin electrolyte membrane. 320 mW cm-2 of peak power density and over 260 mW cm-2 at 0.4 V are obtained when working at 90 °C with normal pressure air supply. It is revealed that the increased anode half-cell performance with temperature contributes primarily to the enhanced performance at elevated temperature. From the comparison of iR-compensated cathode potential of methanol/air with that of H2/air fuel cell, the impact of methanol crossover on cathode performance decreases with current density and becomes negligible at high current density. Current density is found to influence fuel efficiency and methanol crossover significantly from the measurement of fuel efficiency at different current density. At high current density, high fuel efficiency can be achieved even at high temperature, indicating decreased methanol crossover.

A Novel Fabrication Approach for Multifunctional Graphene-based Thin Film Nano-composite Membranes with Enhanced Desalination and Antibacterial Characteristics.

PubMed

Hegab, Hanaa M; ElMekawy, Ahmed; Barclay, Thomas G; Michelmore, Andrew; Zou, Linda; Losic, Dusan; Saint, Christopher P; Ginic-Markovic, Milena

2017-08-08

A practical fabrication technique is presented to tackle the trade-off between the water flux and salt rejection of thin film composite (TFC) reverse osmosis (RO) membranes through controlled creation of a thinner active selective polyamide (PA) layer. The new thin film nano-composite (TFNC) RO membranes were synthesized with multifunctional poly tannic acid-functionalized graphene oxide nanosheets (pTA-f-GO) embedded in its PA thin active layer, which is produced through interfacial polymerization. The incorporation of pTA-f-GOL into the fabricated TFNC membranes resulted in a thinner PA layer with lower roughness and higher hydrophilicity compared to pristine membrane. These properties enhanced both the membrane water flux (improved by 40%) and salt rejection (increased by 8%) of the TFNC membrane. Furthermore, the incorporation of biocidal pTA-f-GO nanosheets into the PA active layer contributed to improving the antibacterial properties by 80%, compared to pristine membrane. The fabrication of the pTA-f-GO nanosheets embedded in the PA layer presented in this study is a very practical, scalable and generic process that can potentially be applied in different types of separation membranes resulting in less energy consumption, increased cost-efficiency and improved performance.

A Novel Approach Toward Fabrication of High Performance Thin Film Composite Polyamide Membranes.

PubMed

Khorshidi, Behnam; Thundat, Thomas; Fleck, Brian A; Sadrzadeh, Mohtada

2016-02-29

A practical method is reported to enhance water permeability of thin film composite (TFC) polyamide (PA) membranes by decreasing the thickness of the selective PA layer. The composite membranes were prepared by interfacial polymerization (IP) reaction between meta-phenylene diamine (MPD)-aqueous and trimesoyl chloride (TMC)-organic solvents at the surface of polyethersulfone (PES) microporous support. Several PA TFC membranes were prepared at different temperatures of the organic solution ranging from -20 °C to 50 °C. The physico-chemical and morphological properties of the synthesized membranes were carefully characterized using serval analytical techniques. The results confirmed that the TFC membranes, synthesized at sub-zero temperatures of organic solution, had thinner and smoother PA layer with a greater degree of cross-linking and wettability compared to the PA films prepared at 50 °C. We demonstrated that reducing the temperature of organic solution effectively decreased the thickness of the PA active layer and thus enhanced water permeation through the membranes. The most water permeable membrane was prepared at -20 °C and exhibited nine times higher water flux compared to the membrane synthesized at room temperature. The method proposed in this report can be effectively applied for energy- and cost-efficient development of high performance nanofiltration and reverse osmosis membranes.

Piezoelectric thin films and their applications for electronics

NASA Astrophysics Data System (ADS)

Yoshino, Yukio

2009-03-01

ZnO and AlN piezoelectric thin films have been studied for applications in bulk acoustic wave (BAW) resonator. This article introduces methods of forming ZnO and AlN piezoelectric thin films by radio frequency sputtering and applications of BAW resonators considering the relationship between the crystallinity of piezoelectric thin films and the characteristics of the BAW resonators. Using ZnO thin films, BAW resonators were fabricated for a contour mode at 3.58 MHz and thickness modes from 200 MHz to 5 GHz. The ZnO thin films were combined with various materials, substrates, and thin films to minimize the temperature coefficient of frequency (TCF). The minimum TCF of BAW resonators was approximately 2 ppm/°C in the range -20 to 80 °C. The electromechanical coupling coefficient (k2) in a 1.9 GHz BAW resonator was 6.9%. Using AlN thin films, 5-20 GHz BAW resonators with an ultrathin membrane were realized. The membrane thickness of a 20 GHz BAW resonator was about 200 nm, k2 was 6.1%, and the quality factor (Q) was about 280. Q decreased with increasing resonant frequency. The value of k2 is almost the same for 5-20 GHz resonators. This result could be obtained by improving the thickness uniformity, by controlling internal stress of thin films, and by controlling the crystallinity of AlN piezoelectric thin film.

Method of preparing water purification membranes. [polymerization of allyl amine as thin films in plasma discharge

NASA Technical Reports Server (NTRS)

Hollahan, J. R.; Wydeven, T. J., Jr. (Inventor)

1974-01-01

Allyl amine and chemically related compounds are polymerized as thin films in the presence of a plasma discharge. The monomer compound can be polymerized by itself or in the presence of an additive gas to promote polymerization and act as a carrier. The polymerized films thus produced show outstanding advantages when used as reverse osmosis membranes.

Ultra-thin Oxide Membranes: Synthesis and Carrier Transport

NASA Astrophysics Data System (ADS)

Sim, Jai Sung

focused ion beam milling, thin membranes of Ti xOy of 100-300 nm thickness have been created. TEM studies indicated polycrystallinity and presence of twins in the FIB-milled nanowalls. Compositional analysis in the transmission electron microscope also showed reduced content of oxygen, confirming non-stoichiometry. Temperature dependence of the electrical resistivity of the nanowall showed semiconducting behavior with an activation energy different from that of TiO2 single crystals and was attributed to formation of TinO2n-1 phases after FIB processing. The CeO2 study involved high temperature conductivity studies on substrate-free self-supported nano-crystalline ceria membranes up to 800 K. Increasing conductivity with oxygen partial pressure directly opposing the behavior of thin film devices 'clamped' by substrate has been observed. This illustrate that the relaxed nature of free standing membranes, and increased surface to volume ratio enables more sensitive electrical response to oxygen adsorption which could have implications for their use in oxygen storage devices, solid oxide fuel cells, and chemical sensors. The work in this thesis advances the understanding of materials in freestanding membrane form and advances fabrication techniques that have not been explored before, having implications for sensors, actuators, SOFC, memristors, and physics of quasi-2D materials.

Charge tunable thin-film composite membranes by gamma-ray triggered surface polymerization.

PubMed

Reis, Rackel; Duke, Mikel C; Tardy, Blaise L; Oldfield, Daniel; Dagastine, Raymond R; Orbell, John D; Dumée, Ludovic F

2017-06-30

Thin-film composite poly(amide) (PA) membranes have greatly diversified water supplies and food products. However, users would benefit from a control of the electrostatic interactions between the liquid and the net surface charge interface in order to benefit wider application. The ionic selectivity of the 100 nm PA semi-permeable layer is significantly affected by the pH of the solution. In this work, for the first time, a convenient route is presented to configure the surface charge of PA membranes by gamma ray induced surface grafting. This rapid and up-scalable method offers a versatile route for surface grafting by adjusting the irradiation total dose and the monomer concentration. Specifically, thin coatings obtained at low irradiation doses between 1 and 10 kGy and at low monomer concentration of 1 v/v% in methanol/water (1:1) solutions, dramatically altered the net surface charge of the pristine membranes from -25 mV to +45 mV, whilst the isoelectric point of the materials shifted from pH 3 to pH 7. This modification resulted in an improved water flux by over 55%, from 45.9 to up 70 L.m -2 .h -1 , whilst NaCl rejection was found to drop by only 1% compared to pristine membranes.

Preparation and Characterization of Chitosan Thin Films on Mixed-Matrix Membranes for Complete Removal of Chromium.

PubMed

Nayak, Vignesh; Jyothi, Mannekote Shivanna; Balakrishna, R Geetha; Padaki, Mahesh; Ismail, Ahmad Fauzi

2015-06-01

Herein we present a new approach for the complete removal of Cr(VI) species, through reduction of Cr(VI) to Cr(III), followed by adsorption of Cr(III). Reduction of chromium from water is an important challenge, as Cr(IV) is one of the most toxic substances emitted from industrial processes. Chitosan (CS) thin films were developed on plain polysulfone (PSf) and PSf/TiO2 membrane substrates by a temperature-induced technique using polyvinyl alcohol as a binder. Structure property elucidation was carried out by X-ray diffraction, microscopy, spectroscopy, contact angle measurement, and water uptake studies. The increase in hydrophilicity followed the order: PSf < PSf/TiO2 < PSf/TiO2/CS membranes. Use of this thin-film composite membrane for chromium removal was investigated with regards to the effects of light and pH. The observations reveal 100 % reduction of Cr(VI) to Cr(III) through electrons and protons donated from OH and NH2 groups of the CS layer; the reduced Cr(III) species are adsorbed onto the CS layer via complexation to give chromium-free water.

Strong thin membrane structure. [solar sails

NASA Technical Reports Server (NTRS)

Frazer, R. E. (Inventor)

1979-01-01

A continuous process is described for producing strong lightweight structures for use as solar sails for spacecraft propulsion by radiation pressure. A thin reflective coating, such as aluminum, is applied to a rotating cylinder. A nylon mesh, applied over the aluminum coating, is then coated with a polymerizing material such as a para-xylylene monomer gas to polymerize as a film bound to the mesh and the aluminum. An emissivity increasing material such as chromium or silicon monoxide is applied to the polymer film to disperse such material colloidally into the growing polymer film, or to the final polymer film. The resulting membrane structure is then removed from the cylinder. Alternately, the membrane structure can be formed by etching a substrate in the form of an organic film such as a polymide, or a metal foil, to remove material from the substrate and reduce its thickness. A thin reflective coating (aluminum) is applied on one side of the substrate, and an emissivity increasing coating is applied on the reverse side of the substrate.

Mechanical and transport properties of layer-by-layer electrospun composite proton exchange membranes for fuel cell applications.

PubMed

Mannarino, Matthew M; Liu, David S; Hammond, Paula T; Rutledge, Gregory C

2013-08-28

Composite membranes composed of highly conductive and selective layer-by-layer (LbL) films and electrospun fiber mats were fabricated and characterized for mechanical strength and electrochemical selectivity. The LbL component consists of a proton-conducting, methanol-blocking poly(diallyl dimethyl ammonium chloride)/sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (PDAC/sPPO) thin film. The electrospun fiber component consists of poly(trimethyl hexamethylene terephthalamide) (PA 6(3)T) fibers in a nonwoven mat of 60-90% porosity. The bare mats were annealed to improve their mechanical properties, which improvements are shown to be retained in the composite membranes. Spray LbL assembly was used as a means for the rapid formation of proton-conducting films that fill the void space throughout the porous electrospun matrix and create a fuel-blocking layer. Coated mats as thin as 15 μm were fabricated, and viable composite membranes with methanol permeabilities 20 times lower than Nafion and through-plane proton selectivity five and a half times greater than Nafion are demonstrated. The mechanical properties of the spray coated electrospun mats are shown to be superior to the LbL-only system and possess intrinsically greater dimensional stability and lower mechanical hysteresis than Nafion under hydrated conditions. The composite proton exchange membranes fabricated here were tested in an operational direct methanol fuel cell. The results show the potential for higher open circuit voltages (OCV) and comparable cell resistances when compared to fuel cells based on Nafion.

Method for making surfactant-templated thin films

DOEpatents

Brinker, C. Jeffrey; Lu, Yunfeng; Fan, Hong You

2010-08-31

An evaporation-induced self-assembly method to prepare a porous, surfactant-templated, thin film by mixing a silica sol, a solvent, a surfactant, and an interstitial compound, evaporating a portion of the solvent to form a liquid, crystalline thin film mesophase material, and then removal of the surfactant template. Coating onto a substrate produces a thin film with the interstitial compound either covalently bonded to the internal surfaces of the ordered or disordered mesostructure framework or physically entrapped within the ordered or disordered mesostructured framework. Particles can be formed by aerosol processing or spray drying rather than coating onto a substrate. The selection of the interstitial compound provides a means for developing thin films for applications including membranes, sensors, low dielectric constant films, photonic materials and optical hosts.

Method for making surfactant-templated thin films

DOEpatents

Brinker, C. Jeffrey; Lu, Yunfeng; Fan, Hongyou

2002-01-01

An evaporation-induced self-assembly method to prepare a porous, surfactant-templated, thin film by mixing a silica sol, a solvent, a surfactant, and an interstitial compound, evaporating a portion of the solvent to form a liquid, crystalline thin film mesophase material, and then removal of the surfactant template. Coating onto a substrate produces a thin film with the interstitial compound either covalently bonded to the internal surfaces of the ordered or disordered mesostructure framework or physically entrapped within the ordered or disordered mesostructured framework. Particles can be formed by aerosol processing or spray drying rather than coating onto a substrate. The selection of the interstitial compound provides a means for developing thin films for applications including membranes, sensors, low dielectric constant films, photonic materials and optical hosts.

Epitaxially grown strained pentacene thin film on graphene membrane.

PubMed

Kim, Kwanpyo; Santos, Elton J G; Lee, Tae Hoon; Nishi, Yoshio; Bao, Zhenan

2015-05-06

Organic-graphene system has emerged as a new platform for various applications such as flexible organic photovoltaics and organic light emitting diodes. Due to its important implication in charge transport, the study and reliable control of molecular packing structures at the graphene-molecule interface are of great importance for successful incorporation of graphene in related organic devices. Here, an ideal membrane of suspended graphene as a molecular assembly template is utilized to investigate thin-film epitaxial behaviors. Using transmission electron microscopy, two distinct molecular packing structures of pentacene on graphene are found. One observed packing structure is similar to the well-known bulk-phase, which adapts a face-on molecular orientation on graphene substrate. On the other hand, a rare polymorph of pentacene crystal, which shows significant strain along the c-axis, is identified. In particular, the strained film exhibits a specific molecular orientation and a strong azimuthal correlation with underlying graphene. Through ab initio electronic structure calculations, including van der Waals interactions, the unusual polymorph is attributed to the strong graphene-pentacene interaction. The observed strained organic film growth on graphene demonstrates the possibility to tune molecular packing via graphene-molecule interactions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mesoscale simulations of confined Nafion thin films.

PubMed

Vanya, P; Sharman, J; Elliott, J A

2017-12-07

The morphology and transport properties of thin films of the ionomer Nafion, with thicknesses on the order of the bulk cluster size, have been investigated as a model system to explain the anomalous behaviour of catalyst/electrode-polymer interfaces in membrane electrode assemblies. We have employed dissipative particle dynamics (DPD) to investigate the interaction of water and fluorocarbon chains, with carbon and quartz as confining materials, for a wide range of operational water contents and film thicknesses. We found confinement-induced clustering of water perpendicular to the thin film. Hydrophobic carbon forms a water depletion zone near the film interface, whereas hydrophilic quartz results in a zone with excess water. There are, on average, oscillating water-rich and fluorocarbon-rich regions, in agreement with experimental results from neutron reflectometry. Water diffusivity shows increasing directional anisotropy of up to 30% with decreasing film thickness, depending on the hydrophilicity of the confining material. A percolation analysis revealed significant differences in water clustering and connectivity with the confining material. These findings indicate the fundamentally different nature of ionomer thin films, compared to membranes, and suggest explanations for increased ionic resistances observed in the catalyst layer.

Mesoscale simulations of confined Nafion thin films

NASA Astrophysics Data System (ADS)

Vanya, P.; Sharman, J.; Elliott, J. A.

2017-12-01

The morphology and transport properties of thin films of the ionomer Nafion, with thicknesses on the order of the bulk cluster size, have been investigated as a model system to explain the anomalous behaviour of catalyst/electrode-polymer interfaces in membrane electrode assemblies. We have employed dissipative particle dynamics (DPD) to investigate the interaction of water and fluorocarbon chains, with carbon and quartz as confining materials, for a wide range of operational water contents and film thicknesses. We found confinement-induced clustering of water perpendicular to the thin film. Hydrophobic carbon forms a water depletion zone near the film interface, whereas hydrophilic quartz results in a zone with excess water. There are, on average, oscillating water-rich and fluorocarbon-rich regions, in agreement with experimental results from neutron reflectometry. Water diffusivity shows increasing directional anisotropy of up to 30% with decreasing film thickness, depending on the hydrophilicity of the confining material. A percolation analysis revealed significant differences in water clustering and connectivity with the confining material. These findings indicate the fundamentally different nature of ionomer thin films, compared to membranes, and suggest explanations for increased ionic resistances observed in the catalyst layer.

Preparation and Characterization of Chitosan Thin Films on Mixed-Matrix Membranes for Complete Removal of Chromium

PubMed Central

Nayak, Vignesh; Jyothi, Mannekote Shivanna; Balakrishna, R Geetha; Padaki, Mahesh; Ismail, Ahmad Fauzi

2015-01-01

Herein we present a new approach for the complete removal of CrVI species, through reduction of CrVI to CrIII, followed by adsorption of CrIII. Reduction of chromium from water is an important challenge, as CrIV is one of the most toxic substances emitted from industrial processes. Chitosan (CS) thin films were developed on plain polysulfone (PSf) and PSf/TiO2 membrane substrates by a temperature-induced technique using polyvinyl alcohol as a binder. Structure property elucidation was carried out by X-ray diffraction, microscopy, spectroscopy, contact angle measurement, and water uptake studies. The increase in hydrophilicity followed the order: PSf < PSf/TiO2 < PSf/TiO2/CS membranes. Use of this thin-film composite membrane for chromium removal was investigated with regards to the effects of light and pH. The observations reveal 100 % reduction of CrVI to CrIII through electrons and protons donated from OH and NH2 groups of the CS layer; the reduced CrIII species are adsorbed onto the CS layer via complexation to give chromium-free water. PMID:26246989

Composite membranes from photochemical synthesis of ultrathin polymer films

NASA Astrophysics Data System (ADS)

Liu, Chao; Martin, Charles R.

1991-07-01

THERE has recently been a resurgence of interest in synthetic membranes and membrane-based processes1-12. This is motivated by a wide variety of technological applications, such as chemical separations1-7, bioreactors and sensors8,9, energy conversion10,11 and drug-delivery systems12. Many of these technologies require the ability to prepare extremely thin, defect-free synthetic (generally polymeric) films, which are supported on microporous supports to form composite membranes. Here we describe a method for producing composite membranes of this sort that incorporate high-quality polymer films less than 50-nm thick. The method involves interfacial photopolymerization of a thin polymer film on the surface of the microporous substrate. We have been able to use this technique to synthesize a variety of functionalized ultrathin films based on electroactive, photoactive and ion-exchange polymers. We demonstrate the method here with composite membranes that show exceptional gas-transport properties.

Surface modification of thin film composite membrane by nanoporous titanate nanoparticles for improving combined organic and inorganic antifouling properties.

PubMed

Emadzadeh, D; Ghanbari, M; Lau, W J; Rahbari-Sisakht, M; Rana, D; Matsuura, T; Kruczek, B; Ismail, A F

2017-06-01

In this study, nanoporous titanate (NT) nanoparticle synthesized by the solvothermal method was used to modify polyamide layer of thin film composite membranes with the aim of improving membrane resistances against organic and inorganic fouling. Thin film nanocomposite membranes (NMs) were synthesized by adding mNTs (modified nanoparticles) into polyamide selective layer followed by characterization using different analytical instruments. The results of XPS and XRD confirmed the presence of mNTs in the polyamide layer of NMs, while FESEM, AFM, zeta potential and contact angle measurement further supported the changes in physical and chemical properties of the membrane surface upon mNTs incorporation. Results of fouling showed that NM1 (the membrane incorporated with 0.01w/v% mNTs) always demonstrated lower degree of flux decline compared to the control membrane when membranes were tested with organic, inorganic and multicomponent synthesized water, brackish water or seawater. Besides showing greater antifouling resistance, the NM also displayed significantly higher water flux compared to the control M membrane. The findings of this work confirmed the positive impact of mNTs in improving the properties of NM with respect to fouling mitigation and flux improvement. Copyright © 2017. Published by Elsevier B.V.

New High-Temperature Membranes Developed for Proton Exchange Membrane Fuel Cells

NASA Technical Reports Server (NTRS)

Kinder, James D.

2004-01-01

Fuel cells are receiving a considerable amount of attention for potential use in a variety of areas, including the automotive industry, commercial power generation, and personal electronics. Research at the NASA Glenn Research Center has focused on the development of fuel cells for use in aerospace power systems for aircraft, unmanned air vehicles, and space transportation systems. These applications require fuel cells with higher power densities and better durability than what is required for nonaerospace uses. In addition, membrane cost is a concern for any fuel cell application. The most widely used membrane materials for proton exchange membrane (PEM) fuel cells are based on sulfonated perfluorinated polyethers, typically Nafion 117, Flemion, or Aciplex. However, these polymers are costly and do not function well at temperatures above 80 C. At higher temperatures, conventional membrane materials dry out and lose their ability to conduct protons, essential for the operation of the fuel cell. Increasing the operating temperature of PEM fuel cells from 80 to 120 C would significantly increase their power densities and enhance their durability by reducing the susceptibility of the electrode catalysts to carbon monoxide poisoning. Glenn's Polymers Branch has focused on developing new, low-cost membranes that can operate at these higher temperatures. A new series of organically modified siloxane (ORMOSIL) polymers were synthesized for use as membrane materials in a high-temperature PEM fuel cell. These polymers have an organic portion that can allow protons to transport through the polymer film and a cross-linked silica network that gives the polymers dimensional stability. These flexible xerogel polymer films are thermally stable, with decomposition onset as high as 380 C. Two types of proton-conducting ORMOSIL films have been produced: (1) NASA-A, which can coordinate many highly acid inorganic salts that facilitate proton conduction and (2) NASA-B, which has been

Polysulfone thin film composite nanofiltration membranes for removal of textile dyes wastewater

NASA Astrophysics Data System (ADS)

Sutedja, Andrew; Aileen Josephine, Claresta; Mangindaan, Dave

2017-12-01

This research was conducted to produce nanofiltration (NF) membranes, which have good performance in terms of removal of textile dye (Reactive Red 120, RR120) from simulated wastewater as one of several eco-engineering developments for sustainable water resource management. Phase inversion technique was utilized to fabricate the membrane with polysulfone (PSF) support, dissolved in N-methyl-2 pyrollidone (NMP) solvent, and diethylene glycol (DEG) as non-solvent additive. The fabricated membrane then modified with the additional of dopamine coating and further modified by interfacial polymerization (IP) to form a thin film composite (TFC)-NF membrane with PSF substrate. TFC was formed from interaction between amine monomer (2 %-weight of m-phenylenediamine (MPD) in deionized water) and acyl chloride (0.2 %-weight of trimesoyl chloride (TMC) in hexane). From this study, the fabricated PSF-TFC membrane could remove dyestuff from RR120 wastewater by 88% rejection at 120 psi. The result of this study is promising to be applied in Indonesia where researches on removal of dyes from textile wastewater by using membranes are still quite rare. Therefore, this paper may open new avenues for development of eco-engineering development in Indonesia.

Characterization of Polyethylene-Graft-Sulfonated Polyarylsulfone Proton Exchange Membranes for Direct Methanol Fuel Cell Applications.

PubMed

Kim, Hyung Kyu; Zhang, Gang; Nam, Changwoo; Chung, T C Mike

2015-12-04

This paper examines polymer film morphology and several important properties of polyethylene-graft-sulfonated polyarylene ether sulfone (PE-g-s-PAES) proton exchange membranes (PEMs) for direct methanol fuel cell applications. Due to the extreme surface energy differences between a semi-crystalline and hydrophobic PE backbone and several amorphous and hydrophilic s-PAES side chains, the PE-g-s-PAES membrane self-assembles into a unique morphology, with many proton conductive s-PAES channels embedded in the stable and tough PE matrix and a thin hydrophobic PE layer spontaneously formed on the membrane surfaces. In the bulk, these membranes show good mechanical properties (tensile strength >30 MPa, Young's modulus >1400 MPa) and low water swelling (λ < 15) even with high IEC >3 mmol/g in the s-PAES domains. On the surface, the thin hydrophobic and semi-crystalline PE layer shows some unusual barrier (protective) properties. In addition to exhibiting higher through-plane conductivity (up to 160 mS/cm) than in-plane conductivity, the PE surface layer minimizes methanol cross-over from anode to cathode with reduced fuel loss, and stops the HO• and HO₂• radicals, originally formed at the anode, entering into PEM matrix. Evidently, the thin PE surface layer provides a highly desirable protecting layer for PEMs to reduce fuel loss and increase chemical stability. Overall, the newly developed PE-g-s-PAES membranes offer a desirable set of PEM properties, including conductivity, selectivity, mechanical strength, stability, and cost-effectiveness for direct methanol fuel cell applications.

Characterization of Polyethylene-Graft-Sulfonated Polyarylsulfone Proton Exchange Membranes for Direct Methanol Fuel Cell Applications

PubMed Central

Kim, Hyung Kyu; Zhang, Gang; Nam, Changwoo; Chung, T.C. Mike

2015-01-01

This paper examines polymer film morphology and several important properties of polyethylene-graft-sulfonated polyarylene ether sulfone (PE-g-s-PAES) proton exchange membranes (PEMs) for direct methanol fuel cell applications. Due to the extreme surface energy differences between a semi-crystalline and hydrophobic PE backbone and several amorphous and hydrophilic s-PAES side chains, the PE-g-s-PAES membrane self-assembles into a unique morphology, with many proton conductive s-PAES channels embedded in the stable and tough PE matrix and a thin hydrophobic PE layer spontaneously formed on the membrane surfaces. In the bulk, these membranes show good mechanical properties (tensile strength >30 MPa, Young’s modulus >1400 MPa) and low water swelling (λ < 15) even with high IEC >3 mmol/g in the s-PAES domains. On the surface, the thin hydrophobic and semi-crystalline PE layer shows some unusual barrier (protective) properties. In addition to exhibiting higher through-plane conductivity (up to 160 mS/cm) than in-plane conductivity, the PE surface layer minimizes methanol cross-over from anode to cathode with reduced fuel loss, and stops the HO• and HO2• radicals, originally formed at the anode, entering into PEM matrix. Evidently, the thin PE surface layer provides a highly desirable protecting layer for PEMs to reduce fuel loss and increase chemical stability. Overall, the newly developed PE-g-s-PAES membranes offer a desirable set of PEM properties, including conductivity, selectivity, mechanical strength, stability, and cost-effectiveness for direct methanol fuel cell applications. PMID:26690232

Antifouling coatings via plasma polymerization and atom transfer radical polymerization on thin film composite membranes for reverse osmosis

NASA Astrophysics Data System (ADS)

Hirsch, Ulrike; Ruehl, Marco; Teuscher, Nico; Heilmann, Andreas

2018-04-01

A major drawback to otherwise highly efficient membrane-based desalination techniques like reverse osmosis (RO) is the susceptibility of the membranes to biofouling. In this work, a combination of plasma activation, plasma bromination and surface-initiated atom transfer radical polymerization (si-ATRP) of hydrophilic and zwitterionic monomers, namely hydroxyethyl methacrylate (HEMA), 2-methacryloyloxyethyl phosphorylcholine (MPC) and [2-(methacryloyloxy)ethyl]-dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA), was applied to generate non-specific, anti-adhesive coatings on thin film composite (TFC) membranes. The antifouling effect of the coatings was shown by short-time batch as well as long-time steady state cultivation experiments with the microorganism Pseudomonas fluorescens. It could be shown that plasma functionalization and polymerization is possible on delicate thin film composite membranes without restricting their filtration performance. All modified membranes showed an increased resistance towards the adhesion of Pseudomonas fluorescens. On average, the biofilm coverage was reduced by 51.4-12.6% (for HEMA, SBMA, and MPC), the highest reduction was monitored for MPC with a biofilm reduction by 85.4%. The hydrophilic coatings applied did not only suppress the adhesion of Pseudomonas fluorescens, but also significantly increase the permeate flux of the membranes relative to uncoated membranes. The stability of the coatings was however not ideal and will have to be improved for future commercial use.

Antifouling Thin-Film Composite Membranes by Controlled Architecture of Zwitterionic Polymer Brush Layer.

PubMed

Liu, Caihong; Lee, Jongho; Ma, Jun; Elimelech, Menachem

2017-02-21

In this study, we demonstrate a highly antifouling thin-film composite (TFC) membrane by grafting a zwitterionic polymer brush via atom-transfer radical-polymerization (ATRP), a controlled, environmentally benign chemical process. Initiator molecules for polymerization were immobilized on the membrane surface by bioinspired catechol chemistry, leading to the grafting of a dense zwitterionic polymer brush layer. Surface characterization revealed that the modified membrane exhibits reduced surface roughness, enhanced hydrophilicity, and lower surface charge. Chemical force microscopy demonstrated that the modified membrane displayed foulant-membrane interaction forces that were 1 order of magnitude smaller than those of the pristine TFC membrane. The excellent fouling resistance imparted by the zwitterionic brush layer was further demonstrated by significantly reduced adsorption of proteins and bacteria. In addition, forward osmosis fouling experiments with a feed solution containing a mixture of organic foulants (bovine-serum albumin, alginate, and natural organic matter) indicated that the modified membrane exhibited significantly lower water flux decline compared to the pristine TFC membrane. The controlled architecture of the zwitterionic polymer brush via ATRP has the potential for a facile antifouling modification of a wide range of water treatment membranes without compromising intrinsic transport properties.

Enhanced Performance of Thin Film Composite Forward Osmosis Membrane by Chemical Post-Treatment

NASA Astrophysics Data System (ADS)

Liu, Zheng; Chen, Jiangrong; Cao, Zhen; Wang, Jian; Guo, Chungang

2018-01-01

Forward osmosis is an attractive technique in water purification and desalination fields. Enhancement of the forward osmosis membrane performance is essential to the application of this technique. In this study, an optimized chemical post-treatment approach which was used to improve RO membrane performance was employed for enhancing water flux of thin film composite forward osmosis membrane. Home-made polysulfide-based forward osmosis membrane was prepared and nitric acid, sulfuric acid, ethanol, 2-propanol were employed as post-treatment solutions. After a short-term treatment, all the membrane samples manifested water flux enhancement compared with their untreated counterparts. Over 50% increase of water flux had been obtained by ethanol solution treatment. The swelling, changes of hydrophobicity and solvency in both active layer and substrate were verified as the major causes for the enhancement of the water flux. It is noted that the treatment time and solution concentration should be controlled to get both appropriate water flux and reverse salt flux. The results obtained in this study will be useful for further FO membrane development and application.

Phosphorus-doped glass proton exchange membranes for low temperature direct methanol fuel cells

NASA Astrophysics Data System (ADS)

Prakash, Shruti; Mustain, William E.; Park, SeongHo; Kohl, Paul A.

Phosphorus-doped silicon dioxide thin films were used as ion exchange membranes in low temperature proton exchange membrane fuel cells. Phosphorus-doped silicon dioxide glass (PSG) was deposited via plasma-enhanced chemical vapor deposition (PECVD). The plasma deposition of PSG films allows for low temperature fabrication that is compatible with current microelectronic industrial processing. SiH 4, PH 3 and N 2O were used as the reactant gases. The effect of plasma deposition parameters, substrate temperature, RF power, and chamber pressure, on the ionic conductivity of the PSG films is elucidated. PSG conductivities as high as 2.54 × 10 -4 S cm -1 were realized, which is 250 times higher than the conductivity of pure SiO 2 films (1 × 10 -6 S cm -1) under identical deposition conditions. The higher conductivity films were deposited at low temperature, moderate pressure, limited reactant gas flow rate, and high RF power.

Simple fabrication of 12 μm thin nanocomposite fuel cell membranes by direct electrospinning and printing

NASA Astrophysics Data System (ADS)

Breitwieser, Matthias; Klose, Carolin; Klingele, Matthias; Hartmann, Armin; Erben, Johannes; Cho, Hyeongrae; Kerres, Jochen; Zengerle, Roland; Thiele, Simon

2017-01-01

Direct membrane deposition (DMD) was recently introduced as a novel polymer electrolyte membrane fabrication method. Here, this approach is extended to fabricate 12 μm thin nanocomposite fuel cell membranes. Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofibers are directly electrospun onto gas diffusion electrodes. By inkjet-printing Nafion ionomer dispersion into the pore space of PVDF-HFP nanofiber mats, composite membranes of 12 μm thickness were fabricated. At 120 °C and 35% relative humidity, stoichiometric 1.5/2.5 H2/air flow and atmospheric pressure, the power density of the DMD fuel cell (0.19 W cm-2), was about 1.7 times higher than that of the reference fuel cell (0.11 W cm-2) with Nafion HP membrane and identical catalyst. A lower ionic resistance and, especially at 120 °C, a reduced charge transfer resistance is found compared to the Nafion HP membrane. A 100 h accelerated stress test revealed a voltage decay of below 0.8 mV h-1, which is in the range of literature values for significantly thicker reinforced membranes. Finally, this novel fabrication approach enables new degrees of freedom in the design of complex composite membranes. The presented combination of scalable deposition techniques has the potential to simplify and thus reduce cost of composite membrane fabrication at a larger scale.

Membrane transfer of crystalline silicon thin film solar cells

NASA Astrophysics Data System (ADS)

Vempati, Venkata Kesari Nandan

Silicon has been dominating the solar industry for many years and has been touted as the gold standard of the photovoltaic world. The factors for its dominance: government subsidies and ease of processing. Silicon holds close to 90% of the market share in the material being used for solar cell production. Of which 14% belongs to single-crystalline Silicon. Although 24% efficient bulk crystalline solar cells have been reported, the industry has been looking for thin film alternatives to reduce the cost of production. Moreover with the new avenues like flexible consumer electronics opening up, there is a need to introduce the flexibility into the solar cells. Thin film films make up for their inefficiency keeping their mechanical properties intact by incorporating Anti-reflective schemes such as surface texturing, textured back reflectors and low reflective surfaces. This thesis investigates the possibility of using thin film crystalline Silicon for fabricating solar cells and has demonstrated a low cost and energy efficient way for fabricating 2microm thick single crystalline Silicon solar cells with an efficiency of 0.8% and fill factor of 35%.

Fabrication of polyamide thin-film nanocomposite membranes with enhanced surface charge for nitrate ion removal from water resources.

PubMed

Ghaee, A; Zerafat, M M; Askari, P; Sabbaghi, S; Sadatnia, B

2017-03-01

Exclusion due to membrane surface charge is considered as one of the main separation mechanisms occurring in charged membranes, which can be varied through various approaches to affect membrane rejection performance. In this study, thin-film composite (TFC) polyamide (PA) membranes were fabricated via interfacial polymerization of m-phenylenediamine (m-PDA) and 2,4-diaminobenzene sulfonic acid with trimesoyl chloride (TMC) on a polysulfone sub-layer. The ability of the prepared membrane to remove nitrate ions from water resources has been investigated. In order to improve membrane permeability, zeolite-PA thin film nanocomposite (TFN) membranes were fabricated by incorporating natural zeolite nanoparticles obtained through ball milling of an Iranian natural zeolite powder in the interfacial polymerization process. The size, morphology and specific surface area of the as-obtained nanozeolite were characterized using particle size analysis, FE-SEM and BET. The functional groups, morphology and surface charge of the membrane were characterized using ATR-FTIR, SEM and zeta potential analyses. Also, field-emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS) were used to determine the distribution of nanozeolite in TFN membranes. The influence of zeolite addition to surface roughness was accessed by atomic force microscopy. The performance of TFC and TFN membranes was evaluated in terms of pure water flux and nitrate rejection. The results showed that in case of sulfonated diamine, nitrate ions rejection was enhanced from 63% to 85% which could be attributed to surface charge enhancement. TFN permeability was almost doubled by the addition of nanozeolite.

The Characterization of Thin Film Nickel Titanium Shape Memory Alloys

NASA Astrophysics Data System (ADS)

Harris Odum, Nicole Latrice

Shape memory alloys (SMA) are able to recover their original shape through the appropriate heat or stress exposure after enduring mechanical deformation at a low temperature. Numerous alloy systems have been discovered which produce this unique feature like TiNb, AgCd, NiAl, NiTi, and CuZnAl. Since their discovery, bulk scale SMAs have undergone extensive material property investigations and are employed in real world applications. However, its thin film counterparts have been modestly investigated and applied. Researchers have introduced numerous theoretical microelectromechanical system (MEMS) devices; yet, the research community's overall unfamiliarity with the thin film properties has delayed growth in this area. In addition, it has been difficult to outline efficient thin film processing techniques. In this dissertation, NiTi thin film processing and characterization techniques will be outlined and discussed. NiTi thin films---1 mum thick---were produced using sputter deposition techniques. Substrate bound thin films were deposited to analysis the surface using Scanning Electron Microscopy; the film composition was obtained using Energy Dispersive Spectroscopy; the phases were identified using X-ray diffraction; and the transformation temperatures acquired using resistivity testing. Microfabrication processing and sputter deposition were employed to develop tensile membranes for membrane deflection experimentation to gain insight on the mechanical properties of the thin films. The incorporation of these findings will aid in the movement of SMA microactuation devices from theory to fruition and greatly benefit industries such as medicinal and aeronautical.

Desertification of the peritoneum by thin-film evaporation during laparoscopy.

PubMed

Ott, Douglas E

2003-01-01

To assess the effects of gas flow during insufflation on peritoneal fluid and peritoneal tissue regarding transient thermal behavior and thin-film evaporation. The effects of laparoscopic gas on peritoneal cell desiccation and peritoneal fluid thin-film evaporation were analyzed. Measurment of tissue and peritoneal fluid and analysis of gas flow dynamics during laparoscopy. High-velocity gas interface conditions during laparoscopic gas insufflation result in peritoneal surface temperature and decreases up to 20 degrees C/second due to rapid thin-film evaporation of the peritoneal fluid. Evaporation of the thin film of peritoneal fluid extends quickly to the peritoneal cell membrane, causing peritoneal cell desiccation, internal cytoplasmic stress, and disruption of the cell membrane, resulting in loss of peritoneal surface continuity and integrity. Changing the gas conditions to 35 degrees C and 95% humidity maintains normal peritoneal fluid thin-film characteristics, cellular integrity, and prevents evaporative losses. Cold, dry gas and the characteristics of the laparoscopic gas delivery apparatus cause local peritoneal damaging alterations by high-velocity gas flow with extremely dry gas, creating extreme arid surface conditions, rapid evaporative and hydrological changes, tissue desiccation, and peritoneal fluid alterations that contribute to the process of desertification and thin-film evaporation. Peritoneal desertification is preventable by preconditioning the gas to 35 degrees C and 95% humidity.

Dynamics of a 4x6-Meter Thin Film Elliptical Inflated Membrane for Space Applications

NASA Technical Reports Server (NTRS)

Casiano, Matthew J.; Hamidzadeh, Hamid R.; Tinker, Michael L.; McConnaughey, Paul R. (Technical Monitor)

2002-01-01

Dynamic characterization of a thin film inflatable elliptical structure is described in detail. A two-step finite element modeling approach in MSC/NASTRAN is utilized, consisting of (1) a nonlinear static pressurization procedure used to obtain the updated stiffness matrix, and (2) a modal "restart" eigen solution that uses the modified stiffness matrix. Unique problems encountered in modeling of this large Hexameter lightweight inflatable arc identified, including considerable difficulty in obtaining convergence in the nonlinear finite element pressurization solution. It was found that the extremely thin polyimide film material (.001 in or 1 mil) presents tremendous problems in obtaining a converged solution when internal pressure loading is applied. Approaches utilized to overcome these difficulties are described. Comparison of finite element predictions for frequency and mode shapes of the inflated structure with closed-form solutions for a flat pre-tensioned membrane indicate reasonable agreement.

Hybrid deposition of thin film solid oxide fuel cells and electrolyzers

DOEpatents

Jankowski, A.F.; Makowiecki, D.M.; Rambach, G.D.; Randich, E.

1998-05-19

The use of vapor deposition techniques enables synthesis of the basic components of a solid oxide fuel cell (SOFC); namely, the electrolyte layer, the two electrodes, and the electrolyte-electrode interfaces. Such vapor deposition techniques provide solutions to each of the three critical steps of material synthesis to produce a thin film solid oxide fuel cell (TFSOFC). The electrolyte is formed by reactive deposition of essentially any ion conducting oxide, such as defect free, yttria stabilized zirconia (YSZ) by planar magnetron sputtering. The electrodes are formed from ceramic powders sputter coated with an appropriate metal and sintered to a porous compact. The electrolyte-electrode interface is formed by chemical vapor deposition of zirconia compounds onto the porous electrodes to provide a dense, smooth surface on which to continue the growth of the defect-free electrolyte, whereby a single fuel cell or multiple cells may be fabricated. 8 figs.

Hybrid deposition of thin film solid oxide fuel cells and electrolyzers

DOEpatents

Jankowski, Alan F.; Makowiecki, Daniel M.; Rambach, Glenn D.; Randich, Erik

1999-01-01

The use of vapor deposition techniques enables synthesis of the basic components of a solid oxide fuel cell (SOFC); namely, the electrolyte layer, the two electrodes, and the electrolyte-electrode interfaces. Such vapor deposition techniques provide solutions to each of the three critical steps of material synthesis to produce a thin film solid oxide fuel cell (TFSOFC). The electrolyte is formed by reactive deposition of essentially any ion conducting oxide, such as defect free, yttria stabilized zirconia (YSZ) by planar magnetron sputtering. The electrodes are formed from ceramic powders sputter coated with an appropriate metal and sintered to a porous compact. The electrolyte-electrode interface is formed by chemical vapor deposition of zirconia compounds onto the porous electrodes to provide a dense, smooth surface on which to continue the growth of the defect-free electrolyte, whereby a single fuel cell or multiple cells may be fabricated.

Hybrid deposition of thin film solid oxide fuel cells and electrolyzers

DOEpatents

Jankowski, Alan F.; Makowiecki, Daniel M.; Rambach, Glenn D.; Randich, Erik

1998-01-01

The use of vapor deposition techniques enables synthesis of the basic components of a solid oxide fuel cell (SOFC); namely, the electrolyte layer, the two electrodes, and the electrolyte-electrode interfaces. Such vapor deposition techniques provide solutions to each of the three critical steps of material synthesis to produce a thin film solid oxide fuel cell (TFSOFC). The electrolyte is formed by reactive deposition of essentially any ion conducting oxide, such as defect free, yttria stabilized zirconia (YSZ) by planar magnetron sputtering. The electrodes are formed from ceramic powders sputter coated with an appropriate metal and sintered to a porous compact. The electrolyte-electrode interface is formed by chemical vapor deposition of zirconia compounds onto the porous electrodes to provide a dense, smooth surface on which to continue the growth of the defect-free electrolyte, whereby a single fuel cell or multiple cells may be fabricated.

Polyurethane Ionophore-Based Thin Layer Membranes for Voltammetric Ion Activity Sensing.

PubMed

Cuartero, Maria; Crespo, Gaston A; Bakker, Eric

2016-06-07

We report on a plasticized polyurethane ionophore-based thin film material (of hundreds of nanometer thickness) for simultaneous voltammetric multianalyte ion activity detection triggered by the oxidation/reduction of an underlying poly(3-octylthiophene) film. This material provides excellent mechanical, physical, and chemical robustness compared to other polymers. Polyurethane films did not exhibit leaching of lipophilic additives after rinsing with a direct water jet and exhibited resistance to detachment from the underlying electrode surface, resulting in a voltammetric current response with less than <1.5% RSD variation (n = 50). In contrast, plasticized poly(vinyl chloride), polystyrene, and poly(acrylate) ionophore-based membranes of the same thickness and composition exhibited a significant deterioration of the signal after identical treatment. While previously reported works emphasized fundamental advancement of multi-ion detection with multi-ionophore-based thin films, polyurethane thin membranes allow one to achieve real world measurements without sacrificing analytical performance. Indeed, polyurethane membranes are demonstrated to be useful for the simultaneous determination of potassium and lithium in undiluted human serum and blood with attractive precision.

Comparison of biofouling mechanisms between cellulose triacetate (CTA) and thin-film composite (TFC) polyamide forward osmosis membranes in osmotic membrane bioreactors.

PubMed

Wang, Xinhua; Zhao, Yanxiao; Yuan, Bo; Wang, Zhiwei; Li, Xiufen; Ren, Yueping

2016-02-01

There are two types of popular forward osmosis (FO) membrane materials applied for researches on FO process, cellulose triacetate (CTA) and thin film composite (TFC) polyamide. However, performance and fouling mechanisms of commercial TFC FO membrane in osmotic membrane bioreactors (OMBRs) are still unknown. In current study, its biofouling behaviors in OMBRs were investigated and further compared to the CTA FO membrane. The results indicated that β-D-glucopyranose polysaccharides and microorganisms accounted for approximately 77% of total biovolume on the CTA FO membrane while β-D-glucopyranose polysaccharides (biovolume ratio of 81.1%) were the only dominant biofoulants on the TFC FO membrane. The analyses on the biofouling structure implied that a tighter biofouling layer with a larger biovolume was formed on the CTA FO membrane. The differences in biofouling behaviors including biofoulants composition and biofouling structure between CTA and TFC FO membranes were attributed to different membrane surface properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

Thin graphite bipolar plate with associated gaskets and carbon cloth flow-field for use in an ionomer membrane fuel cell

DOEpatents

Marchetti, George A.

2003-01-03

The present invention comprises a thin graphite plate with associated gaskets and pieces of carbon cloth that comprise a flow-field. The plate, gaskets and flow-field comprise a "plate and gasket assembly" for use in an ionomer membrane fuel cell, fuel cell stack or battery.

Solid oxide MEMS-based fuel cells

DOEpatents

Jankowksi, Alan F.; Morse, Jeffrey D.

2007-03-13

A micro-electro-mechanical systems (MEMS) based thin-film fuel cells for electrical power applications. The MEMS-based fuel cell may be of a solid oxide type (SOFC), a solid polymer type (SPFC), or a proton exchange membrane type (PEMFC), and each fuel cell basically consists of an anode and a cathode separated by an electrolyte layer. The electrolyte layer can consist of either a solid oxide or solid polymer material, or proton exchange membrane electrolyte materials may be used. Additionally catalyst layers can also separate the electrodes (cathode and anode) from the electrolyte. Gas manifolds are utilized to transport the fuel and oxidant to each cell and provide a path for exhaust gases. The electrical current generated from each cell is drawn away with an interconnect and support structure integrated with the gas manifold. The fuel cells utilize integrated resistive heaters for efficient heating of the materials. By combining MEMS technology with thin-film deposition technology, thin-film fuel cells having microflow channels and full-integrated circuitry can be produced that will lower the operating temperature an will yield an order of magnitude greater power density than the currently known fuel cells.

Solid polymer MEMS-based fuel cells

DOEpatents

Jankowski, Alan F [Livermore, CA; Morse, Jeffrey D [Pleasant Hill, CA

2008-04-22

A micro-electro-mechanical systems (MEMS) based thin-film fuel cells for electrical power applications. The MEMS-based fuel cell may be of a solid oxide type (SOFC), a solid polymer type (SPFC), or a proton exchange membrane type (PEMFC), and each fuel cell basically consists of an anode and a cathode separated by an electrolyte layer. The electrolyte layer can consist of either a solid oxide or solid polymer material, or proton exchange membrane electrolyte materials may be used. Additionally catalyst layers can also separate the electrodes (cathode and anode) from the electrolyte. Gas manifolds are utilized to transport the fuel and oxidant to each cell and provide a path for exhaust gases. The electrical current generated from each cell is drawn away with an interconnect and support structure integrated with the gas manifold. The fuel cells utilize integrated resistive heaters for efficient heating of the materials. By combining MEMS technology with thin-film deposition technology, thin-film fuel cells having microflow channels and full-integrated circuitry can be produced that will lower the operating temperature an will yield an order of magnitude greater power density than the currently known fuel cells.

Toward Effective Shell Modeling of Wrinkled Thin-Film Membranes Exhibiting Stress Concentrations

NASA Technical Reports Server (NTRS)

Tessler, Alexander; Sleight, David W.

2004-01-01

Geometrically nonlinear shell finite element analysis has recently been applied to solar-sail membrane problems in order to model the out-of-plane deformations due to structural wrinkling. Whereas certain problems lend themselves to achieving converged nonlinear solutions that compare favorably with experimental observations, solutions to tensioned membranes exhibiting high stress concentrations have been difficult to obtain even with the best nonlinear finite element codes and advanced shell element technology. In this paper, two numerical studies are presented that pave the way to improving the modeling of this class of nonlinear problems. The studies address the issues of mesh refinement and stress-concentration alleviation, and the effects of these modeling strategies on the ability to attain converged nonlinear deformations due to wrinkling. The numerical studies demonstrate that excessive mesh refinement in the regions of stress concentration may be disadvantageous to achieving wrinkled equilibrium states, causing the nonlinear solution to lock in the membrane response mode, while totally discarding the very low-energy bending response that is necessary to cause wrinkling deformation patterns. An element-level, strain-energy density criterion is suggested for facilitating automated, adaptive mesh refinements specifically aimed at the modeling of thin-film membranes undergoing wrinkling deformations.

Method for making surfactant-templated, high-porosity thin films

DOEpatents

Brinker, C. Jeffrey; Lu, Yunfeng; Fan, Hongyou

2001-01-01

An evaporation-induced self-assembly method to prepare a surfactant-templated thin film by mixing a silica sol, a surfactant, and a hydrophobic polymer and then evaporating a portion of the solvent during coating onto a substrate and then heating to form a liquid-phase, thin film material with a porosity greater than approximately 50 percent. The high porosity thin films can have dielectric constants less than 2 to be suitable for applications requiring low-dielectric constants. An interstitial compound can be added to the mixture, with the interstitial compound either covalently bonded to the pores or physically entrapped within the porous structure. The selection of the interstitial compound provides a means for developing thin films for applications including membranes, sensors, low dielectric constant films, photonic materials and optical hosts.

Effects of Aloe Vera and Chitosan Nanoparticle Thin-Film Membranes on Wound Healing in Full Thickness Infected Wounds with Methicillin Resistant Staphylococcus Aureus.

PubMed

Ranjbar, Reza; Yousefi, Alireza

2018-01-01

To assess effect of Aleo vera with chitosan nanoparticle biofilm on wound healing in full thickness infected wounds with antibiotic resistant gram positive bacteria. Thirty rats were randomized into five groups of six rats each. Group I: Animals with uninfected wounds treated with 0.9% saline solution. Group II: Animals with infected wounds treated with saline. Group III: Animals with infected wounds were dressed with chitosan nanoparticle thin-film membranes. Group IV: Animals with infected wounds were treated topically with Aloe vera and Group V: Animals with infected wounds were treated topically with Aloe vera and dressed with chitosan nanoparticle thin-film membranes. Wound size was measured on 6, 9, 12, 15, 18 and 21days after surgery. Microbiology, reduction in wound area and hydroxyproline contents indicated that there was significant difference ( p <0.05) between group V and other groups. Quantitative histological studies and mean rank of the qualitative studies demonstrated that there was significant difference ( p <0.05) between group V and other groups. The Aloe vera with chitosan nanoparticle thin-film membranes had a reproducible wound healing potential and hereby justified its use in practice.

Effects of Aloe Vera and Chitosan Nanoparticle Thin-Film Membranes on Wound Healing in Full Thickness Infected Wounds with Methicillin Resistant Staphylococcus Aureus

PubMed Central

Ranjbar, Reza; Yousefi, Alireza

2018-01-01

Objective : To assess effect of Aleo vera with chitosan nanoparticle biofilm on wound healing in full thickness infected wounds with antibiotic resistant gram positive bacteria. Method: Thirty rats were randomized into five groups of six rats each. Group I: Animals with uninfected wounds treated with 0.9% saline solution. Group II: Animals with infected wounds treated with saline. Group III: Animals with infected wounds were dressed with chitosan nanoparticle thin-film membranes. Group IV: Animals with infected wounds were treated topically with Aloe vera and Group V: Animals with infected wounds were treated topically with Aloe vera and dressed with chitosan nanoparticle thin-film membranes. Wound size was measured on 6, 9, 12, 15, 18 and 21days after surgery. Results: Microbiology, reduction in wound area and hydroxyproline contents indicated that there was significant difference (p<0.05) between group V and other groups. Quantitative histological studies and mean rank of the qualitative studies demonstrated that there was significant difference (p<0.05) between group V and other groups. Conclusion: The Aloe vera with chitosan nanoparticle thin-film membranes had a reproducible wound healing potential and hereby justified its use in practice. PMID:29379804

Extending the 3ω method: thermal conductivity characterization of thin films.

PubMed

Bodenschatz, Nico; Liemert, André; Schnurr, Sebastian; Wiedwald, Ulf; Ziemann, Paul

2013-08-01

A lock-in technique for measurement of thermal conductivity and volumetric heat capacity of thin films is presented. The technique is based on the 3ω approach using electrical generation and detection of oscillatory heat along a thin metal strip. Thin films are deposited onto the backside of commercial silicon nitride membranes, forming a bilayer geometry with distinct thermal parameters. Stepwise comparison to an adapted heat diffusion model delivers these parameters for both layers. Highest sensitivity is found for metallic thin films.

Pentachlorophenol removal from water using surfactant-enhanced filtration through low-pressure thin film composite membranes.

PubMed

Kumar, Yogesh; Popat, K M; Brahmbhatt, H; Ganguly, B; Bhattacharya, A

2008-06-15

Removal of pentachlorophenol from water is investigated using the surfactant-enhanced cross-flow membrane filtration technique in which anionic surfactant; sodium dodecyl sulfate (SDS) is the carrier of pentachlorophenol. The separation performances are studied by varying SDS concentrations (membrane. The performance is co-related with the separation of markers (glucose and sucrose) as well as salt rejection of the membrane. SDS, in feed induces the charge due to its polar head and thus separation improves due to electrostatic repulsion of membrane and associated molecule. The higher hydrophobicity of pentachlorophenol is also the factor. The study reveals that there is better improvement in pentachlorophenol separation upon addition of SDS for the thin film composite membrane which is of more permeability.

On the Preparation and Testing of Fuel Cell Catalysts Using the Thin Film Rotating Disk Electrode Method.

PubMed

Inaba, Masanori; Quinson, Jonathan; Bucher, Jan Rudolf; Arenz, Matthias

2018-03-16

We present a step-by-step tutorial to prepare proton exchange membrane fuel cell (PEMFC) catalysts, consisting of Pt nanoparticles (NPs) supported on a high surface area carbon, and to test their performance in thin film rotating disk electrode (TF-RDE) measurements. The TF-RDE methodology is widely used for catalyst screening; nevertheless, the measured performance sometimes considerably differs among research groups. These uncertainties impede the advancement of new catalyst materials and, consequently, several authors discussed possible best practice methods and the importance of benchmarking. The visual tutorial highlights possible pitfalls in the TF-RDE testing of Pt/C catalysts. A synthesis and testing protocol to assess standard Pt/C catalysts is introduced that can be used together with polycrystalline Pt disks as benchmark catalysts. In particular, this study highlights how the properties of the catalyst film on the glassy carbon (GC) electrode influence the measured performance in TF-RDE testing. To obtain thin, homogeneous catalyst films, not only the catalyst preparation, but also the ink deposition and drying procedures are essential. It is demonstrated that an adjustment of the ink's pH might be necessary, and how simple control measurements can be used to check film quality. Once reproducible TF-RDE measurements are obtained, determining the Pt loading on the catalyst support (expressed as Pt wt%) and the electrochemical surface area is necessary to normalize the determined reaction rates to either surface area or Pt mass. For the surface area determination, so-called CO stripping, or the determination of the hydrogen underpotential deposition (Hupd) charge, are standard. For the determination of the Pt loading, a straightforward and cheap procedure using digestion in aqua regia with subsequent conversion of Pt(IV) to Pt(II) and UV-vis measurements is introduced.

On the Preparation and Testing of Fuel Cell Catalysts Using the Thin Film Rotating Disk Electrode Method

PubMed Central

Inaba, Masanori; Quinson, Jonathan; Bucher, Jan Rudolf; Arenz, Matthias

2018-01-01

We present a step-by-step tutorial to prepare proton exchange membrane fuel cell (PEMFC) catalysts, consisting of Pt nanoparticles (NPs) supported on a high surface area carbon, and to test their performance in thin film rotating disk electrode (TF-RDE) measurements. The TF-RDE methodology is widely used for catalyst screening; nevertheless, the measured performance sometimes considerably differs among research groups. These uncertainties impede the advancement of new catalyst materials and, consequently, several authors discussed possible best practice methods and the importance of benchmarking. The visual tutorial highlights possible pitfalls in the TF-RDE testing of Pt/C catalysts. A synthesis and testing protocol to assess standard Pt/C catalysts is introduced that can be used together with polycrystalline Pt disks as benchmark catalysts. In particular, this study highlights how the properties of the catalyst film on the glassy carbon (GC) electrode influence the measured performance in TF-RDE testing. To obtain thin, homogeneous catalyst films, not only the catalyst preparation, but also the ink deposition and drying procedures are essential. It is demonstrated that an adjustment of the ink's pH might be necessary, and how simple control measurements can be used to check film quality. Once reproducible TF-RDE measurements are obtained, determining the Pt loading on the catalyst support (expressed as Pt wt%) and the electrochemical surface area is necessary to normalize the determined reaction rates to either surface area or Pt mass. For the surface area determination, so-called CO stripping, or the determination of the hydrogen underpotential deposition (Hupd) charge, are standard. For the determination of the Pt loading, a straightforward and cheap procedure using digestion in aqua regia with subsequent conversion of Pt(IV) to Pt(II) and UV-vis measurements is introduced. PMID:29608166

Simulated Thin-Film Growth and Imaging

NASA Astrophysics Data System (ADS)

Schillaci, Michael

2001-06-01

Thin-films have become the cornerstone of the electronics, telecommunications, and broadband markets. A list of potential products includes: computer boards and chips, satellites, cell phones, fuel cells, superconductors, flat panel displays, optical waveguides, building and automotive windows, food and beverage plastic containers, metal foils, pipe plating, vision ware, manufacturing equipment and turbine engines. For all of these reasons a basic understanding of the physical processes involved in both growing and imaging thin-films can provide a wonderful research project for advanced undergraduate and first-year graduate students. After producing rudimentary two- and three-dimensional thin-film models incorporating ballsitic deposition and nearest neighbor Coulomb-type interactions, the QM tunneling equations are used to produce simulated scanning tunneling microscope (SSTM) images of the films. A discussion of computational platforms, languages, and software packages that may be used to accomplish similar results is also given.

Thin film surface modifications of thin/tunable liquid/gas diffusion layers for high-efficiency proton exchange membrane electrolyzer cells

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

Kang, Zhenye; Mo, Jingke; Yang, Gaoqiang

We present that a proton exchange membrane electrolyzer cell (PEMEC) is one of the most promising devices for high-efficiency and low-cost energy storage and ultrahigh purity hydrogen production. As one of the critical components in PEMECs, the titanium thin/tunable LGDL (TT-LGDL) with its advantages of small thickness, planar surface, straight-through pores, and well-controlled pore morphologies, achieved superior multifunctional performance for hydrogen and oxygen production from water splitting even at low temperature. Different thin film surface treatments on the novel TT-LGDLs for enhancing the interfacial contacts and PEMEC performance were investigated both in-situ and ex-situ for the first time. Surface modifiedmore » TT-LGDLs with about 180 nm thick Au thin film yielded performance improvement (voltage reduction), from 1.6849 V with untreated TT-LGDLs to only 1.6328 V with treated TT-LGDLs at 2.0 A/cm 2 and 80°C. Furthermore, the hydrogen/oxygen production rate was increased by about 28.2% at 1.60 V and 80°C. The durability test demonstrated that the surface treated TT-LGDL has good stability as well. Finally, the gold electroplating surface treatment is a promising method for the PEMEC performance enhancement and titanium material protection even in harsh environment.« less

Thin film surface modifications of thin/tunable liquid/gas diffusion layers for high-efficiency proton exchange membrane electrolyzer cells

DOE PAGES

Kang, Zhenye; Mo, Jingke; Yang, Gaoqiang; ...

2017-09-14

We present that a proton exchange membrane electrolyzer cell (PEMEC) is one of the most promising devices for high-efficiency and low-cost energy storage and ultrahigh purity hydrogen production. As one of the critical components in PEMECs, the titanium thin/tunable LGDL (TT-LGDL) with its advantages of small thickness, planar surface, straight-through pores, and well-controlled pore morphologies, achieved superior multifunctional performance for hydrogen and oxygen production from water splitting even at low temperature. Different thin film surface treatments on the novel TT-LGDLs for enhancing the interfacial contacts and PEMEC performance were investigated both in-situ and ex-situ for the first time. Surface modifiedmore » TT-LGDLs with about 180 nm thick Au thin film yielded performance improvement (voltage reduction), from 1.6849 V with untreated TT-LGDLs to only 1.6328 V with treated TT-LGDLs at 2.0 A/cm 2 and 80°C. Furthermore, the hydrogen/oxygen production rate was increased by about 28.2% at 1.60 V and 80°C. The durability test demonstrated that the surface treated TT-LGDL has good stability as well. Finally, the gold electroplating surface treatment is a promising method for the PEMEC performance enhancement and titanium material protection even in harsh environment.« less

Plasma surface modification of nanofiltration (NF) thin-film composite (TFC) membranes to improve anti organic fouling

NASA Astrophysics Data System (ADS)

Kim, Eun-Sik; Yu, Qingsong; Deng, Baolin

2011-09-01

Commercial nanofiltration (NF) thin-film composite (TFC) membranes were treated by low-pressure NH3 plasma, and the effects of the plasma treatment were investigated in terms of the membrane hydrophilicity, pure water flux, salt rejection, protein adsorption, and humic acid fouling. Experimental results indicated that the membrane surface hydrophilicity was increased by the plasma treatment, and changes in the hydrophilicity as well as membrane performance including permeate flux and fouling varied with the original membrane characteristics (e.g., roughness and hydrophilicity). Water flux of plasma treated membranes was the highest with 10 min and 90 W of plasma treatment, and salt rejection was mainly affected by the intensity of the plasma power. Results of bovine serum albumin (BSA) adsorption demonstrated that the protein adsorption decreased with increasing plasma treatment time. The plasma treatment that resulted in more negatively charged surfaces could also better prevent Aldrich humic acid (AHA) attachment on the membrane surface.

High performance novel gadolinium doped ceria/yttria stabilized zirconia/nickel layered and hybrid thin film anodes for application in solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Garcia-Garcia, F. J.; Beltrán, A. M.; Yubero, F.; González-Elipe, A. R.; Lambert, R. M.

2017-09-01

Magnetron sputtering under oblique angle deposition was used to produce Ni-containing ultra thin film anodes comprising alternating layers of gadolinium doped ceria (GDC) and yttria stabilized zirconia (YSZ) of either 200 nm or 1000 nm thickness. The evolution of film structure from initial deposition, through calcination and final reduction was examined by XRD, SEM, TEM and TOF-SIMS. After subsequent fuel cell usage, the porous columnar architecture of the two-component layered thin film anodes was maintained and their resistance to delamination from the underlying YSZ electrolyte was superior to that of corresponding single component Ni-YSZ and Ni-GDC thin films. Moreover, the fuel cell performance of the 200 nm layered anodes compared favorably with conventional commercially available thick anodes. The observed dependence of fuel cell performance on individual layer thicknesses prompted study of equivalent but more easily fabricated hybrid anodes consisting of simultaneously deposited Ni-GDC and Ni-YSZ, which procedure resulted in exceptionally intimate mixing and interaction of the components. The hybrids exhibited very unusual and favorable Isbnd V characteristics, along with exceptionally high power densities at high currents. Their discovery is the principal contribution of the present work.

Electrochemical Deposition of Lanthanum Telluride Thin Films and Nanowires

NASA Astrophysics Data System (ADS)

Chi, Su (Ike); Farias, Stephen; Cammarata, Robert

2013-03-01

Tellurium alloys are characterized by their high performance thermoelectric properties and recent research has shown nanostructured tellurium alloys display even greater performance than bulk equivalents. Increased thermoelectric efficiency of nanostructured materials have led to significant interests in developing thin film and nanowire structures. Here, we report on the first successful electrodeposition of lanthanum telluride thin films and nanowires. The electrodeposition of lanthanum telluride thin films is performed in ionic liquids at room temperature. The synthesis of nanowires involves electrodepositing lanthanum telluride arrays into anodic aluminum oxide (AAO) nanoporous membranes. These novel procedures can serve as an alternative means of simple, inexpensive and laboratory-environment friendly methods to synthesize nanostructured thermoelectric materials. The thermoelectric properties of thin films and nanowires will be presented to compare to current state-of-the-art thermoelectric materials. The morphologies and chemical compositions of the deposited films and nanowires are characterized using SEM and EDAX analysis.

Thin-film Nanofibrous Composite Membranes Containing Cellulose or Chitin Barrier Layers Fabricated by Ionic Liquids

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

H Ma; B Hsiao; B Chu

The barrier layer of high-flux ultrafiltration (UF) thin-film nanofibrous composite (TFNC) membranes for purification of wastewater (e.g., bilge water) have been prepared by using cellulose, chitin, and a cellulose-chitin blend, regenerated from an ionic liquid. The structures and properties of regenerated cellulose, chitin, and a cellulose-chitin blend were analyzed with thermogravimetric analysis (TGA) and wide-angle X-ray diffraction (WAXD). The surface morphology, pore size and pore size distribution of TFNC membranes were determined by SEM images and molecular weight cut-off (MWCO) methods. An oil/water emulsion, a model of bilge water, was used as the feed solution, and the permeation flux andmore » rejection ratio of the membranes were investigated. TFNC membranes based on the cellulose-chitin blend exhibited 10 times higher permeation flux when compared with a commercial UF membrane (PAN10, Sepro) with a similar rejection ratio after filtration over a time period of up to 100 h, implying the practical feasibility of such membranes for UF applications.« less

Reduction of methanol crossover by thin cracked metal barriers at the interface between membrane and electrode in direct methanol fuel cells

NASA Astrophysics Data System (ADS)

Kim, Sungjun; Jang, Segeun; Kim, Sang Moon; Ahn, Chi-Yeong; Hwang, Wonchan; Cho, Yong-Hun; Sung, Yung-Eun; Choi, Mansoo

2017-09-01

This work reports the successful reduction in methanol crossover by creating a thin cracked metal barrier at the interface between a Nafion® membrane and an electrode in direct methanol fuel cells (DMFCs). The cracks are generated by simple mechanical stretching of a metal deposited Nafion® membrane as a result of the elastic mismatch between the two attached surfaces. The cracked metal barriers with varying strains (∼0.5 and ∼1.0) are investigated and successfully incorporated into the DMFC. Remarkably, the membrane electrode assembly with the thin metal crack exhibits comparable ohmic resistance as well as reduction of methanol crossover, which enhanced the device performance.

Inorganic Thin-film Sensor Membranes with PLD-prepared Chalcogenide Glasses: Challenges and Implementation

PubMed Central

Kloock, Joachim P.; Mourzina, Youlia G.; Ermolenko, Yuri; Doll, Theodor; Schubert, Jürgen; Schöning, Michael J.

2004-01-01

Chalcogenide glasses offer an excellent “challenge” for their use and implementation in sensor arrays due to their good sensor-specific advantages in comparison to their crystalline counterparts. This paper will give an introduction on the preparation of chalcogenide glasses in the thin-film state. First, single microsensors have been prepared with the methods of semiconductor technology. In a next step, three microsensors are implemented onto one single silicon substrate to an “one chip” sensor array. Different ionselective chalcogenide glass membranes (PbSAgIAs2S3, CdSAgIAs2S3, CuAgAsSeTe and TlAgAsIS) were prepared by means of the pulsed laser deposition (PLD) process. The different sensor membranes and structures have been physically characterized by means of Rutherford backscattering spectrometry, scanning electron microscopy and video microscopy. The electrochemical behavior has been investigated by potentiometric measurements.

Impacts of zeolite nanoparticles on substrate properties of thin film nanocomposite membranes for engineered osmosis

NASA Astrophysics Data System (ADS)

Salehi, Tahereh Mombeini; Peyravi, Majid; Jahanshahi, Mohsen; Lau, Woei-Jye; Rad, Ali Shokuhi

2018-04-01

In this work, microporous substrates modified by zeolite nanoparticles were prepared and used for composite membrane making with the aim of reducing internal concentration polarization (ICP) effect of membranes during engineered osmosis applications. Nanocomposite substrates were fabricated via phase inversion technique by embedding nanostructured zeolite (clinoptilolite) in the range of 0-0.6 wt% into matrix of polyethersulfone (PES) substrate. Of all the substrates prepared, the PES0.4 substrate (with 0.4 wt% zeolite) exhibited unique characteristics, i.e., increased surface porosity, lower structural parameter ( S) (from 0.78 to 0.48 mm), and enhanced water flux. The thin film nanocomposite (TFN) membrane made of this optimized substrate was also reported to exhibit higher water flux compared to the control composite membrane during forward osmosis (FO) and pressure-retarded osmosis (PRO) test, without compromising reverse solute flux. The water flux of such TFN membrane was 43% higher than the control TFC membrane (1.93 L/m2 h bar) with salt rejection recorded at 94.7%. An increment in water flux is ascribed to the reduction in structural parameter, leading to reduced ICP effect.

Process for making dense thin films

DOEpatents

Jacobson, Craig P.; Visco, Steven J.; DeJonghe, Lutgard C.

2005-07-26

Provided are low-cost, mechanically strong, highly electronically conductive porous substrates and associated structures for solid-state electrochemical devices, techniques for forming these structures, and devices incorporating the structures. The invention provides solid state electrochemical device substrates of novel composition and techniques for forming thin electrode/membrane/electrolyte coatings on the novel or more conventional substrates. In particular, in one embodiment the invention provides techniques for firing of device substrate to form densified electrolyte/membrane films 5 to 20 microns thick. In another embodiment, densified electrolyte/membrane films 5 to 20 microns thick may be formed on a pre-sintered substrate by a constrained sintering process. In some cases, the substrate may be a porous metal, alloy, or non-nickel cermet incorporating one or more of the transition metals Cr, Fe, Cu and Ag, or alloys thereof.

Finite Element Modeling of the Deformation of a Thin Magnetoelastic Film Compared to a Membrane Model

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

Barham, M; White, D; Steigmann, D

2009-04-08

Recently a new class of biocompatible elastic polymers loaded with small ferrous particles (magnetoelastomer) was developed at Lawrence Livermore National Laboratory. This new material was formed as a thin film using spin casting. The deformation of this material using a magnetic field has many possible applications to microfluidics. Two methods will be used to calculate the deformation of a circular magneto-elastomeric film subjected to a magnetic field. The first method is an arbitrary Lagrangian-Eulerian (ALE) finite element method (FEM) and the second is based on nonlinear continuum electromagnetism and continuum elasticity in the membrane limit. The comparison of these twomore » methods is used to test/validate the finite element method.« less

Multi-layer thin-film electrolytes for metal supported solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Haydn, Markus; Ortner, Kai; Franco, Thomas; Uhlenbruck, Sven; Menzler, Norbert H.; Stöver, Detlev; Bräuer, Günter; Venskutonis, Andreas; Sigl, Lorenz S.; Buchkremer, Hans-Peter; Vaßen, Robert

2014-06-01

A key to the development of metal-supported solid oxide fuel cells (MSCs) is the manufacturing of gas-tight thin-film electrolytes, which separate the cathode from the anode. This paper focuses the electrolyte manufacturing on the basis of 8YSZ (8 mol.-% Y2O3 stabilized ZrO2). The electrolyte layers are applied by a physical vapor deposition (PVD) gas flow sputtering (GFS) process. The gas-tightness of the electrolyte is significantly improved when sequential oxidic and metallic thin-film multi-layers are deposited, which interrupt the columnar grain structure of single-layer electrolytes. Such electrolytes with two or eight oxide/metal layers and a total thickness of about 4 μm obtain leakage rates of less than 3 × 10-4 hPa dm3 s-1 cm-2 (Δp: 100 hPa) at room temperature and therefore fulfill the gas tightness requirements. They are also highly tolerant with respect to surface flaws and particulate impurities which can be present on the graded anode underground. MSC cell tests with double-layer and multilayer electrolytes feature high power densities more than 1.4 W cm-2 at 850 °C and underline the high potential of MSC cells.

Oxygen Reduction Reaction Activity of Platinum Thin Films with Different Densities

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

Ergul, Busra; Begum, Mahbuba; Kariuki, Nancy

Platinum thin films with different densities were grown on glassy carbon electrodes by high pressure sputtering deposition and evaluated as oxygen reduction reaction catalysts for polymer electrolyte fuel cells using cyclic voltammetry and rotating disk electrode techniques in aqueous perchloric acid electrolyte. The electrochemically active surface area, ORR mass activity (MA) and specific activity (SA) of the thin film electrodes were obtained. MA and SA were found to be higher for low-density films than for high-density film.

Microstructured Electrolyte Membranes to Improve Fuel Cell Performance

NASA Astrophysics Data System (ADS)

Wei, Xue

Fuel cells, with the advantages of high efficiency, low greenhouse gas emission, and long lifetime are a promising technology for both portable power and stationary power sources. The development of efficient electrolyte membranes with high ionic conductivity, good mechanical durability and dense structure at low cost remains a challenge to the commercialization of fuel cells. This thesis focuses on exploring novel composite polymer membranes and ceramic electrolytes with the microstructure engineered to improve performance in direct methanol fuel cells (DMFCs) and solid oxide fuel cells (SOFCs), respectively. Polymer/particle composite membranes hold promise to meet the demands of DMFCs at lower cost. The structure of composite membranes was controlled by aligning proton conducting particles across the membrane thickness under an applied electric field. The field-induced structural changes caused the membranes to display an enhanced water uptake, proton conductivity, and methanol permeability in comparison to membranes prepared without an applied field. Although both methanol permeability and proton conductivity are enhanced by the applied field, the permeability increase is relatively lower than the proton conductivity improvement, which results in enhanced proton/methanol selectivity and improved DMFC performance. Apatite ceramics are a new class of fast ion conductors being studied as alternative SOFC electrolytes in the intermediate temperature range. An electrochemical/hydrothermal deposition method was developed to grow fully dense apatite membranes containing well-developed crystals with c-axis alignment to promote ion conductivity. Hydroxyapatite seed crystals were first deposited onto a metal substrate electrochemically. Subsequent ion substitution during the hydrothermal growth process promoted the formation of dense, fully crystalline films with microstructure optimal for ion transport. The deposition parameters were systematically investigated, such as

Thin PDMS Films Using Long Spin Times or Tert-Butyl Alcohol as a Solvent

PubMed Central

Koschwanez, John H.; Carlson, Robert H.; Meldrum, Deirdre R.

2009-01-01

Thin polydimethylsiloxane (PDMS) films are frequently used in “lab on a chip” devices as flexible membranes. The common solvent used to dilute the PDMS for thin films is hexane, but hexane can swell the underlying PDMS substrate. A better solvent would be one that dissolves uncured PDMS but doesn't swell the underlying substrate. Here, we present protocols and spin curves for two alternatives to hexane dilution: longer spin times and dilution in tert-butyl alcohol. The thickness of the PDMS membranes under different spin speeds, spin times, and PDMS concentrations was measured using an optical profilometer. The use of tert-butyl alcohol to spin thin PDMS films does not swell the underlying PDMS substrate, and we have used these films to construct multilayer PDMS devices. PMID:19238212

Nanopore thin film enabled optical platform for drug loading and release.

PubMed

Song, Chao; Che, Xiangchen; Que, Long

2017-08-07

In this paper, a drug loading and release device fabricated using nanopore thin film and layer-by-layer (LbL) nanoassembly is reported. The nanopore thin film is a layer of anodic aluminum oxide (AAO), consisting of honeycomb-shape nanopores. Using the LbL nanoassembly process, the drug, using gentamicin sulfate (GS) as the model, can be loaded into the nanopores and the stacked layers on the nanopore thin film surface. The drug release from the device is achieved by immersing it into flowing DI water. Both the loading and release processes can be monitored optically. The effect of the nanopore size/volume on drug loading and release has also been evaluated. Further, the neuron cells have been cultured and can grow normally on the nanopore thin film, verifying its bio-compatibility. The successful fabrication of nanopore thin film device on silicon membrane render it as a potential implantable controlled drug release device.

Combustion synthesized indium-tin-oxide (ITO) thin film for source/drain electrodes in all solution-processed oxide thin-film transistors

NASA Astrophysics Data System (ADS)

Tue, Phan Trong; Inoue, Satoshi; Takamura, Yuzuru; Shimoda, Tatsuya

2016-06-01

We report combustion solution synthesized (SCS) indium-tin-oxide (ITO) thin film, which is a well-known transparent conductive oxide, for source/drain (S/D) electrodes in solution-processed amorphous zirconium-indium-zinc-oxide TFT. A redox-based combustion synthetic approach is applied to ITO thin film using acetylacetone as a fuel and metal nitrate as oxidizer. The structural and electrical properties of SCS-ITO precursor solution and thin films were systematically investigated with changes in tin concentration, indium metal precursors, and annealing conditions such as temperature, time, and ambient. It was found that at optimal conditions the SCS-ITO thin film exhibited high crystalline quality, atomically smooth surface (RMS ~ 4.1 Å), and low electrical resistivity (4.2 × 10-4 Ω cm). The TFT using SCS-ITO film as the S/D electrodes showed excellent electrical properties with negligible hysteresis. The obtained "on/off" current ratio, subthreshold swing factor, subthreshold voltage, and field-effect mobility were 5 × 107, 0.43 V/decade, 0.7 V, and 2.1 cm2/V s, respectively. The performance and stability of the SCS-ITO TFT are comparable to those of the sputtered-ITO TFT, emphasizing that the SCS-ITO film is a promising candidate for totally solution-processed oxide TFTs.

Super-Anticoagulant Heparin-Mimicking Hydrogel Thin Film Attached Substrate Surfaces to Improve Hemocompatibility.

PubMed

He, Min; Cui, Xiaofei; Jiang, Huiyi; Huang, Xuelian; Zhao, Weifeng; Zhao, Changsheng

2017-02-01

In this study, heparin-mimicking hydrogel thin films are covalently attached onto poly(ether sulfone) membrane surfaces to improve anticoagulant property. The hydrogel films display honeycomb-like porous structure with well controlled thickness and show long-term stability. After immobilizing the hydrogel films, the membranes show excellent anticoagulant property confirmed by the activated partial thromboplastin time values exceeding 600 s. Meanwhile, the thrombin time values increase from 20 to 61 s as the sodium allysulfonate proportions increase from 0 to 80 mol%. In vitro investigations of protein adsorption and blood-related complement activation also confirm that the membranes exhibit super-anticoagulant property. Furthermore, gentamycin sulfate is loaded into the hydrogel films, and the released drug shows significant inhibition toward E. coli bacteria. It is believed that the surface attached heparin-mimicking hydrogel thin films may show high potential for the applications in various biological fields, such as blood contacting materials and drug loading materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation and Characterization of Thin-Film Composite Membrane with Nanowire-Modified Support for Forward Osmosis Process

PubMed Central

Low, Ze-Xian; Liu, Qi; Shamsaei, Ezzatollah; Zhang, Xiwang; Wang, Huanting

2015-01-01

Internal concentration polarization (ICP) in forward osmosis (FO) process is a characteristic problem for asymmetric thin-film composite (TFC) FO membrane which leads to lower water flux. To mitigate the ICP effect, modification of the substrates’ properties has been one of the most effective methods. A new polyethersulfone-based ultrafiltration membrane with increased surface porosity and high water flux was recently produced by incorporating Zn2GeO4 nanowires. The composite membrane was used as a substrate for the fabrication of TFC FO membrane, by coating a thin layer of polyamide on top of the substrate. The substrate and the nanowires were characterized by a range of techniques such as SEM, XRD, and contact angle goniometry. The water permeability and molecular weight cut-offs (MWCO) of the substrate; and the FO performance of the TFC membrane were also determined. The Zn2GeO4-modified membrane showed ~45% increase in water permeability and NaCl salt rejection of 80% under RO mode. In FO mode, the ratio of water flux to reverse solute flux was also improved. However, lower FO flux was obtained which could be due to ICP. The result shows that Zn2GO4 nanowire may be used as a modifier to the substrate to improve the quality of the polyamide layer on the substrate to improve the flux and selectivity, but not as effective in reducing ICP. This work demonstrates that the incorporation of nanomaterials to the membrane substrate may be an alternative approach to improve the formation of polyamide skin layer to achieve better FO performance. PMID:25803239

MATERIAL AND PROCESS DEVELOPMENT LEADING TO ECONOMICAL HIGH-PERFORMANCE THIN-FILM SOLID OXIDE FUEL CELLS

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

Jie Guan; Atul Verma; Nguyen Minh

2003-04-01

This document summarizes the technical progress from September 2002 to March 2003 for the program, Material and Process Development Leading to Economical High-Performance Thin-Film Solid Oxide Fuel Cells, contract number DE-AC26-00NT40711. The causes have been identified for the unstable open circuit voltage (OCV) and low performance exhibited by the anode-supported lanthanum gallate based cells from the earlier development. Promising results have been obtained in the area of synthesis of electrolyte and cathode powders, which showed excellent sintering and densification at low temperatures. The fabrication of cells using tapecalendering process for anode-supported thin lanthanum gallate electrolyte cells and their performance optimizationmore » is in progress.« less

Detection of water in jet fuel using layer-by-layer thin film coated long period grating sensor.

PubMed

Puckett, Sean D; Pacey, Gilbert E

2009-04-15

The quantitative measurement of jet fuel additives in the field is of interest to the Air Force. The "smart nozzle" project was designed as a state-of-the-art diagnostics package attached to a single-point refueling nozzle for assessing key fuel properties as the fuel is dispensed. The objective of the work was to show proof of concept that a layer-by-layer thin film and long period grating fibers could be used to detect the presence of water in jet fuel. The data for the nafion/PDMA film and a long period grating fiber is a combination capable of quantitative measurement of water in kerosene. The average response (spectral loss wavelength shift) to the kerosene sample ranged from -6.0 for 15 ppm to -126.5 for 60 ppm water. The average calculated value for the check standard was 21.71 and ranged from 21.25 to 22.00 with a true value of 22.5 ppm water. Potential interferences were observed and are judged to be insignificant in real samples.

Mitigation of Biofilm Development on Thin-Film Composite Membranes Functionalized with Zwitterionic Polymers and Silver Nanoparticles.

PubMed

Liu, Caihong; Faria, Andreia F; Ma, Jun; Elimelech, Menachem

2017-01-03

We demonstrate the functionalization of thin-film composite membranes with zwitterionic polymers and silver nanoparticles (AgNPs) for combating biofouling. Combining hydrophilic zwitterionic polymer brushes and biocidal AgNPs endows the membrane with dual functionality: antiadhesion and bacterial inactivation. An atom transfer radical polymerization (ATRP) reaction is used to graft zwitterionic poly(sulfobetaine methacrylate) (PSBMA) brushes to the membrane surface, while AgNPs are synthesized in situ through chemical reduction of silver. Two different membrane architectures (Ag-PSBMA and PSBMA-Ag TFC) are developed according to the sequence AgNPs, and PSBMA brushes are grafted on the membrane surface. A static adhesion assay shows that both modified membranes significantly reduced the adsorption of proteins, which served as a model organic foulant. However, improved antimicrobial activity is observed for PSBMA-Ag TFC (i.e., AgNPs on top of the polymer brush) in comparison to the Ag-PSBMA TFC membrane (i.e., polymer brush on top of AgNPs), indicating that architecture of the antifouling layer is an important factor in the design of zwitterion-silver membranes. Confocal laser scanning microscopy (CLSM) imaging indicated that PSBMA-Ag TFC membranes effectively inhibit biofilm formation under dynamic cross-flow membrane biofouling tests. Finally, we demonstrate the regeneration of AgNPs on the membrane after depletion of silver from the surface of the PSBMA-Ag TFC membrane.

Laser ablation for membrane processing of AlGaN/GaN- and micro structured ferroelectric thin film MEMS and SiC pressure sensors for extreme conditions

NASA Astrophysics Data System (ADS)

Zehetner, J.; Vanko, G.; Dzuba, J.; Ryger, I.; Lalinsky, T.; Benkler, Manuel; Lucki, Michal

2015-05-01

AlGaN/GaN based high electron mobility transistors (HEMTs), Schottky diodes and/or resistors have been presented as sensing devices for mechanical or chemical sensors operating in extreme conditions. In addition we investigate ferroelectric thin films for integration into micro-electro-mechanical-systems (MEMS). Creation of appropriate diaphragms and/or cantilevers out of SiC is necessary for further improvement of sensing properties of such MEMS sensors. For example sensitivity of the AlGaN/GaN based MEMS pressure sensor can be modified by membrane thickness. We demonstrated that a 4H-SiC 80μm thick diaphragms can be fabricated much faster with laser ablation than by electrochemical, photochemical or reactive ion etching (RIE). We were able to verify the feasibility of this process by fabrication of micromechanical membrane structures also in bulk 3C-SiC, borosilicate glass, sapphire and Al2O3 ceramic substrates by femtosecond laser (520nm) ablation. On a 350μm thick 4H-SiC substrate we produced an array of 275μm deep and 1000μm to 3000μm of diameter blind holes without damaging the 2μm AlN layer at the back side. In addition we investigated ferroelectric thin films as they can be deposited and micro-patterned by a direct UV-lithography method after the ablation process for a specific membrane design. The risk to harm or damage the function of thin films was eliminated by that means. Some defects in the ablated membranes are also affected by the polarisation of the laser light. Ripple structures oriented perpendicular to the laser polarisation promote creation of pin holes which would perforate a thin membrane. We developed an ablation technique strongly inhibiting formation of ripples and pin poles.

Advances in Thin Film Thermocouple Durability Under High Temperature and Pressure Testing Conditions

NASA Technical Reports Server (NTRS)

Martin, Lisa C.; Fralick, Gustave C.; Taylor, Keith F.

1999-01-01

Thin film thermocouples for measuring material surface temperature have been previously demonstrated on several material systems and in various hostile test environments. A well-developed thin film fabrication procedure utilizing shadow masking for patterning the sensors elements had produced thin films with sufficient durability for applications in high temperature and pressure environments that exist in air-breathing and hydrogen-fueled burner rig and engine test facilities. However, while shadow masking had been a reliable method for specimens with flat and gently curved surfaces, it had not been consistently reliable for use on test components with sharp contours. This work reports on the feasibility of utilizing photolithography processing for patterning thin film thermocouples. Because this patterning process required changes in the thin film deposition process from that developed for shadow masking, the effect of these changes on thin film adherence during burner rig testing was evaluated. In addition to the results of changing the patterning method, the effects on thin film adherence of other processes used in the thin film fabrication procedure is also presented.

Thin-film optical initiator

DOEpatents

Erickson, Kenneth L.

2001-01-01

A thin-film optical initiator having an inert, transparent substrate, a reactive thin film, which can be either an explosive or a pyrotechnic, and a reflective thin film. The resultant thin-film optical initiator system also comprises a fiber-optic cable connected to a low-energy laser source, an output charge, and an initiator housing. The reactive thin film, which may contain very thin embedded layers or be a co-deposit of a light-absorbing material such as carbon, absorbs the incident laser light, is volumetrically heated, and explodes against the output charge, imparting about 5 to 20 times more energy than in the incident laser pulse.

Layered conductive polymer on nylon membrane templates for high performance, thin-film supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Shi, HaoTian Harvey; Naguib, Hani E.

2016-04-01

Flexible Thin-film Electrochemical Capacitors (ECs) are emerging technology that plays an important role as energy supply for various electronics system for both present era and the future. Intrinsically conductive polymers (ICPs) are promising pseudo-capacitive materials as they feature both good electrical conductivity and high specific capacitance. This study focuses on the construction and characterization of ultra-high surface area porous electrodes based on coating of nano-sized conductive polymer materials on nylon membrane templates. Herein, a novel nano-engineered electrode material based on nylon membranes was presented, which allows the creation of super-capacitor devices that is capable of delivering competitive performance, while maintaining desirable mechanical characteristics. With the formation of a highly conductive network with the polyaniline nano-layer, the electrical conductivity was also increased dramatically to facilitate the charge transfer process. Cyclic voltammetry and specific capacitance results showed promising application of this type of composite materials for future smart textile applications.

In-situ membrane hydration measurement of proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Lai, Yeh-Hung; Fly, Gerald W.; Clapham, Shawn

2015-01-01

Achieving proper membrane hydration control is one of the most critical aspects of PEM fuel cell development. This article describes the development and application of a novel 50 cm2 fuel cell device to study the in-situ membrane hydration by measuring the through-thickness membrane swelling via an array of linear variable differential transducers. Using this setup either as an air/air (dummy) cell or as a hydrogen/air (operating) cell, we performed a series of hydration and dehydration experiments by cycling the RH of the inlet gas streams at 80 °C. From the linear relationship between the under-the-land swelling and the over-the-channel water content, the mechanical constraint within the fuel cell assembly can suppress the membrane water uptake by 11%-18%. The results from the air/air humidity cycling test show that the membrane can equilibrate within 120 s for all RH conditions and that membrane can reach full hydration at a RH higher than 140% in spite of the use of a liquid water impermeable Carbel MP30Z microporous layer. This result confirms that the U.S. DOE's humidity cycling mechanical durability protocol induces sufficient humidity swings to maximize hygrothermal mechanical stresses. This study shows that the novel experimental technique can provide a robust and accurate means to study the in-situ hydration of thin membranes subject to a wide range of fuel cell conditions.

Modification of thin-film polyamide membrane with multi-walled carbon nanotubes by interfacial polymerization

NASA Astrophysics Data System (ADS)

Al-Hobaib, Abdullah S.; Al-Sheetan, Kh. M.; Shaik, Mohammed Rafi; Al-Suhybani, M. S.

2017-12-01

Polyamide thin-film composite (TFC) was fabricated on polysulfone (PS-20) base by interfacial polymerization of aqueous m-phenylenediamine (MPD) solution and 1,3,5-benzenetricarbonyl trichloride (TMC) in hexane organic solution. Multi-wall carbon nanotubes (MWCNT) were carboxylated by heating MWCNT powder in a mixture of HNO3 and H2SO4 (1:3 v/v) at 70 °C under constant sonication for different periods. Polyamide nanocomposites were prepared by incorporating MWCNT and the carboxylated MWCNT (MWCNT-COOH) at different concentrations (0.001-0.009 wt%). The developed composites were analyzed by Fourier transform infrared spectroscopy-attenuated total reflection, scanning electron microscopy, transmission electron microscopy, contact angle measurement, determination of salt rejection and water permeate flux capabilities. The surface morphological studies displayed that the amalgamation of MWCNT considerably changed the surface properties of modified membranes. The surface hydrophilicity was increased as observed in the enhancement in water flux and pure water permeance, due to the presence of hydrophilic nanotubes. Salt rejection was obtained between 94 and 99% and varied water flux values for TFC-reference membrane, pristine-MWCNT in MPD, pristine-MWCNT in TMC and MWCNT-COOH in MPD were 20.5, 38, 40 and 43 L/m2h. The water flux and salt rejection performances revealed that the MWCNT-COOH membrane was superior membrane as compared to the other prepared membranes.

Magnetic hysteresis measurements of thin films under isotropic stress.

NASA Astrophysics Data System (ADS)

Holland, Patrick; Dubey, Archana; Geerts, Wilhelmus

2000-10-01

Nowadays, ferromagnetic thin films are widely applied in devices for information technology (credit cards, video recorder tapes, floppies, hard disks) and sensors (air bags, anti-breaking systems, navigation systems). Thus, with the increase in the use of magnetic media continued investigation of magnetic properties of materials is necessary to help in determining the useful properties of materials for new or improved applications. We are currently interested in studying the effect of applied external stress on Kerr hysteresis curves of thin magnetic films. The Ni and NiFe films were grown using DC magnetron sputtering with Ar as the sputter gas (pAr=4 mTorr; Tsub=55-190 C). Seed and cap layers of Ti were used on all films for adhesion and oxidation protection, respectively. A brass membrane pressure cell was designed to apply in-plane isotropic stress to thin films. In this pressure cell, gas pressure is used to deform a flexible substrate onto which a thin magnetic film has been sputtered. The curvature of the samples could be controlled by changing the gas pressure to the cell. Magneto-Optical in-plane hysteresis curves at different values of strain were measured. The results obtained show that the stress sensitivity is dependent on the film thickness. For the 500nm NiFe films, the coercivity strongly decreased as a function of the applied stress.

Pyrolyzed thin film carbon

NASA Technical Reports Server (NTRS)

Harder, Theodore (Inventor); Konishi, Satoshi (Inventor); Miserendino, Scott (Inventor); Tai, Yu-Chong (Inventor); Liger, Matthieu (Inventor)

2010-01-01

A method of making carbon thin films comprises depositing a catalyst on a substrate, depositing a hydrocarbon in contact with the catalyst and pyrolyzing the hydrocarbon. A method of controlling a carbon thin film density comprises etching a cavity into a substrate, depositing a hydrocarbon into the cavity, and pyrolyzing the hydrocarbon while in the cavity to form a carbon thin film. Controlling a carbon thin film density is achieved by changing the volume of the cavity. Methods of making carbon containing patterned structures are also provided. Carbon thin films and carbon containing patterned structures can be used in NEMS, MEMS, liquid chromatography, and sensor devices.

Improved separation and antifouling properties of thin-film composite nanofiltration membrane by the incorporation of cGO

NASA Astrophysics Data System (ADS)

Li, Hongbin; Shi, Wenying; Du, Qiyun; Zhou, Rong; Zhang, Haixia; Qin, Xiaohong

2017-06-01

Poly(piperazine amide) composite nanofiltration (NF) membranes were modified through the incorporation of carboxylated graphene oxide (cGO) in the polyamide layer during the interfacial polymerization (IP) process on the polysulfone (PSF)/nonwoven fabric (NWF) ultrafiltration (UF) substrate membrane surface. The composition and morphology of the prepared NF membrane surface were determined by means of ATR-FTIR, SEM-EDX and AFM. The effects of cGO contents on membrane hydrophilicity, separation performance and antifouling properties were investigated through Water Contact Angle (WCA) analysis, the permeance and three-cycle fouling measurements. The growth model of cGO-incorporated polyamide thin-film was proposed. Compared to the original NF membranes, the surface hydrophilicity, water permeability, salt rejection and antifouling properties of the cGO-incorporated NF membrane had all improved. When cGO content was 100 ppm, the MgSO4 rejection of composite NF membrane reached a maximum value of 99.2% meanwhile membrane obtained an obvious enhanced water flux (81.6 L m-2 h-1, at 0.7 MPa) which was nearly three times compared to the virginal NF membrane. The cGO-incorporated NF membrane showed an excellent selectivity of MgSO4 and NaCl with the rejection ratio of MgSO4/NaCl of approximately 8.0.

Thin Robust Anion Exchange Membranes for Fuel Cell Applications

DTIC Science & Technology

2014-01-01

water diffsuion. Here we use a Polyphenylene Oxide dibock polymer co-polymerized with polyvinyl benzyl trimethyl ammonium blocks ( PPO -b-PVBTMA[F...in PPO -b-PVBTMA[F-] AEM under saturated humidity environment ECS Transactions, 64 (3) 1185-1194 (2014) 1191 Conductivity of this membrane was...makes it a promising material for applications in anion exchange membrane fuel cells. Figure 5: Conductivity of PPO -b-PVBTMA[F-] under 95% Relative

Surface-supported metal-organic framework thin films: fabrication methods, applications, and challenges.

PubMed

Liu, Jinxuan; Wöll, Christof

2017-10-02

Surface-supported metal-organic framework thin films are receiving increasing attention as a novel form of nanotechnology. New deposition techniques that enable the control of the film thickness, homogeneity, morphology, and dimensions with a huge number of metal-organic framework compounds offer tremendous opportunities in a number of different application fields. In response to increasing demands for environmental sustainability and cleaner energy, much effort in recent years has been devoted to the development of MOF thin films for applications in photovoltaics, CO 2 reduction, energy storage, water splitting, and electronic devices, as well as for the fabrication of membranes. Although existing applications are promising and encouraging, MOF thin films still face numerous challenges, including the need for a more thorough understanding of the thin-film growth mechanism, stability of the internal and external interfaces, strategies for doping and models for charge carrier transport. In this paper, we review the recent advances in MOF thin films, including fabrication and patterning strategies and existing nanotechnology applications. We conclude by listing the most attractive future opportunities as well as the most urgent challenges.

High-Performance Protonic Ceramic Fuel Cells with Thin-Film Yttrium-Doped Barium Cerate-Zirconate Electrolytes on Compositionally Gradient Anodes.

PubMed

Bae, Kiho; Lee, Sewook; Jang, Dong Young; Kim, Hyun Joong; Lee, Hunhyeong; Shin, Dongwook; Son, Ji-Won; Shim, Joon Hyung

2016-04-13

In this study, we used a compositionally gradient anode functional layer (AFL) consisting of Ni-BaCe(0.5)Zr(0.35)Y(0.15)O(3-δ) (BCZY) with increasing BCZY contents toward the electrolyte-anode interface for high-performance protonic ceramic fuel cells. It is identified that conventional homogeneous AFLs fail to stably accommodate a thin film of BCZY electrolyte. In contrast, a dense 2 μm thick BCZY electrolyte was successfully deposited onto the proposed gradient AFL with improved adhesion. A fuel cell containing this thin electrolyte showed a promising maximum peak power density of 635 mW cm(-2) at 600 °C, with an open-circuit voltage of over 1 V. Impedance analysis confirmed that minimizing the electrolyte thickness is essential for achieving a high power output, suggesting that the anode structure is important in stably accommodating thin electrolytes.

Thin Films of Novel Linear-Dendritic Diblock Copolymers

NASA Astrophysics Data System (ADS)

Iyer, Jyotsna; Hammond, Paula

1998-03-01

A series of diblock copolymers with one linear block and one dendrimeric block have been synthesized with the objective of forming ultrathin film nanoporous membranes. Polyethyleneoxide serves as the linear hydrophilic portion of the diblock copolymer. The hyperbranched dendrimeric block consists of polyamidoamine with functional end groups. Thin films of these materials made by spin casting and the Langmuir-Blodgett techniques are being studied. The effect of the polyethylene oxide block size and the number and chemical nature of the dendrimer end group on the nature and stability of the films formed willbe discussed.

Thin polymeric films for building biohybrid microrobots.

PubMed

Ricotti, Leonardo; Fujie, Toshinori

2017-03-06

This paper aims to describe the disruptive potential that polymeric thin films have in the field of biohybrid devices and to review the recent efforts in this area. Thin (thickness  <  1 mm) and ultra-thin (thickness  <  1 µm) matrices possess a series of intriguing features, such as large surface area/volume ratio, high flexibility, chemical and physical surface tailorability, etc. This enables the fabrication of advanced bio/non-bio interfaces able to efficiently drive cell-material interactions, which are the key for optimizing biohybrid device performances. Thin films can thus represent suitable platforms on which living and artificial elements are coupled, with the aim of exploiting the unique features of living cells/tissues. This may allow to carry out certain tasks, not achievable with fully artificial technologies. In the paper, after a description of the desirable chemical/physical cues to be targeted and of the fabrication, functionalization and characterization procedures to be used for thin and ultra-thin films, the state-of-the-art of biohybrid microrobots based on micro/nano-membranes are described and discussed. The research efforts in this field are rather recent and they focus on: (1) self-beating cells (such as cardiomyocytes) able to induce a relatively large deformation of the underlying substrates, but affected by a limited controllability by external users; (2) skeletal muscle cells, more difficult to engineer in mature and functional contractile tissues, but featured by a higher controllability. In this context, the different materials used and the performances achieved are analyzed. Despite recent interesting advancements and signs of maturity of this research field, important scientific and technological steps are still needed. In the paper some possible future perspectives are described, mainly concerning thin film manipulation and assembly in multilayer 3D systems, new advanced materials to be used for the fabrication

Dewetting of Thin Polymer Films

NASA Astrophysics Data System (ADS)

Dixit, P. S.; Sorensen, J. L.; Kent, M.; Jeon, H. S.

2001-03-01

DEWETTING OF THIN POLYMER FILMS P. S. Dixit,(1) J. L. Sorensen,(2) M. Kent,(2) H. S. Jeon*(1) (1) Department of Petroleum and Chemical Engineering, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801, jeon@nmt.edu (2) Department 1832, Sandia National Laboratories, Albuquerque, NM. Dewetting of thin polymer films is of technological importance for a variety of applications such as protective coatings, dielectric layers, and adhesives. Stable and smooth films are required for the above applications. Above the glass transition temperature (Tg) the instability of polymer thin films on a nonwettable substrate can be occurred. The dewetting mechanism and structure of polypropylene (Tg = -20 ^circC) and polystyrene (Tg = 100 ^circC) thin films is investigated as a function of film thickness (25 Åh < 250 Åand quenching temperature. Contact angle measurements are used in conjunction with optical microscope to check the surface homogeneity of the films. Uniform thin films are prepared by spin casting the polymer solutions onto silicon substrates with different contact angles. We found that the stable and unstable regions of the thin films as a function of the film thickness and quenching temperature, and then constructed a stability diagram for the dewetting of thin polymer films. We also found that the dewetting patterns of the thin films are affected substantially by the changes of film thickness and quenching temperature.

Thin film superconductor magnetic bearings

DOEpatents

Weinberger, Bernard R.

1995-12-26

A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.

High-Temperature, Thin-Film Ceramic Thermocouples Developed

NASA Technical Reports Server (NTRS)

Sayir, Ali; Blaha, Charles A.; Gonzalez, Jose M.

2005-01-01

To enable long-duration, more distant human and robotic missions for the Vision for Space Exploration, as well as safer, lighter, quieter, and more fuel efficient vehicles for aeronautics and space transportation, NASA is developing instrumentation and material technologies. The high-temperature capabilities of thin-film ceramic thermocouples are being explored at the NASA Glenn Research Center by the Sensors and Electronics Branch and the Ceramics Branch in partnership with Case Western Reserve University (CWRU). Glenn s Sensors and Electronics Branch is developing thin-film sensors for surface measurement of strain, temperature, heat flux, and surface flow in propulsion system research. Glenn s Ceramics Branch, in conjunction with CWRU, is developing structural and functional ceramic technology for aeropropulsion and space propulsion.

Comprehensive study of thin film evaporation from nanoporous membranes for enhanced thermal management

NASA Astrophysics Data System (ADS)

Wilke, Kyle; Barabadi, Banafsheh; Lu, Zhengmao; Zhang, Tiejun; Wang, Evelyn

Performance of emerging electronics is often dictated by the ability to dissipate heat generated in the device. Thin film evaporation from nanopores promises enhanced thermal management by reducing the thermal transport resistance across the liquid film while providing capillary pumping. We present a study of the dependence of evaporation from nanopores on a variety of geometric parameters. Anodic aluminum oxide membranes were used as an experimental template. A biphilic treatment was also used to create a hydrophobic section of the pore to control meniscus location. We demonstrated different heat transfer regimes and observed more than an order of magnitude increase in dissipated heat flux by confining fluid within the nanopore. Pore diameter had little effect on evaporation performance at pore radii of this length scale due to the negligible conduction resistance from the pore wall to the evaporating interface. The dissipated heat flux scaled linearly with porosity as the evaporative area increased. Furthermore, it was demonstrated that moving the meniscus as little as 1 μm into the pore could decrease performance significantly. The results provide a better understanding of evaporation from nanopores and provide guidance in future device design.

Enhanced surface hydrophilicity of thin-film composite membranes for nanofiltration: an experimental and DFT study.

PubMed

Lv, Zhiwei; Hu, Jiahui; Zhang, Xuan; Wang, Lianjun

2015-10-07

In the current study, thin-film composite (TFC) nanofiltration membranes desirable for water softening were successfully developed through interfacial polymerization using N-(2-hydroxyethyl)ethylenediamine (HEDA) as the amine monomer in the aqueous phase. The hydrophilicity of the membrane surface was greatly enhanced with the introduction of the residual hydroxyl groups during the fabrication process. The TFC membranes possessed a permeate flux of 15.8 L m(-2) h(-1) under 0.6 MPa, with a rejection of 85.9%, 73.8%, and 99.8% for Na2SO4, MgSO4 and Congo red, respectively. The interplays of the solvent, solute and polymer matrix on the separation performance were investigated by means of the solubility parameter study. Moreover, density functional theory was employed to calculate the Fukui function by the Hirshfeld charge, which gave the global and local softness values to predict the reactivity of the atomic sites in the HEDA molecule. The findings of this study support the possible forming mechanism of the barrier layer for the first time. The TFC membrane was found to be stable and displayed good separation ability over a week-long filtration process. The combined results of this work suggest that these HEDA/TMC TFC nanofiltration membranes are promising candidates for various applications, such as desalination and dye removal from wastewater.

[Spectral emissivity of thin films].

PubMed

Zhong, D

2001-02-01

In this paper, the contribution of multiple reflections in thin film to the spectral emissivity of thin films of low absorption is discussed. The expression of emissivity of thin films derived here is related to the thin film thickness d and the optical constants n(lambda) and k(lambda). It is shown that in the special case d-->infinity the emissivity of thin films is equivalent to that of the bulk material. Realistic numerical and more precise general numerical results for the dependence of the emissivity on d, n(lambda) and k(lambda) are given.

Ceramic Composite Thin Films

NASA Technical Reports Server (NTRS)

Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor); Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor)

2013-01-01

A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

Micromachined Thin-Film Sensors for SOI-CMOS Co-Integration

NASA Astrophysics Data System (ADS)

Laconte, Jean; Flandre, D.; Raskin, Jean-Pierre

Co-integration of sensors with their associated electronics on a single silicon chip may provide many significant benefits regarding performance, reliability, miniaturization and process simplicity without significantly increasing the total cost. Micromachined Thin-Film Sensors for SOI-CMOS Co-integration covers the challenges and interests and demonstrates the successful co-integration of gas flow sensors on dielectric membrane, with their associated electronics, in CMOS-SOI technology. We firstly investigate the extraction of residual stress in thin layers and in their stacking and the release, in post-processing, of a 1 μm-thick robust and flat dielectric multilayered membrane using Tetramethyl Ammonium Hydroxide (TMAH) silicon micromachining solution.

A Thin Film Nanocomposite Membrane with MCM-41 Silica Nanoparticles for Brackish Water Purification.

PubMed

Kadhom, Mohammed; Yin, Jun; Deng, Baolin

2016-12-06

Thin film nanocomposite (TFN) membranes containing MCM-41 silica nanoparticles (NPs) were synthesized by the interfacial polymerization (IP) process. An m -phenylenediamine (MPD) aqueous solution and an organic phase with trimesoyl chloride (TMC) dissolved in isooctane were used in the IP reaction, occurring on a nanoporous polysulfone (PSU) support layer. Isooctane was introduced as the organic solvent for TMC in this work due to its intermediate boiling point. MCM-41 silica NPs were loaded in MPD and TMC solutions in separate experiments, in a concentration range from 0 to 0.04 wt %, and the membrane performance was assessed and compared based on salt rejection and water flux. The prepared membranes were characterized via scanning electron microscopy (SEM), transmission electron microscopy (TEM), contact angle measurement, and attenuated total reflection Fourier transform infrared (ATR FT-IR) analysis. The results show that adding MCM-41 silica NPs into an MPD solution yields slightly improved and more stable results than adding them to a TMC solution. With 0.02% MCM-41 silica NPs in the MPD solution, the water flux was increased from 44.0 to 64.1 L/m²·h, while the rejection virtually remained the same at 95% (2000 ppm NaCl saline solution, 25 °C, 2068 kPa (300 psi)).

Polycrystalline-thin-film thermophotovoltaic cells

NASA Astrophysics Data System (ADS)

Dhere, Neelkanth G.

1996-02-01

Thermophotovoltaic (TPV) cells convert thermal energy to electricity. Modularity, portability, silent operation, absence of moving parts, reduced air pollution, rapid start-up, high power densities, potentially high conversion efficiencies, choice of a wide range of heat sources employing fossil fuels, biomass, and even solar radiation are key advantages of TPV cells in comparison with fuel cells, thermionic and thermoelectric convertors, and heat engines. The potential applications of TPV systems include: remote electricity supplies, transportation, co-generation, electric-grid independent appliances, and space, aerospace, and military power applications. The range of bandgaps for achieving high conversion efficiencies using low temperature (1000-2000 K) black-body or selective radiators is in the 0.5-0.75 eV range. Present high efficiency convertors are based on single crystalline materials such as In1-xGaxAs, GaSb, and Ga1-xInxSb. Several polycrystalline thin films such as Hg1-xCdxTe, Sn1-xCd2xTe2, and Pb1-xCdxTe, etc., have great potential for economic large-scale applications. A small fraction of the high concentration of charge carriers generated at high fluences effectively saturates the large density of defects in polycrystalline thin films. Photovoltaic conversion efficiencies of polycrystalline thin films and PV solar cells are comparable to single crystalline Si solar cells, e.g., 17.1% for CuIn1-xGaxSe2 and 15.8% for CdTe. The best recombination-state density Nt is in the range of 10-15-10-16 cm-3 acceptable for TPV applications. Higher efficiencies may be achieved because of the higher fluences, possibility of bandgap tailoring, and use of selective emitters such as rare earth oxides (erbia, holmia, yttria) and rare earth-yttrium aluminium garnets. As compared to higher bandgap semiconductors such as CdTe, it is easier to dope the lower bandgap semiconductors. TPV cell development can benefit from the more mature PV solar cell and opto

Specific considerations for obtaining appropriate La1-xSrxGa1-yMgyO3-δ thin films using pulsed-laser deposition and its influence on the performance of solid-oxide fuel cells

NASA Astrophysics Data System (ADS)

Hwang, Jaeyeon; Lee, Heon; Lee, Jong-Ho; Yoon, Kyung Joong; Kim, Hyoungchul; Hong, Jongsup; Son, Ji-Won

2015-01-01

To obtain La1-xSrxGa1-yMgyO3-δ (LSGM) thin films with the appropriate properties, pulsed-laser deposition (PLD) is employed, and specific considerations regarding control of the deposition parameters is investigated. It is demonstrated that with a target of stoichiometric composition, appropriate LSGM thin films cannot be produced because of the deviation of the composition from the target to the thin film. Only after adjusting the target composition an LSGM thin film with an appropriate composition and phase can be obtained. The optimized LSGM thin film possesses an electrical conductivity close to that of the bulk LSGM. In contrast, non-optimized thin films do not yield any measurable electrical conductivity. The impact of the optimization of the LSGM thin-film electrolyte on the cell performance is quite significant, in that a solid-oxide fuel cell (SOFC) with an optimized LSGM thin-film electrolyte produces a maximum power density of 1.1 W cm-2 at 600 °C, whereas an SOFC with a non-optimal LSGM thin-film electrolyte is not operable.

Fabrication of hydrophobic fluorinated silica-polyamide thin film nanocomposite reverse osmosis membranes with dramatically improved salt rejection.

PubMed

Pang, Ruizhi; Zhang, Kaisong

2018-01-15

Thin film nanocomposite reverse osmosis (TFN RO) membranes incorporated with hydrophilic nanoparticles show a potential problem that the salt rejection can not be improved significantly. In this study, novel TFN RO membranes incorporated with hydrophobic fluorinated silica nanoparticles were fabricated to improve the salt rejection. Fluorinated silica nanoparticles were well dispersed in organic phase during the interfacial polymerization (IP) process. The TFN RO membranes were characterized with attenuated total reflectance infra-red, field emission scanning electron microscopy, atomic force microscopy and water contact angle measurements. The preparation conditions of TFN RO membranes, including IP reaction time, organic solvent removal time, and fluorinated silica loading, were optimized by characterizing desalination performance using 2000ppm NaCl aqueous solution at 1.55MPa and 25°C. The salt rejection increased significantly from 96.0% without fluorinated silica nanoparticles to 98.6% with the optimal 0.12% (w/v) fluorinated silica nanoparticles, while the water flux decreased slightly from 0.99m 3 /m 2 /day to 0.93m 3 /m 2 /day. This study demonstrated the potential use of hydrophobic nanoparticles in high-performance TFN RO membranes. Copyright © 2017 Elsevier Inc. All rights reserved.

Thin-film sensors for space propulsion technology: Fabrication and preparation for testing

NASA Technical Reports Server (NTRS)

Kim, Walter S.; Hepp, Aloysius F.

1989-01-01

The goal of this work is to develop and test thin-film thermocouples for Space Shuttle Main Engine (SSME) components. Thin-film thermocouples have been developed for aircraft gas turbine engines and are in use for temperature measurement on turbine blades up to 1800 F. Established aircraft engine gas turbine technology is currently being adapted to turbine engine blade materials and the environment encountered in the SSME, especially severe thermal shock from cryogenic fuel to combustion temperatures. Initial results using coupons of MAR M-246 (+Hf) and PWA 1480 have been followed by fabrication of thin-film thermocouples on SSME turbine blades. Current efforts are focused on preparing for testing in the Turbine Blade Tester at the NASA Marshall Space Flight Center (MSFC). Future work will include testing of thin-film thermocouples on SSME blades of single crystal PWA 1480 at MSFC.

Laser-induced vibration of a thin soap film.

PubMed

Emile, Olivier; Emile, Janine

2014-09-21

We report on the vibration of a thin soap film based on the optical radiation pressure force. The modulated low power laser induces a counter gravity flow in a vertical free-standing draining film. The thickness of the soap film is then higher in the upper region than in the lower region of the film. Moreover, the lifetime of the film is dramatically increased by a factor of 2. Since the laser beam only acts mechanically on the film interfaces, such a film can be employed in an optofluidic diaphragm pump, the interfaces behaving like a vibrating membrane and the liquid in-between being the fluid to be pumped. Such a pump could then be used in delicate micro-equipment, in chips where temperature variations are detrimental and even in biological systems.

Specific heat measurement set-up for quench condensed thin superconducting films.

PubMed

Poran, Shachaf; Molina-Ruiz, Manel; Gérardin, Anne; Frydman, Aviad; Bourgeois, Olivier

2014-05-01

We present a set-up designed for the measurement of specific heat of very thin or ultra-thin quench condensed superconducting films. In an ultra-high vacuum chamber, materials of interest can be thermally evaporated directly on a silicon membrane regulated in temperature from 1.4 K to 10 K. On this membrane, a heater and a thermometer are lithographically fabricated, allowing the measurement of heat capacity of the quench condensed layers. This apparatus permits the simultaneous thermal and electrical characterization of successively deposited layers in situ without exposing the deposited materials to room temperature or atmospheric conditions, both being irreversibly harmful to the samples. This system can be used to study specific heat signatures of phase transitions through the superconductor to insulator transition of quench condensed films.

NMR characterization of thin films

DOEpatents

Gerald II, Rex E.; Klingler, Robert J.; Rathke, Jerome W.; Diaz, Rocio; Vukovic, Lela

2010-06-15

A method, apparatus, and system for characterizing thin film materials. The method, apparatus, and system includes a container for receiving a starting material, applying a gravitational force, a magnetic force, and an electric force or combinations thereof to at least the starting material, forming a thin film material, sensing an NMR signal from the thin film material and analyzing the NMR signal to characterize the thin film of material.

NMR characterization of thin films

DOEpatents

Gerald, II, Rex E.; Klingler, Robert J.; Rathke, Jerome W.; Diaz, Rocio; Vukovic, Lela

2008-11-25

A method, apparatus, and system for characterizing thin film materials. The method, apparatus, and system includes a container for receiving a starting material, applying a gravitational force, a magnetic force, and an electric force or combinations thereof to at least the starting material, forming a thin film material, sensing an NMR signal from the thin film material and analyzing the NMR signal to characterize the thin film of material.

Thin film cell development workshop report

NASA Technical Reports Server (NTRS)

Woodyard, James R.

1991-01-01

The Thin Film Development Workshop provided an opportunity for those interested in space applications of thin film cells to debate several topics. The unique characteristics of thin film cells as well as a number of other issues were covered during the discussions. The potential of thin film cells, key research and development issues, manufacturing issues, radiation damage, substrates, and space qualification of thin film cells were discussed.

YSZ thin films with minimized grain boundary resistivity

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

Mills, Edmund M.; Kleine-Boymann, Matthias; Janek, Juergen

2016-03-31

In recent years, interface engineering of solid electrolytes has been explored to increase their ionic conductivity and improve the performance of solid oxide fuel cells and other electrochemical power sources. It has been observed that the ionic conductivity of epitaxially grown thin films of some electrolytes is dramatically enhanced, which is often attributed to effects (e. g. strain-induced mobility changes) at the heterophase boundary with the substrate. Still largely unexplored is the possibility of manipulation of grain boundary resistivity in polycrystalline solid electrolyte films, clearly a limiting factor in their ionic conductivity. Here we report that the ionic conductivity ofmore » yttria stabilized zirconia thin films with nano-­ columnar grains grown on a MgO substrate nearly reaches that of the corresponding single crystal when the thickness of the films becomes less than roughly 8 nm (smaller by a factor of three at 500°C). Using impedance spectroscopy, the grain boundary resistivity was probed as a function of film thickness. The resistivity of the grain boundaries near the film- substrate interface and film surface (within 4 nm of each) was almost entirely eliminated. This minimization of grain boundary resistivity is attributed to Mg2+ diffusion from the MgO substrate into the YSZ grain boundaries, which is supported by time of flight secondary ion mass spectroscopy measurements. We suggest grain boundary “design” as an attractive method to obtain highly conductive solid electrolyte thin films.« less

Radiation grafted and sulfonated (FEP-g-polysterene) - An alternative to perfluorinated membranes for PEM fuel cells?

NASA Astrophysics Data System (ADS)

Buechi, F. N.; Gupta, B.; Rouilly, M.; Hauser, P. C.; Chapiro, A.; Scherer, G. G.

Partially fluorinated proton exchange membranes (PEMs) were synthesized for fuel cell applications by simultaneous radiation grafting of styrene on FEP films followed by sulfonation. Properties of the synthesized membranes can be tailored by varying the degree of grafting and crosslinking. The performance of these membranes was tested in H2/O2 fuel cells. Long time testing showed steady performance for high grafted membranes over periods of more than 300 h at a cell temperature of 60 C. Low grafted membranes and the Morgane CDS membrane showed considerable decay of cell power on the same time scale. A fast degradation of all membranes occurred at a cell temperature of 80 C. It is noted that grafting in film form makes this process a potentially cheap and easy technique for the preparation of solid polymer fuel cell electrolytes.

Ultrahigh PEMFC performance of a thin-film, dual-electrode assembly with tailored electrode morphology.

PubMed

Jung, Chi-Young; Kim, Tae-Hyun; Yi, Sung-Chul

2014-02-01

A dual-electrode membrane electrode assembly (MEA) for proton exchange membrane fuel cells with enhanced polarization under zero relative humidity (RH) is fabricated by introducing a phase-separated morphology in an agglomerated catalyst layer of Pt/C (platinum on carbon black) and Nafion. In the catalyst layer, a sufficient level of phase separation is achieved by dispersing the Pt catalyst and the Nafion dispersion in a mixed-solvent system (propane-1,2,3-triol/1-methyl-2-pyrrolidinone).The high polymer chain mobility results in improved water uptake and regular pore-size distribution with small pore diameters. The electrochemical performance of the dual-film electrode assembly with different levels of phase separation is compared to conventional electrode assemblies. As a result, good performance at 0 % RH is obtained because self-humidification is dramatically improved by attaching this dense and phase-separated catalytic overlayer onto the conventional catalyst layer. A MEA prepared using the thin-film, dual-layered electrode exhibits 39-fold increased RH stability and 28-fold improved start-up recovery time during the on-off operation relative to the conventional device. We demonstrate the successful operation of the dual-layered electrode comprised of discriminatively phase-separated agglomerates with an ultrahigh zero RH fuel-cell performance reaching over 95 % performance of a fully humidified MEA. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structurally-driven Enhancement of Thermoelectric Properties within Poly(3,4-ethylenedioxythiophene) thin Films

PubMed Central

Petsagkourakis, Ioannis; Pavlopoulou, Eleni; Portale, Giuseppe; Kuropatwa, Bryan A.; Dilhaire, Stefan; Fleury, Guillaume; Hadziioannou, Georges

2016-01-01

Due to the rising need for clean energy, thermoelectricity has raised as a potential alternative to reduce dependence on fossil fuels. Specifically, thermoelectric devices based on polymers could offer an efficient path for near-room temperature energy harvesters. Thus, control over thermoelectric properties of conducting polymers is crucial and, herein, the structural, electrical and thermoelectric properties of poly(3,4-ethylenedioxythiophene) (PEDOT) thin films doped with p-toluenesulfonate (Tos) molecules were investigated with regards to thin film processing. PEDOT:Tos thin films were prepared by in-situ polymerization of (3,4-ethylenedioxythiophene) monomers in presence of iron(III) p-toluenesulfonate with different co-solvents in order to tune the film structure. While the Seebeck coefficient remained constant, a large improvement in the electrical conductivity was observed for thin films processed with high boiling point additives. The increase of electrical conductivity was found to be solely in-plane mobility-driven. Probing the thin film structure by Grazing Incidence Wide Angle X-ray Scattering has shown that this behavior is dictated by the structural properties of the PEDOT:Tos films; specifically by the thin film crystallinity combined to the preferential edge-on orientation of the PEDOT crystallites. Consequentially enhancement of the power factor from 25 to 78.5 μW/mK2 has been readily obtained for PEDOT:Tos thin films following this methodology. PMID:27470637

Structurally-driven Enhancement of Thermoelectric Properties within Poly(3,4-ethylenedioxythiophene) thin Films.

PubMed

Petsagkourakis, Ioannis; Pavlopoulou, Eleni; Portale, Giuseppe; Kuropatwa, Bryan A; Dilhaire, Stefan; Fleury, Guillaume; Hadziioannou, Georges

2016-07-29

Due to the rising need for clean energy, thermoelectricity has raised as a potential alternative to reduce dependence on fossil fuels. Specifically, thermoelectric devices based on polymers could offer an efficient path for near-room temperature energy harvesters. Thus, control over thermoelectric properties of conducting polymers is crucial and, herein, the structural, electrical and thermoelectric properties of poly(3,4-ethylenedioxythiophene) (PEDOT) thin films doped with p-toluenesulfonate (Tos) molecules were investigated with regards to thin film processing. Tos thin films were prepared by in-situ polymerization of (3,4-ethylenedioxythiophene) monomers in presence of iron(III) p-toluenesulfonate with different co-solvents in order to tune the film structure. While the Seebeck coefficient remained constant, a large improvement in the electrical conductivity was observed for thin films processed with high boiling point additives. The increase of electrical conductivity was found to be solely in-plane mobility-driven. Probing the thin film structure by Grazing Incidence Wide Angle X-ray Scattering has shown that this behavior is dictated by the structural properties of the Tos films; specifically by the thin film crystallinity combined to the preferential edge-on orientation of the PEDOT crystallites. Consequentially enhancement of the power factor from 25 to 78.5 μW/mK(2) has been readily obtained for Tos thin films following this methodology.

Low work function, stable thin films

DOEpatents

Dinh, Long N.; McLean, II, William; Balooch, Mehdi; Fehring, Jr., Edward J.; Schildbach, Marcus A.

2000-01-01

Generation of low work function, stable compound thin films by laser ablation. Compound thin films with low work function can be synthesized by simultaneously laser ablating silicon, for example, and thermal evaporating an alkali metal into an oxygen environment. For example, the compound thin film may be composed of Si/Cs/O. The work functions of the thin films can be varied by changing the silicon/alkali metal/oxygen ratio. Low work functions of the compound thin films deposited on silicon substrates were confirmed by ultraviolet photoelectron spectroscopy (UPS). The compound thin films are stable up to 500.degree. C. as measured by x-ray photoelectron spectroscopy (XPS). Tests have established that for certain chemical compositions and annealing temperatures of the compound thin films, negative electron affinity (NEA) was detected. The low work function, stable compound thin films can be utilized in solar cells, field emission flat panel displays, electron guns, and cold cathode electron guns.

3D visualization of membrane failures in fuel cells

NASA Astrophysics Data System (ADS)

Singh, Yadvinder; Orfino, Francesco P.; Dutta, Monica; Kjeang, Erik

2017-03-01

Durability issues in fuel cells, due to chemical and mechanical degradation, are potential impediments in their commercialization. Hydrogen leak development across degraded fuel cell membranes is deemed a lifetime-limiting failure mode and potential safety issue that requires thorough characterization for devising effective mitigation strategies. The scope and depth of failure analysis has, however, been limited by the 2D nature of conventional imaging. In the present work, X-ray computed tomography is introduced as a novel, non-destructive technique for 3D failure analysis. Its capability to acquire true 3D images of membrane damage is demonstrated for the very first time. This approach has enabled unique and in-depth analysis resulting in novel findings regarding the membrane degradation mechanism; these are: significant, exclusive membrane fracture development independent of catalyst layers, localized thinning at crack sites, and demonstration of the critical impact of cracks on fuel cell durability. Evidence of crack initiation within the membrane is demonstrated, and a possible new failure mode different from typical mechanical crack development is identified. X-ray computed tomography is hereby established as a breakthrough approach for comprehensive 3D characterization and reliable failure analysis of fuel cell membranes, and could readily be extended to electrolyzers and flow batteries having similar structure.

Drop dynamics on a thin film: Thin film rupture

NASA Astrophysics Data System (ADS)

Carlson, Andreas; Kim, Pilnam; Stone, Howard A.

2011-11-01

The spreading of a water drop on an oil film that covers a solid substrate is a common event in many industrial processes. We study in experiments the dynamics of a water drop on a thin silicone oil film and quantify its interaction with the solid substrate that supports the film. The oil film becomes unstable and ruptures for solids that are hydrophilic. We determine the ``waiting time,'' the time it takes the water drop to drain the silicone film. This timescale is found to highly depend on how well water wets the solid, illustrating the interplay between intermolecular and hydrodynamic forces in the phenomenon. A phase diagram for the thin film stability is extracted based on waters equilibrium contact angle on the solid, which shows that we can either promote or inhibit de-wetting. As water comes in direct contact with the solid, it spreads and peels off the silicone film. We show the influence of viscosity, equilibrium contact angle and film height on the opening radius of the hole formed as the solid de-wets.

A thin film nitinol heart valve.

PubMed

Stepan, Lenka L; Levi, Daniel S; Carman, Gregory P

2005-11-01

In order to create a less thrombogenic heart valve with improved longevity, a prosthetic heart valve was developed using thin film nitinol (NiTi). A "butterfly" valve was constructed using a single, elliptical piece of thin film NiTi and a scaffold made from Teflon tubing and NiTi wire. Flow tests and pressure readings across the valve were performed in vitro in a pulsatile flow loop. Bio-corrosion experiments were conducted on untreated and passivated thin film nitinol. To determine the material's in vivo biocompatibility, thin film nitinol was implanted in pigs using stents covered with thin film NiTi. Flow rates and pressure tracings across the valve were comparable to those through a commercially available 19 mm Perimount Edwards tissue valve. No signs of corrosion were present on thin film nitinol samples after immersion in Hank's solution for one month. Finally, organ and tissue samples explanted from four pigs at 2, 3, 4, and 6 weeks after thin film NiTi implantation appeared without disease, and the thin film nitinol itself was without thrombus formation. Although long term testing is still necessary, thin film NiTi may be very well suited for use in artificial heart valves.

YSZ thin films with minimized grain boundary resistivity

DOE PAGES

Mills, Edmund M.; Kleine-Boymann, Matthias; Janek, Juergen; ...

2016-03-31

In recent years, interface engineering of solid electrolytes has been explored to increase their ionic conductivity and improve the performance of solid oxide fuel cells and other electrochemical power sources. It has been observed that the ionic conductivity of epitaxially grown thin films of some electrolytes is dramatically enhanced, which is often attributed to effects (e.g. strain-induced mobility changes) at the heterophase boundary with the substrate. Still largely unexplored is the possibility of manipulation of grain boundary resistivity in polycrystalline solid electrolyte films, clearly a limiting factor in their ionic conductivity. Here in this paper, we report that the ionicmore » conductivity of yttria stabilized zirconia thin films with nano-columnar grains grown on a MgO substrate nearly reaches that of the corresponding single crystal when the thickness of the films becomes less than roughly 8 nm (smaller by a factor of three at 500 °C). Using impedance spectroscopy, the grain boundary resistivity was probed as a function of film thickness. The resistivity of the grain boundaries near the film–substrate interface and film surface (within 4 nm of each) was almost entirely eliminated. This minimization of grain boundary resistivity is attributed to Mg 2+ diffusion from the MgO substrate into the YSZ grain boundaries, which is supported by time of flight secondary ion mass spectroscopy measurements. We suggest grain boundary “design” as an attractive method to obtain highly conductive solid electrolyte thin films.« less

Polycaprolactone thin films for retinal tissue engineering and drug delivery

NASA Astrophysics Data System (ADS)

Steedman, Mark Rory

This dissertation focuses on the development of polycaprolactone thin films for retinal tissue engineering and drug delivery. We combined these thin films with techniques such as micro and nanofabrication to develop treatments for age-related macular degeneration (AMD), a disease that leads to the death of rod and cone photoreceptors. Current treatments are only able to slow or limit the progression of the disease, and photoreceptors cannot be regenerated or replaced by the body once lost. The first experiments presented focus on a potential treatment for AMD after photoreceptor death has occurred. We developed a polymer thin film scaffold technology to deliver retinal progenitor cells (RPCs) to the affected area of the eye. Earlier research showed that RPCs destined to become photoreceptors are capable of incorporating into a degenerated retina. In our experiments, we showed that RPC attachment to a micro-welled polycaprolactone (PCL) thin film surface enhanced the differentiation of these cells toward a photoreceptor fate. We then used our PCL thin films to develop a drug delivery device capable of sustained therapeutic release over a multi-month period that would maintain an effective concentration of the drug in the eye and eliminate the need for repeated intraocular injections. We first investigated the biocompatibility of PCL in the rabbit eye. We injected PCL thin films into the anterior chamber or vitreous cavity of rabbit eyes and monitored the animals for up to 6 months. We found that PCL thin films were well tolerated in the rabbit eye, showing no signs of chronic inflammation due to the implant. We then developed a multilayered thin film device containing a microporous membrane. We loaded these devices with lyophilized proteins and quantified drug elution for 10 weeks, finding that both bovine serum albumin and immunoglobulin G elute from these devices with zero order release kinetics. These experiments demonstrate that PCL is an extremely useful

Decoupling thermal, chemical, and mechanical strain components in thin films

NASA Astrophysics Data System (ADS)

Silberstein, Meredith; Crumlin, Ethan; Shao-Horn, Yang; Boyce, Mary

2011-03-01

Many electrochemical systems have performance which is affected by internal strains due to thermal and/or chemical stimuli. The bi-material curvature method is a means to quantify these thermal and chemical strains and their coupling with mechanical stress. In this method, a thin layer of the material of interest is deposited on a substrate of intermediate thickness. The composite assumes a curvature that depends on the mismatch strains between the substrate and film. The Stoney formula provides an explicit expression for the film stress as a function of the elastic substrate properties, film and substrate thickness, and curvature. Here we study two distinct materials systems: Nafion used as the polymer electrolyte in low temperature fuel cells, and epitaxial perovskite thin films used as a catalyst for the oxygen reduction reaction in solid oxide fuel cells. The thermal, chemical, and mechanical strains are quantitatively determined as functions of temperature and atmospheric conditions by monitoring the curvature evolution with changes in these parameters. The extent of coupling of the thermal and chemical strains with mechanical stress is evaluated by conducting the experiment at multiple substrate thicknesses.

Nonlinear Shell Modeling of Thin Membranes with Emphasis on Structural Wrinkling

NASA Technical Reports Server (NTRS)

Tessler, Alexander; Sleight, David W.; Wang, John T.

2003-01-01

Thin solar sail membranes of very large span are being envisioned for near-term space missions. One major design issue that is inherent to these very flexible structures is the formation of wrinkling patterns. Structural wrinkles may deteriorate a solar sail's performance and, in certain cases, structural integrity. In this paper, a geometrically nonlinear, updated Lagrangian shell formulation is employed using the ABAQUS finite element code to simulate the formation of wrinkled deformations in thin-film membranes. The restrictive assumptions of true membranes, i.e. Tension Field theory (TF), are not invoked. Two effective modeling strategies are introduced to facilitate convergent solutions of wrinkled equilibrium states. Several numerical studies are carried out, and the results are compared with recent experimental data. Good agreement is observed between the numerical simulations and experimental data.

Flexible thin-film black gold membranes with ultrabroadband plasmonic nanofocusing for efficient solar vapour generation.

PubMed

Bae, Kyuyoung; Kang, Gumin; Cho, Suehyun K; Park, Wounjhang; Kim, Kyoungsik; Padilla, Willie J

2015-12-14

Solar steam generation has been achieved by surface plasmon heating with metallic nanoshells or nanoparticles, which have inherently narrow absorption bandwidth. For efficient light-to-heat conversion from a wider solar spectrum, we employ adiabatic plasmonic nanofocusing to attain both polarization-independent ultrabroadband light absorption and high plasmon dissipation loss. Here we demonstrate large area, flexible thin-film black gold membranes, which have multiscale structures of varying metallic nanoscale gaps (0-200 nm) as well as microscale funnel structures. The adiabatic nanofocusing of self-aggregated metallic nanowire bundle arrays produces average absorption of 91% at 400-2,500 nm and the microscale funnel structures lead to average reflection of 7% at 2.5-17 μm. This membrane allows heat localization within the few micrometre-thick layer and continuous water provision through micropores. We efficiently generate water vapour with solar thermal conversion efficiency up to 57% at 20 kW m(-2). This new structure has a variety of applications in solar energy harvesting, thermoplasmonics and related technologies.

Flexible thin-film black gold membranes with ultrabroadband plasmonic nanofocusing for efficient solar vapour generation

PubMed Central

Bae, Kyuyoung; Kang, Gumin; Cho, Suehyun K.; Park, Wounjhang; Kim, Kyoungsik; Padilla, Willie J.

2015-01-01

Solar steam generation has been achieved by surface plasmon heating with metallic nanoshells or nanoparticles, which have inherently narrow absorption bandwidth. For efficient light-to-heat conversion from a wider solar spectrum, we employ adiabatic plasmonic nanofocusing to attain both polarization-independent ultrabroadband light absorption and high plasmon dissipation loss. Here we demonstrate large area, flexible thin-film black gold membranes, which have multiscale structures of varying metallic nanoscale gaps (0–200 nm) as well as microscale funnel structures. The adiabatic nanofocusing of self-aggregated metallic nanowire bundle arrays produces average absorption of 91% at 400–2,500 nm and the microscale funnel structures lead to average reflection of 7% at 2.5–17 μm. This membrane allows heat localization within the few micrometre-thick layer and continuous water provision through micropores. We efficiently generate water vapour with solar thermal conversion efficiency up to 57% at 20 kW m−2. This new structure has a variety of applications in solar energy harvesting, thermoplasmonics and related technologies. PMID:26657535

Efficient Nonlinear Atomization Model for Thin 3D Free Liquid Films

NASA Astrophysics Data System (ADS)

Mehring, Carsten

2007-03-01

Reviewed is a nonlinear reduced-dimension thin-film model developed by the author and aimed at the prediction of spray formation from thin films such as those found in gas-turbine engines (e.g., prefilming air-blast atomizers), heavy-fuel-oil burners (e.g., rotary-cup atomizers) and in the paint industry (e.g., flat-fan atomizers). Various implementations of the model focusing on different model-aspects, i.e., effect of film geometry, surface tension, liquid viscosity, coupling with surrounding gas-phase flow, influence of long-range intermolecular forces during film rupture are reviewed together with a validation of the nonlinear wave propagation characteristics predicted by the model for inviscid planar films using a two-dimensional vortex- method. An extension and generalization of the current nonlinear film model for implementation into a commercial flow- solver is outlined.

Manufacturing polymer thin films in a micro-gravity environment

NASA Technical Reports Server (NTRS)

Vera, Ivan

1987-01-01

This project represents Venezuela's first scientific experiment in space. The apparatus for the automatic casting of two polymer thin films will be contained in NASA's Payload No. G-559 of the Get Away Special program for a future orbital space flight in the U.S. Space Shuttle. Semi-permeable polymer membranes have important applications in a variety of fields, such as medicine, energy, and pharmaceuticals and in general fluid separation processes, such as reverse osmosis, ultrafiltration, and electrodialysis. The casting of semi-permeable membranes in space will help to identify the roles of convection in determining the structure of these membranes.

Emissivity measurements in thin metallized membrane reflectors used for microwave radiometer sensors

NASA Technical Reports Server (NTRS)

Schroeder, Lyle C.; Cravey, Robin L.; Scherner, Michael J.; Hearn, Chase P.; Blume, Hans-Juergen C.

1995-01-01

This paper is concerned with electromagnetic losses in metallized films used for inflatable reflectors. An inflatable membrane is made of tough elastic material such as Kapton, and it is not electromagnetically reflective by design. A film of conducting metal is added to the membrane to enhance its reflective properties. Since the impetus for use of inflatables for spacecraft is the light weight and compact packaging, it is important that the metal film be as thin as possible. However, if the material is not conductive or thick enough, the radiation due to the emissivity of the reflector could be a significant part of the radiation gathered by the radiometer. The emissivity would be of little consequence to a radar or solar collector; but for a radiometer whose signal is composed of thermal radiation, this contribution could be severe. Bulk properties of the metal film cannot be used to predict its loss. For this reason, a program of analysis and measurement was undertaken to determine the emissivities of a number of candidate metallized film reflectors. This paper describes the three types of measurements which were performed on the metallized thin films: (1) a network analyzer system with an L-band waveguide; (2) an S-band radiometer; and (3) a network analyzer system with a C-band antenna free-space transmission system.

Modeling Thin Film Oxide Growth

NASA Astrophysics Data System (ADS)

Sherman, Quentin

Thin film oxidation is investigated using two modeling techniques in the interest of better understanding the roles of space charge and non-equilibrium effects. An electrochemical phase-field model of an oxide-metal interface is formulated in one dimension and studied at equilibrium and during growth. An analogous sharp interface model is developed to validate the phase-field model in the thick film limit. Electrochemical profiles across the oxide are shown to deviate from the sharp interface prediction when the oxide film is thin compared to the Debye length, however no effect on the oxidation kinetics is found. This is attributed to the simple thermodynamic and kinetic models used therein. The phase-field model provides a framework onto to which additional physics can be added to better model thin film oxidation. A model for solute trapping during the oxidation of binary alloys is developed to study non-equilibrium effects during the early stages of oxide growth. The model is applied to NiCr alloys, and steady-state interfacial composition maps are presented for the growth of an oxide with the rock salt structure. No detailed experimental data is available to verify the predictions of the solute trapping model, however it is shown to be consistent with the trends observed during the early stages of NiCr oxidation. Lastly, experimental studies of the wet infiltration technique for decorating solid oxide fuel cell anodes with nickel nanoparticles are presented. The effect of nickel nitrate calcination parameters on the resulting nickel oxide microstructures are studied on both porous and planar substrates. Decreasing the calcination temperature and dwell time, as well as a dehydration step after nickel nitrate infiltration, are all shown to decrease the initial nickel oxide particle size, but other factors such as geometry and nickel loading per unit area also affected the final nickel particle size and morphology upon reduction.

Nanoscale Thermoelectrics: A Study of the Absolute Seebeck Coefficient of Thin Films

NASA Astrophysics Data System (ADS)

Mason, Sarah J.

The worlds demand for energy is ever increasing. Likewise, the environmental impact of climate change due generating that energy through combustion of fossil fuels is increasingly alarming. Due to these factors new sources of renewable energies are constantly being sought out. Thermoelectric devices have the ability to generate clean, renewable, energy out of waste heat. However promising that is, their inefficiency severely inhibits applicability and practical use. The usefulness of a thermoelectric material increases with the dimensionless quantity, ZT, which depends on the Seebeck coefficient and electrical and thermal conductivity. These characteristic material parameters have interdependent energy transport contributions that classically prohibit the optimization of one with out the detriment of another. Encouraging advancements of ZT have occurred in the past ten years due to the decoupling of the thermal and electrical conductivity. Further advancements are necessary in order to produce applicable devices. One auspicious way of decoupling or tuning energy transport properties, is through size reduction to the nanoscale. However, with reduced dimensions come complications in measuring material properties. Measurements of properties such as the Seebeck coefficient, S, are primarily contingent upon the measurement apparatus. The Seebeck coefficient is defined as the amount of voltage generated by a thermal gradient. Measuring a thermally generated voltage by traditional methods gives, the voltage measured as a linear function of the Seebeck coefficient of the leads and of the material being tested divided by the applied thermal gradient. If accurate values of the Seebeck coefficients of the leads are available, simple subtraction provides the answer. This is rarely the case in nanoscale measurement devices with leads exclusively made from thin film materials that do not have well known bulk-like thermopower values. We have developed a technique to directly

Thin film hydrogen sensor

DOEpatents

Cheng, Y.T.; Poli, A.A.; Meltser, M.A.

1999-03-23

A thin film hydrogen sensor includes a substantially flat ceramic substrate with first and second planar sides and a first substrate end opposite a second substrate end; a thin film temperature responsive resistor on the first planar side of the substrate proximate to the first substrate end; a thin film hydrogen responsive metal resistor on the first planar side of the substrate proximate to the fist substrate end and proximate to the temperature responsive resistor; and a heater on the second planar side of the substrate proximate to the first end. 5 figs.

Thin film hydrogen sensor

DOEpatents

Cheng, Yang-Tse; Poli, Andrea A.; Meltser, Mark Alexander

1999-01-01

A thin film hydrogen sensor, includes: a substantially flat ceramic substrate with first and second planar sides and a first substrate end opposite a second substrate end; a thin film temperature responsive resistor on the first planar side of the substrate proximate to the first substrate end; a thin film hydrogen responsive metal resistor on the first planar side of the substrate proximate to the fist substrate end and proximate to the temperature responsive resistor; and a heater on the second planar side of the substrate proximate to the first end.

Molecular dynamics simulations of disjoining pressure effects in ultra-thin water films on a metal surface

NASA Astrophysics Data System (ADS)

Hu, Han; Sun, Ying

2013-11-01

Disjoining pressure, the excess pressure in an ultra-thin liquid film as a result of van der Waals interactions, is important in lubrication, wetting, flow boiling, and thin film evaporation. The classic theory of disjoining pressure is developed for simple monoatomic liquids. However, real world applications often utilize water, a polar liquid, for which fundamental understanding of disjoining pressure is lacking. In the present study, molecular dynamics (MD) simulations are used to gain insights into the effect of disjoining pressure in a water thin film. Our MD models were firstly validated against Derjaguin's experiments on gold-gold interactions across a water film and then verified against disjoining pressure in an argon thin film using the Lennard-Jones potential. Next, a water thin film adsorbed on a gold surface was simulated to examine the change of vapor pressure with film thickness. The results agree well with the classic theory of disjoining pressure, which implies that the polar nature of water molecules does not play an important role. Finally, the effects of disjoining pressure on thin film evaporation in nanoporous membrane and on bubble nucleation are discussed.

Improved performance of single-chamber microbial fuel cells through control of membrane deformation.

PubMed

Zhang, Xiaoyuan; Cheng, Shaoan; Huang, Xia; Logan, Bruce E

2010-03-15

Cation (CEMs) and anion exchange membrane (AEMs) are commonly used in microbial fuel cells (MFCs) to enhance Coulombic efficiencies (CEs) by reducing the flux of oxygen through the cathode to bacteria on the anode. AEMs typically work better than CEMs, but in initial experiments we observed the opposite using a membrane electrode assembly MFC. The reason was identified to be membrane deformation, which resulted in water and gas trapped between the membrane and cathode. To correct this, stainless steel mesh was used to press the membrane flat against the cathode. With the steel mesh, AEM performance increased to 46+/-4 W/m(3) in a single cathode MFC, and 98+/-14 W/m(3) in a double-cathode MFC. These power densities were higher than those using a CEM of 32+/-2 W/m(3) (single cathode) and 63+/-6 W/m(3) (double cathode). Higher pH gradients across the membrane and salt precipitation on the cathode were responsible for the reduced performance of the CEM compared to the AEM. CEs reached over 90% for both membranes at >2A/m(2). These results demonstrate the importance of avoiding water accumulation in thin films between membranes and electrodes, and explain additional reasons for poorer performance of CEMs compared to AEMs. (c) 2009 Elsevier B.V. All rights reserved.

Modeling Mass and Thermal Transport in Thin Porous Media of PEM Fuel Cells

NASA Astrophysics Data System (ADS)

Konduru, Vinaykumar

Water transport in the Porous Transport Layer (PTL) plays an important role in the efficient operation of polymer electrolyte membrane fuel cells (PEMFC). Excessive water content as well as dry operating conditions are unfavorable for efficient and reliable operation of the fuel cell. The effect of thermal conductivity and porosity on water management are investigated by simulating two-phase flow in the PTL of the fuel cell using a network model. In the model, the PTL consists of a pore-phase and a solid-phase. Different models of the PTLs are generated using independent Weibull distributions for the pore-phase and the solid-phase. The specific arrangement of the pores and solid elements is varied to obtain different PTL realizations for the same Weibull parameters. The properties of PTL are varied by changing the porosity and thermal conductivity. The parameters affecting operating conditions include the temperature, relative humidity in the flow channel and voltage and current density. In addition, a novel high-speed capable Surface Plasmon Resonance (SPR) microscope was built based on Kretschmann's configuration utilizing a collimated Kohler illumination. The SPR allows thin film characterization in a thickness of approximately 0-200nm by measuring the changes in the refractive index. Various independent experiments were run to measure film thickness during droplet coalescence during condensation.

Bench Scale Thin Film Composite Hollow Fiber Membranes for Post-Combustion Carbon Dioxide Capture

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

Glaser, Paul; Bhandari, Dhaval; Narang, Kristi

2015-04-01

GE Global Research, Idaho National Laboratory (INL), Georgia Institute of Technology (Georgia Tech), and Western Research Institute (WRI) proposed to develop high performance thin film polymer composite hollow fiber membranes and advanced processes for economical post-combustion carbon dioxide (CO 2) capture from pulverized coal flue gas at temperatures typical of existing flue gas cleanup processes. The project sought to develop and then optimize new gas separations membrane systems at the bench scale, including tuning the properties of a novel polyphosphazene polymer in a coating solution and fabricating highly engineered porous hollow fiber supports. The project also sought to define themore » processes needed to coat the fiber support to manufacture composite hollow fiber membranes with high performance, ultra-thin separation layers. Physical, chemical, and mechanical stability of the materials (individual and composite) towards coal flue gas components was considered via exposure and performance tests. Preliminary design, technoeconomic, and economic feasibility analyses were conducted to evaluate the overall performance and impact of the process on the cost of electricity (COE) for a coal-fired plant including capture technologies. At the onset of the project, Membranes based on coupling a novel selective material polyphosphazene with an engineered hollow fiber support was found to have the potential to capture greater than 90% of the CO 2 in flue gas with less than 35% increase in COE, which would achieve the DOE-targeted performance criteria. While lab-scale results for the polyphosphazene materials were very promising, and the material was incorporated into hollow-fiber modules, difficulties were encountered relating to the performance of these membrane systems over time. Performance, as measured by both flux of and selectivity for CO 2 over other flue gas constituents was found to deteriorate over time, suggesting a system that was more dynamic than

Carbon Nanotube Thin-Film Antennas.

PubMed

Puchades, Ivan; Rossi, Jamie E; Cress, Cory D; Naglich, Eric; Landi, Brian J

2016-08-17

Multiwalled carbon nanotube (MWCNT) and single-walled carbon nanotube (SWCNT) dipole antennas have been successfully designed, fabricated, and tested. Antennas of varying lengths were fabricated using flexible bulk MWCNT sheet material and evaluated to confirm the validity of a full-wave antenna design equation. The ∼20× improvement in electrical conductivity provided by chemically doped SWCNT thin films over MWCNT sheets presents an opportunity for the fabrication of thin-film antennas, leading to potentially simplified system integration and optical transparency. The resonance characteristics of a fabricated chlorosulfonic acid-doped SWCNT thin-film antenna demonstrate the feasibility of the technology and indicate that when the sheet resistance of the thin film is >40 ohm/sq no power is absorbed by the antenna and that a sheet resistance of <10 ohm/sq is needed to achieve a 10 dB return loss in the unbalanced antenna. The dependence of the return loss performance on the SWCNT sheet resistance is consistent with unbalanced metal, metal oxide, and other CNT-based thin-film antennas, and it provides a framework for which other thin-film antennas can be designed.

Surface nanostructuring of thin film composite membranes via grafting polymerization and incorporation of ZnO nanoparticles

NASA Astrophysics Data System (ADS)

Isawi, Heba; El-Sayed, Magdi H.; Feng, Xianshe; Shawky, Hosam; Abdel Mottaleb, Mohamed S.

2016-11-01

A new approach for modification of polyamid thin film composite membrane PA(TFC) using synthesized ZnO nanoparticles (ZnO NPs) was shown to enhance the membrane performances for reverse osmosis water desalination. First, active layer of synthesis PA(TFC) membrane was activated with an aqueous solution of free radical graft polymerization of hydrophilic methacrylic acid (MAA) monomer onto the surface of the PA(TFC) membrane resulting PMAA-g-PA(TFC). Second, the PA(TFC) membrane has been developed by incorporation of ZnO NPs into the MAA grafting solution resulting the ZnO NPs modified PMAA-g-PA(TFC) membrane. The surface properties of the synthesized nanoparticles and prepared membranes were investigated using the FTIR, XRD and SEM. Morphology studies demonstrated that ZnO NPs have been successfully incorporated into the active grafting layer over PA(TFC) composite membranes. The zinc leaching from the ZnO NPs modified PMAA-g-PA(TFC) was minimal, as shown by batch tests that indicated stabilization of the ZnO NPs on the membrane surfaces. Compared with the a pure PA(TFC) and PMAA-g-PA(TFC) membranes, the ZnO NPs modified PMAA-g-PA(TFC) was more hydrophilic, with an improved water contact angle (∼50 ± 3°) over the PMAA-g-PA(TFC) (63 ± 2.5°). The ZnO NPs modified PMAA-g-PA(TFC) membrane showed salt rejection of 97% (of the total groundwater salinity), 99% of dissolved bivalent ions (Ca2+, SO42-and Mg2+), and 98% of mono valent ions constituents (Cl- and Na+). In addition, antifouling performance of the membranes was determined using E. coli as a potential foulant. This demonstrates that the ZnO NPs modified PMAA-g-PA(TFC) membrane can significantly improve the membrane performances and was favorable to enhance the selectivity, permeability, water flux, mechanical properties and the bio-antifouling properties of the membranes for water desalination.

High power density proton exchange membrane fuel cells

NASA Technical Reports Server (NTRS)

Murphy, Oliver J.; Hitchens, G. Duncan; Manko, David J.

1993-01-01

Proton exchange membrane (PEM) fuel cells use a perfluorosulfonic acid solid polymer film as an electrolyte which simplifies water and electrolyte management. Their thin electrolyte layers give efficient systems of low weight, and their materials of construction show extremely long laboratory lifetimes. Their high reliability and their suitability for use in a microgravity environment makes them particularly attractive as a substitute for batteries in satellites utilizing high-power, high energy-density electrochemical energy storage systems. In this investigation, the Dow experimental PEM (XUS-13204.10) and unsupported high platinum loading electrodes yielded very high power densities, of the order of 2.5 W cm(exp -2). A platinum black loading of 5 mg per cm(exp 2) was found to be optimum. On extending the three-dimensional reaction zone of fuel cell electrodes by impregnating solid polymer electrolyte into the electrode structures, Nafion was found to give better performance than the Dow experimental PEM. The depth of penetration of the solid polymer electrolyte into electrode structures was 50-70 percent of the thickness of the platinum-catalyzed active layer. However, the degree of platinum utilization was only 16.6 percent and the roughness factor of a typical electrode was 274.

Long-wave dynamics of an elastic sheet lubricated by a thin liquid film on a wetting substrate

NASA Astrophysics Data System (ADS)

Young, Y.-N.; Stone, H. A.

2017-06-01

The dynamics of an elastic sheet lubricated by a thin liquid film on a wetting solid substrate is examined using both numerical simulations of a long-wave lubrication equation and a quasistatic model. Interactions between the liquid and the wetting substrate are modeled by a disjoining pressure that gives rise to an ultrathin (precursor) film. For a fluid interface without elastic bending stiffness, a flat precursor film may be linearly unstable and evolve towards an equilibrium of a single "drop" connected to a flat ultrathin film. Similar behavior is found when the thin film is covered by an elastic sheet: The sheet deforms, rearranging the thin liquid film, and contributes regulating surface forces such as a bending resistance and/or a tensile force, which may arise from interactions between the sheet and liquid or inextensibility of the sheet. Glasner's quasistatic model [Phys. Fluids 15, 1837 (2003), 10.1063/1.1578076], developed for a liquid film, is adopted to investigate the combined effects of elastic and tensile forces in the sheet on the thin film dynamics. The equilibrium height of the drop is found to vary inversely with the bending rigidity. When the elastic sheet is inextensible (such as a lipid bilayer membrane), a compressive tensile force may occur and the equilibrium film height is dependent less on the bending rigidity and more on the excess area of the membrane. Analyses of the lubrication equation also show that the precursor film transitions monotonically to the core film for tension-dominated dynamics. In contrast, for elasticity-dominated dynamics, a spatial oscillation of film height in the contact line region is found. In addition, elasticity in the sheet causes a sliding motion of the thin film: the contact angle is rendered zero by elasticity, and the contact line moves at a finite speed.

An asymptotic membrane model for wrinkling of very thin films

NASA Astrophysics Data System (ADS)

Battista, Antonio; Hamdouni, Aziz; Millet, Olivier

2018-05-01

In this work, a formal deduction of a two-dimensional membrane theory, similar to Landau-Lifshitz model, is performed via an asymptotic development of the weak formulation of the three-dimensional equations of elasticity. Some interesting aspects of the deduced model are investigated, in particular the property of obtaining a hyperbolic equation for the out-of-plane displacement under a certain class of boundary conditions and loads. Some simple cases are analyzed to show the relevant aspects of the model and the phenomenology that can be addressed. In particular, it is shown how this mathematical formulation is capable to describe instabilities well known as wrinkling, often observed for the buckling of very thin membranes.

Evaluation of pulsed laser deposited SrNb0.1Co0.9O3-δ thin films as promising cathodes for intermediate-temperature solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Chen, Dengjie; Chen, Chi; Gao, Yang; Zhang, Zhenbao; Shao, Zongping; Ciucci, Francesco

2015-11-01

SrNb0.1Co0.9O3-δ (SNC) thin films prepared on single-crystal yttria-stabilized zirconia (YSZ) electrolytes are evaluated as promising cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Geometrically well-defined polycrystalline SNC thin films with low surface roughness and high surface oxygen vacancy concentration are successfully fabricated by pulsed laser deposition. The thin films are characterized by basic techniques, e.g., X-ray diffraction for phase structure identification, scanning electron microscopy and atomic force microscopy for microstructures measurement, and X-ray photoelectron spectroscopy for elements quantification. Electrochemical impedance spectroscopy (EIS) is used to investigate oxygen reduction reaction activities of SNC thin films in symmetric electrochemical cells. Current collectors (Ag paste, Ag strip, and Au strip) are found to have negligible impact on polarization resistances. A slight decrease of the electrode polarization resistances is observed after adding a samarium doped ceria (SDC) buffer layer between SNC and YSZ. SNC thin-film electrodes exhibit low electrode polarization resistances, e.g., 0.237 Ω cm2 (SNC/SDC/YSZ/SDC/SNC) and 0.274 Ω cm2 (SNC/YSZ/SNC) at 700 °C and 0.21 atm, demonstrating the promise of SNC materials for IT-SOFCs. An oxygen reduction reaction mechanism of SNC thin films is also derived by analyzing EIS at temperature of 550-700 °C under oxygen partial pressure range of 0.04-1 atm.

Thin Films

NASA Astrophysics Data System (ADS)

Khorshidi, Zahra; Bahari, Ali; Gholipur, Reza

2014-11-01

Effect of annealing temperature on the characteristics of sol-gel-driven Ta ax La(1- a) x O y thin film spin-coated on Si substrate as a high- k gate dielectric was studied. Ta ax La(1- a) x O y thin films with different amounts of a were prepared (as-prepared samples). X-ray diffraction measurements of the as-prepared samples indicated that Ta0.3 x La0.7 x Oy film had an amorphous structure. Therefore, Ta0.3 x La0.7 x O y film was chosen to continue the present studies. The morphology of Ta0.3 x La0.7 x O y films was studied using scanning electron microscopy and atomic force microscopy techniques. The obtained results showed that the size of grain boundaries on Ta0.3 x La0.7 x O y film surfaces was increased with increasing annealing temperature. Electrical and optical characterizations of the as-prepared and annealed films were investigated as a function of annealing temperature using capacitance-voltage ( C- V) and current density-voltage ( J- V) measurements and the Tauc method. The obtained results demonstrated that Ta0.3 x La0.7 x O y films had high dielectric constant (≈27), wide band gap (≈4.5 eV), and low leakage current density (≈10-6 A/cm2 at 1 V).

Performance and Durability of Thin Film Thermocouple Array on a Porous Electrode.

PubMed

Guk, Erdogan; Ranaweera, Manoj; Venkatesan, Vijay; Kim, Jung-Sik

2016-08-23

Management of solid oxide fuel cell (SOFC) thermal gradients is vital to limit thermal expansion mismatch and thermal stress. However, owing to harsh operation conditions of SOFCs and limited available space in stack configuration, the number of techniques available to obtain temperature distribution from the cell surface is limited. The authors previously developed and studied a thermocouple array pattern to detect surface temperature distribution on an SOFC in open circuit conditions. In this study, the performance in terms of mechanical durability and oxidation state of the thin film thermoelements of the thermocouple array on the porous SOFC cathode is investigated. A thin-film multi-junction thermocouple array was sputter deposited using a magnetron sputter coater. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) characterisation techniques were carried out to understand characteristics of the thin film before and after temperature (20 °C-800 °C) measurement. Temperature readings from the sensor agreed well with the closely placed commercial thermocouple during heating segments. However, a sensor failure occurred at around 350 °C during the cooling segment. The SEM and XPS tests revealed cracks on the thin film thermoelements and oxidation to the film thickness direction.

Performance and Durability of Thin Film Thermocouple Array on a Porous Electrode

PubMed Central

Guk, Erdogan; Ranaweera, Manoj; Venkatesan, Vijay; Kim, Jung-Sik

2016-01-01

Management of solid oxide fuel cell (SOFC) thermal gradients is vital to limit thermal expansion mismatch and thermal stress. However, owing to harsh operation conditions of SOFCs and limited available space in stack configuration, the number of techniques available to obtain temperature distribution from the cell surface is limited. The authors previously developed and studied a thermocouple array pattern to detect surface temperature distribution on an SOFC in open circuit conditions. In this study, the performance in terms of mechanical durability and oxidation state of the thin film thermoelements of the thermocouple array on the porous SOFC cathode is investigated. A thin-film multi-junction thermocouple array was sputter deposited using a magnetron sputter coater. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) characterisation techniques were carried out to understand characteristics of the thin film before and after temperature (20 °C–800 °C) measurement. Temperature readings from the sensor agreed well with the closely placed commercial thermocouple during heating segments. However, a sensor failure occurred at around 350 °C during the cooling segment. The SEM and XPS tests revealed cracks on the thin film thermoelements and oxidation to the film thickness direction. PMID:27563893

An energy landscape based approach for studying supercooled liquid and glassy thin films

NASA Astrophysics Data System (ADS)

Shah, Pooja; Mittal, Jeetain; Truskett, Thomas M.

2004-03-01

Materials in confined spaces are important in science and technology. Examples include biological fluids in membranes, liquids trapped in porous rocks, and thin-film materials used in high-resolution patterning technologies. However, few reliable rules exist to predict how the properties of materials will be affected by thin-film confinement. We have recently shown that the potential energy landscape formalism can be used to study, by both theory [1] and simulation [2], how the behavior of thin-film materials depends on sample dimensions and film-substrate interactions. Our landscape-based mean-field theory [1] can be used to study both the thermodynamic properties and the ideal glass transition of thin films. It predicts that, in the case of neutral or repulsive walls, the ideal glass transition temperature is lowered by decreasing film thickness. This is in qualitative agreement with experimental trends for the kinetic glass transition in confined fluids. Landscape-based approaches are also valuable for understanding the structural and mechanical properties of thin-film glasses. We demonstrate how the concept of an "equation of state of the energy landscape" [3] can be generalized to thin films [1, 2], where it gives insights into potential molecular mechanisms of tensile strength. [1] T. M. Truskett and V. Ganesan, J. Chem. Phys. 119, 1897-1900(2003); J. Mittal, P. Shah and T. M. Truskett, to be submitted to Langmuir. [2] P. Shah and T. M. Truskett, to be submitted to J. Phys. Chem. B. [3] S. Sastry, P. G. Debenedetti and F. H. Stillinger, Phys. Rev. E 56, 5533 (1997)

Decoding Nucleation and Growth of Zeolitic Imidazolate Framework Thin Films with Atomic Force Microscopy and Vibrational Spectroscopy.

PubMed

Öztürk, Zafer; Filez, Matthias; Weckhuysen, Bert M

2017-08-10

The synthesis of metal-organic framework (MOF) thin films has garnered significant attention during the past decade. By better understanding the parameters governing the nucleation and growth of such thin films, their properties can be rationally tuned, empowering their application as (reactive) membranes. Here, a combined AFM-vibrational spectroscopy research strategy is employed to detail the chemistries governing the nucleation and growth of zeolitic imidazolate framework (ZIF) thin films, in particular isostructural Co-ZIF-67 and Zn-ZIF-8. First, a single step direct synthesis approach is used to investigate the influence of different synthesis parameters -metal/linker ratio, temperature, and metal type- on the thin film nucleation and growth behaviour. While the metal/linker ratio has a pronounced effect on the thin film nucleation rate, the temperature mainly influences the growth kinetics of nuclei forming the thin film. In addition, the nucleation and growth of ZIF thin films is shown to be highly dependent on the electronegativity of the metal type. Thin-film thickness control can be achieved by using a multistep synthesis strategy, implying repetitive applications of single step deposition under identical synthesis conditions, for which a growth mechanism is proposed. This study provides insight into the influence of synthesis parameters on the ZIF thin film properties, using tools at hand to rationally tune MOF thin film properties. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Substrate spacing and thin-film yield in chemical bath deposition of semiconductor thin films

NASA Astrophysics Data System (ADS)

Arias-Carbajal Reádigos, A.; García, V. M.; Gomezdaza, O.; Campos, J.; Nair, M. T. S.; Nair, P. K.

2000-11-01

Thin-film yield in the chemical bath deposition technique is studied as a function of separation between substrates in batch production. Based on a mathematical model, it is proposed and experimentally verified in the case of CdS thin films that the film thickness reaches an asymptotic maximum with increase in substrate separation. It is shown that at a separation less than 1 mm between substrates the yield, i.e. percentage in moles of a soluble cadmium salt deposited as a thin film of CdS, can exceed 50%. This behaviour is explained on the basis of the existence of a critical layer of solution near the substrate, within which the relevant ionic species have a higher probability of interacting with the thin-film layer than of contributing to precipitate formation. The critical layer depends on the solution composition and the temperature of the bath as well as the duration of deposition. An effective value for the critical layer thickness has been defined as half the substrate separation at which 90% of the maximum film thickness for the particular bath composition, bath temperature and duration of deposition is obtained. In the case of CdS thin films studied as an example, the critical layer is found to extend from 0.5 to 2.5 mm from the substrate surface, depending on the deposition conditions.

Dielectric loss of strontium titanate thin films

NASA Astrophysics Data System (ADS)

Dalberth, Mark Joseph

1999-12-01

Interest in strontium titanate (STO) thin films for microwave device applications continues to grow, fueled by the telecommunications industry's interest in phase shifters and tunable filters. The optimization of these devices depends upon increasing the phase or frequency tuning and decreasing the losses in the films. Currently, the dielectric response of thin film STO is poorly understood through lack of data and a theory to describe it. We have studied the growth of STO using pulsed laser deposition and single crystal substrates like lanthanum aluminate and neodymium gallate. We have researched ways to use ring resonators to accurately measure the dielectric response as a function of temperature, electric field, and frequency from low radio frequencies to a few gigahertz. Our films grown on lanthanum aluminate show marked frequency dispersion in the real part of the dielectric constant and hints of thermally activated loss behavior. We also found that films grown with conditions that optimized the dielectric constant showed increased losses. In an attempt to simplify the system, we developed a technique called epitaxial lift off, which has allowed us to study films removed from their growth substrates. These free standing films have low losses and show obvious thermally activated behavior. The "amount of tuning," as measured by a figure of merit, KE, is greater in these films than in the films still attached to their growth substrates. We have developed a theory that describes the real and imaginary parts of the dielectric constant. The theory models the real part using a mean field description of the ionic motion in the crystal and includes the loss by incorporating the motion of charged defects in the films.

Robust fabrication of thin film polyamide-TiO2 nanocomposite membranes with enhanced thermal stability and anti-biofouling propensity.

PubMed

Khorshidi, Behnam; Biswas, Ishita; Ghosh, Tanushree; Thundat, Thomas; Sadrzadeh, Mohtada

2018-01-15

The development of nano-enabled composite materials has led to a paradigm shift in the manufacture of high-performance nanocomposite membranes with enhanced permeation, thermo-mechanical, and antibacterial properties. The major challenges to the successful incorporation of nanoparticles (NPs) to polymer films are the severe aggregation of the NPs and the weak compatibility of NPs with polymers. These two phenomena lead to the formation of non-selective voids at the interface of the polymer and NPs, which adversely affect the separation performance of the membrane. To overcome these challenges, we have developed a new method for the fabrication of robust TFN reverse osmosis membranes. This approach relies on the simultaneous synthesis and surface functionalization of TiO 2 NPs in an organic solvent (heptane) via biphasic solvothermal reaction. The resulting stable suspension of the TiO 2 NPs in heptane was then utilized in the interfacial (in-situ) polymerization reaction where the NPs were entrapped within the matrix of the polyamide (PA) membrane. TiO 2 NPs of 10 nm were effectively incorporated into the thin PA layer and improved the thermal stability and anti-biofouling properties of the resulting TFN membranes. These features make our synthesized membranes potential candidates for applications where the treatment of high-temperature streams containing biomaterials is desirable.

Praseodymium Cuprate Thin Film Cathodes for Intermediate Temperature Solid Oxide Fuel Cells: Roles of Doping, Orientation, and Crystal Structure.

PubMed

Mukherjee, Kunal; Hayamizu, Yoshiaki; Kim, Chang Sub; Kolchina, Liudmila M; Mazo, Galina N; Istomin, Sergey Ya; Bishop, Sean R; Tuller, Harry L

2016-12-21

Highly textured thin films of undoped, Ce-doped, and Sr-doped Pr 2 CuO 4 were synthesized on single crystal YSZ substrates using pulsed laser deposition to investigate their area-specific resistance (ASR) as cathodes in solid-oxide fuel cells (SOFCs). The effects of T' and T* crystal structures, donor and acceptor doping, and a-axis and c-axis orientation on ASR were systematically studied using electrochemical impedance spectroscopy on half cells. The addition of both Ce and Sr dopants resulted in improvements in ASR in c-axis oriented films, as did the T* crystal structure with the a-axis orientation. Pr 1.6 Sr 0.4 CuO 4 is identified as a potential cathode material with nearly an order of magnitude faster oxygen reduction reaction kinetics at 600 °C compared to thin films of the commonly studied cathode material La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3-δ . Orientation control of the cuprate films on YSZ was achieved using seed layers, and the anisotropy in the ASR was found to be less than an order of magnitude. The rare-earth doped cuprate was found to be a versatile system for study of relationships between bulk properties and the oxygen reduction reaction, critical for improving SOFC performance.

Imidazolium-Based Polymeric Materials as Alkaline Anion-Exchange Fuel Cell Membranes

NASA Technical Reports Server (NTRS)

Narayan, Sri R.; Yen, Shiao-Ping S.; Reddy, Prakash V.; Nair, Nanditha

2012-01-01

Polymer electrolyte membranes that conduct hydroxide ions have potential use in fuel cells. A variety of polystyrene-based quaternary ammonium hydroxides have been reported as anion exchange fuel cell membranes. However, the hydrolytic stability and conductivity of the commercially available membranes are not adequate to meet the requirements of fuel cell applications. When compared with commercially available membranes, polystyrene-imidazolium alkaline membrane electrolytes are more stable and more highly conducting. At the time of this reporting, this has been the first such usage for imidazolium-based polymeric materials for fuel cells. Imidazolium salts are known to be electrochemically stable over wide potential ranges. By controlling the relative ratio of imidazolium groups in polystyrene-imidazolium salts, their physiochemical properties could be modulated. Alkaline anion exchange membranes based on polystyrene-imidazolium hydroxide materials have been developed. The first step was to synthesize the poly(styrene-co-(1-((4-vinyl)methyl)-3- methylimidazolium) chloride through a free-radical polymerization. Casting of this material followed by in situ treatment of the membranes with sodium hydroxide solutions provided the corresponding hydroxide salts. Various ratios of the monomers 4-chloromoethylvinylbenzine (CMVB) and vinylbenzine (VB) provided various compositions of the polymer. The preferred material, due to the relative ease of casting the film, and its relatively low hygroscopic nature, was a 2:1 ratio of CMVB to VB. Testing confirmed that at room temperature, the new membranes outperformed commercially available membranes by a large margin. With fuel cells now in use at NASA and in transportation, and with defense potential, any improvement to fuel cell efficiency is a significant development.

Thin-film metal hydrides.

PubMed

Remhof, Arndt; Borgschulte, Andreas

2008-12-01

The goal of the medieval alchemist, the chemical transformation of common metals into nobel metals, will forever be a dream. However, key characteristics of metals, such as their electronic band structure and, consequently, their electric, magnetic and optical properties, can be tailored by controlled hydrogen doping. Due to their morphology and well-defined geometry with flat, coplanar surfaces/interfaces, novel phenomena may be observed in thin films. Prominent examples are the eye-catching hydrogen switchable mirror effect, the visualization of solid-state diffusion and the formation of complex surface morphologies. Thin films do not suffer as much from embrittlement and/or decrepitation as bulk materials, allowing the study of cyclic absorption and desorption. Therefore, thin-metal hydride films are used as model systems to study metal-insulator transitions, for high throughput combinatorial research or they may be used as indicator layers to study hydrogen diffusion. They can be found in technological applications as hydrogen sensors, in electrochromic and thermochromic devices. In this review, we discuss the effect of hydrogen loading of thin niobium and yttrium films as archetypical examples of a transition metal and a rare earth metal, respectively. Our focus thereby lies on the hydrogen induced changes of the electronic structure and the morphology of the thin films, their optical properties, the visualization and the control of hydrogen diffusion and on the study of surface phenomena and catalysis.

Temperature Behavior of Thin Film Varactor

DTIC Science & Technology

2012-01-01

Temperature Behavior of Thin Film Varactor By Richard X. Fu ARL-TR-5905 January 2012...Thin Film Varactor Richard X. Fu Sensors and Electron Devices Directorate, ARL...DD-MM-YYYY) January 2012 2. REPORT TYPE Final 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Temperature Behavior of Thin Film Varactor 5a

Self-Limited Growth in Pentacene Thin Films

PubMed Central

2017-01-01

Pentacene is one of the most studied organic semiconducting materials. While many aspects of the film formation have already been identified in very thin films, this study provides new insight into the transition from the metastable thin-film phase to bulk phase polymorphs. This study focuses on the growth behavior of pentacene within thin films as a function of film thickness ranging from 20 to 300 nm. By employing various X-ray diffraction methods, combined with supporting atomic force microscopy investigations, one crystalline orientation for the thin-film phase is observed, while three differently tilted bulk phase orientations are found. First, bulk phase crystallites grow with their 00L planes parallel to the substrate surface; second, however, crystallites tilted by 0.75° with respect to the substrate are found, which clearly dominate the former in ratio; third, a different bulk phase polymorph with crystallites tilted by 21° is found. The transition from the thin-film phase to the bulk phase is rationalized by the nucleation of the latter at crystal facets of the thin-film-phase crystallites. This leads to a self-limiting growth of the thin-film phase and explains the thickness-dependent phase behavior observed in pentacene thin films, showing that a large amount of material is present in the bulk phase much earlier during the film growth than previously thought. PMID:28287698

Self-Limited Growth in Pentacene Thin Films.

PubMed

Pachmajer, Stefan; Jones, Andrew O F; Truger, Magdalena; Röthel, Christian; Salzmann, Ingo; Werzer, Oliver; Resel, Roland

2017-04-05

Pentacene is one of the most studied organic semiconducting materials. While many aspects of the film formation have already been identified in very thin films, this study provides new insight into the transition from the metastable thin-film phase to bulk phase polymorphs. This study focuses on the growth behavior of pentacene within thin films as a function of film thickness ranging from 20 to 300 nm. By employing various X-ray diffraction methods, combined with supporting atomic force microscopy investigations, one crystalline orientation for the thin-film phase is observed, while three differently tilted bulk phase orientations are found. First, bulk phase crystallites grow with their 00L planes parallel to the substrate surface; second, however, crystallites tilted by 0.75° with respect to the substrate are found, which clearly dominate the former in ratio; third, a different bulk phase polymorph with crystallites tilted by 21° is found. The transition from the thin-film phase to the bulk phase is rationalized by the nucleation of the latter at crystal facets of the thin-film-phase crystallites. This leads to a self-limiting growth of the thin-film phase and explains the thickness-dependent phase behavior observed in pentacene thin films, showing that a large amount of material is present in the bulk phase much earlier during the film growth than previously thought.

An Effective Design of Electrically Conducting Thin-Film Composite (TFC) Membranes for Bio and Organic Fouling Control in Forward Osmosis (FO).

PubMed

Liu, Qing; Qiu, Guanglei; Zhou, Zhengzhong; Li, Jingguo; Amy, Gary Lee; Xie, Jianping; Lee, Jim Yang

2016-10-04

The organic foulants and bacteria in secondary wastewater treatment can seriously impair the membrane performance in a water treatment plant. The embedded electrode approach using an externally applied potential to repel organic foulants and inhibit bacterial adhesion can effectively reduce the frequency of membrane replacement. Electrode embedment in membranes is often carried out by dispensing a conductor (e.g., carbon nanotubes, or CNTs) in the membrane substrate, which gives rise to two problems: the leaching-out of the conductor and a percolation-limited membrane conductivity that results in an added energy cost. This study presents a facile method for the embedment of a continuous electrode in thin-film composite (TFC) forward osmosis (FO) membranes. Specifically, a conducting porous carbon paper is used as the understructure for the formation of a membrane substrate by the classical phase inversion process. The carbon paper and the membrane substrate polymer form an interpenetrating structure with good stability and low electrical resistance (only about 1Ω/□). The membrane-electrode assembly was deployed as the cathode of an electrochemical cell, and showed good resistance to organic and microbial fouling with the imposition of a 2.0 V DC voltage. The carbon paper-based FO TFC membranes also possess good mechanical stability for practical use.

Metallic Thin-Film Bonding and Alloy Generation

NASA Technical Reports Server (NTRS)

Peotter, Brian S. (Inventor); Fryer, Jack Merrill (Inventor); Campbell, Geoff (Inventor); Droppers, Lloyd (Inventor)

2016-01-01

Diffusion bonding a stack of aluminum thin films is particularly challenging due to a stable aluminum oxide coating that rapidly forms on the aluminum thin films when they are exposed to atmosphere and the relatively low meting temperature of aluminum. By plating the individual aluminum thin films with a metal that does not rapidly form a stable oxide coating, the individual aluminum thin films may be readily diffusion bonded together using heat and pressure. The resulting diffusion bonded structure can be an alloy of choice through the use of a carefully selected base and plating metals. The aluminum thin films may also be etched with distinct patterns that form a microfluidic fluid flow path through the stack of aluminum thin films when diffusion bonded together.

Silver Nanoparticle Enhanced Freestanding Thin-Film Silicon Solar Cells

NASA Astrophysics Data System (ADS)

Winans, Joshua David

As the supply of fossil fuels diminishes in quantity the demand for alternative energy sources will consistently increase. Solar cells are an environmentally friendly and proven technology that suffer in sales due to a large upfront cost. In order to help facilitate the transition from fossil fuels to photovoltaics, module costs must be reduced to prices well below $1/Watt. Thin-film solar cells are more affordable because of the reduced materials costs, but lower in efficiency because less light is absorbed before passing through the cell. Silver nanoparticles placed at the front surface of the solar cell absorb and reradiate the energy of the light in ways such that more of the light ends being captured by the silicon. Silver nanoparticles can do this because they have free electron clouds that can take on the energy of an incident photon through collective action. This bulk action of the electrons is called a plasmon. This work begins by discussing the economics driving the need for reduced material use, and the pros and cons of taking this step. Next, the fundamental theory of light-matter interaction is briefly described followed by an introduction to the study of plasmonics. Following that we discuss a traditional method of silver nanoparticle formation and the initial experimental studies of their effects on the ability of thin-film silicon to absorb light. Then, Finite-Difference Time-Domain simulation software is used to simulate the effects of nanoparticle morphology and size on the scattering of light at the surface of the thin-film.

Printable CIGS thin film solar cells

NASA Astrophysics Data System (ADS)

Fan, Xiaojuan

2014-03-01

Among the various thin film solar cells in the market, CuInGaSe thin film cells have been considered as the most promising alternatives to silicon solar cells because of their high photo-electricity efficiency, reliability, and stability. However, many fabrication of CIGS thin film are based on vacuum processes such as evaporation sputtering techniques which are not cost efficient. This work develops a method using paste or ink liquid spin-coated on glass that would be to conventional ways in terms of cost effective, non-vacuum needed, quick processing. A mixture precursor was prepared by dissolving appropriate amounts of chemicals. After the mixture solution was cooled, a viscous paste prepared and ready for spin-coating process. A slight bluish CIG thin film substrate was then put in a tube furnace with evaporation of metal Se by depositing CdS layer and ZnO nanoparticle thin film coating to a solar cell fabrication. Structure, absorption spectrum, and photo-conversion efficiency for the as-grown CIGS thin film solar cell under study.

Highly robust thin-film composite pressure retarded osmosis (PRO) hollow fiber membranes with high power densities for renewable salinity-gradient energy generation.

PubMed

Han, Gang; Wang, Peng; Chung, Tai-Shung

2013-07-16

The practical application of pressure retarded osmosis (PRO) technology for renewable blue energy (i.e., osmotic power generation) from salinity gradient is being hindered by the absence of effective membranes. Compared to flat-sheet membranes, membranes with a hollow fiber configuration are of great interest due to their high packing density and spacer-free module fabrication. However, the development of PRO hollow fiber membranes is still in its infancy. This study aims to open up new perspectives and design strategies to molecularly construct highly robust thin film composite (TFC) PRO hollow fiber membranes with high power densities. The newly developed TFC PRO membranes consist of a selective polyamide skin formed on the lumen side of well-constructed Matrimid hollow fiber supports via interfacial polymerization. For the first time, laboratory PRO power generation tests demonstrate that the newly developed PRO hollow fiber membranes can withstand trans-membrane pressures up to 16 bar and exhibit a peak power density as high as 14 W/m(2) using seawater brine (1.0 M NaCl) as the draw solution and deionized water as the feed. We believe that the developed TFC PRO hollow fiber membranes have great potential for osmotic power harvesting.

Thin film temperature sensor

NASA Technical Reports Server (NTRS)

Grant, H. P.; Przybyszewski, J. S.

1980-01-01

Thin film surface temperature sensors were developed. The sensors were made of platinum-platinum/10 percent rhodium thermocouples with associated thin film-to-lead wire connections and sputtered on aluminum oxide coated simulated turbine blades for testing. Tests included exposure to vibration, low velocity hydrocarbon hot gas flow to 1250 K, and furnace calibrations. Thermal electromotive force was typically two percent below standard type S thermocouples. Mean time to failure was 42 hours at a hot gas flow temperature of 1250 K and an average of 15 cycles to room temperature. Failures were mainly due to separation of the platinum thin film from the aluminum oxide surface. Several techniques to improve the adhesion of the platinum are discussed.

Capillarity-induced folds fuel extreme shape changes in thin wicked membranes.

PubMed

Grandgeorge, Paul; Krins, Natacha; Hourlier-Fargette, Aurélie; Laberty-Robert, Christel; Neukirch, Sébastien; Antkowiak, Arnaud

2018-04-20

Soft deformable materials are needed for applications such as stretchable electronics, smart textiles, or soft biomedical devices. However, the design of a durable, cost-effective, or biologically compatible version of such a material remains challenging. Living animal cells routinely cope with extreme deformations by unfolding preformed membrane reservoirs available in the form of microvilli or membrane folds. We synthetically mimicked this behavior by creating nanofibrous liquid-infused tissues that spontaneously form similar reservoirs through capillarity-induced folding. By understanding the physics of membrane buckling within the liquid film, we developed proof-of-concept conformable chemical surface treatments and stretchable basic electronic circuits. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Analysis of Hard Thin Film Coating

NASA Technical Reports Server (NTRS)

Shen, Dashen

1998-01-01

Marshall Space Flight Center (MSFC) is interested in developing hard thin film coating for bearings. The wearing of the bearing is an important problem for space flight engine. Hard thin film coating can drastically improve the surface of the bearing and improve the wear-endurance of the bearing. However, many fundamental problems in surface physics, plasma deposition, etc, need further research. The approach is using Electron Cyclotron Resonance Chemical Vapor Deposition (ECRCVD) to deposit hard thin film on stainless steel bearing. The thin films in consideration include SiC, SiN and other materials. An ECRCVD deposition system is being assembled at MSFC.

Analysis of Hard Thin Film Coating

NASA Technical Reports Server (NTRS)

Shen, Dashen

1998-01-01

MSFC is interested in developing hard thin film coating for bearings. The wearing of the bearing is an important problem for space flight engine. Hard thin film coating can drastically improve the surface of the bearing and improve the wear-endurance of the bearing. However, many fundamental problems in surface physics, plasma deposition, etc, need further research. The approach is using electron cyclotron resonance chemical vapor deposition (ECRCVD) to deposit hard thin film an stainless steel bearing. The thin films in consideration include SiC, SiN and other materials. An ECRCVD deposition system is being assembled at MSFC.

Nanocrystal thin film fabrication methods and apparatus

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

Kagan, Cherie R.; Kim, David K.; Choi, Ji-Hyuk

Nanocrystal thin film devices and methods for fabricating nanocrystal thin film devices are disclosed. The nanocrystal thin films are diffused with a dopant such as Indium, Potassium, Tin, etc. to reduce surface states. The thin film devices may be exposed to air during a portion of the fabrication. This enables fabrication of nanocrystal-based devices using a wider range of techniques such as photolithography and photolithographic patterning in an air environment.

Thin-film rechargeable lithium batteries

NASA Astrophysics Data System (ADS)

Dudney, N. J.; Bates, J. B.; Lubben, D.

1994-11-01

Small thin-film rechargeable cells have been fabricated with a lithium phosphorus oxynitride electrolyte, Li metal anode, and Li(1-x)Mn2O4 as the cathode film. The cathode films were fabricated by several different techniques resulting in both crystalline and amorphous films. These were compared by observing the cell discharge behavior. Estimates have been made for the scale-up of such a thin-film battery to meet the specifications for the electric vehicle application. The specific energy, energy density, and cycle life are expected to meet the USABC mid-term criteria. However, the areas of the thin-films needed to fabricate such a cell are very large. The required areas could be greatly reduced by operating the battery at temperatures near 100 C or by enhancing the lithium ion transport rate in the cathode material.

Copper Phthalocyanine Functionalized Single-Walled Carbon Nanotubes: Thin Films for Optical Detection.

PubMed

Banimuslem, Hikmat; Hassan, Aseel; Basova, Tamara; Durmuş, Mahmut; Tuncel, Sinem; Esenpinar, Aliye Asli; Gürek, Ayşe Gül; Ahsen, Vefa

2015-03-01

Thin films of non-covalently hybridized single-walled carbon nanotubes (SWCNT) and tetra-substituted copper phthalocyanine (CuPcR4) molecules have been produced from their solutions in dimethylformamide (DMF). FTIR spectra revealed the 7π-7π interaction between SWCNTs and CuPcR4 molecules. DC conductivity of films of acid-treated SWCNT/CuPcR4 hybrid has increased by more than three orders of.magnitude in comparison with conductivity of CuPcR4 films. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurements have shown that films obtained from the acid-treated SWCNTs/CuPcR4 hybrids demonstrated more homogenous surface which is ascribed to the highly improved solubility of the hybrid powder in DMF Using total internal reflection ellipsometry spectroscopy (TIRE), thin films of the new hybrid have been examined as an optical sensing membrane for the detection of benzo[a]pyrene in water to demonstrate the sensing properties of the hybrid.

Thin film-coated polymer webs

DOEpatents

Wenz, Robert P.; Weber, Michael F.; Arudi, Ravindra L.

1992-02-04

The present invention relates to thin film-coated polymer webs, and more particularly to thin film electronic devices supported upon a polymer web, wherein the polymer web is treated with a purifying amount of electron beam radiation.

Thin film solar cell workshop

NASA Technical Reports Server (NTRS)

Armstrong, Joe; Jeffrey, Frank

1993-01-01

A summation of responses to questions posed to the thin-film solar cell workshop and the ensuing discussion is provided. Participants in the workshop included photovoltaic manufacturers (both thin film and crystalline), cell performance investigators, and consumers.

The reasons for the high power density of fuel cells fabricated with directly deposited membranes

NASA Astrophysics Data System (ADS)

Vierrath, Severin; Breitwieser, Matthias; Klingele, Matthias; Britton, Benjamin; Holdcroft, Steven; Zengerle, Roland; Thiele, Simon

2016-09-01

In a previous study, we reported that polymer electrolyte fuel cells prepared by direct membrane deposition (DMD) produced power densities in excess of 4 W/cm2. In this study, the underlying origins that give rise to these high power densities are investigated and reported. The membranes of high power, DMD-fabricated fuel cells are relatively thin (12 μm) compared to typical benchmark, commercially available membranes. Electrochemical impedance spectroscopy, at high current densities (2.2 A/cm2) reveals that mass transport resistance was half that of reference, catalyst-coated-membranes (CCM). This is attributed to an improved oxygen supply in the cathode catalyst layer by way of a reduced propensity of flooding, and which is facilitated by an enhancement in the back diffusion of water from cathode to anode through the thin directly deposited membrane. DMD-fabricated membrane-electrode-assemblies possess 50% reduction in ionic resistance (15 mΩcm2) compared to conventional CCMs, with contributions of 9 mΩcm2 for the membrane resistance and 6 mΩcm2 for the contact resistance of the membrane and catalyst layer ionomer. The improved mass transport is responsible for 90% of the increase in power density of the DMD fuel cell, while the reduced ionic resistance accounts for a 10% of the improvement.

Structural and electrical transport properties of La2Mo2O9 thin films prepared by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Paul, T.; Ghosh, A.

2017-04-01

We have studied the structure and electrical properties of La2Mo2O9 thin films of different thicknesses prepared by the laser deposition technique at different substrate temperatures. The structural properties of the thin films have been investigated using XRD, XPS, AFM, TEM, SEM, and Raman spectroscopy. The electrical transport properties of the thin films have been investigated in wide temperature and frequency ranges. The cubic nature of the thin films has been confirmed from structural analysis. An enhancement of the oxygen ion conductivity of the films up to five orders of magnitude is obtained compared to that of the bulk La2Mo2O9, suggesting usefulness of the thin films as electrolytes in micro-solid oxide fuel cells. The enhanced dc ionic conductivity of the thin films has been interpreted using the rule of the mixture model, while a power law model has been used to investigate the frequency and temperature dependences of the conductivity. The analysis of the results predicts the three-dimensional oxygen ion conduction in the thin films.

Infrared radiation of thin plastic films.

NASA Technical Reports Server (NTRS)

Tien, C. L.; Chan, C. K.; Cunnington, G. R.

1972-01-01

A combined analytical and experimental study is presented for infrared radiation characteristics of thin plastic films with and without a metal substrate. On the basis of the thin-film analysis, a simple analytical technique is developed for determining band-averaged optical constants of thin plastic films from spectral normal transmittance data for two different film thicknesses. Specifically, the band-averaged optical constants of polyethylene terephthalate and polyimide were obtained from transmittance measurements of films with thicknesses in the range of 0.25 to 3 mil. The spectral normal reflectance and total normal emittance of the film side of singly aluminized films are calculated by use of optical constants; the results compare favorably with measured values.

Thin Polymer Films with Continuous Vertically Aligned 1 nm Pores Fabricated by Soft Confinement

DOE PAGES

Feng, Xunda; Nejati, Siamak; Cowan, Matthew G.; ...

2015-12-03

Membrane separations are critically important in areas ranging from health care and analytical chemistry to bioprocessing and water purification. An ideal nanoporous membrane would consist of a thin film with physically continuous and vertically aligned nanopores and would display a narrow distribution of pore sizes. However, the current state of the art departs considerably from this ideal and is beset by intrinsic trade-offs between permeability and selectivity. We demonstrate an effective and scalable method to fabricate polymer films with ideal membrane morphologies consisting of submicron thickness films with physically continuous and vertically aligned 1 nm pores. The approach is basedmore » on soft confinement to control the orientation of a cross-linkable mesophase in which the pores are produced by self-assembly. The scalability, exceptional ease of fabrication, and potential to create a new class of nanofiltration membranes stand out as compelling aspects.« less

Relation of planar Hall and planar Nernst effects in thin film permalloy

NASA Astrophysics Data System (ADS)

Wesenberg, D.; Hojem, A.; Bennet, R. K.; Zink, B. L.

2018-06-01

We present measurements of the planar Nernst effect (PNE) and the planar Hall effect (PHE) of nickel-iron (Ni–Fe) alloy thin films. We suspend the thin-film samples, measurement leads, and lithographically-defined heaters and thermometers on silicon-nitride membranes to greatly simplify control and measurement of thermal gradients essential to quantitative determination of magnetothermoelectric effects. Since these thermal isolation structures allow measurements of longitudinal thermopower, or the Seebeck coefficient, and four-wire electrical resistivity of the same thin film, we can quantitatively demonstrate the link between the longitudinal and transverse effects as a function of applied in-plane field and angle. Finite element thermal analysis of this essentially 2D structure allows more confident determination of the thermal gradient, which is reduced from the simplest assumptions due to the particular geometry of the membranes, which are more than 350 μm wide in order to maximize sensitivity to transverse thermoelectric effects. The resulting maximum values of the PNE and PHE coefficients for the Ni–Fe film with 80% Ni we study here are and , respectively. All signals are exclusively symmetry with applied field, ruling out long-distance spin transport effects. We also consider a Mott-like relation between the PNE and PHE, and use both this and the standard Mott relation to determine the energy-derivative of the resistivity at the Fermi energy to be , which is very similar to values for films we previously measured using similar thermal platforms. Finally, using an estimated value for the lead contribution to the longitudinal thermopower, we show that the anisotropic magnetoresistance (AMR) ratio in this Ni–Fe film is two times larger than the magnetothermopower ratio, which is the first evidence of a deviation from strict adherence to the Mott relation between Seebeck coefficient and resistivity.

Permanent laser conditioning of thin film optical materials

DOEpatents

Wolfe, C. Robert; Kozlowski, Mark R.; Campbell, John H.; Staggs, Michael; Rainer, Frank

1995-01-01

The invention comprises a method for producing optical thin films with a high laser damage threshold and the resulting thin films. The laser damage threshold of the thin films is permanently increased by irradiating the thin films with a fluence below an unconditioned laser damage threshold.

Permanent laser conditioning of thin film optical materials

DOEpatents

Wolfe, C.R.; Kozlowski, M.R.; Campbell, J.H.; Staggs, M.; Rainer, F.

1995-12-05

The invention comprises a method for producing optical thin films with a high laser damage threshold and the resulting thin films. The laser damage threshold of the thin films is permanently increased by irradiating the thin films with a fluence below an unconditioned laser damage threshold. 9 figs.

Inkjet-Printed Porous Silver Thin Film as a Cathode for a Low-Temperature Solid Oxide Fuel Cell.

PubMed

Yu, Chen-Chiang; Baek, Jong Dae; Su, Chun-Hao; Fan, Liangdong; Wei, Jun; Liao, Ying-Chih; Su, Pei-Chen

2016-04-27

In this work we report a porous silver thin film cathode that was fabricated by a simple inkjet printing process for low-temperature solid oxide fuel cell applications. The electrochemical performance of the inkjet-printed silver cathode was studied at 300-450 °C and was compared with that of silver cathodes that were fabricated by the typical sputtering method. Inkjet-printed silver cathodes showed lower electrochemical impedance due to their porous structure, which facilitated oxygen gaseous diffusion and oxygen surface adsorption-dissociation reactions. A typical sputtered nanoporous silver cathode became essentially dense after the operation and showed high impedance due to a lack of oxygen supply. The results of long-term fuel cell operation show that the cell with an inkjet-printed cathode had a more stable current output for more than 45 h at 400 °C. A porous silver cathode is required for high fuel cell performance, and the simple inkjet printing technique offers an alternative method of fabrication for such a desirable porous structure with the required thermal-morphological stability.

Investigation of nanoporous platinum thin films fabricated by reactive sputtering: Application as micro-SOFC electrode

NASA Astrophysics Data System (ADS)

Jung, WooChul; Kim, Jae Jin; Tuller, Harry L.

2015-02-01

Highly porous Pt thin films, with nano-scale porosity, were fabricated by reactive sputtering. The strategy involved deposition of thin film PtOx at room temperature, followed by the subsequent decomposition of the oxide by rapid heat treatment. The resulting films exhibited percolating Pt networks infiltrated with interconnected nanosized pores, critical for superior solid oxide fuel cell cathode performance. This approach is particularly attractive for micro-fabricated solid oxide fuel cells, since it enables fabrication of the entire cell stack (anode/electrolyte/cathode) within the sputtering chamber, without breaking vacuum. In this work, the morphological, crystallographic and chemical properties of the porous electrode were systematically varied by control of deposition conditions. Oxygen reduction reaction kinetics were investigated by means of electrochemical impedance spectroscopy, demonstrating the critical role of nano-pores in achieving satisfactory micro-SOFC cathode performance.

Thin Film Photovoltaic Partnership Project | Photovoltaic Research | NREL

Science.gov Websites

Thin Film Photovoltaic Partnership Project Thin Film Photovoltaic Partnership Project NREL's Thin Film Photovoltaic (PV) Partnership Project led R&D on emerging thin-film solar technologies in the National Laboratory developed low-cost transparent encapsulation schemes for CIGS cells that reduced power

Multifunctional thin film surface

DOEpatents

Brozik, Susan M.; Harper, Jason C.; Polsky, Ronen; Wheeler, David R.; Arango, Dulce C.; Dirk, Shawn M.

2015-10-13

A thin film with multiple binding functionality can be prepared on an electrode surface via consecutive electroreduction of two or more aryl-onium salts with different functional groups. This versatile and simple method for forming multifunctional surfaces provides an effective means for immobilization of diverse molecules at close proximities. The multifunctional thin film has applications in bioelectronics, molecular electronics, clinical diagnostics, and chemical and biological sensing.

Thin film tritium dosimetry

DOEpatents

Moran, Paul R.

1976-01-01

The present invention provides a method for tritium dosimetry. A dosimeter comprising a thin film of a material having relatively sensitive RITAC-RITAP dosimetry properties is exposed to radiation from tritium, and after the dosimeter has been removed from the source of the radiation, the low energy electron dose deposited in the thin film is determined by radiation-induced, thermally-activated polarization dosimetry techniques.

High index glass thin film processing for photonics and photovoltaic (PV) applications

NASA Astrophysics Data System (ADS)

Ogbuu, Okechukwu Anthony

To favorably compete with fossil-fuel technology, the greatest challenge for thin film solar-cells is to improve efficiency and reduce material cost. Thickness scaling to thin film reduces material cost but affects the light absorption in the cells; therefore a concept that traps incident photons and increases its optical path length is needed to boost absorption in thin film solar cells. One approach is the integration of low symmetric gratings (LSG), using high index material, on either the front-side or backside of 30 um thin c-Si cells. In this study, Multicomponent TeO2--Bi2O 3--ZnO (TBZ) glass thin films were prepared using RF magnetron sputtering under different oxygen flow rates. The influences of oxygen flow rate on the structural and optical properties of the resulting thin films were investigated. The structural origin of the optical property variation was studied using X-ray diffraction, X-ray photoelectron spectroscopy, Raman Spectroscopy, and transmission electron microscopy. The results indicate that TBZ glass thin film is a suitable material for front side LSG material photovoltaic and photonics applications due to their amorphous nature, high refractive index (n > 2), broad band optical transparency window, low processing temperature. We developed a simple maskless method to pattern sputtered tellurite based glass thin films using unconventional agarose hydrogel mediated wet etching. Conventional wet etching process, while claiming low cost and high throughput, suffers from reproducibility and pattern fidelity issues due to the isotropic nature of wet chemical etching when applied to glasses and polymers. This method overcomes these challenges by using an agarose hydrogel stamp to mediate a conformal etching process. In our maskless method, agarose hydrogel stamps are patterned following a standard soft lithography and replica molding process from micropatterned masters and soaked in a chemical etchant. The micro-scale features on the stamp are

Thermo-optically tunable thin film devices

NASA Astrophysics Data System (ADS)

Domash, Lawrence H.

2003-10-01

We report advances in tunable thin film technology and demonstration of multi-cavity tunable filters. Thin film interference coatings are the most widely used optical technology for telecom filtering, but until recently no tunable versions have been known except for mechanically rotated filters. We describe a new approach to broadly tunable components based on the properties of semiconductor thin films with large thermo-optic coefficients. The technology is based on amorphous silicon deposited by plasma-enhanced chemical vapor deposition (PECVD), a process adapted for telecom applications from its origins in the flat-panel display and solar cell industries. Unlike MEMS devices, tunable thin films can be constructed in sophisticated multi-cavity, multi-layer optical designs.

Comparison of full 3-D, thin-film 3-D, and thin-film plate analyses of a postbuckled embedded delamination

NASA Technical Reports Server (NTRS)

Whitcomb, John D.

1989-01-01

Strain-energy release rates are often used to predict when delamination growth will occur in laminates under compression. Because of the inherently high computational cost of performing such analyses, less rigorous analyses such as thin-film plate analysis were used. The assumptions imposed by plate theory restrict the analysis to the calculation of total strain energy, G(sub t). The objective is to determine the accuracy of thin-film plate analysis by comparing the distribution of G(sub t) calculated using fully three dimensional (3D), thin-film 3D, and thin-film plate analyses. Thin-film 3D analysis is the same as thin-film plate analysis, except 3D analysis is used to model the sublaminate. The 3D stress analyses were performed using the finite element program NONLIN3D. The plate analysis results were obtained from published data, which used STAGS. Strain-energy release rates were calculated using variations of the virtual crack closure technique. The results demonstrate that thin-film plate analysis can predict the distribution of G(sub t) quite well, at least for the configurations considered. Also, these results verify the accuracy of the strain-energy release rate procedure for plate analysis.

Thin film ion conducting coating

DOEpatents

Goldner, Ronald B.; Haas, Terry; Wong, Kwok-Keung; Seward, George

1989-01-01

Durable thin film ion conducting coatings are formed on a transparent glass substrate by the controlled deposition of the mixed oxides of lithium:tantalum or lithium:niobium. The coatings provide durable ion transport sources for thin film solid state storage batteries and electrochromic energy conservation devices.

Temperature dependence of LRE-HRE-TM thin films

NASA Astrophysics Data System (ADS)

Li, Zuoyi; Cheng, Xiaomin; Lin, Gengqi; Li, Zhen; Huang, Zhixin; Jin, Fang; Wang, Xianran; Yang, Xiaofei

2003-04-01

Temperature dependence of the properties of RE-TM thin films is very important for MO recording. In this paper, we studied the temperature dependence of the magnetic and magneto-optical properties of the amorphous LRE-HRE-TM single layer thin films and LRE-HRE-TM/HRE-TM couple-bilayered thin films. For LRE-HRE-TM single layer thin films, the temperature dependence of the magnetization was investigated by using the mean field theory. The experimental and theoretical results matched very well. With the LRE substitution in HRE-TM thin film, the compensation temperature Tcomp decreased and the curie temperature Tc remained unchanged. Kerr rotation angle became larger and the saturation magnetization Ms at room temperature increased. For LRE-HRE-TM/HRE-TM couple-bilayered thin films, comparisons of the temperature dependences of the coercivities and Kerr rotation angles were made between isolated sublayers and couple-bilayered thin film.

Method of producing amorphous thin films

DOEpatents

Brusasco, Raymond M.

1992-01-01

Disclosed is a method of producing thin films by sintering which comprises: a. coating a substrate with a thin film of an inorganic glass forming parulate material possessing the capability of being sintered, and b. irridiating said thin film of said particulate material with a laser beam of sufficient power to cause sintering of said material below the temperature of liquidus thereof. Also disclosed is the article produced by the method claimed.

Method of producing amorphous thin films

DOEpatents

Brusasco, R.M.

1992-09-01

Disclosed is a method of producing thin films by sintering which comprises: (a) coating a substrate with a thin film of an inorganic glass forming material possessing the capability of being sintered; and (b) irradiating said thin film of said particulate material with a laser beam of sufficient power to cause sintering of said material below the temperature of liquidus thereof. Also disclosed is the article produced by the method claimed. 4 figs.

Method for making thin carbon foam electrodes

DOEpatents

Pekala, Richard W.; Mayer, Steven T.; Kaschmitter, James L.; Morrison, Robert L.

1999-01-01

A method for fabricating thin, flat carbon electrodes by infiltrating highly porous carbon papers, membranes, felts, metal fibers/powders, or fabrics with an appropriate carbon foam precursor material. The infiltrated carbon paper, for example, is then cured to form a gel-saturated carbon paper, which is subsequently dried and pyrolyzed to form a thin sheet of porous carbon. The material readily stays flat and flexible during curing and pyrolyzing to form thin sheets. Precursor materials include polyacrylonitrile (PAN), polymethylacrylonitrile (PMAN), resorcinol/formaldehyde, catechol/formaldehyde, phenol/formaldehyde, etc., or mixtures thereof. These thin films are ideal for use as high power and energy electrodes in batteries, capacitors, and fuel cells, and are potentially useful for capacitive deionization, filtration and catalysis.

Barium ferrite thin-film recording media

NASA Astrophysics Data System (ADS)

Sui, Xiaoyu; Scherge, Matthias; Kryder, Mark H.; Snyder, John E.; Harris, Vincent G.; Koon, Norman C.

1996-03-01

Both longitudinal and perpendicular barium ferrite thin films are being pursued as overcoatless magnetic recording media. In this paper, prior research on thin-film Ba ferrite is reviewed and the most recent results are presented. Self-textured high-coercivity longitudinal Ba ferrite thin films have been achieved using conventional rf diode sputtering. Microstructural studies show that c-axis in-plane oriented grains have a characteristic acicular shape, while c-axis perpendicularly oriented grains have a platelet shape. Extended X-ray absorption fine structure (EXAFS) measurements indicate that the crystal orientations are predetermined by the structural anisotropy in the as-sputtered 'amorphous' state. Recording tests on 1500 Oe coercivity longitudinal Ba ferrite disks show performance comparable with that of a 1900 Oe Co alloy disk. To further improve the recording performance, both grain size and aspect ratio need to be reduced. Initial tribological tests indicate high hardness of Ba ferrite thin films. However, surface roughness needs to be reduced. For future ultrahigh-density contact recording, it is believed that perpendicular recording may be used. A thin Pt underlayer has been found to be capable of producing Ba ferrite thin films with excellent c-axis perpendicular orientation.

Membrane thinning for efficient CO2 capture

PubMed Central

Selyanchyn, Roman; Fujikawa, Shigenori

2017-01-01

Abstract Enhancing the fluxes in gas separation membranes is required for utilizing the membranes on a mass scale for CO2 capture. Membrane thinning is one of the most promising approaches to achieve high fluxes. In addition, sophisticated molecular transport across membranes can boost gas separation performance. In this review, we attempt to summarize the current state of CO2 separation membranes, especially from the viewpoint of thinning the selective layers and the membrane itself. The gas permeation behavior of membranes with ultimate thicknesses and their future directions are discussed. PMID:29152016

Composite fuel cell membranes

DOEpatents

Plowman, K.R.; Rehg, T.J.; Davis, L.W.; Carl, W.P.; Cisar, A.J.; Eastland, C.S.

1997-08-05

A bilayer or trilayer composite ion exchange membrane is described suitable for use in a fuel cell. The composite membrane has a high equivalent weight thick layer in order to provide sufficient strength and low equivalent weight surface layers for improved electrical performance in a fuel cell. In use, the composite membrane is provided with electrode surface layers. The composite membrane can be composed of a sulfonic fluoropolymer in both core and surface layers.

Composite fuel cell membranes

DOEpatents

Plowman, Keith R.; Rehg, Timothy J.; Davis, Larry W.; Carl, William P.; Cisar, Alan J.; Eastland, Charles S.

1997-01-01

A bilayer or trilayer composite ion exchange membrane suitable for use in a fuel cell. The composite membrane has a high equivalent weight thick layer in order to provide sufficient strength and low equivalent weight surface layers for improved electrical performance in a fuel cell. In use, the composite membrane is provided with electrode surface layers. The composite membrane can be composed of a sulfonic fluoropolymer in both core and surface layers.

Ferroelectric and structural properties of stress-constrained and stress-relaxed polycrystalline BiFeO3 thin films

NASA Astrophysics Data System (ADS)

Nakashima, Seiji; Ricinschi, Dan; Park, Jung Min; Kanashima, Takeshi; Fujisawa, Hironori; Shimizu, Masaru; Okuyama, Masanori

2009-03-01

The stress influence of the structural and ferroelectric properties of polycrystalline BiFeO3 (BFO) thin films has been investigated using a membrane substrate for relaxing stress. Reciprocal space mapping (RSM) measurement has been performed to confirm the stress dependence of the crystal structure of polycrystalline BFO thin films on the Pt (200 nm)/TiO2 (50 nm)/SiO2 (600 nm)/Si (625 μm) substrate (stress-constrained BFO film) and the Pt (200 nm)/TiO2 (50 nm)/SiO2 (600 nm)/Si (15 μm) membrane substrate (stress-relaxed BFO film). The BFO thin films prepared by pulsed laser deposition were polycrystalline and mainly exhibit a texture with (001) and (110) plane orientations. From the RSM results, the crystal structure of the (001)-oriented domain changes from Pm monoclinic to Cm monoclinic or to R3c rhombohedral due to stress relaxation. Moreover, at room temperature as well as at 150 K, remanent polarization (Pr) increases and double coercive field (2Ec) decreases (in the latter case from 88 to 94 μC/cm2 and from 532 to 457 kV/cm, respectively) due to relaxing stress. The enhancement of ferroelectricity is attributed to the crystal structural deformation and/or transition and angle change between the polarization direction and film plane.

Sputtered highly oriented PZT thin films for MEMS applications

NASA Astrophysics Data System (ADS)

Kalpat, Sriram S.

Recently there has been an explosion of interest in the field of micro-electro-mechanical systems (MEMS). MEMS device technology has become critical in the growth of various fields like medical, automotive, chemical, and space technology. Among the many applications of ferroelectric thin films in MEMS devices, microfluidics is a field that has drawn considerable amount of research from bio-technology industries as well as chemical and semiconductor manufacturing industries. PZT thin films have been identified as best suited materials for micro-actuators and micro-sensors used in MEMS devices. A promising application for piezoelectric thin film based MEMS devices is disposable drug delivery systems that are capable of sensing biological parameters, mixing and delivering minute and precise amounts of drugs using micro-pumps or micro mixers. These devices call for low driving voltages, so that they can be battery operated. Improving the performance of the actuator material is critical in achieving battery operated disposal drug delivery systems. The device geometry and power consumption in MEMS devices largely depends upon the piezoelectric constant of the films, since they are most commonly used to convert electrical energy into a mechanical response of a membrane or cantilever and vice versa. Phenomenological calculation on the crystal orientation dependence of piezoelectric coefficients for PZT single crystal have reported a significant enhancement of the piezoelectric d33 constant by more than 3 times along [001] in the rhombohedral phase as compared to the conventionally used orientation PZT(111) since [111] is the along the spontaneous polarization direction. This could mean considerable improvement in the MEMS device performance and help drive the operating voltages lower. The motivation of this study is to investigate the crystal orientation dependence of both dielectric and piezoelectric coefficients of PZT thin films in order to select the appropriate

Broadly tunable thin-film intereference coatings: active thin films for telecom applications

NASA Astrophysics Data System (ADS)

Domash, Lawrence H.; Ma, Eugene Y.; Lourie, Mark T.; Sharfin, Wayne F.; Wagner, Matthias

2003-06-01

Thin film interference coatings (TFIC) are the most widely used optical technology for telecom filtering, but until recently no tunable versions have been known except for mechanically rotated filters. We describe a new approach to broadly tunable TFIC components based on the thermo-optic properties of semiconductor thin films with large thermo-optic coefficients 3.6X10[-4]/K. The technology is based on amorphous silicon thin films deposited by plasma-enhanced chemical vapor deposition (PECVD), a process adapted for telecom applications from its origins in the flat-panel display and solar cell industries. Unlike MEMS devices, tunable TFIC can be designed as sophisticated multi-cavity, multi-layer optical designs. Applications include flat-top passband filters for add-drop multiplexing, tunable dispersion compensators, tunable gain equalizers and variable optical attenuators. Extremely compact tunable devices may be integrated into modules such as optical channel monitors, tunable lasers, gain-equalized amplifiers, and tunable detectors.

Electrochemical ion transfer mediated by a lipophilic Os(ii)/Os(iii) dinonyl bipyridyl probe incorporated in thin film membranes.

PubMed

Jansod, Sutida; Wang, Lu; Cuartero, Maria; Bakker, Eric

2017-09-28

A new lipophilic dinonyl bipyridyl Os(ii)/Os(iii) complex successfully mediates ion transfer processes across voltammetric thin membranes. An added lipophilic cation-exchanger may impose voltammetric anion or cation transfer waves of Gaussian shape that are reversible and repeatable. The peak potential is found to shift with the ion concentration in agreement with the Nernst equation. The addition of tridodecylmethylammonium nitrate to the polymeric film dramatically reduces the peak separation from 240 mV to 65 mV, and the peak width to a near-theoretical value of 85 mV, which agrees with a surface confined process. It is suggested that the cationic additive serves as a phase transfer catalyst.

Low-Cost Proton Conducting Membranes for PEM Fuel Cells

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

Hu, Hongxing

Proton exchange membrane (PEM) is the key component in PEM fuel cells that critically determines the system performance and its economic viability. Presently, the state-of-the-art PEMs, such as Nafion membranes, are based on perfluorosulfonic acid (PFSA) ionomers. But these ionomer materials are expensive, particularly at the low volumes that will be needed for initial commercialization. Besides, they are not suitable for fuel cells operated beyond 100°C, because of the limitations connected to the humidification requirement of such membrane materials, limiting the maximum operating temperature to about 90°C. Fuel cells for transportation applications are required to operate in a wide temperaturemore » range from –20°C to 120°C. Low-cost PEMs with capabilities in a range of temperature and humidity conditions are urgently needed to meet the DOE fuel cell targets for transportation applications. Amsen Technologies LLC chooses to address the DOE call with a novel reinforced PEM approach based on new, non-PFSA proton conducting ionomers developed from our previous DOE SBIR projects. Along with this approach is the use of very cheap, ultra thin and highly porous microporous polymer meshes as the support for the membrane. The new PEM is expected to have significant cost advantages over traditional PEMs. The microporous polyolefin support costs $2-3/m 2; and the new ionomers that Amsen has developed are estimated at ~$250/kg at the higher end including material costs and labor costs (which may go down in the future as the processing is optimized and production scaled up). These have led to an estimate of total material cost for the membrane at $11 to $12/m 2, offering high potential of meeting the DOE cost targets (≤$20/m 2) after adding processing cost and profit margin. The Phase I results have successfully demonstrated that it is very promising to develop the intended low-cost, high-performance PEM membrane. Suitable material system has been identified, and

Nanocrystalline mesoporous SMO thin films prepared by sol gel process for MEMS-based hydrogen sensor

NASA Astrophysics Data System (ADS)

Gong, Jianwei; Fei, Weifeng; Seal, Sudipta; Chen, Quanfang

2004-01-01

MEMS based SnO2 gas sensor with sol gel synthesized mesoporous nanocrystalline (<10 nm) semiconductor thin (100~150 nm) film has been recently developed. The SnO2 nano film is fabricated with the combination of polymeric sol gel chemistry with block copolymers used for structure directing agents. The novel hydrogen sensor has a fast response time (1s) and quick recovery time (3s), as well as good sensitivity (about 90%), comparing to other hydrogen sensors developed. The improved capabilities are credited to the large surface to volume ratio of gas sensing thin film with nano sized porous surface topology, which can greatly increase the sensitivity even at relatively low working temperature. The gas sensing film is deposited onto a thin dielectric membrane of low thermal conductivity, which provides good thermal isolation between substrate and the gas-sensitive heated area on the membrane. In this way the power consumption can be kept very low. Since the fabrication process is completely compatible with IC industry, it makes mass production possible and greatly reduces the cost. The working temperature of the new sensor can be reduced as low as 100°C. The low working temperature posse advantages such as lower power consumption, lower thermal induced signal shift as well as safe detection in certain environments where temperature is strictly limited.

Low Voltage MEMS Digital Loudspeaker Array Based on Thin-film PZT Actuators

NASA Astrophysics Data System (ADS)

Fanget, S.; Casset, F.; Dejaeger, R.; Maire, F.; Desloges, B.; Deutzer, J.; Morisson, R.; Bohard, Y.; Laroche, B.; Escato, J.; Leclere, Q.

This paper reports on the development of a Digital Loudspeaker Array (DLA) solution based on Pb(Zr0.52,Ti0.48)O3 (PZT) thin-film actuated membranes. These membranes called speaklets are arranged in a matrix and operate in a binary manner by emitting short pulses of sound pressure. Using the principle of additivity of pressures in the air, it is possible to reconstruct audible sounds. For the first time, electromechanical and acoustic characterizations are reported on a 256-MEMS-membranes DLA. Sounds audible as far as several meters from the loudspeaker have been generated using low voltage (8 V).

Advanced platform for the in-plane ZT measurement of thin films

NASA Astrophysics Data System (ADS)

Linseis, V.; Völklein, F.; Reith, H.; Nielsch, K.; Woias, P.

2018-01-01

The characterization of nanostructured samples with at least one restricted dimension like thin films or nanowires is challenging, but important to understand their structure and transport mechanism, and to improve current industrial products and production processes. We report on the 2nd generation of a measurement chip, which allows for a simplified sample preparation process, and the measurement of samples deposited from the liquid phase using techniques like spin coating and drop casting. The new design enables us to apply much higher temperature gradients for the Seebeck coefficient measurement in a shorter time, without influencing the sample holder's temperature distribution. Furthermore, a two membrane correction method for the 3ω thermal conductivity measurement will be presented, which takes the heat loss due to radiation into account and increases the accuracy of the measurement results significantly. Errors caused by different sample compositions, varying sample geometries, and different heat profiles are avoided with the presented measurement method. As a showcase study displaying the validity and accuracy of our platform, we present temperature-dependent measurements of the thermoelectric properties of an 84 nm Bi87Sb13 thin film and a 15 μm PEDOT:PSS thin film.

Semiconductor-nanocrystal/conjugated polymer thin films

DOEpatents

Alivisatos, A. Paul; Dittmer, Janke J.; Huynh, Wendy U.; Milliron, Delia

2014-06-17

The invention described herein provides for thin films and methods of making comprising inorganic semiconductor-nanocrystals dispersed in semiconducting-polymers in high loading amounts. The invention also describes photovoltaic devices incorporating the thin films.

Semiconductor-nanocrystal/conjugated polymer thin films

DOEpatents

Alivisatos, A. Paul; Dittmer, Janke J.; Huynh, Wendy U.; Milliron, Delia

2010-08-17

The invention described herein provides for thin films and methods of making comprising inorganic semiconductor-nanocrystals dispersed in semiconducting-polymers in high loading amounts. The invention also describes photovoltaic devices incorporating the thin films.

Thin film absorber for a solar collector

DOEpatents

Wilhelm, William G.

1985-01-01

This invention pertains to energy absorbers for solar collectors, and more particularly to high performance thin film absorbers. The solar collectors comprising the absorber of this invention overcome several problems seen in current systems, such as excessive hardware, high cost and unreliability. In the preferred form, the apparatus features a substantially rigid planar frame with a thin film window bonded to one planar side of the frame. An absorber in accordance with the present invention is comprised of two thin film layers that are sealed perimetrically. In a preferred embodiment, thin film layers are formed from a metal/plastic laminate. The layers define a fluid-tight planar envelope of large surface area to volume through which a heat transfer fluid flows. The absorber is bonded to the other planar side of the frame. The thin film construction of the absorber assures substantially full envelope wetting and thus good efficiency. The window and absorber films stress the frame adding to the overall strength of the collector.

Self-assembly of dodecaphenyl POSS thin films

NASA Astrophysics Data System (ADS)

Handke, Bartosz; Klita, Łukasz; Niemiec, Wiktor

2017-12-01

The self-assembly abilities of Dodecaphenyl Polyhedral Oligomeric Silsesquioxane thin films on Si(1 0 0) surfaces were studied. Due to their thermal properties - relatively low sublimation temperature and preservation of molecular structure - cage type silsesquioxanes are ideal material for the preparation of a thin films by Physical Vapor Deposition. The Ultra-High Vacuum environment and the deposition precision of the PVD method enable the study of early stages of thin film growth and its molecular organization. X-ray Reflectivity and Atomic Force Microscopy measurements allow to pursuit size-effects in the structure of thin films with thickness ranges from less than a single molecular layer up to several tens of layers. Thermal treatment of the thin films triggered phase change: from a poorly ordered polycrystalline film into a well-ordered multilayer structure. Self-assembly of the layers is the effect of the π-stacking of phenyl rings, which force molecules to arrange in a superlattice, forming stacks of alternating organic-inorganic layers.

Thin-film Rechargeable Lithium Batteries

DOE R&D Accomplishments Database

Dudney, N. J.; Bates, J. B.; Lubben, D.

1995-06-01

Thin film rechargeable lithium batteries using ceramic electrolyte and cathode materials have been fabricated by physical deposition techniques. The lithium phosphorous oxynitride electrolyte has exceptional electrochemical stability and a good lithium conductivity. The lithium insertion reaction of several different intercalation materials, amorphous V{sub 2}O{sub 5}, amorphous LiMn{sub 2}O{sub 4}, and crystalline LiMn{sub 2}O{sub 4} films, have been investigated using the completed cathode/electrolyte/lithium thin film battery.

Fuel cell membrane humidification

DOEpatents

Wilson, Mahlon S.

1999-01-01

A polymer electrolyte membrane fuel cell assembly has an anode side and a cathode side separated by the membrane and generating electrical current by electrochemical reactions between a fuel gas and an oxidant. The anode side comprises a hydrophobic gas diffusion backing contacting one side of the membrane and having hydrophilic areas therein for providing liquid water directly to the one side of the membrane through the hydrophilic areas of the gas diffusion backing. In a preferred embodiment, the hydrophilic areas of the gas diffusion backing are formed by sewing a hydrophilic thread through the backing. Liquid water is distributed over the gas diffusion backing in distribution channels that are separate from the fuel distribution channels.

An overview of thin film nitinol endovascular devices.

PubMed

Shayan, Mahdis; Chun, Youngjae

2015-07-01

Thin film nitinol has unique mechanical properties (e.g., superelasticity), excellent biocompatibility, and ultra-smooth surface, as well as shape memory behavior. All these features along with its low-profile physical dimension (i.e., a few micrometers thick) make this material an ideal candidate in developing low-profile medical devices (e.g., endovascular devices). Thin film nitinol-based devices can be collapsed and inserted in remarkably smaller diameter catheters for a wide range of catheter-based procedures; therefore, it can be easily delivered through highly tortuous or narrow vascular system. A high-quality thin film nitinol can be fabricated by vacuum sputter deposition technique. Micromachining techniques were used to create micro patterns on the thin film nitinol to provide fenestrations for nutrition and oxygen transport and to increase the device's flexibility for the devices used as thin film nitinol covered stent. In addition, a new surface treatment method has been developed for improving the hemocompatibility of thin film nitinol when it is used as a graft material in endovascular devices. Both in vitro and in vivo test data demonstrated a superior hemocompatibility of the thin film nitinol when compared with commercially available endovascular graft materials such as ePTFE or Dacron polyester. Promising features like these have motivated the development of thin film nitinol as a novel biomaterial for creating endovascular devices such as stent grafts, neurovascular flow diverters, and heart valves. This review focuses on thin film nitinol fabrication processes, mechanical and biological properties of the material, as well as current and potential thin film nitinol medical applications. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Stretchable, adhesive and ultra-conformable elastomer thin films.

PubMed

Sato, Nobutaka; Murata, Atsushi; Fujie, Toshinori; Takeoka, Shinji

2016-11-16

Thermoplastic elastomers are attractive materials because of the drastic changes in their physical properties above and below the glass transition temperature (T g ). In this paper, we report that free-standing polystyrene (PS, T g : 100 °C) and polystyrene-polybutadiene-polystyrene triblock copolymer (SBS, T g : -70 °C) thin films with a thickness of hundreds of nanometers were prepared by a gravure coating method. Among the mechanical properties of these thin films determined by bulge testing and tensile testing, the SBS thin films exhibited a much lower elastic modulus (ca. 0.045 GPa, 212 nm thickness) in comparison with the PS thin films (ca. 1.19 GPa, 217 nm thickness). The lower elastic modulus and lower thickness of the SBS thin films resulted in higher conformability and thus higher strength of adhesion to an uneven surface such as an artificial skin model with roughness (R a = 10.6 μm), even though they both have similar surface energies. By analyzing the mechanical properties of the SBS thin films, the elastic modulus and thickness of the thin films were strongly correlated with their conformability to a rough surface, which thus led to a high adhesive strength. Therefore, the SBS thin films will be useful as coating layers for a variety of materials.

The Thin Oil Film Equation

NASA Technical Reports Server (NTRS)

Brown, James L.; Naughton, Jonathan W.

1999-01-01

A thin film of oil on a surface responds primarily to the wall shear stress generated on that surface by a three-dimensional flow. The oil film is also subject to wall pressure gradients, surface tension effects and gravity. The partial differential equation governing the oil film flow is shown to be related to Burgers' equation. Analytical and numerical methods for solving the thin oil film equation are presented. A direct numerical solver is developed where the wall shear stress variation on the surface is known and which solves for the oil film thickness spatial and time variation on the surface. An inverse numerical solver is also developed where the oil film thickness spatial variation over the surface at two discrete times is known and which solves for the wall shear stress variation over the test surface. A One-Time-Level inverse solver is also demonstrated. The inverse numerical solver provides a mathematically rigorous basis for an improved form of a wall shear stress instrument suitable for application to complex three-dimensional flows. To demonstrate the complexity of flows for which these oil film methods are now suitable, extensive examination is accomplished for these analytical and numerical methods as applied to a thin oil film in the vicinity of a three-dimensional saddle of separation.

Development of High Resistive and High Magnetization Soft Thin Film and Fabrication of Thin Film Inductors

DTIC Science & Technology

2004-11-01

properties of Co- doped ZnO nanocluster films", .J. of Appl. Phys. in press, 2005 2. Presentations (contributed): Conference Contributions: 1) Y. Qiang...gigahertz band applications. The effects of substrates bias, sputter parameters, and seed-layer have thoroughly been investigated. The magnetic...Adequate properties of soft magnetic thin film were evaluated by an analytical calculation [1] to meet the requirement for gigahertz band thin-film

Black thin film silicon

NASA Astrophysics Data System (ADS)

Koynov, Svetoslav; Brandt, Martin S.; Stutzmann, Martin

2011-08-01

"Black etching" has been proposed previously as a method for the nanoscale texturing of silicon surfaces, which results in an almost complete suppression of reflectivity in the spectral range of absorption relevant for photovoltaics. The method modifies the topmost 150 to 300 nm of the material and thus also is applicable for thin films of silicon. The present work is focused on the optical effects induced by the black-etching treatment on hydrogenated amorphous and microcrystalline silicon thin films, in particular with respect to their application in solar cells. In addition to a strong reduction of the reflectivity, efficient light trapping within the modified thin films is found. The enhancement of the optical absorption due to the light trapping is investigated via photometric measurements and photothermal deflection spectroscopy. The correlation of the texture morphology (characterized via atomic force microscopy) with the optical effects is discussed in terms of an effective medium with gradually varying optical density and in the framework of the theory of statistical light trapping. Photoconductivity spectra directly show that the light trapping causes a significant prolongation of the light path within the black silicon films by up to 15 μm for ˜1 μm thick films, leading to a significant increase of the absorption in the red.

Thin-Film Photovoltaic Solar Array Parametric Assessment

NASA Technical Reports Server (NTRS)

Hoffman, David J.; Kerslake, Thomas W.; Hepp, Aloysius F.; Jacobs, Mark K.; Ponnusamy, Deva

2000-01-01

This paper summarizes a study that had the objective to develop a model and parametrically determine the circumstances for which lightweight thin-film photovoltaic solar arrays would be more beneficial, in terms of mass and cost, than arrays using high-efficiency crystalline solar cells. Previous studies considering arrays with near-term thin-film technology for Earth orbiting applications are briefly reviewed. The present study uses a parametric approach that evaluated the performance of lightweight thin-film arrays with cell efficiencies ranging from 5 to 20 percent. The model developed for this study is described in some detail. Similar mass and cost trends for each array option were found across eight missions of various power levels in locations ranging from Venus to Jupiter. The results for one specific mission, a main belt asteroid tour, indicate that only moderate thin-film cell efficiency (approx. 12 percent) is necessary to match the mass of arrays using crystalline cells with much greater efficiency (35 percent multi-junction GaAs based and 20 percent thin-silicon). Regarding cost, a 12 percent efficient thin-film array is projected to cost about half is much as a 4-junction GaAs array. While efficiency improvements beyond 12 percent did not significantly further improve the mass and cost benefits for thin-film arrays, higher efficiency will be needed to mitigate the spacecraft-level impacts associated with large deployed array areas. A low-temperature approach to depositing thin-film cells on lightweight, flexible plastic substrates is briefly described. The paper concludes with the observation that with the characteristics assumed for this study, ultra-lightweight arrays using efficient, thin-film cells on flexible substrates may become a leading alternative for a wide variety of space missions.

Thin film atomic hydrogen detectors

NASA Technical Reports Server (NTRS)

Gruber, C. L.

1977-01-01

Thin film and bead thermistor atomic surface recombination hydrogen detectors were investigated both experimentally and theoretically. Devices were constructed on a thin Mylar film substrate. Using suitable Wheatstone bridge techniques sensitivities of 80 microvolts/2x10 to the 13th power atoms/sec are attainable with response time constants on the order of 5 seconds.

Electronic Devices Based on Oxide Thin Films Fabricated by Fiber-to-Film Process.

PubMed

Meng, You; Liu, Ao; Guo, Zidong; Liu, Guoxia; Shin, Byoungchul; Noh, Yong-Young; Fortunato, Elvira; Martins, Rodrigo; Shan, Fukai

2018-05-30

Technical development for thin-film fabrication is essential for emerging metal-oxide (MO) electronics. Although impressive progress has been achieved in fabricating MO thin films, the challenges still remain. Here, we report a versatile and general thermal-induced nanomelting technique for fabricating MO thin films from the fiber networks, briefly called fiber-to-film (FTF) process. The high quality of the FTF-processed MO thin films was confirmed by various investigations. The FTF process is generally applicable to numerous technologically relevant MO thin films, including semiconducting thin films (e.g., In 2 O 3 , InZnO, and InZrZnO), conducting thin films (e.g., InSnO), and insulating thin films (e.g., AlO x ). By optimizing the fabrication process, In 2 O 3 /AlO x thin-film transistors (TFTs) were successfully integrated by fully FTF processes. High-performance TFT was achieved with an average mobility of ∼25 cm 2 /(Vs), an on/off current ratio of ∼10 7 , a threshold voltage of ∼1 V, and a device yield of 100%. As a proof of concept, one-transistor-driven pixel circuit was constructed, which exhibited high controllability over the light-emitting diodes. Logic gates based on fully FTF-processed In 2 O 3 /AlO x TFTs were further realized, which exhibited good dynamic logic responses and voltage amplification by a factor of ∼4. The FTF technique presented here offers great potential in large-area and low-cost manufacturing for flexible oxide electronics.

Dynamic delamination of patterned thin films

NASA Astrophysics Data System (ADS)

Kandula, Soma S. V.; Tran, Phuong; Geubelle, Philippe H.; Sottos, Nancy R.

2008-12-01

We investigate laser-induced dynamic delamination of a patterned thin film on a substrate. Controlled delamination results from our insertion of a weak adhesion region beneath the film. The inertial forces acting on the weakly bonded portion of the film lead to stable propagation of a crack along the film/substrate interface. Through a simple energy balance, we extract the critical energy for interfacial failure, a quantity that is difficult and sometimes impossible to characterize by more conventional methods for many thin film/substrate combinations.

Surface plasmon resonance spectroscopy studies of membrane proteins: transducin binding and activation by rhodopsin monitored in thin membrane films.

PubMed Central

Salamon, Z; Wang, Y; Soulages, J L; Brown, M F; Tollin, G

1996-01-01

Surface plasmon resonance (SPR) spectroscopy can provide useful information regarding average structural properties of membrane films supported on planar solid substrates. Here we have used SPR spectroscopy for the first time to monitor the binding and activation of G-protein (transducin or Gt) by bovine rhodopsin incorporated into an egg phosphatidylcholine bilayer deposited on a silver film. Rhodopsin incorporation into the membrane, performed by dilution of a detergent solution of the protein, proceeds in a saturable manner. Before photolysis, the SPR data show that Gt binds tightly (Keq approximately equal to 60 nM) and with positive cooperativity to rhodopsin in the lipid layer to form a closely packed film. A simple multilayer model yields a calculated average thickness of about 57 A, in good agreement with the structure of Gt. The data also demonstrate that Gt binding saturates at a Gt/rhodopsin ratio of approximately 0.6. Moreover, upon visible light irradiation, characteristic changes occur in the SPR spectrum, which can be modeled by a 6 A increase in the average thickness of the lipid/protein film caused by formation of metarhodopsin II (MII). Upon subsequent addition of GTP, further SPR spectral changes are induced. These are interpreted as resulting from dissociation of the alpha-subunit of Gt, formation of new MII-Gt complexes, and possible conformational changes of Gt as a consequence of complex formation. The above results clearly demonstrate the ability of SPR spectroscopy to monitor interactions among the proteins associated with signal transduction in membrane-bound systems. Images FIGURE 1 PMID:8804611

Chemical and radiation crosslinked polymer electrolyte membranes prepared from radiation-grafted ETFE films for DMFC applications

NASA Astrophysics Data System (ADS)

Chen, Jinhua; Asano, Masaharu; Yamaki, Tetsuya; Yoshida, Masaru

To develop a highly chemically stable polymer electrolyte membrane for application in a direct methanol fuel cell (DMFC), doubly crosslinked membranes were prepared by chemical crosslinking using bifunctional monomers, such as divinylbenzene (DVB) and bis(p, p-vinyl phenyl) ethane (BVPE), and by radiation crosslinking. The membranes were prepared by grafting of m, p-methylstyrene (MeSt) and p-tert-butylstyrene (tBuSt) into poly(ethylene- co-tetrafluoroethylene) (ETFE) films and subsequent sulfonation. The effects of the DVB and BVPE crosslinkers on the grafting kinetics and the properties of the prepared membranes, such as water uptake, proton conductivity and chemical stability were investigated. Radiation crosslinking was introduced by irradiation of the ETFE base film, the grafted film or the sulfonated membrane. The membrane crosslinked by DVB and BVPE crosslinkers and post-crosslinked by γ-ray irradiation of the corresponding grafted film possessed the highest chemical stability among the prepared membranes, a significantly lower methanol permeability compared to Nafion ® membranes, and a better DMFC performance for high methanol feed concentration. Therefore, this doubly crosslinked membrane was promising for application in a DMFC where relatively high methanol concentration could be fed.

Thin film composition with biological substance and method of making

DOEpatents

Campbell, Allison A.; Song, Lin

1999-01-01

The invention provides a thin-film composition comprising an underlying substrate of a first material including a plurality of attachment sites; a plurality of functional groups chemically attached to the attachment sites of the underlying substrate; and a thin film of a second material deposited onto the attachment sites of the underlying substrate, and a biologically active substance deposited with the thin-film. Preferably the functional groups are attached to a self assembling monolayer attached to the underlying substrate. Preferred functional groups attached to the underlying substrate are chosen from the group consisting of carboxylates, sulfonates, phosphates, optionally substituted, linear or cyclo, alkyl, alkene, alkyne, aryl, alkylaryl, amine, hydroxyl, thiol, silyl, phosphoryl, cyano, metallocenyl, carbonyl, and polyphosphate. Preferred materials for the underlying substrate are selected from the group consisting of a metal, a metal alloy, a plastic, a polymer, a proteic film, a membrane, a glass or a ceramic. The second material is selected from the group consisting of inorganic crystalline structures, inorganic amorphus structures, organic crystalline structures, and organic amorphus structures. Preferred second materials are phosphates, especially calcium phosphates and most particularly calcium apatite. The biologically active molecule is a protein, peptide, DNA segment, RNA segment, nucleotide, polynucleotide, nucleoside, antibiotic, antimicrobal, radioisotope, chelated radioisotope, chelated metal, metal salt, anti-inflamatory, steriod, nonsteriod anti-inflammatory, analgesic, antihistamine, receptor binding agent, or chemotherapeutic agent, or other biologically active material. Preferably the biologically active molecule is an osteogenic factor the compositions listed above.

Tungsten-doped thin film materials

DOEpatents

Xiang, Xiao-Dong; Chang, Hauyee; Gao, Chen; Takeuchi, Ichiro; Schultz, Peter G.

2003-12-09

A dielectric thin film material for high frequency use, including use as a capacitor, and having a low dielectric loss factor is provided, the film comprising a composition of tungsten-doped barium strontium titanate of the general formula (Ba.sub.x Sr.sub.1-x)TiO.sub.3, where X is between about 0.5 and about 1.0. Also provided is a method for making a dielectric thin film of the general formula (Ba.sub.x Sr.sub.1-x)TiO.sub.3 and doped with W, where X is between about 0.5 and about 1.0, a substrate is provided, TiO.sub.2, the W dopant, Ba, and optionally Sr are deposited on the substrate, and the substrate containing TiO.sub.2, the W dopant, Ba, and optionally Sr is heated to form a low loss dielectric thin film.

Time-Resolved In Situ Liquid-Phase Atomic Force Microscopy and Infrared Nanospectroscopy during the Formation of Metal-Organic Framework Thin Films.

PubMed

Mandemaker, Laurens D B; Filez, Matthias; Delen, Guusje; Tan, Huanshu; Zhang, Xuehua; Lohse, Detlef; Weckhuysen, Bert M

2018-04-19

Metal-organic framework (MOF) thin films show unmatched promise as smart membranes and photocatalytic coatings. However, their nucleation and growth resulting from intricate molecular assembly processes are not well understood yet are crucial to control the thin film properties. Here, we directly observe the nucleation and growth behavior of HKUST-1 thin films by real-time in situ AFM at different temperatures in a Cu-BTC solution. In combination with ex situ infrared (nano)spectroscopy, synthesis at 25 °C reveals initial nucleation of rapidly growing HKUST-1 islands surrounded by a continuously nucleating but slowly growing HKUST-1 carpet. Monitoring at 13 and 50 °C shows the strong impact of temperature on thin film formation, resulting in (partial) nucleation and growth inhibition. The nucleation and growth mechanisms as well as their kinetics provide insights to aid in future rational design of MOF thin films.

Time-Resolved In Situ Liquid-Phase Atomic Force Microscopy and Infrared Nanospectroscopy during the Formation of Metal–Organic Framework Thin Films

PubMed Central

2018-01-01

Metal–organic framework (MOF) thin films show unmatched promise as smart membranes and photocatalytic coatings. However, their nucleation and growth resulting from intricate molecular assembly processes are not well understood yet are crucial to control the thin film properties. Here, we directly observe the nucleation and growth behavior of HKUST-1 thin films by real-time in situ AFM at different temperatures in a Cu-BTC solution. In combination with ex situ infrared (nano)spectroscopy, synthesis at 25 °C reveals initial nucleation of rapidly growing HKUST-1 islands surrounded by a continuously nucleating but slowly growing HKUST-1 carpet. Monitoring at 13 and 50 °C shows the strong impact of temperature on thin film formation, resulting in (partial) nucleation and growth inhibition. The nucleation and growth mechanisms as well as their kinetics provide insights to aid in future rational design of MOF thin films. PMID:29595980

Development of Membrane Process for Carbon Dioxide Separation from Diving Atmosphere

DTIC Science & Technology

1990-05-01

backing, or support layer, as is shown in Figure 17b. The ultrathin film and backing of this composite membrane, which is sometimes called a " thin - film ...As a result, the properties and performance of a thin - film laminate can be better controlled, in principle, than those of a "skinned" membrane...method of preparing an asymmetric membrane is by coating a thin nonporous film directly on the surface of a suitable microporous t __ .. NEW DEVELOPMEN"TS

In-membrane micro fuel cell

DOEpatents

Omosebi, Ayokunle; Besser, Ronald

2016-09-06

An in-membrane micro fuel cell comprises an electrically-insulating membrane that is permissive to the flow of cations, such as protons, and a pair of electrodes deposited on channels formed in the membrane. The channels are arranged as conduits for fluids, and define a membrane ridge between the channels. The electrodes are porous and include catalysts for promoting the liberation of a proton and an electron from a chemical species and/or or the recombination of a proton and an electron with a chemical specie. The fuel cell may be provided a biosensor, an electrochemical sensor, a microfluidic device, or other microscale devices fabricated in the fuel cell membrane.

Determination of acoustic properties of thin polymer films utilizing the frequency dependence of the reflection coefficient of ultrasound.

PubMed

Tohmyoh, Hironori; Sakamoto, Yuhei

2015-11-01

This paper reports on a technique to measure the acoustic properties of a thin polymer film utilizing the frequency dependence of the reflection coefficient of ultrasound reflected back from a system comprising a reflection plate, the film, and a material that covers the film. The frequency components of the echo reflected from the back of the plate, where the film is attached, take their minimum values at the resonant frequency, and from these frequency characteristics, the acoustic impedance, sound velocity, and the density of the film can be determined. We applied this technique to characterize an ion exchange membrane, which has high water absorbability, and successfully determined the acoustic properties of the membrane without getting it wet.

Thermal conductivity model for nanoporous thin films

NASA Astrophysics Data System (ADS)

Huang, Congliang; Zhao, Xinpeng; Regner, Keith; Yang, Ronggui

2018-03-01

Nanoporous thin films have attracted great interest because of their extremely low thermal conductivity and potential applications in thin thermal insulators and thermoelectrics. Although there are some numerical and experimental studies about the thermal conductivity of nanoporous thin films, a simplified model is still needed to provide a straightforward prediction. In this paper, by including the phonon scattering lifetimes due to film thickness boundary scattering, nanopore scattering and the frequency-dependent intrinsic phonon-phonon scattering, a fitting-parameter-free model based on the kinetic theory of phonon transport is developed to predict both the in-plane and the cross-plane thermal conductivities of nanoporous thin films. With input parameters such as the lattice constants, thermal conductivity, and the group velocity of acoustic phonons of bulk silicon, our model shows a good agreement with available experimental and numerical results of nanoporous silicon thin films. It illustrates that the size effect of film thickness boundary scattering not only depends on the film thickness but also on the size of nanopores, and a larger nanopore leads to a stronger size effect of the film thickness. Our model also reveals that there are different optimal structures for getting the lowest in-plane and cross-plane thermal conductivities.

Method for making thin carbon foam electrodes

DOEpatents

Pekala, R.W.; Mayer, S.T.; Kaschmitter, J.L.; Morrison, R.L.

1999-08-03

A method for fabricating thin, flat carbon electrodes by infiltrating highly porous carbon papers, membranes, felts, metal fibers/powders, or fabrics with an appropriate carbon foam precursor material is disclosed. The infiltrated carbon paper, for example, is then cured to form a gel-saturated carbon paper, which is subsequently dried and pyrolyzed to form a thin sheet of porous carbon. The material readily stays flat and flexible during curing and pyrolyzing to form thin sheets. Precursor materials include polyacrylonitrile (PAN), polymethylacrylonitrile (PMAN), resorcinol/formaldehyde, catechol/formaldehyde, phenol/formaldehyde, etc., or mixtures thereof. These thin films are ideal for use as high power and energy electrodes in batteries, capacitors, and fuel cells, and are potentially useful for capacitive deionization, filtration and catalysis.

Characterization of aluminum selenide bi-layer thin film

NASA Astrophysics Data System (ADS)

Boolchandani, Sarita; Soni, Gyanesh; Srivastava, Subodh; Vijay, Y. K.

2018-05-01

The Aluminum Selenide (AlSe) bi-layer thin films were grown on glass substrate using thermal evaporation method under high vacuum condition. The morphological characterization was done using SEM. Electrical measurement with temperature variation shows that thin films exhibit the semiconductor nature. The optical properties of prepared thin films have also been characterized by UV-VIS spectroscopy measurements. The band gap of composite thin films has been calculated by Tauc's relation at different temperature ranging 35°C-100°C.

Low-Cost Detection of Thin Film Stress during Fabrication

NASA Technical Reports Server (NTRS)

Nabors, Sammy A.

2015-01-01

NASA's Marshall Space Flight Center has developed a simple, cost-effective optical method for thin film stress measurements during growth and/or subsequent annealing processes. Stress arising in thin film fabrication presents production challenges for electronic devices, sensors, and optical coatings; it can lead to substrate distortion and deformation, impacting the performance of thin film products. NASA's technique measures in-situ stress using a simple, noncontact fiber optic probe in the thin film vacuum deposition chamber. This enables real-time monitoring of stress during the fabrication process and allows for efficient control of deposition process parameters. By modifying process parameters in real time during fabrication, thin film stress can be optimized or controlled, improving thin film product performance.

Methods for preparing colloidal nanocrystal-based thin films

DOEpatents

Kagan, Cherie R.; Fafarman, Aaron T.; Choi, Ji-Hyuk; Koh, Weon-kyu; Kim, David K.; Oh, Soong Ju; Lai, Yuming; Hong, Sung-Hoon; Saudari, Sangameshwar Rao; Murray, Christopher B.

2016-05-10

Methods of exchanging ligands to form colloidal nanocrystals (NCs) with chalcogenocyanate (xCN)-based ligands and apparatuses using the same are disclosed. The ligands may be exchanged by assembling NCs into a thin film and immersing the thin film in a solution containing xCN-based ligands. The ligands may also be exchanged by mixing a xCN-based solution with a dispersion of NCs, flocculating the mixture, centrifuging the mixture, discarding the supernatant, adding a solvent to the pellet, and dispersing the solvent and pellet to form dispersed NCs with exchanged xCN-ligands. The NCs with xCN-based ligands may be used to form thin film devices and/or other electronic, optoelectronic, and photonic devices. Devices comprising nanocrystal-based thin films and methods for forming such devices are also disclosed. These devices may be constructed by depositing NCs on to a substrate to form an NC thin film and then doping the thin film by evaporation and thermal diffusion.

Sputter-deposited fuel cell membranes and electrodes

NASA Technical Reports Server (NTRS)

Narayanan, Sekharipuram R. (Inventor); Jeffries-Nakamura, Barbara (Inventor); Chun, William (Inventor); Ruiz, Ron P. (Inventor); Valdez, Thomas I. (Inventor)

2001-01-01

A method for preparing a membrane for use in a fuel cell membrane electrode assembly includes the steps of providing an electrolyte membrane, and sputter-depositing a catalyst onto the electrolyte membrane. The sputter-deposited catalyst may be applied to multiple sides of the electrolyte membrane. A method for forming an electrode for use in a fuel cell membrane electrode assembly includes the steps of obtaining a catalyst, obtaining a backing, and sputter-depositing the catalyst onto the backing. The membranes and electrodes are useful for assembling fuel cells that include an anode electrode, a cathode electrode, a fuel supply, and an electrolyte membrane, wherein the electrolyte membrane includes a sputter-deposited catalyst, and the sputter-deposited catalyst is effective for sustaining a voltage across a membrane electrode assembly in the fuel cell.

The effect of Argon pressure dependent V thin film on the phase transition process of (020) VO2 thin film

NASA Astrophysics Data System (ADS)

Meng, Yifan; Huang, Kang; Tang, Zhou; Xu, Xiaofeng; Tan, Zhiyong; Liu, Qian; Wang, Chunrui; Wu, Binhe; Wang, Chang; Cao, Juncheng

2018-01-01

It has been proved challenging to fabricate the single crystal orientation of VO2 thin film by a simple method. Based on chemical reaction thermodynamic and crystallization analysis theory, combined with our experimental results, we find out that when stoichiometric number of metallic V in the chemical equation is the same, the ratio of metallic V thin film surface average roughness Ra to thin film average particle diameter d decreases with the decreasing sputtering Argon pressure. Meanwhile, the oxidation reaction equilibrium constant K also decreases, which will lead to the increases of oxidation time, thereby the crystal orientation of the VO2 thin film will also become more uniform. By sputtering oxidation coupling method, metallic V thin film is deposited on c-sapphire substrate at 1 × 10-1 Pa, and then oxidized in the air with the maximum oxidation time of 65s, high oriented (020) VO2 thin film has been fabricated successfully, which exhibits ∼4.6 orders sheet resistance change across the metal-insulator transition.

Hyper-Cross-Linked Additives that Impede Aging and Enhance Permeability in Thin Polyacetylene Films for Organic Solvent Nanofiltration.

PubMed

Cheng, Xi Quan; Konstas, Kristina; Doherty, Cara M; Wood, Colin D; Mulet, Xavier; Xie, Zongli; Ng, Derrick; Hill, Matthew R; Shao, Lu; Lau, Cher Hon

2017-04-26

Membrane materials with high permeability to solvents while rejecting dissolved contaminants are crucial to lowering the energy costs associated with liquid separations. However, the current lack of stable high-permeability materials require innovative engineering solutions to yield high-performance, thin membranes using stable polymers with low permeabilities. Poly[1-(trimethylsilyl)-1-propyne] (PTMSP) is one of the most permeable polymers but is extremely susceptible to physical aging. Despite recent developments in anti-aging polymer membranes, this research breakthrough has yet to be demonstrated on thin PTMSP films supported on porous polymer substrates, a crucial step toward commercializing anti-aging membranes for industrial applications. Here we report the development of scalable, thin film nanocomposite membranes supported on polymer substrates that are resistant to physical aging while having high permeabilities to alcohols. The selective layer is made up of PTMSP and nanoporous polymeric additives. The nanoporous additives provide additional passageways to solvents, enhancing the high permeability of the PTMSP materials further. Through intercalation of polyacetylene chains into the sub-nm pores of organic additives, physical aging in the consequent was significantly hindered in continuous long-term operation. Remarkably we also demonstrate that the additives enhance both membrane permeability and rejection of dissolved contaminants across the membranes, as ethanol permeability at 5.5 × 10 -6 L m m -2 h -1 bar -1 with 93% Rose Bengal (1017.6 g mol -1 ) rejection, drastically outperforming commercial and state-of-the-art membranes. These membranes can replace energy-intensive separation processes such as distillation, lowering operation costs in well-established pharmaceutical production processes.

Sustainable Process for the Preparation of High-Performance Thin-Film Composite Membranes using Ionic Liquids as the Reaction Medium.

PubMed

Mariën, Hanne; Bellings, Lotte; Hermans, Sanne; Vankelecom, Ivo F J

2016-05-23

A new form of interfacial polymerization to synthesize thin-film composite membranes realizes a more sustainable membrane preparation and improved nanofiltration performance. By introducing an ionic liquid (IL) as the organic reaction phase, the extremely different physicochemical properties to those of commonly used organic solvents influenced the top-layer formation in several beneficial ways. In addition to the elimination of hazardous solvents in the preparation, the m-phenylenediamine (MPD) concentration could be reduced 20-fold, and the use of surfactants and catalysts became redundant. Together with the more complete recycling of the organic phase in the water/IL system, these factors resulted in a 50 % decrease in the mass intensity of the top-layer formation. Moreover, a much thinner top layer with a high ethanol permeance of 0.61 L m(-2)  h(-1)  bar(-1) [99 % Rose Bengal (RB, 1017 Da) retention; 1 bar=0.1 MPa] was formed without the use of any additives. This EtOH permeance is 555 and 161 % higher than that for the conventional interfacial polymerization (without and with additives, respectively). In reverse osmosis, high NaCl retentions of 97 % could be obtained. Finally, the remarkable decrease in the membrane surface roughness indicates the potential for reduced fouling with this new type of membrane. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improvement in interfacial characteristics of low-voltage carbon nanotube thin-film transistors with solution-processed boron nitride thin films

NASA Astrophysics Data System (ADS)

Jeon, Jun-Young; Ha, Tae-Jun

2017-08-01

In this article, we demonstrate the potential of solution-processed boron nitride (BN) thin films for high performance single-walled carbon nanotube thin-film transistors (SWCNT-TFTs) with low-voltage operation. The use of BN thin films between solution-processed high-k dielectric layers improved the interfacial characteristics of metal-insulator-metal devices, thereby reducing the current density by three orders of magnitude. We also investigated the origin of improved device performance in SWCNT-TFTs by employing solution-processed BN thin films as an encapsulation layer. The BN encapsulation layer improves the electrical characteristics of SWCNT-TFTs, which includes the device key metrics of linear field-effect mobility, sub-threshold swing, and threshold voltage as well as the long-term stability against the aging effect in air. Such improvements can be achieved by reduced interaction of interfacial localized states with charge carriers. We believe that this work can open up a promising route to demonstrate the potential of solution-processed BN thin films on nanoelectronics.

Piezoelectric MEMS: Ferroelectric thin films for MEMS applications

NASA Astrophysics Data System (ADS)

Kanno, Isaku

2018-04-01

In recent years, piezoelectric microelectromechanical systems (MEMS) have attracted attention as next-generation functional microdevices. Typical applications of piezoelectric MEMS are micropumps for inkjet heads or micro-gyrosensors, which are composed of piezoelectric Pb(Zr,Ti)O3 (PZT) thin films and have already been commercialized. In addition, piezoelectric vibration energy harvesters (PVEHs), which are regarded as one of the key devices for Internet of Things (IoT)-related technologies, are promising future applications of piezoelectric MEMS. Significant features of piezoelectric MEMS are their simple structure and high energy conversion efficiency between mechanical and electrical domains even on the microscale. The device performance strongly depends on the function of the piezoelectric thin films, especially on their transverse piezoelectric properties, indicating that the deposition of high-quality piezoelectric thin films is a crucial technology for piezoelectric MEMS. On the other hand, although the difficulty in measuring the precise piezoelectric coefficients of thin films is a serious obstacle in the research and development of piezoelectric thin films, a simple unimorph cantilever measurement method has been proposed to obtain precise values of the direct or converse transverse piezoelectric coefficient of thin films, and recently this method has become to be the standardized testing method. In this article, I will introduce fundamental technologies of piezoelectric thin films and related microdevices, especially focusing on the deposition of PZT thin films and evaluation methods for their transverse piezoelectric properties.

Operation of Thin-Film Electrolyte Metal-Supported Solid Oxide Fuel Cells in Lightweight and Stationary Stacks: Material and Microstructural Aspects

PubMed Central

Roehrens, Daniel; Packbier, Ute; Fang, Qingping; Blum, Ludger; Sebold, Doris; Bram, Martin; Menzler, Norbert

2016-01-01

In this study we report on the development and operational data of a metal-supported solid oxide fuel cell with a thin film electrolyte under varying conditions. The metal-ceramic structure was developed for a mobile auxiliary power unit and offers power densities of 1 W/cm2 at 800 °C, as well as robustness under mechanical, thermal and chemical stresses. A dense and thin yttria-doped zirconia layer was applied to a nanoporous nickel/zirconia anode using a scalable adapted gas-flow sputter process, which allowed the homogeneous coating of areas up to 100 cm2. The cell performance is presented for single cells and for stack operation, both in lightweight and stationary stack designs. The results from short-term operation indicate that this cell technology may be a very suitable alternative for mobile applications. PMID:28773883

Applications of Thin Film Thermocouples for Surface Temperature Measurement

NASA Technical Reports Server (NTRS)

Martin, Lisa C.; Holanda, Raymond

1994-01-01

Thin film thermocouples provide a minimally intrusive means of measuring surface temperature in hostile, high temperature environments. Unlike wire thermocouples, thin films do not necessitate any machining of the surface, therefore leaving intact its structural integrity. Thin films are many orders of magnitude thinner than wire, resulting in less disruption to the gas flow and thermal patterns that exist in the operating environment. Thin film thermocouples have been developed for surface temperature measurement on a variety of engine materials. The sensors are fabricated in the NASA Lewis Research Center's Thin Film Sensor Lab, which is a class 1000 clean room. The thermocouples are platinum-13 percent rhodium versus platinum and are fabricated by the sputtering process. Thin film-to-leadwire connections are made using the parallel-gap welding process. Thermocouples have been developed for use on superalloys, ceramics and ceramic composites, and intermetallics. Some applications of thin film thermocouples are: temperature measurement of space shuttle main engine turbine blade materials, temperature measurement in gas turbine engine testing of advanced materials, and temperature and heat flux measurements in a diesel engine. Fabrication of thin film thermocouples is described. Sensor durability, drift rate, and maximum temperature capabilities are addressed.

PZT thin film actuated elastic fin micromotor.

PubMed

Dubois, M A; Muralt, P

1998-01-01

A piezoelectric elastic fin micromotor based on a PbZr(0.53 )Ti(0.47)O(3) thin film driving a micromachined silicon membrane was fabricated and studied. The stator was characterized by interferometry, and a laser set-up was used to measure the angular velocity and acceleration of the motor. The torque, the output power, and the efficiency of the device were extracted from these measurements. Values up to 1020 rpm and 0.94 microNm were observed for the velocity and the torque, respectively, which would be sufficient for a wristwatch application. The present version exhibited an efficiency of 0.17%, which could theoretically be increased to 4.8%

Comprehensive Study on Ceramic Membranes for Low‐Cost Microbial Fuel Cells

PubMed Central

Pasternak, Grzegorz; Greenman, John

2016-01-01

Abstract Microbial fuel cells (MFCs) made with different types of ceramic membranes were investigated to find a low‐cost alternative to commercially available proton exchange membranes. The MFCs operated with fresh human urine as the fuel. Pyrophyllite and earthenware produced the best performance to reach power densities of 6.93 and 6.85 W m−3, respectively, whereas mullite and alumina achieved power densities of 4.98 and 2.60 W m−3, respectively. The results indicate the dependence of bio‐film growth and activity on the type of ceramic membrane applied. The most favourable conditions were created in earthenware MFCs. The performance of the ceramic membranes was related to their physical and chemical properties determined by environmental scanning electron microscopy and energy dispersive X‐ray spectroscopy. The cost of mullite, earthenware, pyrophyllite and alumina was estimated to be 13.61, 4.14, 387.96 and 177.03 GBP m−2, respectively. The results indicate that earthenware and mullite are good substitutes for commercially available proton exchange membranes, which makes the MFC technology accessible in developing countries. PMID:26692569

Nanoporous structures on ZnO thin films

NASA Astrophysics Data System (ADS)

Gür, Emre; Kılıç, Bayram; Coşkun, C.; Tüzemen, S.; Bayrakçeken, Fatma

2010-01-01

Porous structures were formed on ZnO thin films which were grown by an electrochemical deposition (ECD) method. The growth processes were carried out in a solution of dimethylsulfoxide (DMSO) zinc perchlorate, Zn(ClO 4) 2, at 120 ∘C on indium tin oxide (ITO) substrates. Optical and structural characterizations of electrochemically grown ZnO thin films have shown that the films possess high (0002) c-axis orientation, high nucleation, high intensity and low FWHM of UV emission at the band edge region and a sharp UV absorption edge. Nanoporous structures were formed via self-assembled monolayers (SAMs) of hexanethiol (C 6SH) and dodecanethiol (C 12SH). Scanning electron microscope (SEM) measurements showed that while a nanoporous structure (pore radius 20 nm) is formed on the ZnO thin films by hexanathiol solution, a macroporous structure (pore radius 360 nm) is formed by dodecanethiol solution. No significant variation is observed in X-ray diffraction (XRD) measurements on the ZnO thin films after pore formation. However, photoluminescence (PL) measurements showed that green emission is observed as the dominant emission for the macroporous structures, while no variation is observed for the thin film nanoporous ZnO sample.

Ambient pressure process for preparing aerogel thin films reliquified sols useful in preparing aerogel thin films

DOEpatents

Brinker, Charles Jeffrey; Prakash, Sai Sivasankaran

1999-01-01

A method for preparing aerogel thin films by an ambient-pressure, continuous process. The method of this invention obviates the use of an autoclave and is amenable to the formation of thin films by operations such as dip coating. The method is less energy intensive and less dangerous than conventional supercritical aerogel processing techniques.

Characterization of Thin Film Polymers Through Dynamic Mechanical Analysis and Permeation

NASA Technical Reports Server (NTRS)

Herring, Helen

2003-01-01

Thin polymer films are being considered, as candidate materials to augment the permeation resistance of cryogenic hydrogen fuel tanks such as would be required for future reusable launch vehicles. To evaluate performance of candidate films after environmental exposure, an experimental study was performed to measure the thermal/mechanical and permeation performance of six, commercial-grade materials. Dynamic storage modulus, as measured by Dynamic Mechanical Analysis, was found over a range of temperatures. Permeability, as measured by helium gas diffusion, was found at room temperature. Test data was correlated with respect to film type and pre-test exposure to moisture, elevated temperature, and cryogenic temperature. Results indicated that the six films were comparable in performance and their resistance to environmental degradation.

In-space fabrication of thin-film structures

NASA Technical Reports Server (NTRS)

Lippman, M. E.

1972-01-01

A conceptual study of physical vapor-deposition processes for in-space fabrication of thin-film structures is presented. Potential advantages of in-space fabrication are improved structural integrity and surface reflectivity of free-standing ultra-thin films and coatings. Free-standing thin-film structures can find use as photon propulsion devices (solar sails). Other applications of the concept involve free-standing shadow shields, or thermal control coatings of spacecraft surfaces. Use of expendables (such as booster and interstage structures) as source material for the physical vapor deposition process is considered. The practicability of producing thin, textured, aluminum films by physical vapor deposition and subsequent separation from a revolving substrate is demonstrated by laboratory experiments. Heating power requirement for the evaporation process is estimated for a specific mission.

Thin film bismuth iron oxides useful for piezoelectric devices

DOEpatents

Zeches, Robert J.; Martin, Lane W.; Ramesh, Ramamoorthy

2016-05-31

The present invention provides for a composition comprising a thin film of BiFeO.sub.3 having a thickness ranging from 20 nm to 300 nm, a first electrode in contact with the BiFeO.sub.3 thin film, and a second electrode in contact with the BiFeO.sub.3 thin film; wherein the first and second electrodes are in electrical communication. The composition is free or essentially free of lead (Pb). The BFO thin film is has the piezoelectric property of changing its volume and/or shape when an electric field is applied to the BFO thin film.

Deposition and characterization of ZnSe nanocrystalline thin films

NASA Astrophysics Data System (ADS)

Temel, Sinan; Gökmen, F. Özge; Yaman, Elif; Nebi, Murat

2018-02-01

ZnSe nanocrystalline thin films were deposited at different deposition times by using the Chemical Bath Deposition (CBD) technique. Effects of deposition time on structural, morphological and optical properties of the obtained thin films were characterized. X-ray diffraction (XRD) analysis was used to study the structural properties of ZnSe nanocrystalline thin films. It was found that ZnSe thin films have a cubic structure with a preferentially orientation of (111). The calculated average grain size value was about 28-30 nm. The surface morphology of these films was studied by the Field Emission Scanning Electron Microscope (FESEM). The surfaces of the thin films were occurred from small stacks and nano-sized particles. The band gap values of the ZnSe nanocrystalline thin films were determined by UV-Visible absorption spectrum and the band gap values were found to be between 2.65-2.86 eV.

Thermal conductivity of catalyst layer of polymer electrolyte membrane fuel cells: Part 1 - Experimental study

NASA Astrophysics Data System (ADS)

Ahadi, Mohammad; Tam, Mickey; Saha, Madhu S.; Stumper, Jürgen; Bahrami, Majid

2017-06-01

In this work, a new methodology is proposed for measuring the through-plane thermal conductivity of catalyst layers (CLs) in polymer electrolyte membrane fuel cells. The proposed methodology is based on deconvolution of bulk thermal conductivity of a CL from measurements of two thicknesses of the CL, where the CLs are sandwiched in a stack made of two catalyst-coated substrates. Effects of hot-pressing, compression, measurement method, and substrate on the through-plane thermal conductivity of the CL are studied. For this purpose, different thicknesses of catalyst are coated on ethylene tetrafluoroethylene (ETFE) and aluminum (Al) substrates by a conventional Mayer bar coater and measured by scanning electron microscopy (SEM). The through-plane thermal conductivity of the CLs is measured by the well-known guarded heat flow (GHF) method as well as a recently developed transient plane source (TPS) method for thin films which modifies the original TPS thin film method. Measurements show that none of the studied factors has any effect on the through-plane thermal conductivity of the CL. GHF measurements of a non-hot-pressed CL on Al yield thermal conductivity of 0.214 ± 0.005 Wṡm-1ṡK-1, and TPS measurements of a hot-pressed CL on ETFE yield thermal conductivity of 0.218 ± 0.005 Wṡm-1ṡK-1.

Electrically Tunable Integrated Thin-Film Magnetoelectric Resonators

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

El-Ghazaly, Amal; Evans, Joseph T.; Sato, Noriyuki

Magnetoelectrics have attracted much attention for their ability to control magnetic behavior electrically and electrical behavior magnetically. This feature provides numerous benefits to electronic systems and can potentially serve as the bridge needed to integrate magnetic devices into mainstream electronics. This natural next step is pursued and thin-film integrated magnetoelectric devices are produced for radio-frequency (RF) electronics. The first fully integrated, thin-film magnetoelectric modulators for tunable RF electronics are presented. Moreover, these devices provide electric field control of magnetic permeability in order to change the phase velocity and resonance frequency of coplanar waveguides. During this study, the various thin-film materialmore » phenomena, trade-offs, and integration considerations for composite magnetoelectrics are analyzed and discussed. The fabricated devices achieve reversible tunability of the resonance frequency, characterized by a remarkable converse magnetoelectric coupling coefficient of up to 24 mG cm V -1 using just thin films. Based on this work, suggestions are given for additional optimizations of future designs that will maximize the thin-film magnetoelectric interactions.« less

Electrically Tunable Integrated Thin-Film Magnetoelectric Resonators

DOE PAGES

El-Ghazaly, Amal; Evans, Joseph T.; Sato, Noriyuki; ...

2017-06-14

Magnetoelectrics have attracted much attention for their ability to control magnetic behavior electrically and electrical behavior magnetically. This feature provides numerous benefits to electronic systems and can potentially serve as the bridge needed to integrate magnetic devices into mainstream electronics. This natural next step is pursued and thin-film integrated magnetoelectric devices are produced for radio-frequency (RF) electronics. The first fully integrated, thin-film magnetoelectric modulators for tunable RF electronics are presented. Moreover, these devices provide electric field control of magnetic permeability in order to change the phase velocity and resonance frequency of coplanar waveguides. During this study, the various thin-film materialmore » phenomena, trade-offs, and integration considerations for composite magnetoelectrics are analyzed and discussed. The fabricated devices achieve reversible tunability of the resonance frequency, characterized by a remarkable converse magnetoelectric coupling coefficient of up to 24 mG cm V -1 using just thin films. Based on this work, suggestions are given for additional optimizations of future designs that will maximize the thin-film magnetoelectric interactions.« less

Nonhumidified High-Temperature Membranes Developed for Proton Exchange Membrane Fuel Cells

NASA Technical Reports Server (NTRS)

Kinder, James D.

2005-01-01

Fuel cells are being considered for a wide variety of aerospace applications. One of the most versatile types of fuel cells is the proton-exchange-membrane (PEM) fuel cell. PEM fuel cells can be easily scaled to meet the power and space requirements of a specific application. For example, small 100-W PEM fuel cells are being considered for personal power for extravehicular activity suit applications, whereas larger PEM fuel cells are being designed for primary power in airplanes and in uninhabited air vehicles. Typically, PEM fuel cells operate at temperatures up to 80 C. To increase the efficiency and power density of the fuel cell system, researchers are pursuing methods to extend the operating temperature of the PEM fuel cell to 180 C. The most widely used membranes in PEM fuel cells are Nafion 112 and Nafion 117--sulfonated perfluorinated polyethers that were developed by DuPont. In addition to their relatively high cost, the properties of these membranes limit their use in a PEM fuel cell to around 80 C. The proton conductivity of Nafion membranes significantly decreases above 80 C because the membrane dehydrates. The useful operating range of Nafion-based PEM fuel cells can be extended to over 100 C if ancillary equipment, such as compressors and humidifiers, is added to maintain moisture levels within the membrane. However, the addition of these components reduces the power density and increases the complexity of the fuel cell system.

Effects of high temperature and film thicknesses on the texture evolution in Ag thin films

NASA Astrophysics Data System (ADS)

Eshaghi, F.; Zolanvari, A.

2017-04-01

In situ high-temperature X-ray diffraction techniques were used to study the effect of high temperatures (up to 600°C) on the texture evolution in silver thin films. Ag thin films with different thicknesses of 40, 80, 120 and 160nm were sputtered on the Si(100) substrates at room temperature. Then, microstructure of thin films was determined using X-ray diffraction. To investigate the influence of temperature on the texture development in the Ag thin films with different thicknesses, (111), (200) and (220) pole figures were evaluated and orientation distribution functions were calculated. Minimizing the total energy of the system which is affected by competition between surface and elastic strain energy was a key factor in the as-deposited and post annealed thin films. Since sputtering depositions was performed at room temperature and at the same thermodynamic conditions, the competition growth caused the formation of the {122} < uvw \\rangle weak fiber texture in as-deposited Ag thin films. It was significantly observed that the post annealed Ag thin films showed {111} < uvw \\rangle orientations as their preferred orientations, but their preferred fiber texture varied with the thickness of thin films. Increasing thin film thickness from 40nm to 160nm led to decreasing the intensity of the {111} < uvw \\rangle fiber texture.

Vapor deposition of thin films

DOEpatents

Smith, David C.; Pattillo, Stevan G.; Laia, Jr., Joseph R.; Sattelberger, Alfred P.

1992-01-01

A highly pure thin metal film having a nanocrystalline structure and a process of preparing such highly pure thin metal films of, e.g., rhodium, iridium, molybdenum, tungsten, rhenium, platinum, or palladium by plasma assisted chemical vapor deposition of, e.g., rhodium(allyl).sub.3, iridium(allyl).sub.3, molybdenum(allyl).sub.4, tungsten(allyl).sub.4, rhenium(allyl).sub.4, platinum(allyl).sub.2, or palladium(allyl).sub.2 are disclosed. Additionally, a general process of reducing the carbon content of a metallic film prepared from one or more organometallic precursor compounds by plasma assisted chemical vapor deposition is disclosed.

pH matters: The influence of the catalyst ink on the oxygen reduction activity determined in thin film rotating disk electrode measurements

NASA Astrophysics Data System (ADS)

Inaba, Masanori; Quinson, Jonathan; Arenz, Matthias

2017-06-01

We investigated the influence of the ink properties of proton exchange membrane fuel cell (PEMFC) catalysts on the oxygen reduction reaction (ORR) activity determined in thin film rotating disk electrode (TF-RDE) measurements. It was found that the adaption of a previously reported ink recipe to home-made catalysts does not lead to satisfying results, although reported work could be reproduced using commercial catalyst samples. It is demonstrated that the pH of the catalyst ink, which has not been addressed in previous TF-RDE studies, is an important parameter that needs to be carefully controlled to determine the intrinsic ORR activity of high surface area catalysts.

MCP performance improvement using alumina thin film

NASA Astrophysics Data System (ADS)

Yang, Yuzhen; Yan, Baojun; Liu, Shulin; Zhao, Tianchi; Yu, Yang; Wen, Kaile; Li, Yumei; Qi, Ming

2017-10-01

The performance improvement using alumina thin film on a dual microchannel plate (MCP) detector for single electron counting was investigated. The alumina thin film was coated on all surfaces of the MCPs by atomic layer deposition method. It was found that the gain, the single electron resolution and the peak-to-valley ratio of the dual MCP detector were significantly enhanced by coating the alumina thin film. The optimum operating conditions of the new dual MCP detector have been studied.

Atomic-scale visualization of oxide thin-film surfaces.

PubMed

Iwaya, Katsuya; Ohsawa, Takeo; Shimizu, Ryota; Okada, Yoshinori; Hitosugi, Taro

2018-01-01

The interfaces of complex oxide heterostructures exhibit intriguing phenomena not observed in their constituent materials. The oxide thin-film growth of such heterostructures has been successfully controlled with unit-cell precision; however, atomic-scale understandings of oxide thin-film surfaces and interfaces have remained insufficient. We examined, with atomic precision, the surface and electronic structures of oxide thin films and their growth processes using low-temperature scanning tunneling microscopy. Our results reveal that oxide thin-film surface structures are complicated in contrast to the general perception and that atomically ordered surfaces can be achieved with careful attention to the surface preparation. Such atomically ordered oxide thin-film surfaces offer great opportunities not only for investigating the microscopic origins of interfacial phenomena but also for exploring new surface phenomena and for studying the electronic states of complex oxides that are inaccessible using bulk samples.

Miniature hybrid microwave IC's using a novel thin-film technology

NASA Astrophysics Data System (ADS)

Eda, Kazuo; Miwa, Tetsuji; Taguchi, Yutaka; Uwano, Tomoki

1990-12-01

A novel thin-film technology for miniature hybrid microwave ICs is presented. All passive components, such as resistors and capacitors, are fully integrated on ordinary alumina ceramic substrates using the thin-film technology with very high yield. The numbers of parts and wiring processes were significantly reduced. This technology was applied to the fabrication of Ku-band solid-state power amplifiers. This thin-film technology offers the following advantages: (1) a very high yield fabrication process of thin-film capacitor having excellent electrical characteristics in the gigahertz range (Q = 230 at 12 GHz) and reliability: (2) two kinds of thin-film resistors having different temperature coefficients of resistivity and a lift-off process to integrate them with thin-film capacitors; and (3) a matching method using the thin-film capacitor.

Transferable and flexible thin film devices for engineering applications

NASA Astrophysics Data System (ADS)

Mutyala, Madhu Santosh K.; Zhou, Jingzhou; Li, Xiaochun

2014-05-01

Thin film devices can be of significance for manufacturing, energy conversion systems, solid state electronics, wireless applications, etc. However, these thin film sensors/devices are normally fabricated on rigid silicon substrates, thus neither flexible nor transferrable for engineering applications. This paper reports an innovative approach to transfer polyimide (PI) embedded thin film devices, which were fabricated on glass, to thin metal foils. Thin film thermocouples (TFTCs) were fabricated on a thin PI film, which was spin coated and cured on a glass substrate. Another layer of PI film was then spin coated again on TFTC/PI and cured to obtain the embedded TFTCs. Assisted by oxygen plasma surface coarsening of the PI film on the glass substrate, the PI embedded TFTC was successfully transferred from the glass substrate to a flexible copper foil. To demonstrate the functionality of the flexible embedded thin film sensors, they were transferred to the sonotrode tip of an ultrasonic metal welding machine for in situ process monitoring. The dynamic temperatures near the sonotrode tip were effectively measured under various ultrasonic vibration amplitudes. This technique of transferring polymer embedded electronic devices onto metal foils yield great potentials for numerous engineering applications.

Advanced Fabrication Method for the Preparation of MOF Thin Films: Liquid-Phase Epitaxy Approach Meets Spin Coating Method.

PubMed

Chernikova, Valeriya; Shekhah, Osama; Eddaoudi, Mohamed

2016-08-10

Here, we report a new and advanced method for the fabrication of highly oriented/polycrystalline metal-organic framework (MOF) thin films. Building on the attractive features of the liquid-phase epitaxy (LPE) approach, a facile spin coating method was implemented to generate MOF thin films in a high-throughput fashion. Advantageously, this approach offers a great prospective to cost-effectively construct thin-films with a significantly shortened preparation time and a lessened chemicals and solvents consumption, as compared to the conventional LPE-process. Certainly, this new spin-coating approach has been implemented successfully to construct various MOF thin films, ranging in thickness from a few micrometers down to the nanometer scale, spanning 2-D and 3-D benchmark MOF materials including Cu2(bdc)2·xH2O, Zn2(bdc)2·xH2O, HKUST-1, and ZIF-8. This method was appraised and proved effective on a variety of substrates comprising functionalized gold, silicon, glass, porous stainless steel, and aluminum oxide. The facile, high-throughput and cost-effective nature of this approach, coupled with the successful thin film growth and substrate versatility, represents the next generation of methods for MOF thin film fabrication. Therefore, paving the way for these unique MOF materials to address a wide range of challenges in the areas of sensing devices and membrane technology.

Electrostatic thin film chemical and biological sensor

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

Prelas, Mark A.; Ghosh, Tushar K.; Tompson, Jr., Robert V.

A chemical and biological agent sensor includes an electrostatic thin film supported by a substrate. The film includes an electrostatic charged surface to attract predetermined biological and chemical agents of interest. A charge collector associated with said electrostatic thin film collects charge associated with surface defects in the electrostatic film induced by the predetermined biological and chemical agents of interest. A preferred sensing system includes a charge based deep level transient spectroscopy system to read out charges from the film and match responses to data sets regarding the agents of interest. A method for sensing biological and chemical agents includesmore » providing a thin sensing film having a predetermined electrostatic charge. The film is exposed to an environment suspected of containing the biological and chemical agents. Quantum surface effects on the film are measured. Biological and/or chemical agents can be detected, identified and quantified based on the measured quantum surface effects.« less

PREFACE: Innovations in Thin Film Processing and Characterisation

NASA Astrophysics Data System (ADS)

Henrion, Gérard; Belmahi, Mohammed; Andrieu, Stéphane

2010-07-01

This special issue contains selected papers which were presented as invited or contributed communications at the 4th International Conference on Innovation in Thin Film Processing and Characterization (ITFPC'09) which was held on 17-20 November, 2009 in Nancy (France) Jointly organized by the French Vacuum Society and the Institut Jean Lamour-a joint research unit specialized in materials, metallurgy, nano-sciences, plasmas and surfaces-the ITFPC conferences aim at providing an open forum to discuss the progress and latest developments in thin film processing and engineering. Invited lectures aim particularly at providing overviews on scientific topics while contributed communications focus on particular cutting-edge aspects of thin film science and technology, including CVD, PVD and ion beam assisted processes. The 2009 conference was organized along the 6 main following topics: Thin films processing and surface engineering Numerical simulation and thin film characterization Protective applications of thin films Energy, environment and health applications of thin films Micro- and nano-patterning of thin films New properties and applications resulting from patterned thin films which were completed by a special half day session devoted to industry-supported innovation. 180 scientists from 20 worldwide countries attended the different sessions along with the 9 invited lectures and 130 contributions were given. Besides the outstanding scientific program, a half-day tutorial session preceded the conference. During the short courses, emphasis was laid on: Lithography for thin film patterning Mechanical properties of thin films Principles and applications of reactive sputtering processes. The French Vacuum Society granted financial aid to PhD students who applied for it in order to encourage the participation of young scientists. The 19 papers published in this volume were accepted for publication after peerreviewal as for regular papers. As chairmen of this conference

Preparation of LiMn{sub 2}O{sub 4} cathode thin films for thin film lithium secondary batteries by a mist CVD process

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

Tadanaga, Kiyoharu, E-mail: tadanaga@chem.osakafu-u.ac.jp; Yamaguchi, Akihiro; Sakuda, Atsushi

2014-05-01

Highlights: • LiMn{sub 2}O{sub 4} thin films were prepared by using the mist CVD process. • An aqueous solution of lithium and manganese acetates is used for the precursor solution. • The cell with the LiMn{sub 2}O{sub 4} thin films exhibited a capacity of about 80 mAh/g. • The cell showed good cycling performance during 10 cycles. - Abstract: LiMn{sub 2}O{sub 4} cathode thin films for thin film lithium secondary batteries were prepared by using so-called the “mist CVD process”, employing an aqueous solution of lithium acetate and manganese acetate, as the source of Li and Mn, respectively. The aqueousmore » solution of starting materials was ultrasonically atomized to form mist particles, and mists were transferred by nitrogen gas to silica glass substrate to form thin films. FE-SEM observation revealed that thin films obtained by this process were dense and smooth, and thin films with a thickness of about 750 nm were obtained. The electrochemical cell with the thin films obtained by sintering at 700 °C exhibited a capacity of about 80 mAh/g, and the cell showed good cycling performance during 10 cycles.« less

Thin film photovoltaic device

DOEpatents

Catalano, Anthony W.; Bhushan, Manjul

1982-01-01

A thin film photovoltaic solar cell which utilizes a zinc phosphide semiconductor is of the homojunction type comprising an n-type conductivity region forming an electrical junction with a p-type region, both regions consisting essentially of the same semiconductor material. The n-type region is formed by treating zinc phosphide with an extrinsic dopant such as magnesium. The semiconductor is formed on a multilayer substrate which acts as an opaque contact. Various transparent contacts may be used, including a thin metal film of the same chemical composition as the n-type dopant or conductive oxides or metal grids.

Thin film photovoltaic device

DOEpatents

Catalano, A.W.; Bhushan, M.

1982-08-03

A thin film photovoltaic solar cell which utilizes a zinc phosphide semiconductor is of the homojunction type comprising an n-type conductivity region forming an electrical junction with a p-type region, both regions consisting essentially of the same semiconductor material. The n-type region is formed by treating zinc phosphide with an extrinsic dopant such as magnesium. The semiconductor is formed on a multilayer substrate which acts as an opaque contact. Various transparent contacts may be used, including a thin metal film of the same chemical composition as the n-type dopant or conductive oxides or metal grids. 5 figs.

Preparation and characterization of mono-sheet bipolar membranes by pre-irradiation grafting method for fuel cell applications

NASA Astrophysics Data System (ADS)

Guan, Yingjie; Fang, Jun; Fu, Tao; Zhou, Huili; Wang, Xin; Deng, Zixiang; Zhao, Jinbao

2016-09-01

A new method for the preparation of the mono-sheet bipolar membrane applied to fuel cells was developed based on the pre-irradiation grafting technology. A series of bipolar membranes were successfully prepared by simultaneously grafting of styrene onto one side of the poly(ethylene-co-tetrafluoroethylene) base film and 1-vinylimidazole onto the opposite side, followed by the sulfonation and alkylation, respectively. The chemical structures and microstructures of the prepared membranes were investigated by ATR-FTIR and SEM-EDS. The TGA measurements demonstrated the prepared bipolar membranes have reasonable thermal stability. The ion exchange capacity, water uptake and ionic conductivity of the membranes were also characterized. The H2/O2 single fuel cells using these membranes were evaluated and revealed a maximum power density of 107 mW cm-2 at 35 °C with unhumidified hydrogen and oxygen. The preliminary performances suggested the great prospect of these membranes in application of bipolar membrane fuel cells.

Method for making thin polypropylene film

DOEpatents

Behymer, R.D.; Scholten, J.A.

1985-11-21

An economical method is provided for making uniform thickness polypropylene film as thin as 100 Angstroms. A solution of polypropylene dissolved in xylene is formed by mixing granular polypropylene and xylene together in a flask at an elevated temperature. A substrate, such as a glass plate or microscope slide is immersed in the solution. When the glass plate is withdrawn from the solution at a uniform rate, a thin polypropylene film forms on a flat surface area of the glass plate as the result of xylene evaporation. The actual thickness of the polypropylene film is functional of the polypropylene in xylene solution concentration, and the particular withdrawal rate of the glass plate from the solution. After formation, the thin polypropylene film is floated from the glass plate onto the surface of water, from which it is picked up with a wire hoop.

High density nonmagnetic cobalt in thin films

NASA Astrophysics Data System (ADS)

Banu, Nasrin; Singh, Surendra; Basu, Saibal; Roy, Anupam; Movva, Hema C. P.; Lauter, V.; Satpati, B.; Dev, B. N.

2018-05-01

Recently high density (HD) nonmagnetic cobalt has been discovered in a nanoscale cobalt thin film, grown on Si(111) single crystal. This form of cobalt is not only nonmagnetic but also superconducting. These promising results have encouraged further investigations of the growth of the nonmagnetic (NM) phase of cobalt. In the original investigation, the cobalt film had a natural cobalt oxide at the top. We have investigated whether the growth of HD NM cobalt layers in the thin film depends on (i) a capping layer on the cobalt film, (ii) the thickness of the cobalt film and (iii) the nature of the substrate on which the cobalt film is grown. The results of such investigations indicate that for cobalt films capped with a thin gold layer, and for various film thicknesses, HD NM cobalt layers are formed. However, instead of a Si substrate, when the cobalt films are grown on oxide substrates, such as silicon oxide or cobalt oxide, HD NM cobalt layers are not formed. The difference is attributed to the nature—crystalline or amorphous—of the substrate.

Nanosphere lithography applied to magnetic thin films

NASA Astrophysics Data System (ADS)

Gleason, Russell

Magnetic nanostructures have widespread applications in many areas of physics and engineering, and nanosphere lithography has recently emerged as promising tool for the fabrication of such nanostructures. The goal of this research is to explore the magnetic properties of a thin film of ferromagnetic material deposited onto a hexagonally close-packed monolayer array of polystyrene nanospheres, and how they differ from the magnetic properties of a typical flat thin film. The first portion of this research focuses on determining the optimum conditions for depositing a monolayer of nanospheres onto chemically pretreated silicon substrates (via drop-coating) and the subsequent characterization of the deposited nanosphere layer with scanning electron microscopy. Single layers of permalloy (Ni80Fe20) are then deposited on top of the nanosphere array via DC magnetron sputtering, resulting in a thin film array of magnetic nanocaps. The coercivities of the thin films are measured using a home-built magneto-optical Kerr effect (MOKE) system in longitudinal arrangement. MOKE measurements show that for a single layer of permalloy (Py), the coercivity of a thin film deposited onto an array of nanospheres increases compared to that of a flat thin film. In addition, the coercivity increases as the nanosphere size decreases for the same deposited layer. It is postulated that magnetic exchange decoupling between neighboring nanocaps suppresses the propagation of magnetic domain walls, and this pinning of the domain walls is thought to be the primary source of the increase in coercivity.

Fabrication and etching processes of silicon-based PZT thin films

NASA Astrophysics Data System (ADS)

Zhao, Hongjin; Liu, Yanxiang; Liu, Jianshe; Ren, Tian-Ling; Liu, Li-Tian; Li, Zhijian

2001-09-01

Lead-zirconate-titanate (PZT) thin films on silicon were prepared by a sol-gel method. Phase characterization and crystal orientation of the films were investigated by x-ray diffraction analysis (XRD). It was shown that the PZT thin films had a perfect perovskite structure after annealed at a low temperature of 600 degrees C. PZT thin films were chemically etched using HCl/HF solution through typical semiconductor lithographic process, and the etching condition was optimized. The scanning electron microscopy results indicated that the PZT thin film etching problem was well solved for the applications of PZT thin film devices.

Integrating seawater desalination and wastewater reclamation forward osmosis process using thin-film composite mixed matrix membrane with functionalized carbon nanotube blended polyethersulfone support layer.

PubMed

Choi, Hyeon-Gyu; Son, Moon; Choi, Heechul

2017-10-01

Thin-film composite mixed matrix membrane (TFC MMM) with functionalized carbon nanotube (fCNT) blended in polyethersulfone (PES) support layer was synthesized via interfacial polymerization and phase inversion. This membrane was firstly tested in lab-scale integrating seawater desalination and wastewater reclamation forward osmosis (FO) process. Water flux of TFC MMM was increased by 72% compared to that of TFC membrane due to enhanced hydrophilicity. Although TFC MMM showed lower water flux than TFC commercial membrane, enhanced reverse salt flux selectivity (RSFS) of TFC MMM was observed compared to TFC membrane (15% higher) and TFC commercial membrane (4% higher), representing membrane permselectivity. Under effluent organic matter (EfOM) fouling test, 16% less normalized flux decline of TFC MMM was observed compared to TFC membrane. There was 8% less decline of TFC MMM compared to TFC commercial membrane due to fCNT effect on repulsive foulant-membrane interaction enhancement, caused by negatively charged membrane surface. After 10 min physical cleaning, TFC MMM displayed higher recovered normalized flux than TFC membrane (6%) and TFC commercial membrane (4%); this was also supported by visualized characterization of fouling layer. This study presents application of TFC MMM to integrated seawater desalination and wastewater reclamation FO process for the first time. It can be concluded that EfOM fouling of TFC MMM was suppressed due to repulsive foulant-membrane interaction. Copyright © 2017 Elsevier Ltd. All rights reserved.

Thin films of mixed metal compounds

DOEpatents

Mickelsen, Reid A.; Chen, Wen S.

1985-01-01

A compositionally uniform thin film of a mixed metal compound is formed by simultaneously evaporating a first metal compound and a second metal compound from independent sources. The mean free path between the vapor particles is reduced by a gas and the mixed vapors are deposited uniformly. The invention finds particular utility in forming thin film heterojunction solar cells.

Thin-Film Power Transformers

NASA Technical Reports Server (NTRS)

Katti, Romney R.

1995-01-01

Transformer core made of thin layers of insulating material interspersed with thin layers of ferromagnetic material. Flux-linking conductors made of thinner nonferromagnetic-conductor/insulator multilayers wrapped around core. Transformers have geometric features finer than those of transformers made in customary way by machining and mechanical pressing. In addition, some thin-film materials exhibit magnetic-flux-carrying capabilities superior to those of customary bulk transformer materials. Suitable for low-cost, high-yield mass production.

Oxide-based thin film transistors for flexible electronics

NASA Astrophysics Data System (ADS)

He, Yongli; Wang, Xiangyu; Gao, Ya; Hou, Yahui; Wan, Qing

2018-01-01

The continuous progress in thin film materials and devices has greatly promoted the development in the field of flexible electronics. As one of the most common thin film devices, thin film transistors (TFTs) are significant building blocks for flexible platforms. Flexible oxide-based TFTs are well compatible with flexible electronic systems due to low process temperature, high carrier mobility, and good uniformity. The present article is a review of the recent progress and major trends in the field of flexible oxide-based thin film transistors. First, an introduction of flexible electronics and flexible oxide-based thin film transistors is given. Next, we introduce oxide semiconductor materials and various flexible oxide-based TFTs classified by substrate materials including polymer plastics, paper sheets, metal foils, and flexible thin glass. Afterwards, applications of flexible oxide-based TFTs including bendable sensors, memories, circuits, and displays are presented. Finally, we give conclusions and a prospect for possible development trends. Project supported in part by the National Science Foundation for Distinguished Young Scholars of China (No. 61425020), in part by the National Natural Science Foundation of China (No. 11674162).

Durability of PEM Fuel Cell Membranes

NASA Astrophysics Data System (ADS)

Huang, Xinyu; Reifsnider, Ken

Durability is still a critical limiting factor for the commercialization of polymer electrolyte membrane (PEM) fuel cells, a leading energy conversion technology for powering future hydrogen fueled automobiles, backup power systems (e.g., for base transceiver station of cellular networks), portable electronic devices, etc. Ionic conducting polymer (ionomer) electrolyte membranes are the critical enabling materials for the PEM fuel cells. They are also widely used as the central functional elements in hydrogen generation (e.g., electrolyzers), membrane cell for chlor-alkali production, etc. A perfluorosulfonic acid (PFSA) polymer with the trade name Nafion® developed by DuPont™ is the most widely used PEM in chlor-alkali cells and PEM fuel cells. Similar PFSA membranes have been developed by Dow Chemical, Asahi Glass, and lately Solvay Solexis. Frequently, such membranes serve the dual function of reactant separation and selective ionic conduction between two otherwise separate compartments. For some applications, the compromise of the "separation" function via the degradation and mechanical failure of the electrolyte membrane can be the life-limiting factor; this is particularly the case for PEM in hydrogen/oxygen fuel cells.

Stretchable metal oxide thin film transistors on engineered substrate for electronic skin applications.

PubMed

Romeo, Alessia; Lacour, Stphanie P

2015-08-01

Electronic skins aim at providing distributed sensing and computation in a large-area and elastic membrane. Control and addressing of high-density soft sensors will be achieved when thin film transistor matrices are also integrated in the soft carrier substrate. Here, we report on the design, manufacturing and characterization of metal oxide thin film transistors on these stretchable substrates. The TFTs are integrated onto an engineered silicone substrate with embedded strain relief to protect the devices from catastrophic cracking. The TFT stack is composed of an amorphous In-Ga-Zn-O active layer, a hybrid AlxOy/Parylene dielectric film, gold electrodes and interconnects. All layers are prepared and patterned with planar, low temperature and dry processing. We demonstrate the interconnected IGZO TFTs sustain applied tensile strain up to 20% without electrical degradation and mechanical fracture. Active devices are critical for distributed sensing. The compatibility of IGZO TFTs with soft and biocompatible substrates is an encouraging step towards wearable electronic skins.

Magnetic damping phenomena in ferromagnetic thin-films and multilayers

NASA Astrophysics Data System (ADS)

Azzawi, S.; Hindmarch, A. T.; Atkinson, D.

2017-11-01

Damped ferromagnetic precession is an important mechanism underpinning the magnetisation processes in ferromagnetic materials. In thin-film ferromagnets and ferromagnetic/non-magnetic multilayers, the role of precession and damping can be critical for spintronic device functionality and as a consequence there has been significant research activity. This paper presents a review of damping in ferromagnetic thin-films and multilayers and collates the results of many experimental studies to present a coherent synthesis of the field. The terms that are used to define damping are discussed with the aim of providing consistent definitions for damping phenomena. A description of the theoretical basis of damping is presented from early developments to the latest discussions of damping in ferromagnetic thin-films and multilayers. An overview of the time and frequency domain methods used to study precessional magnetisation behaviour and damping in thin-films and multilayers is also presented. Finally, a review of the experimental observations of magnetic damping in ferromagnetic thin-films and multilayers is presented with the most recent explanations. This brings together the results from many studies and includes the effects of ferromagnetic film thickness, the effects of composition on damping in thin-film ferromagnetic alloys, the influence of non-magnetic dopants in ferromagnetic films and the effects of combining thin-film ferromagnets with various non-magnetic layers in multilayered configurations.

Diamond Thin-Film Thermionic Generator

NASA Astrophysics Data System (ADS)

Clewell, J. M.; Ordonez, C. A.; Perez, J. M.

1997-03-01

Since the eighteen-hundreds scientists have sought to develop the highest thermal efficiency in heat engines such as thermionic generators. Modern research in the emerging diamond film industry has indicated the work functions of diamond thin-films can be much less than one electron volt, compelling fresh investigation into their capacity as thermionic generators and inviting new methodology for determining that efficiency. Our objective is to predict the efficiency of a low-work-function, degenerate semiconductor (diamond film) thermionic generator operated as a heat engine between two constant-temperature thermal reservoirs. Our presentation will focus on a theoretical model which predicts the efficiency of the system by employing a Monte Carlo computational technique from which we report results for the thermal efficiency and the thermionic current densities of diamond thin-films.

Optimization of high quality Cu2ZnSnS4 thin film by low cost and environment friendly sol-gel technique for thin film solar cells applications

NASA Astrophysics Data System (ADS)

Chaudhari, J. J.; Joshi, U. S.

2018-05-01

In this study kesterite Cu2ZnSnS4 (CZTS) thin films suitable for absorber layer in thin film solar cells (TFSCs) were successfully fabricated on glass substrate by sol-gel method. The effects of complexing agent on formation of CZTS thin films have been investigated. X-ray diffraction (XRD) analysis confirms formation of polycrystalline CZTS thin films with single phase kesterite structure. XRD and Raman spectroscopy analysis of CZTS thin films with optimized concentration of complexing agent confirmed formation of kesterite phase in CZTS thin films. The direct optical band gap energy of CZTS thin films is found to decrease from 1.82 to 1.50 eV with increase of concentration of complexing agent triethanolamine. Morphological analysis of CZTS thin films shows smooth, uniform and densely packed CZTS grains and increase in the grain size with increase of concentration of complexing agent. Hall measurements revealed that concentration of charge carrier increases and resistivity decreases in CZTS thin films as amount of complexing agent increases.

All-Ceramic Thin Film Battery

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

BOYLE, TIMOTHY J.; INGERSOLL, DAVID; CYGAN, RANDALL T.

2002-11-01

We have undertaken the synthesis of a thin film ''All Ceramic Battery'' (ACB) using solution route processes. Based on the literature and experimental results, we selected SnO{sub 2}, LiCoO{sub 2}, and LiLaTiO{sub 3} (LLT) as the anode, cathode, and electrolyte, respectively. Strain induced by lattice mismatch between the cathode and bottom electrode, as estimated by computational calculations, indicate that thin film orientations for batteries when thicknesses are as low as 500 {angstrom} are strongly controlled by surface energies. Therefore, we chose platinized silicon as the basal platform based on our previous experience with this material. The anode thin films weremore » generated by standard spin-cast methods and processing using a solution of [Sn(ONep)]{sub 8} and HOAc which was found to form Sn{sub 6}(O){sub 4}(ONep){sub 4}. Electrochemical evaluation showed that the SnO{sub 2} was converted to Sn{sup o} during the first cycle. The cathode was also prepared by spin coating using the novel [Li(ONep)]{sub 8} and Co(OAc){sub 2}. The films could be electrochemically cycled (i.e., charged/discharged), with all of the associated structural changes being observable by XRD. Computational models indicated that the LLT electrolyte would be the best available ceramic material for use as the electrolyte. The LLT was synthesized from [Li(ONep)]{sub 8}, [Ti(ONep){sub 4}]{sub 2}, and La(DIP){sub 3}(py){sub 3} with RTP processing at 900 C being necessary to form the perovskite phase. Alternatively, a novel route to thin films of the block co-polymer ORMOLYTE was developed. The integration of these components was undertaken with each part of the assembly being identifiably by XRD analysis (this will allow us to follow the progress of the charge/discharge cycles of the battery during use). SEM investigations revealed the films were continuous with minimal mixing. All initial testing of the thin-film cathode/electrolyte/anode ACB devices revealed electrical shorting

Polymer electrolyte membrane assembly for fuel cells

NASA Technical Reports Server (NTRS)

Yen, Shiao-Ping S. (Inventor); Kindler, Andrew (Inventor); Yavrouian, Andre (Inventor); Halpert, Gerald (Inventor)

2002-01-01

An electrolyte membrane for use in a fuel cell can contain sulfonated polyphenylether sulfones. The membrane can contain a first sulfonated polyphenylether sulfone and a second sulfonated polyphenylether sulfone, wherein the first sulfonated polyphenylether and the second sulfonated polyphenylether sulfone have equivalent weights greater than about 560, and the first sulfonated polyphenylether and the second sulfonated polyphenylether sulfone also have different equivalent weights. Also, a membrane for use in a fuel cell can contain a sulfonated polyphenylether sulfone and an unsulfonated polyphenylether sulfone. Methods for manufacturing a membrane electrode assemblies for use in fuel cells can include roughening a membrane surface. Electrodes and methods for fabricating such electrodes for use in a chemical fuel cell can include sintering an electrode. Such membranes and electrodes can be assembled into chemical fuel cells.

Polymer electrolyte membrane assembly for fuel cells

NASA Technical Reports Server (NTRS)

Yen, Shiao-Ping S. (Inventor); Kindler, Andrew (Inventor); Yavrouian, Andre (Inventor); Halpert, Gerald (Inventor)

2000-01-01

An electrolyte membrane for use in a fuel cell can contain sulfonated polyphenylether sulfones. The membrane can contain a first sulfonated polyphenylether sulfone and a second sulfonated polyphenylether sulfone, wherein the first sulfonated polyphenylether and the second sulfonated polyphenylether sulfone have equivalent weights greater than about 560, and the first sulfonated polyphenylether and the second sulfonated polyphenylether sulfone also have different equivalent weights. Also, a membrane for use in a fuel cell can contain a sulfonated polyphenylether sulfone and an unsulfonated polyphenylether sulfone. Methods for manufacturing a membrane electrode assemblies for use in fuel cells can include roughening a membrane surface. Electrodes and methods for fabricating such electrodes for use in a chemical fuel cell can include sintering an electrode. Such membranes and electrodes can be assembled into chemical fuel cells.

Tailoring Thin Film-Lacquer Coatings for Space Application

NASA Technical Reports Server (NTRS)

Peters, Wanda C.; Harris, George; Miller, Grace; Petro, John

1998-01-01

Thin film coatings have the capability of obtaining a wide range of thermal radiative properties, but the development of thin film coatings can sometimes be difficult and costly when trying to achieve highly specular surfaces. Given any space mission's thermal control requirements, there is often a need for a variation of solar absorptance (Alpha(s)), emittance (epsilon) and/or highly specular surfaces. The utilization of thin film coatings is one process of choice for meeting challenging thermal control requirements because of its ability to provide a wide variety of Alpha(s)/epsilon ratios. Thin film coatings' radiative properties can be tailored to meet specific thermal control requirements through the use of different metals and the variation of dielectric layer thickness. Surface coatings can be spectrally selective to enhance radiative coupling and decoupling. The application of lacquer to a surface can also provide suitable specularity for thin film application without the cost and difficulty associated with polishing.

Tailoring Thin Film-Lacquer Coatings for Space Applications

NASA Technical Reports Server (NTRS)

Peters, Wanda C.; Harris, George; Miller, Grace; Petro, John

1998-01-01

Thin film coatings have the capability of obtaining a wide range of thermal radiative properties, but the development of thin film coatings can sometimes be difficult and costly when trying to achieve highly specular surfaces. Given any space mission's then-nal control requirements, there is often a need for a variation of solar absorptance (alpha(sub s)), emittance (epsilon) and/or highly specular surfaces. The utilization of thin film coatings is one process of choice for meeting challenging thermal control requirements because of its ability to provide a wide variety of alpha(sub s)/epsilon ratios. Thin film coatings' radiative properties can be tailored to meet specific thermal control requirements through the use of different metals and the variation of dielectric layer thickness. Surface coatings can be spectrally selective to enhance radiative coupling and decoupling. The application of lacquer to a surface can also provide suitable specularity for thin film application without the cost and difficulty associated with polishing.

Gas Separation Properties of Polyimide Thin Films on Ceramic Supports for High Temperature Applications

PubMed Central

Escorihuela, Sara; Brinkmann, Torsten

2018-01-01

Novel selective ceramic-supported thin polyimide films produced in a single dip coating step are proposed for membrane applications at elevated temperatures. Layers of the polyimides P84®, Matrimid 5218®, and 6FDA-6FpDA were successfully deposited onto porous alumina supports. In order to tackle the poor compatibility between ceramic support and polymer, and to get defect-free thin films, the effect of the viscosity of the polymer solution was studied, giving the entanglement concentration (C*) for each polymer. The C* values were 3.09 wt. % for the 6FDA-6FpDA, 3.52 wt. % for Matrimid®, and 4.30 wt. % for P84®. A minimum polymer solution concentration necessary for defect-free film formation was found for each polymer, with the inverse order to the intrinsic viscosities (P84® ≥ Matrimid® >> 6FDA-6FpDA). The effect of the temperature on the permeance of prepared membranes was studied for H2, CH4, N2, O2, and CO2. As expected, activation energy of permeance for hydrogen was higher than for CO2, resulting in H2/CO2 selectivity increase with temperature. More densely packed polymers lead to materials that are more selective at elevated temperatures. PMID:29518942

Glass transition dynamics of stacked thin polymer films

NASA Astrophysics Data System (ADS)

Fukao, Koji; Terasawa, Takehide; Oda, Yuto; Nakamura, Kenji; Tahara, Daisuke

2011-10-01

The glass transition dynamics of stacked thin films of polystyrene and poly(2-chlorostyrene) were investigated using differential scanning calorimetry and dielectric relaxation spectroscopy. The glass transition temperature Tg of as-stacked thin polystyrene films has a strong depression from that of the bulk samples. However, after annealing at high temperatures above Tg, the stacked thin films exhibit glass transition at a temperature almost equal to the Tg of the bulk system. The α-process dynamics of stacked thin films of poly(2-chlorostyrene) show a time evolution from single-thin-film-like dynamics to bulk-like dynamics during the isothermal annealing process. The relaxation rate of the α process becomes smaller with increase in the annealing time. The time scale for the evolution of the α dynamics during the annealing process is very long compared with that for the reptation dynamics. At the same time, the temperature dependence of the relaxation time for the α process changes from Arrhenius-like to Vogel-Fulcher-Tammann dependence with increase of the annealing time. The fragility index increases and the distribution of the α-relaxation times becomes smaller with increase in the annealing time for isothermal annealing. The observed change in the α process is discussed with respect to the interfacial interaction between the thin layers of stacked thin polymer films.

Synthesis, characterization, and photocatalytic properties of nanocrystalline NZO thin films

NASA Astrophysics Data System (ADS)

Aryanto, D.; Hastuti, E.; Husniya, N.; Sudiro, T.; Nuryadin, B. W.

2018-03-01

Nanocrystalline Ni-doped ZnO (NZO) thin films were synthesized on glass substrate using sol-gel spin coating methods. The effect of annealing on the structural and optical properties of nanocrystalline thin film was studied using X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM), UV-VIS spectrophotometry, and photoluminescence (PL). The results showed that the annealing temperature strongly influenced the physical properties of nanocrystalline NZO thin films. The photocatalytic properties of nanocrystalline NZO thin films were evaluated using an aqueous solution of Rhodamine-B. The photocatalytic activity of nanocrystalline NZO thin films increased with the increase of annealing temperature. The results indicated that the structure, morphology, and band gap energy of nanocrystalline NZO thin films played an important role in photocatalytic activity.

Electrolyte and Electrode Passivation for Thin Film Batteries

NASA Technical Reports Server (NTRS)

West, W.; Whitacre, J.; Ratnakumar, B.; Brandon, E.; Blosiu, J.; Surampudi, S.

2000-01-01

Passivation films for thin film batteries have been prepared and the conductivity and voltage stability window have been measured. Thin films of Li2CO3 have a large voltage stability window of 4.8V, which facilitates the use of this film as a passivation at both the lithium anode-electrolyte interface at high cathodic potentials.

Thin film mechanics

NASA Astrophysics Data System (ADS)

Cooper, Ryan C.

This doctoral thesis details the methods of determining mechanical properties of two classes of novel thin films suspended two-dimensional crystals and electron beam irradiated microfilms of polydimethylsiloxane (PDMS). Thin films are used in a variety of surface coatings to alter the opto-electronic properties or increase the wear or corrosion resistance and are ideal for micro- and nanoelectromechanical system fabrication. One of the challenges in fabricating thin films is the introduction of strains which can arise due to application techniques, geometrical conformation, or other spurious conditions. Chapters 2-4 focus on two dimensional materials. This is the intrinsic limit of thin films-being constrained to one atomic or molecular unit of thickness. These materials have mechanical, electrical, and optical properties ideal for micro- and nanoelectromechanical systems with truly novel device functionality. As such, the breadth of applications that can benefit from a treatise on two dimensional film mechanics is reason enough for exploration. This study explores the anomylously high strength of two dimensional materials. Furthermore, this work also aims to bridge four main gaps in the understanding of material science: bridging the gap between ab initio calculations and finite element analysis, bridging the gap between ab initio calculations and experimental results, nanoscale to microscale, and microscale to mesoscale. A nonlinear elasticity model is used to determine the necessary elastic constants to define the strain-energy density function for finite strain. Then, ab initio calculations-density functional theory-is used to calculate the nonlinear elastic response. Chapter 2 focuses on validating this methodology with atomic force microscope nanoindentation on molybdenum disulfide. Chapter 3 explores the convergence criteria of three density functional theory solvers to further verify the numerical calculations. Chapter 4 then uses this model to investigate

Thin film ceramic thermocouples

NASA Technical Reports Server (NTRS)

Gregory, Otto (Inventor); Fralick, Gustave (Inventor); Wrbanek, John (Inventor); You, Tao (Inventor)

2011-01-01

A thin film ceramic thermocouple (10) having two ceramic thermocouple (12, 14) that are in contact with each other in at least on point to form a junction, and wherein each element was prepared in a different oxygen/nitrogen/argon plasma. Since each element is prepared under different plasma conditions, they have different electrical conductivity and different charge carrier concentration. The thin film thermocouple (10) can be transparent. A versatile ceramic sensor system having an RTD heat flux sensor can be combined with a thermocouple and a strain sensor to yield a multifunctional ceramic sensor array. The transparent ceramic temperature sensor that could ultimately be used for calibration of optical sensors.

Thin film resonator technology.

PubMed

Lakin, Kenneth M

2005-05-01

Advances in wireless systems have placed increased demands on high performance frequency control devices for operation into the microwave range. With spectrum crowding, high bandwidth requirements, miniaturization, and low cost requirements as a background, the thin film resonator technology has evolved into the mainstream of applications. This technology has been under development for over 40 years in one form or another, but it required significant advances in integrated circuit processing to reach microwave frequencies and practical manufacturing for high-volume applications. This paper will survey the development of the thin film resonator technology and describe the core elements that give rise to resonators and filters for today's high performance wireless applications.

A generalized theory of thin film growth

NASA Astrophysics Data System (ADS)

Du, Feng; Huang, Hanchen

2018-03-01

This paper reports a theory of thin film growth that is generalized for arbitrary incidence angle during physical vapor deposition in two dimensions. The accompanying kinetic Monte Carlo simulations serve as verification. A special theory already exists for thin film growth with zero incidence angle, and another theory also exists for nanorod growth with a glancing angle. The theory in this report serves as a bridge to describe the transition from thin film growth to nanorod growth. In particular, this theory gives two critical conditions in analytical form of critical coverage, ΘI and ΘII. The first critical condition defines the onset when crystal growth or step dynamics stops following the wedding cake model for thin film growth. The second critical condition defines the onset when multiple-layer surface steps form to enable nanorod growth. Further, this theory also reveals a critical incidence angle, below which nanorod growth is impossible. The critical coverages, together with the critical incidence angle, defines a phase diagram of thin growth versus nanorod growth.

Comprehensive Study on Ceramic Membranes for Low-Cost Microbial Fuel Cells.

PubMed

Pasternak, Grzegorz; Greenman, John; Ieropoulos, Ioannis

2016-01-08

Microbial fuel cells (MFCs) made with different types of ceramic membranes were investigated to find a low-cost alternative to commercially available proton exchange membranes. The MFCs operated with fresh human urine as the fuel. Pyrophyllite and earthenware produced the best performance to reach power densities of 6.93 and 6.85 W m(-3), respectively, whereas mullite and alumina achieved power densities of 4.98 and 2.60 W m(-3), respectively. The results indicate the dependence of bio-film growth and activity on the type of ceramic membrane applied. The most favourable conditions were created in earthenware MFCs. The performance of the ceramic membranes was related to their physical and chemical properties determined by environmental scanning electron microscopy and energy dispersive X-ray spectroscopy. The cost of mullite, earthenware, pyrophyllite and alumina was estimated to be 13.61, 4.14, 387.96 and 177.03 GBP m(-2), respectively. The results indicate that earthenware and mullite are good substitutes for commercially available proton exchange membranes, which makes the MFC technology accessible in developing countries. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thin-Film Photovoltaics: Status and Applications to Space Power

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.; Hepp, Aloysius F.

1991-01-01

The potential applications of thin film polycrystalline and amorphous cells for space are discussed. There have been great advances in thin film solar cells for terrestrial applications; transfer of this technology to space applications could result in ultra low weight solar arrays with potentially large gains in specific power. Recent advances in thin film solar cells are reviewed, including polycrystalline copper iridium selenide and related I-III-VI2 compounds, polycrystalline cadmium telluride and related II-VI compounds, and amorphous silicon alloys. The possibility of thin film multi bandgap cascade solar cells is discussed.

Electron Damage Effects on Carbon Nanotube Thin Films

DTIC Science & Technology

2013-03-01

ELECTRON DAMAGE EFFECTS ON CARBON NANOTUBE THIN FILMS THESIS Jeremy S. Best, Captain, USMC AFIT-ENP-13-M-37 DEPARTMENT OF THE AIR FORCE AIR...Government and is not subject to copyright protection in the United States. AFIT-ENP-13-M-37 ELECTRON DAMAGE EFFECTS ON CARBON NANOTUBE THIN FILMS...M-37 ELECTRON DAMAGE EFFECTS ON CARBON NANOTUBE THIN FILMS Jeremy S. Best, BS Aerospace Engineering Captain, USMC Approved: Dr. John McClory

Methods for fabricating thin film III-V compound solar cell

DOEpatents

Pan, Noren; Hillier, Glen; Vu, Duy Phach; Tatavarti, Rao; Youtsey, Christopher; McCallum, David; Martin, Genevieve

2011-08-09

The present invention utilizes epitaxial lift-off in which a sacrificial layer is included in the epitaxial growth between the substrate and a thin film III-V compound solar cell. To provide support for the thin film III-V compound solar cell in absence of the substrate, a backing layer is applied to a surface of the thin film III-V compound solar cell before it is separated from the substrate. To separate the thin film III-V compound solar cell from the substrate, the sacrificial layer is removed as part of the epitaxial lift-off. Once the substrate is separated from the thin film III-V compound solar cell, the substrate may then be reused in the formation of another thin film III-V compound solar cell.

Micromachined sensor for stress measurement and micromechanical study of free-standing thin films for MEMS applications

NASA Astrophysics Data System (ADS)

Zhang, Ping

Microelectromechanical systems (MEMS) have a wide range of applications. In the field of wireless and microwave technology, considerable attention has been given to the development and integration of MEMS-based RF (radio frequency) components. An RF MEMS switch requires low insertion loss, high isolation, and low actuation voltage - electrical aspects that have been extensively studied. The mechanical requirements of the switch, such as low sensitivity to built-in stress and high reliability, greatly depend on the micromechanical properties of the switch materials, and have not been thoroughly explored. RF MEMS switches are typically in the form of a free-standing thin film structure. Large stress gradients and across-wafer stress variations developed during fabrication severely degrade their electrical performance. A micromachined stress measurement sensor has been developed that can potentially be employed for in-situ monitoring of stress evolution and stress variation. The sensors were micromachined using five masks on two wafer levels, each measuring 5x3x1 mm. They function by means of an electron tunneling mechanism, where a 2x2 mm silicon nitride membrane elastically deflects under an applied deflection voltage via an external feedback circuitry. For the current design, the sensors are capable of measuring tensile stresses up to the GPa range under deflection voltages of 50--100 V. Sensor functionality was studied by finite element modeling and a theoretical analysis of square membrane deflection. While the mechanical properties of thin films on substrates have been extensively studied, studies of free-standing thin films have been limited due to the practical difficulties in sample handling and testing. Free-standing Al and Al-Ti thin films specimens have been successfully fabricated and microtensile and stress relaxation tests have been performed using a custom-designed micromechanical testing apparatus. A dedicated TEM (transmission electron microscopy

Thin-film sensors for reusable space propulsion systems

NASA Technical Reports Server (NTRS)

Hepp, Aloysius F.; Kim, Walter S.

1989-01-01

Thin-film thermocouples (TFTCs) were developed for aircraft gas turbine engines and are in use for temperature measurement on turbine blades up to 1800 F. Established aircraft engine gas turbine technology is currently being adapted to turbine engine blade materials and the environment encountered in the Space Shuttle Main Engine (SSME)-severe thermal shock from cryogenic fuel to combustion temperatures. Initial results with coupons of MAR M-246 (+Hf) and PWA 1480 were followed by fabrication of TFTC on SSME turbine blades. Current efforts are focused on preparation for testing in the Turbine Blade Tester at NASA Marshall Space Flight Center.

Freestanding and Reactive Thin Films Fabricated by Covalent Layer-by-Layer Assembly and Subsequent Lift-Off of Azlactone-Containing Polymer Multilayers

PubMed Central

Buck, Maren E.

2010-01-01

We report an approach to the fabrication of freestanding and amine-reactive thin films that is based on the reactive layer-by-layer assembly and subsequent lift-off of azlactone-containing polymer multilayers. We demonstrate that covalently crosslinked multilayers fabricated using the azlactone-functionalized polymer poly(2-vinyl-4,4-dimethylazlactone) (PVDMA) and a primary amine-containing polymer [poly(ethyleneimine) (PEI)] can be delaminated from planar glass and silicon surfaces by immersion in mildly acidic aqueous environments to yield flexible freestanding membranes. These freestanding membranes are robust and can withstand exposure to strong acid, strong base, or incubation in high ionic strength solutions that typically lead to the disruption and erosion of polymer multilayers assembled by reversible weak interactions (e.g., ‘polyelectrolyte multilayers’ assembled by electrostatic interactions or hydrogen bonding). We demonstrate further that these PEI/PVDMA assemblies contain residual reactive azlactone functionality that can be exploited to chemically modify the films (either directly after fabrication or after they have been lifted off of the substrates on which they were fabricated) using a variety of amine-functionalized small molecules. These freestanding membranes can also be transferred readily onto other objects (for example, onto the surfaces of planar substrates containing holes or pores) to fabricate suspended polymer membranes and other film-functionalized interfaces. In addition to planar, two-dimensional freestanding films, this approach can be used to fabricate and isolate three-dimensional freestanding membranes (e.g., curved films or tubes) by layer-by-layer assembly on, and subsequent lift-off from, the surfaces of topologically complex substrates (e.g., the curved ends of glass tubing, etc.). The results of this investigation, when combined, suggest the basis of methods for the fabrication of stable, chemically-reactive, and

Through a Window, Brightly: A Review of Selected Nanofabricated Thin-Film Platforms for Spectroscopy, Imaging, and Detection.

PubMed

Dwyer, Jason R; Harb, Maher

2017-09-01

We present a review of the use of selected nanofabricated thin films to deliver a host of capabilities and insights spanning bioanalytical and biophysical chemistry, materials science, and fundamental molecular-level research. We discuss approaches where thin films have been vital, enabling experimental studies using a variety of optical spectroscopies across the visible and infrared spectral range, electron microscopies, and related techniques such as electron energy loss spectroscopy, X-ray photoelectron spectroscopy, and single molecule sensing. We anchor this broad discussion by highlighting two particularly exciting exemplars: a thin-walled nanofluidic sample cell concept that has advanced the discovery horizons of ultrafast spectroscopy and of electron microscopy investigations of in-liquid samples; and a unique class of thin-film-based nanofluidic devices, designed around a nanopore, with expansive prospects for single molecule sensing. Free-standing, low-stress silicon nitride membranes are a canonical structural element for these applications, and we elucidate the fabrication and resulting features-including mechanical stability, optical properties, X-ray and electron scattering properties, and chemical nature-of this material in this format. We also outline design and performance principles and include a discussion of underlying material preparations and properties suitable for understanding the use of alternative thin-film materials such as graphene.

Synthesis, characterization, and pulsed laser ablation of molecular sieves for thin film applications

NASA Astrophysics Data System (ADS)

Munoz, Trinidad, Jr.

1998-12-01

Molecular sieves are one class of crystalline low density metal oxides which are made up of one-, two-, and three dimensional pores and/or cages. We have investigated the synthesis and characterization of metal substituted aluminophosphates and all silica molecular sieves for thin film applications. A new copper substituted aluminophosphate, CuAPO-5 has been synthesized and characterized using x-ray powder diffraction, FT-IR spectroscopy and scanning electron microscopy. Electron spin resonance and electron spin echo modulation provided supporting evidence of framework incorporation of Cu(II) ions. Thus, an exciting addition has been added to the family of metal substituted aluminophosphates where substitution of the metal has been demonstrated as framework species. Also presented here is the synthesis and characterization of an iron substituted aluminophosphate, FeAPO-5, and an all silica zeolite, UTD-1 for thin film applications. Pulsed laser ablation has been employed as the technique to generate thin films. Here an excimer laser (KrFsp*, 248 nm) was used to deposit the molecular sieves on a variety of substrates including polished silicon, titanium nitride, and porous stainless steel disks. The crystallinity of the deposited films was enhanced by a post hydrothermal treatment. A vapor phase treatment of the laser deposited FeAPO-5 films has been shown to increase the crystallinity of the film without increasing film thickness. Thin films of the FeAPO-5 molecular sieves were subsequently used as the dielectric phase in capacitive type chemical sensors. The capacitance change of the FeAPO-5 devices to the relative moisture makes them potential humidity sensors. The all silica zeolite UTD-1 thin films were deposited on polished silicon and porous supports. A brief post hydrothermal treatment of the laser deposited films deposited on polished silicon and porous metal supports resulted in oriented film growth lending these films to applications in gas separations

Novel photon management for thin-film photovoltaics

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

Menon, Rajesh

2016-11-11

The objective of this project is to enable commercially viable thin-film photovoltaics whose efficiencies are increased by over 10% using a novel optical spectral-separation technique. A thin planar diffractive optic is proposed that efficiently separates the solar spectrum and assigns these bands to optimal thin-film sub-cells. An integrated device that is comprised of the optical element, an array of sub-cells and associated packaging is proposed.

Thin film drainage between pre-inflated capsules or vesicles

NASA Astrophysics Data System (ADS)

Keh, Martin; Walter, Johann; Leal, Gary

2013-11-01

Capsules and vesicles are often used as vehicles to carry active ingredients or fragrance in drug delivery and consumer products and oftentimes in these applications the particles may be pre-inflated due to the existence of a small osmotic pressure difference between the interior and exterior fluid. We study the dynamics of thin film drainage between capsules and vesicles in flow as it is crucial to fusion and deposition of the particles and, therefore, the stability and effectiveness of the products. Simulations are conducted using a numerical model coupling the boundary integral method for the motion of the fluids and a finite element method for the membrane mechanics. For low capillary numbers, the drainage behavior of vesicles and capsules are approximately the same, and also similar to that of drops as the flow-independent and uniform tension due to pre-inflation dominates. The tension due to deformation caused by flow will become more important as the strength of the external flow (i.e. the capillary number) increases. In this case, the shapes of the thin film region are fundamentally different for capsules and vesicles, and the drainage behavior in both cases differs from a drop. Funded by P&G.

Germanium Lift-Off Masks for Thin Metal Film Patterning

NASA Technical Reports Server (NTRS)

Brown, Ari

2012-01-01

A technique has been developed for patterning thin metallic films that are, in turn, used to fabricate microelectronics circuitry and thin-film sensors. The technique uses germanium thin films as lift-off masks. This requires development of a technique to strip or undercut the germanium chemically without affecting the deposited metal. Unlike in the case of conventional polymeric lift-off masks, the substrate can be exposed to very high temperatures during processing (sputter deposition). The reason why polymeric liftoff masks cannot be exposed to very high temperatures (greater than 100 C) is because (a) they can become cross linked, making lift-off very difficult if not impossible, and (b) they can outgas nitrogen and oxygen, which then can react with the metal being deposited. Consequently, this innovation is expected to find use in the fabrication of transition edge sensors and microwave kinetic inductance detectors, which use thin superconducting films deposited at high temperature as their sensing elements. Transition edge sensors, microwave kinetic inductance detectors, and their circuitry are comprised of superconducting thin films, for example Nb and TiN. Reactive ion etching can be used to pattern these films; however, reactive ion etching also damages the underlying substrate, which is unwanted in many instances. Polymeric lift-off techniques permit thin-film patterning without any substrate damage, but they are difficult to remove and the polymer can outgas during thin-film deposition. The outgassed material can then react with the film with the consequence of altered and non-reproducible materials properties, which, in turn, is deleterious for sensors and their circuitry. The purpose of this innovation was to fabricate a germanium lift-off mask to be used for patterning thin metal films.

Rechargeable Thin-film Lithium Batteries

DOE R&D Accomplishments Database

Bates, J. B.; Gruzalski, G. R.; Dudney, N. J.; Luck, C. F.; Yu, Xiaohua

1993-08-01

Rechargeable thin film batteries consisting of lithium metal anodes, an amorphous inorganic electrolyte, and cathodes of lithium intercalation compounds have recently been developed. The batteries, which are typically less than 6 {mu}m thick, can be fabricated to any specified size, large or small, onto a variety of substrates including ceramics, semiconductors, and plastics. The cells that have been investigated include Li TiS{sub 2}, Li V{sub 2}O{sub 5}, and Li Li{sub x}Mn{sub 2}O{sub 4}, with open circuit voltages at full charge of about 2.5, 3.6, and 4.2, respectively. The development of these batteries would not have been possible without the discovery of a new thin film lithium electrolyte, lithium phosphorus oxynitride, that is stable in contact with metallic lithium at these potentials. Deposited by rf magnetron sputtering of Li{sub 3}PO{sub 4} in N{sub 2}, this material has a typical composition of Li{sub 2.9}PO{sub 3.3}N{sub 0.46} and a conductivity at 25{degrees}C of 2 {mu}S/cm. The maximum practical current density obtained from the thin film cells is limited to about 100 {mu}A/cm{sup 2} due to a low diffusivity of Li{sup +} ions in the cathodes. In this work, the authors present a short review of their work on rechargeable thin film lithium batteries.

Synthesis and characterization of nanostructured bismuth selenide thin films.

PubMed

Sun, Zhengliang; Liufu, Shengcong; Chen, Lidong

2010-12-07

Nanostructured bismuth selenide thin films have been successfully fabricated on a silicon substrate at low temperature by rational design of the precursor solution. Bi(2)Se(3) thin films were constructed of coalesced lamella in the thickness of 50-80 nm. The nucleation and growth process of Bi(2)Se(3) thin films, as well as the influence of solution chemistry on the film structure were investigated in detail. As one of the most promising thermoelectric materials, the thermoelectric properties of the prepared Bi(2)Se(3) thin films were also investigated. The power factor increased with increasing carrier mobility, coming from the enlarged crystallites and enhanced coalesced structure, and reached 1 μW cm(-1) K(-1).

Composite polymeric film and method for its use in installing a very-thin polymeric film in a device

DOEpatents

Duchane, D.V.; Barthell, B.L.

1982-04-26

A composite polymeric film and a method for its use in forming and installing a very thin (< 10 ..mu..m) polymeric film are disclosed. The composite film consists of a thin film layer and a backing layer. The backing layer is soluble in a solvent in which the thin film layer is not soluble. In accordance with the method, the composite film is installed in a device in the same position in which it is sought to finally emplace the thin film. The backing layer is then selectiely dissolved in the solvent to leave the insoluble thin film layer as an unbacked film. The method permits a very thin film to e successfully installed in devices where the fragility of the film would preclude handling and installation by conventional methods.

Composite polymeric film and method for its use in installing a very thin polymeric film in a device

DOEpatents

Duchane, David V.; Barthell, Barry L.

1984-01-01

A composite polymeric film and a method for its use in forming and installing a very thin (<10 .mu.m) polymeric film are disclosed. The composite film consists of a thin film layer and a backing layer. The backing layer is soluble in a solvent in which the thin film layer is not soluble. In accordance with the method, the composite film is installed in a device in the same position in which it is sought to finally emplace the thin film. The backing layer is then selectively dissolved in the solvent to leave the insoluble thin film layer as an unbacked film. The method permits a very thin film to be successfully installed in devices where the fragility of the film would preclude handling and installation by conventional methods.

Pulsed photonic fabrication of nanostructured metal oxide thin films

NASA Astrophysics Data System (ADS)

Bourgeois, Briley B.; Luo, Sijun; Riggs, Brian C.; Adireddy, Shiva; Chrisey, Douglas B.

2017-09-01

Nanostructured metal oxide thin films with a large specific surface area are preferable for practical device applications in energy conversion and storage. Herein, we report instantaneous (milliseconds) photonic synthesis of three-dimensional (3-D) nanostructured metal oxide thin films through the pulsed photoinitiated pyrolysis of organometallic precursor films made by chemical solution deposition. High wall-plug efficiency-pulsed photonic irradiation (xenon flash lamp, pulse width of 1.93 ms, fluence of 7.7 J/cm2 and frequency of 1.2 Hz) is used for scalable photonic processing. The photothermal effect of subsequent pulses rapidly improves the crystalline quality of nanocrystalline metal oxide thin films in minutes. The following paper highlights pulsed photonic fabrication of 3-D nanostructured TiO2, Co3O4, and Fe2O3 thin films, exemplifying a promising new method for the low-cost and high-throughput manufacturing of nanostructured metal oxide thin films for energy applications.

Emergent Topological Phenomena in Thin Films of Pyrochlore Iridates

NASA Astrophysics Data System (ADS)

Yang, Bohm-Jung; Nagaosa, Naoto

2014-06-01

Because of the recent development of thin film and artificial superstructure growth techniques, it is possible to control the dimensionality of the system, smoothly between two and three dimensions. In this Letter we unveil the dimensional crossover of emergent topological phenomena in correlated topological materials. In particular, by focusing on the thin film of pyrochlore iridate antiferromagnets grown along the [111] direction, we demonstrate that the thin film can have a giant anomalous Hall conductance, proportional to the thickness of the film, even though there is no Hall effect in 3D bulk material. Moreover, in the case of ultrathin films, a quantized anomalous Hall conductance can be observed, despite the fact that the system is an antiferromagnet. In addition, we uncover the emergence of a new topological phase, the nontrivial topological properties of which are hidden in the bulk insulator and manifest only in thin films. This shows that the thin film of correlated topological materials is a new platform to search for unexplored novel topological phenomena.

Drop impact on thin liquid films using TIRM

NASA Astrophysics Data System (ADS)

Pack, Min; Ying Sun Team

2015-11-01

Drop impact on thin liquid films is relevant to a number of industrial processes such as pesticide spraying and repellent surface research such as self-cleaning applications. In this study, we systematically investigate the drop impact dynamics on thin liquid films on plain glass substrates by varying the film thickness, viscosity and impact velocity. High speed imaging is used to track the droplet morphology and trajectory over time as well as observing instability developments at high Weber number impacts. Moreover, the air layer between the drop and thin film upon drop impact is probed by total internal reflection microscopy (TIRM) where the grayscale intensity is used to measure the air layer thickness and spreading radius over time. For low We impact on thick films (We ~ 10), the effect of the air entrainment is pronounced where the adhesion of the droplet to the wall is delayed by the air depletion and liquid film drainage, whereas for high We impact (We >100) the air layer is no longer formed and instead, the drop contact with the wall is limited only to the film drainage for all film thicknesses. In addition, the maximum spreading radius of the droplet is analyzed for varying thin film thickness and viscosity.

Thin-Film Thermocouple Technology Demonstrated for Reliable Heat Transfer Measurements

NASA Technical Reports Server (NTRS)

1996-01-01

Exploratory work is in progress to apply thin-film thermocouples to localized heat transfer measurements on turbine engine vanes and blades. The emerging thin-film thermocouple technology shows great potential to improve the accuracy of local heat transfer measurements. To verify and master the experimental methodology of thin-film thermocouples, the NASA Lewis Research Center conducted a proof-of-concept experiment in a controlled environment before applying the thin-film sensors to turbine tests.

Atomic Layer Deposited Thin Films for Dielectrics, Semiconductor Passivation, and Solid Oxide Fuel Cells

NASA Astrophysics Data System (ADS)

Xu, Runshen

, ultra-thin layer of encapsulating ZnS is coated on the surface of GaSb and GaSb/InAs substrates. The 2 nm-thick ZnS film is found to provide a long-term protection against reoxidation for one order and a half longer times than prior reported passivation likely due to its amorphous structure without pinholes. Finally, a combination of binary ALD processes is developed and demonstrated for the growth of yttria-stabilized zirconia films using alkylamido-cyclopentadiengyls zirconium and tris(isopropyl-cyclopentadienyl)yttrium, as zirconium and yttrium precursors, respectively, with ozone being the oxidant. The desired cubic structure of YSZ films is apparently achieved after post-deposition annealing. Further, platinum is atomic layer deposited as electrode on YSZ (8 mol% of Yttria) within the same system. In order to control the morphology of as-deposited Pt thin structure, the nucleation behavior of Pt on amorphous and cubic YSZ is investigated. Three different morphologies of Pt are observed, including nanoparticle, porous and dense films, which are found to depend on the ALD cycle number and the structure and morphology of they underlying ALD YSZ films.

Synchrotron X-ray studies of model SOFC cathodes, part I: Thin film cathodes

DOE PAGES

Chang, Kee-Chul; Ingram, Brian; Ilavsky, Jan; ...

2017-10-14

In this work, we present synchrotron x-ray investigations of thin film La 0.6Sr 0.4Co 0.2Fe 0.8O 3-δ (LSCF) model cathodes for solid oxide fuel cells, grown on electrolyte substrates by pulse laser deposition, in situ during half-cell operations. We observed dynamic segregations of cations, such as Sr and Co, on the surfaces of the film cathodes. The effects of temperature, applied potentials, and capping layers on the segregations were investigated using a surfacesensitive technique of total external reflection x-ray fluorescence. We also studied patterned thin film LSCF cathodes using high-resolution micro-beam diffraction measurements. We find chemical expansion decreases for narrowmore » stripes. This suggests the expansion is dominated by the bulk pathway reactions. Lastly, the chemical expansion vs. the distance from the electrode contact was measured at three temperatures and an oxygen vacancy activation energy was estimated to be ~1.4 eV.« less

Thermoelectric effects of amorphous Ga-Sn-O thin film

NASA Astrophysics Data System (ADS)

Matsuda, Tokiyoshi; Uenuma, Mutsunori; Kimura, Mutsumi

2017-07-01

The thermoelectric effects of an amorphous Ga-Sn-O (a-GTO) thin film have been evaluated as a physical parameter of a novel oxide semiconductor. Currently, a-GTO thin films are greatly desired not only because they do not contain rare metals and are therefore free from problems on the exhaustion of resources and the increase in cost but also because their initial characteristics and performance stabilities are excellent when they are used in thin-film transistors. In this study, an a-GTO thin film was deposited on a quartz substrate by RF magnetron sputtering and postannealing was performed in air at 350 °C for 1 h using an annealing furnace. The Seebeck coefficient and electrical conductivity of the a-GTO thin film were -137 µV/K and 31.8 S/cm at room temperature, and -183 µV/K and 43.8 S/cm at 397 K, respectively, and as a result, the power factor was 1.47 µW/(cm·K2) at 397 K; these values were roughly as high as those of amorphous In-Ga-Zn-O (a-IGZO) thin films. Therefore, a-GTO thin films will be a candidate material for thermoelectric devices fabricated in a large area at a low cost by controlling the carrier mobility, carrier density, device structures, and so forth.

Synthesis of thin film containing 4-amino-1,2,4-triazole iron(II) complexes

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

Onggo, Djulia, E-mail: djulia@Chem.itb.ac.id

The Iron(II) complex with 4-amino-1,2,4 triazole (NH{sub 2}-trz) ligand has potential applications as smart material since the compounds show a distinct color change from lilac at low temperature to colorless at high temperature. The lilac color of the complex represent the diamagnetic low spin state while the colorless correspond to the paramagnetic high spin state of iron(II). The transition between the two states could be tuned by changing the anionic group. Generally, the complex was synthesized directly from aqueous solution of iron(II) salt with considerable amounts of NH{sub 2}-trz solution produced solid powder compound. For application as an electronic molecularmore » device, the complex should be obtained as a thin film. The transparent [Fe(NH{sub 2}trz){sub 3}]-Nafion film has been successfully obtained, however, no anion variation can be produced since the nafion is an anionic resin. In this work, the [Fe(NH{sub 2}trz){sub 3}]-complexes with several anions have been synthesized inside nata de coco membrane that commonly used as a medium for deposition metal nano-particles. After drying the membrane containing the complex became a thin film. At room temperature, the film containing iron(II) complexes of sulphate and nitrate salts show lilac color, similar to that of the original complexes in the powder form. On heating, the color of the complex film changed to colorless and this color change was observed reversibly. In contrast, the films containing perchlorate and tetrafluoroborate iron(II) complexes are colorless at room temperature and changed to lilac on cooling. The significant color changing of the iron(II)complexes in the nata de coco film can be used for demonstration thermo chromic effect of smart materials with relatively small amount of the compounds.« less

Simulation and in situ measurement of stress distribution in a polymer electrolyte membrane fuel cell stack

NASA Astrophysics Data System (ADS)

de la Cruz, Javier; Cano, Ulises; Romero, Tatiana

2016-10-01

A critical parameter for PEM fuel cell's electric contact is the nominal clamping pressure. Predicting the mechanical behavior of all components in a fuel cell stack is a very complex task due to the diversity of materials properties. Prior to the integration of a 3 kW PEMFC power plant, a numerical simulation was performed in order to obtain the mechanical stress distribution for two of the most pressure sensitive components of the stack: the membrane, and the graphite plates. The stress distribution of the above mentioned components was numerically simulated by finite element analysis and the stress magnitude for the membrane was confirmed using pressure films. Stress values were found within the elastic zone which guarantees mechanical integrity of fuel cell components. These low stress levels particularly for the membrane will allow prolonging the life and integrity of the fuel cell stack according to its design specifications.

Thin Film Nanocomposite Membrane Filled with Metal-Organic Frameworks UiO-66 and MIL-125 Nanoparticles for Water Desalination

PubMed Central

Kadhom, Mohammed; Hu, Weiming; Deng, Baolin

2017-01-01

Knowing that the world is facing a shortage of fresh water, desalination, in its different forms including reverse osmosis, represents a practical approach to produce potable water from a saline source. In this report, two kinds of Metal-Organic Frameworks (MOFs) nanoparticles (NPs), UiO-66 (~100 nm) and MIL-125 (~100 nm), were embedded separately into thin-film composite membranes in different weight ratios, 0%, 0.05%, 0.1%, 0.15%, 0.2%, and 0.3%. The membranes were synthesized by the interfacial polymerization (IP) of m-phenylenediamine (MPD) in aqueous solution and trimesoyl chloride (TMC) in an organic phase. The as-prepared membranes were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), contact angle measurement, attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy, and salt rejection and water flux assessments. Results showed that both UiO-66 and MIL-125 could improve the membranes’ performance and the impacts depended on the NPs loading. At the optimum NPs loadings, 0.15% for UiO-66 and 0.3% for MIL-125, the water flux increased from 62.5 L/m2 h to 74.9 and 85.0 L/m2 h, respectively. NaCl rejection was not significantly affected (UiO-66) or slightly improved (MIL-125) by embedding these NPs, always at >98.5% as tested at 2000 ppm salt concentration and 300 psi transmembrane pressure. The results from this study demonstrate that it is promising to apply MOFs NPs to enhance the TFC membrane performance for desalination. PMID:28613247

AZO nanorods thin films by sputtering method

NASA Astrophysics Data System (ADS)

Rosli, A. B.; Shariffudin, S. S.; Awang, Z.; Herman, S. H.

2018-05-01

Al-doped zinc oxide (AZO) nanorods thin film were deposited on Au catalyst using RF sputtering at 300 °C. The 15 nm thickness Au catalyst were deposited on glass substrates by sputtering method followed by annealing for 15 min at 500 °C to form Au nanostructures on the glass substrate. The AZO thin films were then deposited on Au catalyst at different RF power ranging from 50 - 200 W. The morphology of AZO was characterized using Field Emission Scanning Electron Microscopy while X-ray Diffraction was used to examine crystallinity of AZO thin films. From this work, the AZO nanorods was found grow at 200 W RF power.

Drop impact onto a thin film: Miscibility effect

NASA Astrophysics Data System (ADS)

Chen, Ningli; Chen, H.; Amirfazli, A.

2017-09-01

In this work a systematic experimental study was performed to understand the process of liquid drop impact onto a thin film made of a different liquid from drop. The drop and film liquids can be miscible or immiscible. Three general outcomes of deposition, crown formation without splashing, and splashing, were observed in the advancing phase of the drop impact onto a solid surface covered by either a miscible or an immiscible thin film. However, for a miscible film, a larger Weber number and film thickness are needed for the formation of a crown and splashing comparing with immiscible cases. The advancing phase of drop impact onto a thin immiscible film with a large viscosity is similar to that of drop impact onto a dry surface; for a miscible film viscous film, the behavior is far from that of a dry surface. The behavior of liquid lamella in the receding phase of drop impact onto a thin miscible film is reported for the first time. The results show that immiscibility is not a necessary condition for the existence of a receding phase. The existence of a receding phase is highly dependent on the interfacial tension between the drop and the film. The miscibility can significantly affect the receding morphology as it will cause mixing of the two liquids.

Transverse spin Seebeck effect versus anomalous and planar Nernst effects in Permalloy thin films.

PubMed

Schmid, M; Srichandan, S; Meier, D; Kuschel, T; Schmalhorst, J-M; Vogel, M; Reiss, G; Strunk, C; Back, C H

2013-11-01

Transverse magnetothermoelectric effects are studied in Permalloy thin films grown on MgO and GaAs substrates and compared to those grown on suspended SiN(x) membranes. The transverse voltage along platinum strips patterned on top of the Permalloy films is measured versus the external magnetic field as a function of the angle and temperature gradients. After the identification of the contribution of the planar and anomalous Nernst effects, we find an upper limit for the transverse spin Seebeck effect, which is several orders of magnitude smaller than previously reported.

Ferroelectric thin-film active sensors for structural health monitoring

NASA Astrophysics Data System (ADS)

Lin, Bin; Giurgiutiu, Victor; Yuan, Zheng; Liu, Jian; Chen, Chonglin; Jiang, Jiechao; Bhalla, Amar S.; Guo, Ruyan

2007-04-01

Piezoelectric wafer active sensors (PWAS) have been proven a valuable tool in structural health monitoring. Piezoelectric wafer active sensors are able to send and receive guided Lamb/Rayleigh waves that scan the structure and detect the presence of incipient cracks and structural damage. In-situ thin-film active sensor deposition can eliminate the bonding layer to improve the durability issue and reduce the acoustic impedance mismatch. Ferroelectric thin films have been shown to have piezoelectric properties that are close to those of single-crystal ferroelectrics but the fabrication of ferroelectric thin films on structural materials (steel, aluminum, titanium, etc.) has not been yet attempted. In this work, in-situ fabrication method of piezoelectric thin-film active sensors arrays was developed using the nano technology approach. Specification for the piezoelectric thin-film active sensors arrays was based on electro-mechanical-acoustical model. Ferroelectric BaTiO3 (BTO) thin films were successfully deposited on Ni tapes by pulsed laser deposition under the optimal synthesis conditions. Microstructural studies by X-ray diffractometer and transmission electron microscopy reveal that the as-grown BTO thin films have the nanopillar structures with an average size of approximately 80 nm in diameter and the good interface structures with no inter-diffusion or reaction. The dielectric and ferroelectric property measurements exhibit that the BTO films have a relatively large dielectric constant, a small dielectric loss, and an extremely large piezoelectric response with a symmetric hysteresis loop. The research objective is to develop the fabrication and optimum design of thin-film active sensor arrays for structural health monitoring applications. The short wavelengths of the micro phased arrays will permit the phased-array imaging of smaller parts and smaller damage than is currently not possible with existing technology.

Ferroelastic switching in a layered-perovskite thin film

PubMed Central

Wang, Chuanshou; Ke, Xiaoxing; Wang, Jianjun; Liang, Renrong; Luo, Zhenlin; Tian, Yu; Yi, Di; Zhang, Qintong; Wang, Jing; Han, Xiu-Feng; Van Tendeloo, Gustaaf; Chen, Long-Qing; Nan, Ce-Wen; Ramesh, Ramamoorthy; Zhang, Jinxing

2016-01-01

A controllable ferroelastic switching in ferroelectric/multiferroic oxides is highly desirable due to the non-volatile strain and possible coupling between lattice and other order parameter in heterostructures. However, a substrate clamping usually inhibits their elastic deformation in thin films without micro/nano-patterned structure so that the integration of the non-volatile strain with thin film devices is challenging. Here, we report that reversible in-plane elastic switching with a non-volatile strain of approximately 0.4% can be achieved in layered-perovskite Bi2WO6 thin films, where the ferroelectric polarization rotates by 90° within four in-plane preferred orientations. Phase-field simulation indicates that the energy barrier of ferroelastic switching in orthorhombic Bi2WO6 film is ten times lower than the one in PbTiO3 films, revealing the origin of the switching with negligible substrate constraint. The reversible control of the in-plane strain in this layered-perovskite thin film demonstrates a new pathway to integrate mechanical deformation with nanoscale electronic and/or magnetoelectronic applications. PMID:26838483

Ferroelastic switching in a layered-perovskite thin film

DOE PAGES

Wang, Chuanshou; Ke, Xiaoxing; Wang, Jianjun; ...

2016-02-03

Here, a controllable ferroelastic switching in ferroelectric/multiferroic oxides is highly desirable due to the non-volatile strain and possible coupling between lattice and other order parameter in heterostructures. However, a substrate clamping usually inhibits their elastic deformation in thin films without micro/nano-patterned structure so that the integration of the non-volatile strain with thin film devices is challenging. Here, we report that reversible in-plane elastic switching with a non-volatile strain of approximately 0.4% can be achieved in layered-perovskite Bi 2WO 6 thin films, where the ferroelectric polarization rotates by 90° within four in-plane preferred orientations. Phase-field simulation indicates that the energy barriermore » of ferroelastic switching in orthorhombic Bi 2WO 6 film is ten times lower than the one in PbTiO 3 films, revealing the origin of the switching with negligible substrate constraint. The reversible control of the in-plane strain in this layered-perovskite thin film demonstrates a new pathway to integrate mechanical deformation with nanoscale electronic and/or magnetoelectronic applications.« less

Effect of solution concentration on MEH-PPV thin films

NASA Astrophysics Data System (ADS)

Affendi, I. H. H.; Sarah, M. S. P.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

2018-05-01

MEH-PPV thin films were prepared with a mixture of THF (tetrahydrofuran) solution deposited by spin coating method. The surface topology of MEH-PPV thin film were characterize by atomic force microscopy (AFM) and optical properties of absorption spectra were characterized by using Ultraviolet-visible-near-infrared (UV-Vis-NIR). The MEH-PPV concentration variation affects the surface and optical properties of the thin film where 0.5 mg/ml MEH-PPV concentration have a good surface topology provided the same film also gives the highest absorption coefficient were then deposited to a TiO2 thin film forming composite layer. The composite layer then shows low current flow of short circuit current of Isc = -5.313E-7 A.

Disconnecting structure and dynamics in glassy thin films

PubMed Central

Sussman, Daniel M.; Cubuk, Ekin D.; Liu, Andrea J.

2017-01-01

Nanometrically thin glassy films depart strikingly from the behavior of their bulk counterparts. We investigate whether the dynamical differences between a bulk and thin film polymeric glass former can be understood by differences in local microscopic structure. Machine learning methods have shown that local structure can serve as the foundation for successful, predictive models of particle rearrangement dynamics in bulk systems. By contrast, in thin glassy films, we find that particles at the center of the film and those near the surface are structurally indistinguishable despite exhibiting very different dynamics. Next, we show that structure-independent processes, already present in bulk systems and demonstrably different from simple facilitated dynamics, are crucial for understanding glassy dynamics in thin films. Our analysis suggests a picture of glassy dynamics in which two dynamical processes coexist, with relative strengths that depend on the distance from an interface. One of these processes depends on local structure and is unchanged throughout most of the film, while the other is purely Arrhenius, does not depend on local structure, and is strongly enhanced near the free surface of a film. PMID:28928147

Microstructural and mechanical characteristics of Ni–Cr thin films