Artículos de revistas: "Films nanoporeux"

1

Abelow, Alexis E., Ryan J. White, Kevin W. Plaxco y Ilya Zharov. "Nanoporous silica colloidal films with molecular transport gated by aptamers responsive to small molecules". Collection of Czechoslovak Chemical Communications 76, n.º 6 (2011): 683–94. http://dx.doi.org/10.1135/cccc2011022.

Texto completo

Resumen

We report the preparation of colloidal nanoporous silica films whose function mimics that of protein channels in gating the transport of small molecules across a cell membrane. Specifically, we report a means of controlling the molecular flux through colloidal nanopores that employ aptamer oligonucleotides binding to a specific organic small molecule (cocaine). These biomacromolecules have been introduced onto the nanopore surface by attaching pre-made oligonucleotides to the activated nanopore surface. The aptamers change their conformation in response to the binding events, and thus alter the free volume of the colloidal nanopores available for molecular transport.

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

Srisuwan, Y., N. Kotsaeng, Y. Baimark, N. Narkkong y W. Simchuer. "Study on Morphology and Thermal Stability of Nanoporous Silk Fibroin Films". Advanced Materials Research 55-57 (agosto de 2008): 721–24. http://dx.doi.org/10.4028/www.scientific.net/amr.55-57.721.

Texto completo

Resumen

Nanoporous silk fibroin (SF) films were prepared as SF film loaded with methoxy poly(ethylene glycol)-b-poly(D,L-lactide) (MPEG-b-PDLL) nanoparticles by film casting of MPEG-b-PDLL nanoparticle suspension-SF solution. Nanoporous structures of the SF films were formed due to self-condensation and nanophase separation of nanoparticles from SF film matrix during drying process. The films with SF/MPEG-b-PDLL ratios of 20/1, 20/2 and 20/3 (w/w) were prepared and investigated. The MPEG-b-PDLL nanoparticles can be observed on film surface and cross-section with 100-300 nm in size. The size of interconnected nanopore was in the range of 20 – 300 nm. The number and size of nanopores increased as increasing the MPEG-b-PDLL ratio. Thermal stability of the films studied from differential thermogravimetric (DTG) thermogram found that the nanoparticles dispersed into the SF films could improve thermal stability of each component. This indicated strong hydrogen bond interactions between SF and MPEG-b-PDLL were existed. Film transparency of the SF nanoporous films decreased when the MPEG-b-PDLL ratio was increased.

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Her, Hyun Jung, Jung Min Kim, Yun Soo Lim, Jae Wan Kim, Y. J. Choi, C. J. Kang y Yong Sang Kim. "Nanoporous Titania by Embossing with PMMA Nanopoles Made from Nanoporous Alumina Template". Materials Science Forum 544-545 (mayo de 2007): 1017–20. http://dx.doi.org/10.4028/www.scientific.net/msf.544-545.1017.

Texto completo

Resumen

We produced highly uniform nanoporous thin films of the dense array of titania (TiO2) pores of 70~80 nm in diameter with nanoimprinting method. Titania in HCl and 2-propanol solution was coated on an indium tin oxide (ITO) surface and embossed with an array of PMMA nanopoles which was produced using a nanoporous alumina (Al2O3) template. Two-step anodization was introduced to produce highly uniform and dense nanopores on the aluminum surface. The polymethyl methacrylate (PMMA) was poured onto and infiltrated into the nanoporous alumina surface which was heated at 150 oC. The alumina nanopores and aluminum plate were removed by wet-etching leaving an array of PMMA nanopoles. These highly uniform nanostructured titania films will be very useful for photovoltaic and photocatalytic applications where nanostructuring of surface with controlled dimensions are essential.

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

Leenheer, Andrew J., Alexander Miedaner, Calvin J. Curtis, Maikel F. A. M. van Hest y David S. Ginley. "Fabrication of nanoporous titania on glass and transparent conducting oxide substrates by anodization of titanium films". Journal of Materials Research 22, n.º 3 (marzo de 2007): 681–87. http://dx.doi.org/10.1557/jmr.2007.0078.

Texto completo

Resumen

Nanoporous titania (TiO2) or titania nanotubes could provide a continuous nanostructured electron-conducting anode for organic photovoltaics. In this work, nanoporous titania was formed by anodizing thin films of titanium on both glass and transparent conducting oxide (TCO) substrates. Titanium thin films (500–700 nm) were deposited by radio frequency (RF) magnetron sputtering. Films were anodized in acidic electrolytes containing small amounts of hydrofluoric acid (HF) at constant voltages ranging from 7 to 15 V. Scanning electron microscope (SEM) analysis revealed a nanoporous structure. Nanoporous titania structures were grown on glass in an electrolyte containing sulfuric acid, trisodium citrate, and potassium fluoride, with pore diameters around 50 nm. Analyzing the films at different anodization times, the stages of nanopore formation were elucidated. Additionally, nanoporous titania was formed on a TCO substrate by anodizing in an electrolyte containing acetic acid and hydrofluoric acid. While not completely transparent, the nanoporous titania is promising for use in organic photovoltaics.

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Chojenka, Juliusz, Arkadiusz Zarzycki, Marcin Perzanowski, Michał Krupiński, Tamás Fodor, Kálmán Vad y Marta Marszałek. "Tuning of the Titanium Oxide Surface to Control Magnetic Properties of Thin Iron Films". Materials 16, n.º 1 (28 de diciembre de 2022): 289. http://dx.doi.org/10.3390/ma16010289.

Texto completo

Resumen

We describe the magnetic properties of thin iron films deposited on the nanoporous titanium oxide templates and analyze their dependance on nanopore radius. We then compare the results to a continuous iron film of the same thickness. Additionally, we investigate the evolution of the magnetic properties of these films after annealing. We demonstrate that the M(H) loops consist of two magnetic phases originating from the iron layer and iron oxides formed at the titanium oxide/iron interface. We perform deconvolution of hysteresis loops to extract information for each magnetic phase. Finally, we investigate the magnetic interactions between the phases and verify the presence of exchange coupling between them. We observe the altering of the magnetic properties by the nanopores as a magnetic hardening of the magnetic material. The ZFC-FC (Zero-field cooled/field cooled) measurements indicate the presence of a disordered glass state below 50 K, which can be explained by the formation of iron oxide at the titanium oxide-iron interface with a short-range magnetic order.

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

Benetti, Giulio, Francesco Banfi, Emanuele Cavaliere y Luca Gavioli. "Mechanical Properties of Nanoporous Metallic Ultrathin Films: A Paradigmatic Case". Nanomaterials 11, n.º 11 (18 de noviembre de 2021): 3116. http://dx.doi.org/10.3390/nano11113116.

Texto completo

Resumen

Nanoporous ultrathin films, constituted by a slab less than 100 nm thick and a certain void volume fraction provided by nanopores, are emerging as a new class of systems with a wide range of possible applications, including electrochemistry, energy storage, gas sensing and supercapacitors. The film porosity and morphology strongly affect nanoporous films mechanical properties, the knowledge of which is fundamental for designing films for specific applications. To unveil the relationships among the morphology, structure and mechanical response, a comprehensive and non-destructive investigation of a model system was sought. In this review, we examined the paradigmatic case of a nanoporous, granular, metallic ultrathin film with comprehensive bottom-up and top-down approaches, both experimentals and theoreticals. The granular film was made of Ag nanoparticles deposited by gas-phase synthesis, thus providing a solvent-free and ultrapure nanoporous system at room temperature. The results, bearing generality beyond the specific model system, are discussed for several applications specific to the morphological and mechanical properties of the investigated films, including bendable electronics, membrane separation and nanofluidic sensing.

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

Yu, Yang-Yen y Chang-Chung Yang. "Preparation of Nanoporous Poly(Methyl Silsesquioxanes) Films Using PS-b-P4VP as Template". Journal of Nanoscience and Nanotechnology 8, n.º 3 (1 de marzo de 2008): 1537–44. http://dx.doi.org/10.1166/jnn.2008.073.

Texto completo

Resumen

Nanoporous poly(methyl silsesquioxane) (PMSSQ) film was prepared through the templating of an amphiphilic block copolymer, poly(styrene-4-vinyl pyridine) (PS-b-P4VP). The experimental and theoretical studies suggest that the intermolecular hydrogen bonding is existed between the PMSSQ precursor and PS-b-P4VP. The miscible hybrid and the narrow thermal decomposition of the PS-b-P4VP lead to nanopores in the prepared films from the results of TGA, AFM, and TEM. The effects of the loading ratio on the morphology and properties of the prepared nanoporous PMSSQ films were investigated. The TEM and AFM studies show that the uniform pore morphology with pore size 10–15 nm can be prepared from a modest porogen loading level for the optimum intermolecular hydrogen bonding. The refractive index and dielectric constant of the prepared nanoporous films decreases with an increase in PS-b-P4VP loading. On the other hand, the porosity increases with an increasing PS-b-P4VP loading. This study demonstrates a methodology to control pore morphology and properties of the nanoporous PMSSQ films through the templating of PS-b-P4VP.

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Yu, Yang Yen, Wen Chen Chien y Shih Ting Chen. "Preparation of Nanoporous Mondispersed Silica Nanoparticles Films Using Poly(styrene)- Block-Poly( 2-Vinyl Pyridine) as Template". Advanced Materials Research 47-50 (junio de 2008): 646–49. http://dx.doi.org/10.4028/www.scientific.net/amr.47-50.646.

Texto completo

Resumen

Nanoporous silica films were prepared through the templating of amphiphilic block copolymer, poly(styrene-2-vinyl pyridine) (PS-b-P2VP), and colloidal silica nanoparticles. The experimental and theoretical studies suggested that the intermolecular hydrogen bonding was existed between the colloidal silica nanoparticles and PS-b-P2VP. The miscible hybrid and the narrow thermal decomposition of the PS-b-P2VP led to nanopores in the prepared films from the results of TGA, AFM, and TEM. The effects of the loading ratio and P2VP chain length on the morphology and properties of the prepared nanoporous silica films were investigated. The TEM and AFM studies showed that the uniform pore morphology with pore size 10-15nm was prepared from a modest porogen loading level for the optimum intermolecular hydrogen bonding. The refractive index and dielectric constant of the prepared nanoporous films decreased with an increase in PS-b-P2VP loading. On the other hand, the porosity increased with an increasing PS-b-P2VP loading. This study demonstrated a methodology to control pore morphology and properties of the nanoporous silica films through the templating of PS-b-P2VP.

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

Her, Hyun-Jung, Jung-Min Kim, C. J. Kang y Yong-Sang Kim. "Fabrication of Thin Film Titania with Nanopores, Nanopoles, and Nanopipes by Nanoporous Alumina Template". Journal of Nanoscience and Nanotechnology 8, n.º 9 (1 de septiembre de 2008): 4808–12. http://dx.doi.org/10.1166/jnn.2008.ic84.

Texto completo

Resumen

We demonstrate the formation of thin film titania (TiO2) with a dense array of nanopores, nanopoles, and nanopipes. The heights of pores, poles, and pipes were approximately 130 nm, 180 nm, and 200 nm, respectively. The aspect ratios of these three structures were approximated between 2 and 3. In order to obtain titania thin films, a nanoporous alumina (Al2O3) template was fabricated by performing a two-step anodization process. The spin-coated titania films were uniformly patterned by a nanoimprinting lithography technique with a textured poly(methyl methacrylate) (PMMA) mold or nanoporous alumina template. The titania films are very useful for solar cells, photocatalytic and sensing applications, in which nano-structuring of surfaces with controlled dimensions is vital.

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

Chou, Chia-Man, Tong-You Wade Wei, Jou-May Maureen Chen, Wei-Ting Chang, Chang-Tze Ricky Yu y Vincent K. S. Hsiao. "Preparation of Nanoporous Polymer Films for Real-Time Viability Monitoring of Cells". Journal of Nanomaterials 2011 (2011): 1–6. http://dx.doi.org/10.1155/2011/436528.

Texto completo

Resumen

We have demonstrated an alternative way to monitor the viability of cells adhered on a nanoporous polymer film in real time. The nanoporous polymer films were prepared by laser interference pattering. During exposure of holographic patterning, the dissolved solvents were phase separated with photocured polymer and the nanopores were created as the solvents evaporated. The diffracted spectra from the nanoporous polymer film responded to each activity of the cell cycle, from initial cell seeding, through growth, and eventual cell death. This cell-based biosensor uses a nanoporous polymer film to noninvasively monitor cell viability and may prove useful for biotechnological applications.

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

Estrada, M., C. Reza, J. Salmones, J. A. Wang, M. E. Manríquez, J. M. Mora, M. L. Hernández, A. Zúñiga y J. L. Contreras. "Synthesis of Nanoporous TiO2 Thin Films for Photocatalytic Degradation of Methylene Blue". Journal of New Materials for Electrochemical Systems 17, n.º 1 (24 de febrero de 2014): 023–28. http://dx.doi.org/10.14447/jnmes.v17i1.439.

Texto completo

Resumen

This work reports a structure and photocatalytic activity of nanoporous titania (TiO2) thin films by an anodizing approach. Xray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) studies showed that tetragonal anatase was the main phase in the thin films that consisted of countless disordered nanopores in the order of 10 to 15 nm. In the photocatalytic degradation of methylene blue, the titania thin films showed a good photocatalytic activity. 82.2 % methylene blue could be photodegraded by titania thin films with UV radiation. XPS results indicate that during the degradation of methylene blue, some Ti3+ may be partially oxidized to Ti4+ in the TiO2 films and the surface hydroxyls directly participate in the reaction. Our nanoporous titania thin films is commensurable to Degussa-25 TiO2 powders because the latter requires filtration in each treatment; it is also much superior to the direct photolysis approach with respect to photoactivity.

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

Li, Jianjun, Weiwei Zhang, Yujun Song, Weiting Yin y Tao Zhang. "Template Transfer Nanoimprint for Uniform Nanopores and Nanopoles". Journal of Nanomaterials 2016 (2016): 1–7. http://dx.doi.org/10.1155/2016/9354364.

Texto completo

Resumen

A new methodology is developed for the fabrication of nanostructures on substrate based on anodized Al2O3(AAO) porous template transfer process. It includes (1) forming amorphous alloy, negative UV-resist resin (i.e., SU-8), or PMMA (polymethylmethacrylate) plate nanorod arrays by hot-press molding amorphous alloy, negative UV-resist resin (i.e., SU-8), or PMMA plate into the anodized Al2O3porous substrates; (2) removing AAO templates by chemical etching process after suitable posttreatment (annealing and/or irradiation) to improve the mechanical strength of the nanorod arrays; (3) reforming nanopore films by hot-embossing the nanorod arrays into a thin layer of polymer film on substrates (e.g., silica); (4) cleaning the bottom residues in pores of the films by oxygen plasmon. The results indicate that the diameters of amorphous alloy (or negative UV-resist resin or PMMA) nanorod arrays can be ranged from 32 nm to 200 nm. The diameters of the imprinted ILR-1050 photoresist nanopores are about 94.5 ± 12.2 nm and the diameters of the imprinted or SU-8 resin on glass slides nanopores are about 207 ± 26.4 nm, which inherit the diameters of AAO templates. This methodology provides a general method to fabricate nanorods arrays and/or thin nanopore films by template transfer nanoimprint process.

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

Ohgai, Takeshi, Masayuki Mizumoto, Shigeki Nomura y Akio Kagawa. "Electrodeposition of Metallic Nanowires in Nanoporous Polycarbonate Films". Materials Science Forum 539-543 (marzo de 2007): 1253–57. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.1253.

Texto completo

Resumen

A polycarbonate membrane filter with numerous cylindrical nanopores was used as a template for growing metallic nanowires such as Ni, Co and Fe. The nanoporous template with pore-diameter of 150 nm, pore-length of 6000 nm, and pore-density of 108 pore•cm-2 was modified as a cathode with sputter-deposited gold layer. Inside the nano-pores, the metallic nanowires were electrochemically deposited from an acidic sulfate solution containing metal ions. The growth rate of metallic nanowires depended on the cathode potential during electrodeposition. The diameter of electrodeposited nanowires corresponded to that of nanopores in the template. TEM diffraction pattern suggested that each metallic nanowire composed of a single crystalline structure.

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

Wang, Sien, Qiyu Chen y Qing Hao. "Extension of the two-layer model to heat transfer coefficient predictions of nanoporous Si thin films". Applied Physics Letters 121, n.º 1 (4 de julio de 2022): 012201. http://dx.doi.org/10.1063/5.0099312.

Texto completo

Resumen

Heat exchange between a solid material and the gas environment is critical for the heat dissipation of miniature electronic devices. In this aspect, existing experimental studies focus on non-porous structures such as solid thin films, nanotubes, and wires. In this work, the proposed two-layer model for the heat transfer coefficient (HTC) between a solid sample and the surrounding air is extended to 70-nm-thick nanoporous Si thin films that are patterned with periodic rectangular nanopores having feature sizes of 100–400 nm. The HTC values are extracted using the 3[Formula: see text] method based on AC self-heating of a suspended sample with better accuracy than steady-state measurements in some studies. The dominance of air conduction in the measured HTCs is confirmed by comparing measurements with varied sample orientations. The two-layer model, developed for nanotubes, is still found to be accurate when the nanoporous film is simply treated as a solid film in the HTC evaluation along with the radiative mean beam length as the characteristic length of the nanoporous film. This finding indicates the potential of increasing HTC by introducing ultra-fine nanoporous patterns, as guided by the two-layer model.

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

Guo, Huiming, Xin Wang, Alexander D. Dupuy, Julie M. Schoenung y William J. Bowman. "Growth of nanoporous high-entropy oxide thin films by pulsed laser deposition". Journal of Materials Research 37, n.º 1 (5 de enero de 2022): 124–35. http://dx.doi.org/10.1557/s43578-021-00473-2.

Texto completo

Resumen

AbstractHigh-entropy oxides (HEO) with entropic stabilization and compositional flexibility have great potential application in batteries and catalysis. In this work, HEO thin films were synthesized by pulsed laser deposition (PLD) from a rock-salt (Co0.2Ni0.2Cu0.2Mg0.2Zn0.2)O ceramic target. The films exhibited the target’s crystal structure, were chemically homogeneous, and possessed a three-dimensional (3D) island morphology with connected randomly shaped nanopores. The effects of varying PLD laser fluence on crystal structure and morphology were explored systematically. Increasing fluence facilitates film crystallization at low substrate temperature (300 °C) and increases film thickness (60–140 nm). The lateral size of columnar grains, islands (19 nm to 35 nm in average size), and nanopores (9.3 nm to 20 nm in average size) increased with increasing fluence (3.4 to 7.0 J/cm2), explained by increased kinetic energy of adatoms and competition between deposition and diffusion. Additionally, increasing fluence reduces the number of undesirable droplets observed on the film surface. The nanoporous HEO films can potentially serve as electrochemical reaction interfaces with tunable surface area and excellent phase stability. Graphical abstract

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Zhanabaev, Z. Zh. "WIDTH OF ENERGY BAND GAP OF NANOPOROUS SEMICONDUCTOR FILMS". Eurasian Physical Technical Journal 17, n.º 2 (24 de diciembre de 2020): 39–44. http://dx.doi.org/10.31489/2020no2/39-44.

Texto completo

Resumen

The aim of this work is to experimentally clarify the reasons for the appearance of jumps in the current and memory of semiconductor nanoporous structures.Porous nanostructures were obtained by electrochemical etching. The current-voltage characteristics of the samples were measured for porous silicon and on thin films of a chalcogenide glassy semiconductor. The existence of jump-like switching and current hysteresis in porous silicon nanofilms under laser illumination is shown experimentally.A connection between the switching voltage values and the dependence of the band gap on the porosity of nanofilms is found. These results make it possible to construct a theory of current switching and its hysteresis based on the concepts of the theory of second-order phase transitions.

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

Rho, Yecheol, Byungcheol Ahn, Jinhwan Yoon y Moonhor Ree. "Comprehensive synchrotron grazing-incidence X-ray scattering analysis of nanostructures in porous polymethylsilsesquioxane dielectric thin films". Journal of Applied Crystallography 46, n.º 2 (23 de febrero de 2013): 466–75. http://dx.doi.org/10.1107/s0021889812050923.

Texto completo

Resumen

A complete grazing-incidence X-ray scattering (GIXS) formula has been derived for nanopores buried in a polymer dielectric thin film supported by a substrate. Using the full power of the scattering formula, GIXS data from nanoporous polymethylsilsesquioxane dielectric thin films, a model nanoporous system, have successfully been analysed. The nanopores were found to be spherical and to have a certain degree of size distribution but were randomly dispersed in the film. In the film, GIXS was confirmed to arise predominantlyviathe first scattering process in which the incident X-ray beam scatters without reflection; the other scattering processes and their contributions were significantly dependent on the grazing angle. This study also confirmed that GIXS scattering can be analysed using only independent scattering terms, but this simple approach can only provide structural parameters. The cross terms were found to make a relatively small contribution to the intensity of the overall scattering but were required for the complete characterization of the measured two-dimensional scattering data, in particular the extracted out-of-plane scattering data, and their inclusion in the analysis enabled film properties such as film thickness, critical angle (i.e.electron density), refractive index and the absorption term to be determined.

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

López Antón, Ricardo, Victor Vega, V. M. Prida, A. Fernández, K. R. Pirota y Manuel Vázquez. "Magnetic Properties of Hexagonally Ordered Arrays of Fe Antidots by Vacuum Thermal Evaporation on Nanoporous Alumina Templates". Solid State Phenomena 152-153 (abril de 2009): 273–76. http://dx.doi.org/10.4028/www.scientific.net/ssp.152-153.273.

Texto completo

Resumen

Highly ordered arrays of Fe antidot films were fabricated by thermal vapor deposition technique using nanoporous alumina templates. The film thickness varies from 20 up to 100 nm, and the antidots array has about 50 nm in diameter and 105 nm of periodic interspacing. Scanning electron microscopy and atomic force microscopy measurements confirmed that the Fe antidots film retains the well-ordered hexagonal structure of the nanoporous alumina template. Meanwhile, the micromagnetic structure was studied by magnetic force microscopy and SQUID measurements. A stripe magnetic domain pattern featuring a large out-of-plane magnetization component is found in the films. Noteworthily, the magnetic domains are not pinned by the nanopores but, on the contrary, several antidots are included in each magnetic domain. According to the magnetic measurements, the easy magnetization axis of the Fe antidot array remains in the film plane, while the hard one lies perpendicular to the plane, which can be explained on the basis of the different contributions of the nanoholes to the total magnetic anisotropy of the antidots film.

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Goncharov, A., A. Guglya, A. Kalchenko, E. Solopikhina, V. Vlasov y E. Lyubchenko. "Nanocrystalline Porous Hydrogen Storage Based on Vanadium and Titanium Nitrides". Journal of Nanotechnology 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/4106067.

Texto completo

Resumen

This review summarizes results of our study of the application of ion-beam assisted deposition (IBAD) technology for creation of nanoporous thin-film structures that can absorb more than 6 wt.% of hydrogen. Data of mathematical modeling are presented highlighting the structure formation and component creation of the films during their deposition at the time of simultaneous bombardment by mixed beam of nitrogen and helium ions with energy of 30 keV. Results of high-resolution transmission electron microscopy revealed that VNxfilms consist of 150–200 nm particles, boundaries of which contain nanopores of 10–15 nm diameters. Particles themselves consist of randomly oriented 10–20 nm nanograins. Grain boundaries also contain nanopores (3–8 nm). Examination of the absorption characteristics of VNx, TiNx, and(V,Ti)Nxfilms showed that the amount of absorbed hydrogen depends very little on the chemical composition of films, but it is determined by the structure pore. The amount of absorbed hydrogen at 0.3 MPa and 20°C is 6-7 wt.%, whereas the bulk of hydrogen is accumulated in the grain boundaries and pores. Films begin to release hydrogen even at 50°C, and it is desorbed completely at the temperature range of 50–250°C. It was found that the electrical resistance of films during the hydrogen desorption increases 104times.

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Castro, Alichandra, Paula Ferreira, Brian J. Rodriguez y Paula M. Vilarinho. "The role of nanoporosity on the local piezo and ferroelectric properties of lead titanate thin films". Journal of Materials Chemistry C 3, n.º 5 (2015): 1035–43. http://dx.doi.org/10.1039/c4tc02378a.

Texto completo

Resumen

Nanoporous PbTiO₃ films present enhanced tetragonality at lower temperatures than respective dense films. Moreover, the porosity present in the nanoporous films allows an increase of the local piezoelectric response and a decrease of the local coercive field. As a result, these nanoporous films might be used to improve the switching behaviour of ferroelectric thin films.

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

Hernández-Rodríguez, Yazmin Mariela, Primavera Lopez-Salazar, Gabriel Juarez-Diaz, Gabriel Romero Paredes-Rubio y Ramón Peña-Sierra. "Synthesis and Characterization of Nanoporous ZnO Films by Controlling the Zn Sublimation by Using ZnO/Zn Precursor Films". Materials 15, n.º 16 (11 de agosto de 2022): 5509. http://dx.doi.org/10.3390/ma15165509.

Texto completo

Resumen

A reliable process for the formation of nanoporous ZnO films supported on amorphous quartz and (100) silicon substrates via the processing of ZnO/Zn precursor films is reported. The process is based on the sublimation mechanism of Zn implemented in a novel ZnO/Zn precursor film to produce a nanoporous film. A scanning electron microscopy analysis of the nanoporous ZnO films’ surfaces revealed the presence of ZnO nano-features with round tips; in contrast, the nanoporous ZnO films supported on (100) Si substrates showed hexagonal nut-like nanostructures. The crystallite size of the nanoporous ZnO films decreased as the sublimation temperature was increased. X-ray photoelectron spectroscopy studies demonstrated that formations of oxygen vacancies were produced during the processing stages (as the main structural lattice defects in the ZnO nanoporous films). The analysis of the photoluminescence response confirmed that the active deep-level centers were also related to the oxygen vacancies generated during the thermal processing of the ZnO/Zn precursor films. Finally, a qualitative mechanism is proposed to explain the formation of nanoporous ZnO films on quartz and crystalline Si substrates. The results suggest that the substrates used have a strong influence on the nanoporous ZnO structures obtained with the Zn-sublimation-controlled process.

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

Dor, S., Th Dittrich, A. Ofir, L. Grinis y A. Zaban. "Postpressing dependence of the effective electron diffusion coefficient in electrophoretically prepared nanoporous ZnO and TiO2 films". Journal of Materials Research 23, n.º 4 (abril de 2008): 975–80. http://dx.doi.org/10.1557/jmr.2008.0116.

Texto completo

Resumen

The porosity of electrophoretically prepared nanoporous ZnO and TiO2 films was systematically decreased by postpressing at different pressures. The nanoporous structure of the films was fixed by sintering after the postpressing procedure. The postpressing-induced change of the internal surface area of the nanoporous films was monitored using the dye-removal technique. The effective electron diffusion coefficient (Deff) of the unpressed nanoporous films depended on the thickness according to Fick’s second law. When pressed, the diffusion coefficient of the films increases significantly. In nanoporous TiO2, the increase of Deff follows the percolation theory where transport rate depends on the particle-coordination number. In contrast to the TiO2 films, the value of Deff of pressed nanoporous ZnO films changed with the porosity much stronger than one would expect from the percolation theory with hard spheres. This property has been attributed to the strong increase of necking between ZnO nanoparticles with increasing pressure as indicated by a strong decrease of the internal surface area.

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

Si, Wei, Chang Chen, Gensheng Wu, Qianyi Sun, Meng Yu, Yu Qiao y Jingjie Sha. "High Efficient Seawater Desalination Based on Parallel Nanopore Systems". Nano 16, n.º 07 (21 de junio de 2021): 2150077. http://dx.doi.org/10.1142/s1793292021500776.

Texto completo

Resumen

Graphene is one of the most attractive two-dimensional materials that can be used for efficient desalination due to its ideal physical properties and high performance in ion selectivity and salt rejection. Here, in this paper, molecular dynamics simulations were applied to investigate the possibility of using a parallel nanopore system to pump ions so that the ions of both cation and anion species in the middle compartment could be evacuated at an extremely rapid rate. By building hexagonal parallel single-layer graphene films with spacing of 3.0 nm and changing the pore numbers and surface charge densities of the nanopores, the efficiency of desalination could be well controlled. It is found that the ion concentration decreases exponentially with time. The more the number of nanopore is, the stronger the surface charge density of nanopore is, the evacuation of ions in the middle compartment is more obvious, offering a new means for controlling the desalination efficiency. The simulations performed here provide theoretical insights for designing and fabricating high efficient and less energy consumption graphene desalination devices in the future.

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

Cheng, Yifan, Alexandra Khlyustova y Rong Yang. "All-dry free radical polymerization inside nanopores: Ion-milling-enabled coating thickness profiling revealed “necking” phenomena". Journal of Vacuum Science & Technology A 40, n.º 3 (mayo de 2022): 033406. http://dx.doi.org/10.1116/6.0001718.

Texto completo

Resumen

Conformal coating of nanopores with functional polymer nanolayers is the key to many emerging technologies such as miniature sensors and membranes for advanced molecular separations. While the polymer coatings are often used to introduce functional moieties, their controlled growth under nanoconfinement could serve as a new approach to manipulate the size and shape of coated nanopores, hence, enabling novel functions like molecular separation. However, precise control of coating thickness in the longitudinal direction of a nanopore is limited by the lack of a characterization method to profile coating thickness within the nanoconfined space. Here, we report an experimental approach that combines ion milling (IM) and high-resolution field emission scanning electron microscopy (FESEM) for acquiring an accurate depth profile of ultrathin (∼20 nm or less) coatings synthesized inside nanopores via initiated chemical vapor deposition (iCVD). The enhanced capability of this approach stems from the excellent x–y resolution achieved by FESEM (i.e., 4.9 nm/pixel), robust depth ( z) control enabled by IM (step size as small as 100 nm with R2 = 0.992), and the statistical power afforded by high-throughput sampling (i.e., ∼2000 individual pores). With that capability, we were able to determine with unparalleled accuracy and precision the depth profile of coating thickness and iCVD kinetics along 110-nm-diameter nanopores. That allowed us to uncover an unexpected coating depth profile featuring a maximum rate of polymerization at ∼250 nm underneath the top surface, i.e., down the pores, which we termed “necking.” The necking phenomenon deviates considerably from the conventionally assumed monotonous decrease in thickness along the longitudinal direction into a nanopore, as predicted by the diffusion-limited kinetics model of free radical polymerization. An initiator-centric collision model was then developed, which suggests that under the experimental conditions, the confinement imposed by the nanopores may lead to local amplification of the effective free radical concentration at z ≤ 100 nm and attenuation at z ≥ 500 nm, thus contributing to the observed necking phenomenon. The ion-milling-enabled depth profiling of ultrathin coatings inside nanopores, along with the initiator-mediated coating thickness control in the z-direction, may serve to enhance the performance of size-exclusion filtration membranes and even provide more flexible control of nanopore shape in the z dimension.

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

Bi, Zhenxing, Osman Anderoglu, Xinghang Zhang, Judith L. MacManus-Driscoll, Hao Yang, Quanxi Jia y Haiyan Wang. "Nanoporous thin films with controllable nanopores processed from vertically aligned nanocomposites". Nanotechnology 21, n.º 28 (28 de junio de 2010): 285606. http://dx.doi.org/10.1088/0957-4484/21/28/285606.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

Villalobos, Luis Francisco, Mohammad Tohidi Vahdat, Mostapha Dakhchoune, Zahra Nadizadeh, Mounir Mensi, Emad Oveisi, Davide Campi, Nicola Marzari y Kumar Varoon Agrawal. "Large-scale synthesis of crystalline g-C3N4 nanosheets and high-temperature H2 sieving from assembled films". Science Advances 6, n.º 4 (enero de 2020): eaay9851. http://dx.doi.org/10.1126/sciadv.aay9851.

Texto completo

Resumen

Poly(triazine imide) (PTI), a crystalline g-C3N4, hosting two-dimensional nanoporous structure with an electron density gap of 0.34 nm, is highly promising for high-temperature hydrogen sieving because of its high chemical and thermal robustness. Currently, layered PTI is synthesized in potentially unsafe vacuum ampules in milligram quantities. Here, we demonstrate a scalable and safe ambient pressure synthesis route leading to several grams of layered PTI platelets in a single batch with 70% yield with respect to the precursor. Solvent exfoliation under anhydrous conditions led to single-layer PTI nanosheets evidenced by the observation of triangular g-C3N4 nanopores. Gas permeation studies confirm that PTI nanopores can sieve He and H2 from larger molecules. Last, high-temperature H2 sieving from PTI nanosheet–based membranes, prepared by the scalable filter coating technique, is demonstrated with H2 permeance reaching 1500 gas permeation units, with H2/CO2, H2/N2, and H2/CH4 selectivities reaching 10, 50, and 60, respectively, at 250°C.

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

Jin, Chunming, Sudhakar Nori, Wei Wei, Ravi Aggarwal, Dhananjay Kumar y Roger J. Narayan. "Pulsed Laser Deposition of Nanoporous Cobalt Thin Films". Journal of Nanoscience and Nanotechnology 8, n.º 11 (1 de noviembre de 2008): 6043–47. http://dx.doi.org/10.1166/jnn.2008.483.

Texto completo

Resumen

Nanoporous cobalt thin films were deposited on anodized aluminum oxide (AAO) membranes at room temperature using pulsed laser deposition. Scanning electron microscopy demonstrated that the nanoporous cobalt thin films retained the monodisperse pore size and high porosity of the anodized aluminum oxide substrates. Temperature- and field-dependent magnetic data obtained between 10 K and 350 K showed large hysteresis behavior in these materials. The increase of coercivity values was larger for nanoporous cobalt thin films than for multilayered cobalt/alumina thin films. The average diameter of the cobalt nanograins in the nanoporous cobalt thin films was estimated to be ∼5 nm for blocking temperatures near room temperature. These results suggest that pulsed laser deposition may be used to fabricate nanoporous magnetic materials with unusual properties for biosensing, drug delivery, data storage, and other technological applications.

Los estilos APA, Harvard, Vancouver, ISO, etc.

28

Wang, Yufei, Shuangle Zhang, Zefeng Wu, Yong Fan, Huaqiang Chen, Qingning Meng, Yang Yan, Zhaoyi Hu, Jing Wang y Engang Fu. "Design and Preparation of Nanoporous Cu/Ag Multilayer Films". Coatings 11, n.º 10 (29 de septiembre de 2021): 1187. http://dx.doi.org/10.3390/coatings11101187.

Texto completo

Resumen

Cu30Al70 and Ag30Al70 multilayer precursor films were prepared by magnetron sputtering, respectively. Then the nanoporous Cu/Ag multilayer composite films were successfully prepared by selecting the appropriate H2SO4 solution as the dealloying solution. It was found that the nanoporous structure was stable in the dealloying solution. The morphology and structure of nanoporous multilayer films are mainly related to the phase composition of precursors. The structure of nanoporous multilayers can be simply regarded as the superposition of single-layer structures. Our work shows that nanoporous multilayers can be well-prepared by magnetron sputtering combined with dealloying.

Los estilos APA, Harvard, Vancouver, ISO, etc.

29

Robbennolt, Shauna, Pengmei Yu, Aliona Nicolenco, Pau Mercier Fernandez, Mariona Coll y Jordi Sort. "Magneto-ionic control of magnetism in two-oxide nanocomposite thin films comprising mesoporous cobalt ferrite conformally nanocoated with HfO2". Nanoscale 12, n.º 10 (2020): 5987–94. http://dx.doi.org/10.1039/c9nr10868h.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

30

Maklakova, Irina A., Oleg V. Gradov, Margaret A. Gradova y Pavel L. Aleksandrov. "Comparison of SEM-Assisted Nanoporometric and Microporometric Morphometric Techniques Applied for the Ultramicroporous Polymer Films". Key Engineering Materials 899 (8 de septiembre de 2021): 660–74. http://dx.doi.org/10.4028/www.scientific.net/kem.899.660.

Texto completo

Resumen

One of the most important applications of polymeric porous nanomaterials is the design of nanoporous structures for operation in patch-clamp systems allowing to establish a gigaohm contact, as well as for the measurements of biomolecules, informational macromolecules, including DNA, translocating through the nanopore arrays. Development of nanopore sequencing techniques leads to fundamentally new big data arrays, but their representativeness and validity, as well as the validity of counting of biomacromolecular particles based on ultramicropore arrays, strongly depends both on the pore size (in engineering lithography unimodal pore size distribution is optimal) and the accuracy of the size distribution measurements using instrumental methods. However, the former is unattainable when using soft matter or stretchable, plastic and elastic polymer materials and films, while the latter depends on the metrological parameters of the instrumental and algorithmic porosimetry techniques. Therefore in this paper the question about the applicability of polymer materials with pore arrays for the studies of biomacromolecules and bionanostructures is proposed to be answered using a comparative analysis of two different porosimetry approaches with the resolution not lower than electron microscopic one.

Los estilos APA, Harvard, Vancouver, ISO, etc.

31

Voon, Chun Hong, Bee Ying Lim, Uda Hashim, Mohd Khairuddin Md Arshad, S. T. Sam, K. L. Foo y Seng Teik Ten. "Effect of Temperature of Distilled Water on the Morphology of Nanoporous Zinc Oxide Synthesized by Anodizing". Applied Mechanics and Materials 754-755 (abril de 2015): 1131–35. http://dx.doi.org/10.4028/www.scientific.net/amm.754-755.1131.

Texto completo

Resumen

In this work, the effect of temperature of distilled water on the morphology of ZnO nanoporous thin films formed by anodizing was studied. ZnO nanoporous thin films were formed by anodizing of Zn plates at voltage 30 V in 500 ml distilled water of temperature ranged from 5 °C to 25°C. As anodized zinc plates were characterized by using SEM and XRD. Characterization of as anodized Zn plates using SEM showed that the morphologies of the as anodized Zn plates were significantly influenced by the temperature of distilled water. Nanoporous ZnO thin films were formed when 15 °C to 25 °C were used while ZnO thin films without nanoporous structures were formed when 5°C and 10 °C were used. XRD analysis indicated the ZnO thin films formed in distilled water of 5 °C to 25°C were of hexagonal wurtzite structures.

Los estilos APA, Harvard, Vancouver, ISO, etc.

32

Yuuki, Kazuo, Yuuki Sato y Shinzo Yoshikado. "Fabrication of Nanoporous Titanium Dioxide Films Using Aerosol Deposition". Key Engineering Materials 582 (septiembre de 2013): 141–44. http://dx.doi.org/10.4028/www.scientific.net/kem.582.141.

Texto completo

Resumen

Fabrication of nanoporous titanium dioxide (TiO2) films was examined for their application as the negative electrode of a dye-sensitized solar cell (DSC). Composite films were fabricated by aerosol deposition using a powder mixture of TiO2and aluminum nitride (AlN). A nanoporous structure was subsequently formed in the film by dissolving the AIN in hot water. Remarkable differences in the surface morphology of the films were observed for different mixing ratios of TiO2and AlN particles. AlN particles remained in the films, but not at the surface. The power conversion efficiency of a DSC was improved by incorporating these nanoporous TiO2films.

Los estilos APA, Harvard, Vancouver, ISO, etc.

33

Tan, Shengwei, Ling Zhang, Lijuan Yu y Lei Xu. "Free-Standing Lipid Bilayers Based on Nanopore Array and Ion Channel Formation". Journal of Nanoscience and Nanotechnology 19, n.º 11 (1 de noviembre de 2019): 7149–55. http://dx.doi.org/10.1166/jnn.2019.16674.

Texto completo

Resumen

Integrated nanopores are novel and versatile single-molecule sensors for individual label-free biopolymer detection and characterization. However, their studies and application requires a stable lipid bilayer to maintain protein function. Herein, we describe a method for producing lipid bilayers across a nanopore array on a silicon nitride substrate. We used a painting technique commonly used with Teflon films to embed α-hemolysin (α-HL) into bilayer lipid membranes (BLMs) to form an ion channel. This was carried out in nanofluid developed in our lab. The membrane formation process, stability of BLMs and ion channel recordings were monitored by patch clamp in real-time. BLM formation was demonstrated by electrical recording (<10 pS conductance) of suspended lipid bilayers spanning a nanopore in the range of ±100 mV. Membrane resistance (Rm) and capacitance (Cm) of the device with the bilayer were assessed by membrane test as above 1.0 GΩ and ~20±2 pF, respectively. The silicon nitride surface and aperture edge were smooth at the nanometer lever leading to remarkable membrane stability. The membrane lifetime was 5–24 h. A single α-HL channel inserted in 30–60 min applied a potential of +100 mV. The α-HL channel currents were recorded at ~100±10 pA. Such integrated nanopores enable analysis of channel functions under various solution conditions from the same BLM. This will open up a variety of applications for ion channels including high-throughput medical screening and diagnosis.

Los estilos APA, Harvard, Vancouver, ISO, etc.

34

Yim, Jin-Heong, Jongseob Kim, David W. Gidley, Richard S. Vallery, Hua-Gen Peng, Duk Keun An, Byoung-Ki Choi, Young-Kwon Park y Jong-Ki Jeon. "Calixarene Derivatives as Novel Nanopore Generators for Templates of Nanoporous Thin Films". Macromolecular Materials and Engineering 291, n.º 4 (7 de abril de 2006): 369–76. http://dx.doi.org/10.1002/mame.200500370.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

35

Shi, Li, Zhao Li, Licheng Ju, Alejandro Carrasco-Pena, Nina Orlovskaya, Haiqing Zhou y Yang Yang. "Promoting nitrogen photofixation over a periodic WS2@TiO2 nanoporous film". Journal of Materials Chemistry A 8, n.º 3 (2020): 1059–65. http://dx.doi.org/10.1039/c9ta12743g.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

36

Kılıç, Bayram, Emre Gür y Sebahattin Tüzemen. "Nanoporous ZnO Photoelectrode for Dye-Sensitized Solar Cell". Journal of Nanomaterials 2012 (2012): 1–7. http://dx.doi.org/10.1155/2012/474656.

Texto completo

Resumen

Nanoporous and macroporous structures were prepared by using self-assembled monolayer (SAM) onto ZnO thin films in order to investigate the efficiency of dye-sensitized solar cells (DSSCs) produced using these films. Using SAM on ZnO thin films, it is obtained successfully assembled large-area, highly ordered porous ZnO thin films. Varying nanoporous radius is observed between 20 and 50 nm sizes, while it is 500–800 nm for macroporous radius. The solar conversion efficiency of 2.75% and IPCE of 29% was obtained using ZnO nanoporous/N719 dye/I−/I3-electrolyte, while macroporous ZnO given solar conversion efficiency of 2.22% and IPCE of 18%.

Los estilos APA, Harvard, Vancouver, ISO, etc.

37

Benea, Lidia, Anca Ravoiu, Veaceslav Neaga y Elena Roxana Axente. "Using Applied Electrochemistry to Obtain Nanoporous TiO2 Films on Ti6Al4V Implant Alloys and Their Preclinical In Vitro Characterization in Biological Solutions". Coatings 13, n.º 3 (14 de marzo de 2023): 614. http://dx.doi.org/10.3390/coatings13030614.

Texto completo

Resumen

Nanoporous TiO2 film is deposited on grade 5 Ti6Al4V implant alloy by electrochemical oxidation. The nanopores of the film, as highlighted by electron microscopy, have a mean diameter of 58.6 nm, which is measured and calculated from an average value of 10 measurements. The increase in oxygen concentration compared to the untreated alloy, which indicates the oxidation of the titanium alloy surface, is visualized using X-ray spectroscopy coupled to an electron microscope. The beneficial effect of the oxidation and controlled formation of the TiO2 film on the implant alloy is proven by the comparative evaluation of degradation over time through the corrosion of both the untreated alloy and the alloy with an electrochemically formed and controlled TiO2 film in Hank’s solution, which simulates the most corrosive biological fluid, blood. The results show that the electrochemical modification of the grade 5 titanium alloy to form a nanoporous TiO2 surface film using the electrochemical oxidation method confirms the potential of improving the anticorrosive properties of titanium alloys used in implant applications.

Los estilos APA, Harvard, Vancouver, ISO, etc.

38

Voon, C. H., M. N. Derman, Uda Hashim, B. Y. Lim, S. T. Sam, K. L. Foo y Seng Teik Ten. "Synthesis of Nanoporous Zinc Oxide by Anodizing of Zinc in Distilled Water". Applied Mechanics and Materials 754-755 (abril de 2015): 1126–30. http://dx.doi.org/10.4028/www.scientific.net/amm.754-755.1126.

Texto completo

Resumen

In this work, ZnO nanoporous thin films were formed by anodizing of Zn plates in 500 ml distilled water of 25°C at voltage ranged from 10 V to 30 V. As anodized zinc plates were characterized by using SEM and XRD. Characterization of as anodized Zn plates using SEM showed that the morphology of the as anodized Zn plates were significantly influenced by the anodizing voltages. Nanoporous ZnO thin films were formed when 25 V and 30 V were used while ZnO thin films without nanoporous structures were formed when 10 V, 15 V and 20 V were used. XRD analysis indicated the ZnO thin films formed at 10 V to 30 V were of hexagonal wurtzite structures.

Los estilos APA, Harvard, Vancouver, ISO, etc.

39

Zuo, Jiaqi, Ning-Ning Song, Jia Wang, Xian Zhao, Meng-Yuan Cheng, Qinyi Wang, Wen Tang, Zekai Yang y Kaipei Qiu. "Review—Single-Molecule Sensors Based on Protein Nanopores". Journal of The Electrochemical Society 168, n.º 12 (1 de diciembre de 2021): 126502. http://dx.doi.org/10.1149/1945-7111/ac39da.

Texto completo

Resumen

The recent development of single-molecule sensors (SMS), which detect individual targets one at a time, allows determination of ultra-low concentrations of structurally similar compounds from a complex matrix. Protein nanopores are one of the earliest methods able to resolve the signal from a single molecule, and have already been successfully employed in commercial DNA sequencers. The protein nanopore based SMS, however, remains challenging, largely because the quantitative single-molecule analysis requires recording a sufficient number of signals for statistical significance within a reasonable time frame, thus restricting the lower limit of detection. This review aims to critically evaluate the strategies developed in this field over the last two decades. The measurement principle of nanopore SMS is first elucidated, followed by a systematic examination of the eight common protein pores, and a comprehensive assessment of the major types of sensing applications. A particular emphasis is placed on the intrinsic relationship between the size and charge of protein nanopores and their sensing capabilities for different kinds of analytes. Innovative approaches to lift the performance of nanopore SMS are also analyzed in detail, with a prediction at the end of the most promising future applications.

Los estilos APA, Harvard, Vancouver, ISO, etc.

40

Henkelmann, Gideon y Jorg Weissmuller. "Self-Detachment of Nanoporous Thin Films". ECS Meeting Abstracts MA2023-02, n.º 21 (22 de diciembre de 2023): 1278. http://dx.doi.org/10.1149/ma2023-02211278mtgabs.

Texto completo

Resumen

Nanoporous metals consist of a network of interconnected ligaments with diameters tunable between 5 and 500 nm. The talk focusses on nanoporous metal thin films prepared by electrochemical dealloying of 300 nm thick Au25Ag75 films deposited on a pure Au base layer. This type of nanoporous gold film is the subject of many studies investigating the material as sensor, as catalyst, or as substrate for energy storage. The massive Au base layer is intended as an adhesion promoter and to prevent the corrosion from attacking the substrate. Yet, contrary to expectation, we observed that the as-dealloyed nanoporous films developed a gap near the base layer, with extremely loose connection. Screening electron micrographs in earlier publications revealed that the deficit in connectivity is ubiquitous – even though it has not been broached. We could readily reproduce the feature in kinetic Monte Carlo simulations of dealloying, with no special assumptions on the processes near the base layer. The talk will describe these observations, and we argue that the evolution of the connectivity in nanoporous thin films is sensitive to gradients, in the direction of the film thickness, of the laterally averaged surface mean curvature. Specifically, surface diffusion driven by the energetically favorable planar substrate results in a net current from ligaments connected to the substrate towards the substrate, leading to degradation and eventual pinch-off of these ligaments. A similar phenomenon occurs at the outer surface, causing densification and retraction of the outermost ligaments. Our findings suggest that this phenomenon may be relevant for all nanoscopic contact interfaces where surface diffusion is sufficiently fast. These results have significant implications for the design and implementation of nanoporous thin films in various applications, including sensor and actuator devices. Mitigation strategies will be discussed. Reference: G. Henkelmann, D. Waldow, M. Liu, L. Lührs, Y. Li and J. Weissmüller; Self-Detachment and Subsurface Densification of Dealloyed Nanoporous Thin Films. Nano Lett 22 (2022) 6787. Figure 1

Los estilos APA, Harvard, Vancouver, ISO, etc.

41

Slepchenkov, Michael M., Igor S. Nefedov y Olga E. Glukhova. "Controlling the Electronic Properties of a Nanoporous Carbon Surface by Modifying the Pores with Alkali Metal Atoms". Materials 13, n.º 3 (30 de enero de 2020): 610. http://dx.doi.org/10.3390/ma13030610.

Texto completo

Resumen

We investigate a process of controlling the electronic properties of a surface of nanoporous carbon glass-like thin films when the surface pores are filled with potassium atoms. The presence of impurities on the surface in the form of chemically adsorbed hydrogen and oxygen atoms, and also in the form of hydroxyl (OH) groups, is taken into account. It is found that even in the presence of impurities, the work function of a carbon nanoporous glass-like film can be reduced by several tenths of an electron volt when the nanopores are filled with potassium atoms. At the same time, almost all potassium atoms are ionized, losing one electron, which passes to the carbon framework of the film. This is due to the nanosizes of the pores in which the electron clouds of the potassium atom interact maximally with the electrons of the carbon framework. As a result, this leads to an improvement in the electrical conductivity and an increase in the electron density at the Fermi level. Thus, we conclude that an increase in the number of nanosized pores on the film surface makes it possible to effectively modify it, providing an effective control of the electronic structure and emission properties.

Los estilos APA, Harvard, Vancouver, ISO, etc.

42

Wi, Eunsol, Vinh Van Tran y Mincheol Chang. "Controlled Nanoporous Structures of Ultrathin π-Conjugated Polymer Films for Highly Sensitive Gas Sensors". ECS Meeting Abstracts MA2022-02, n.º 64 (9 de octubre de 2022): 2403. http://dx.doi.org/10.1149/ma2022-02642403mtgabs.

Texto completo

Resumen

Conventional OFET-based chemical sensors have severe limitations in terms of sensitivity owing to poor analyte diffusion and poor interaction between the analyte and charge carriers in the CP film. To overcome this drawback, it is imperative to fabricate CP films that can facilitate analyte diffusion and provide large adsorption sites for interactions between the analytes and charge carriers concentrated in the conducting channel of OFETs. This study is to develop a facile strategy to fabricate ultrathin nanoporous Conducting polymer(CP) films for high-performance OFET gas sensors based on shearing-assisted phase separation (SAPS) of polymer blends, followed by selective solvent etching. In this method, the morphological features of nanoporous CP films, such as pore size and film thickness, can be tuned in the nanoscale regime by simply varying the shear rate. This indicates that the nanoporous P3HT films were ultrathin. Owing to these morphological features, the resulting OFET sensors exhibited excellent sensing performance when exposed to NH3 gas. We demonstrated that our approach for modulating the morphological features of CP thin films is also applicable to other CP/insulating-polymer-blend systems, including P3HT/PMMA and DPP-DTT/PS. The proposed strategy is simple and universal and can be used to fabricate ultrathin nanoporous CP films, which in turn can enable the development of high-performance, low-cost, portable OFET sensors for various commercial applications.

Los estilos APA, Harvard, Vancouver, ISO, etc.

43

Miu, Dana, Ruxandra Birjega y Cristian Viespe. "Surface Acoustic Wave Hydrogen Sensors Based on Nanostructured Pd/WO3 Bilayers". Sensors 18, n.º 11 (26 de octubre de 2018): 3636. http://dx.doi.org/10.3390/s18113636.

Texto completo

Resumen

The effect of nanostructure of PLD (Pulsed Laser Deposition)-deposited Pd/WO3 sensing films on room temperature (RT) hydrogen sensing properties of SAW (Surface Acoustic Wave) sensors was studied. WO3 thin films with different morphologies and crystalline structures were obtained for different substrate temperatures and oxygen deposition pressures. Nanoporous films are obtained at high deposition pressures regardless of the substrate temperature. At lower pressures, high temperatures lead to WO3 c-axis nanocolumnar growth, which promotes the diffusion of hydrogen but only once H2 has been dissociated in the nanoporous Pd layer. XRD (X-ray Diffraction) analysis indicates texturing of the WO3 layer not only in the case of columnar growth but for other deposition conditions as well. However, it is only the predominantly c-axis growth that influences film sensing properties. Bilayers consisting of nanoporous Pd layers deposited on top of such WO3 layers lead to good sensing results at RT. RT sensitivities of 0.12–0.13 Hz/ppm to hydrogen are attained for nanoporous bilayer Pd/WO3 films and of 0.1 Hz/ppm for bilayer films with a nanocolumnar WO3 structure. SAW sensors based on such layers compare favorably with WO3-based hydrogen detectors, which use other sensing methods, and with SAW sensors with dense Pd/WO3 bilayers.

Los estilos APA, Harvard, Vancouver, ISO, etc.

44

Mangkornkarn, Chayangkoon, Benjarong Samransuksamer, Mati Horprathum, Pitak Eiamchai, Apiluck Eiad-Ua y Korakot Onlaor. "Effect of Anodizing Voltage on Anodic Titanium Dioxide (ATO) Growth Based on an Ethylene Glycol Solution Containing NH₄F". Materials Science Forum 872 (septiembre de 2016): 147–51. http://dx.doi.org/10.4028/www.scientific.net/msf.872.147.

Texto completo

Resumen

We reported on the influence of applied voltage on the surface morphology of anodic titanium dioxide (ATO) thin films. At first, titanium (Ti) thin films were prepared by DC-magnetron sputtering for use as a base material in the anodization process. The titanium dioxide (TiO2) nanoporous ATO was fabricated by the anodization process from the Ti thin film, with different applied voltages from 20 V to 60 V in an electrolyte based on an ethylene glycol containing NH4F. Pore size distribution of ATO thin films can be varied from 20-50 nm by increasing the applied voltage, while the thickness of the film also increases. In addition, to observe the effect of time, the optimal condition of anodizing voltage was studied by increasing the anodizing time. The results clearly showed the nanoporous ATO over the films and the thickness of the nanoporous ATO is approximately 260 nm.

Los estilos APA, Harvard, Vancouver, ISO, etc.

45

Li, Yuanwei, Xueyang Zhao, Hui Liu, Wei Li y Xiaojian Wang. "Synthesis and Morphology Control of Nanoporous Cu2O/Cu and Their Application as Electrode Materials for Capacitors". Nanomaterials 9, n.º 3 (2 de marzo de 2019): 340. http://dx.doi.org/10.3390/nano9030340.

Texto completo

Resumen

In this paper, nanoporous copper (NPC) was prepared by dealloying ZrCuAl metallic glass ribbons with HF acid solutions. The effect of dealloying time on the porous structures and thickness of the obtained NPC films was investigated. It was found that the ligament sizes of the NPC could be tuned in a range from 20 to 300 nm, and the thicknesses of the NPC films from 3.1 to 14.4 μm, with properly selected dealloying times. Furthermore, nanoporous composites made of NPC and nanoporous Cu2O were prepared by oxidizing the NPC with ethanol. The nanoporous composite electrodes exhibited superior charge-discharge performance and would have broad potential applications in flexible high-performance energy storage devices.

Los estilos APA, Harvard, Vancouver, ISO, etc.

46

CAO, GUANG SHENG, RUILIN WANG, PEILONG WANG, XIN LI, YUE WANG, GUILONG WANG y JUNPING LI. "ELECTROCHEMICAL Co3O4 NANOPOROUS THIN FILMS SENSOR FOR HYDROGEN PEROXIDE DETECTION". Nano 09, n.º 04 (junio de 2014): 1450047. http://dx.doi.org/10.1142/s1793292014500477.

Texto completo

Resumen

The nanoporous Co 3 O 4 thin films were prepared on indium tin oxide (ITO) glasses by an electrodeposition method. The surface morphology and composition of the nanoporous Co 3 O 4 films were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDS) and X-ray photoelectron spectroscopy (XPS). The results show that the as-deposited nanoporous Co 3 O 4 film is constructed by many interconnected nanoflakes with thickness of about 40 nm. The cyclic voltammetry (CV) measurement indicates that the nanoporous Co 3 O 4 films exhibit remarkable electrocatalytic activities for the hydrogen peroxide ( H 2 O 2) reduction which shows that it is a good candidate to be employed as electrode materials for electrochemical sensing of H 2 O 2. Further analysis indicated that the detection sensitivity of the sensor was 1.357 mA mM-1 cm-2 and the detection limit was estimated to be about 0.2 mM.

Los estilos APA, Harvard, Vancouver, ISO, etc.

47

Sooknoi, Tawan y Attawit Aryuwat. "B-21 Nanopore zeolite membrane for selective separation of ethanol-water(Session: Films/Membrane)". Proceedings of the Asian Symposium on Materials and Processing 2006 (2006): 44–45. http://dx.doi.org/10.1299/jsmeasmp.2006.44.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

48

Liu, Xiaotao, Xiaomeng Zhang, Maria Kosmidou, Michael J. Detisch y Thomas John Balk. "Synthesizing Nanoporous Stainless Steel Films via Vacuum Thermal Dealloying". Metals 13, n.º 7 (10 de julio de 2023): 1255. http://dx.doi.org/10.3390/met13071255.

Texto completo

Resumen

Vacuum thermal dealloying is a recently developed technique and was newly introduced to produce nanoporous metals, due to its intriguing advantages, i.e., preventing oxidation and producing no chemical waste, etc. Here, we report on the fabrication of nanoporous stainless steel films by vacuum thermal dealloying of sputtered stainless steel–magnesium precursor films. It was found that crack-free nanoporous stainless steel films can be successfully attained under a broad temperature range of 450–600 °C, with a dealloying time of 0.5–2 h. The resulting structure and ligaments were temperature- and time-dependent, and moreover, the condition of “600 °C + 2 h” generated the most homogeneous structure. Moreover, small amounts of residual Mg were found at pore sites in the resultant structures, suggesting that the dealloying was not fully complete.

Los estilos APA, Harvard, Vancouver, ISO, etc.

49

Hegemann, Dirk. "(Invited, Digital Presentation) Formation of Nanostructures and Nanopores By Plasma Deposition and Etching Processes". ECS Meeting Abstracts MA2022-02, n.º 18 (9 de octubre de 2022): 879. http://dx.doi.org/10.1149/ma2022-0218879mtgabs.

Texto completo

Resumen

Plasma processing represents an environmentally friendly, cost efficient and versatile method to modify materials surfaces at low temperatures. Plasma etching processes on polymers, for example, are well studied to enhance the adhesion of coatings and composite materials involving surface nanostructuring. Plasma sputtering is examined to deposit defective metal oxide coatings such as TiO2-x containing oxygen vacancies that are doped by another metal such as Ag. Plasma post-oxidation is applied to tune the nanostructuring of the dopant forming oxidized Ag islets strongly enhancing the catalytic properties to produce reactive oxygen species (ROS). Such coatings can even be functionalized by a plasma polymer cover layer. Non-toxic antimicrobial properties are thus enabled. Plasma polymer deposition with intermittent plasma etching is explored to produce highly nanoporous thin films. Preferential etching of residual hydrocarbons in SiOx layers induces interconnected nanopores in the growing film. Such films allow water diffusion and loading with hydrogels, e.g., as lubricants. Deposition of a nm-thick hydrophobic cover layer finally enables the control of water penetration yielding the nanoconfinement of water molecules that can form a dipolar field. The adsorption of bacteria was found to be affected by the resulting water structuring. Potential biomedical and other technical applications are discussed.

Los estilos APA, Harvard, Vancouver, ISO, etc.

50

Gall, Ken, Yiping Liu, Dmitri Routkevitch y Dudley S. Finch. "Instrumented Microindentation of Nanoporous Alumina Films". Journal of Engineering Materials and Technology 128, n.º 2 (21 de junio de 2005): 225–33. http://dx.doi.org/10.1115/1.2172626.

Texto completo

Resumen

We examine the mechanical behavior of anodic alumina thin films with organized nanometer-scale porosity. The cylindrical pores in the alumina film are arranged perpendicular to the film thickness in a near-perfect triangular lattice. The films used in this work had pore diameters ranging from 35 to 75nm, and volume fractions ranging from 10% to 45%. Films with both amorphous and crystalline structures were considered. Mechanical properties of the thin films were studied using an instrumented indentor to measure the force-depth response of the films during indentation or the force-deflection response of micromachined beams in bending. The films showed increasing hardness/modulus with a decrease in pore volume fraction or transformation from amorphous to a polycrystalline alpha-alumina phase. The asymmetric films show higher hardness and modulus on their barrier side (with closed pores) relative to their open pore side. The force-depth response, measured with a spherical ball indentor, demonstrates fairly good agreement with an elastic Hertzian contact solution. The force-depth response, measured with a sharp Vickers indentor, shows an elastoplastic response. Microcracking at the corners of sharp indentations was not observed in amorphous nanoporous films, and rarely in harder, crystalline nanoporous films. High-resolution scanning electron microscopy revealed a collapse of the nanoporous structure beneath the indentor tip during sharp indentation. The results are discussed in light of continuum-based models for the elastic properties of porous solids. In general, the models are not capable of predicting the change in modulus of the films, given pore volume fraction and the properties of bulk crystalline alumina.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Artículos de revistas sobre el tema "Films nanoporeux"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros