Superstructure Films Research Articles

Ag Nanoparticles-Coated Shish-Kebab Superstructure Film for Wearable Heater.

Passive and active wearable heaters have received widespread attention due to their efficient utilization of solar energy and all-weather heating capabilities, but the current challenges are their preparation processes being time-consuming and equipment expensive. Herein, a simple and facilitated preparation method for the multifunctional wearable heater was developed, which springs Ag nanoparticles on the shish-kebab superstructure film via deposited melanin-like polydopamine as the adhesive. The light absorption ability of the resultant wearable heater in the visible region can be significantly enhanced by the addition of polydopamine, realizing a highly efficient photothermal conversion ability. Accordingly, it can achieve rapid warming ability whether passive heating (up to 45 °C about 60 s at 100 mW/cm2) or active heating (up to 72 °C about 40 s at 0.6 V), compared to ordinary cotton fabric. In addition, it can realize a 6.3 °C temperature difference with Cotton, showing excellent heat preservation ability. This study demonstrates a simple and low-cost approach for the prepared shish-kebab superstructure-based wearable heaters.

Broadband spectrally selective infrared radiation and its applications of a superstructure film of combined circular patches

Selective infrared radiation is crucial for achieving infrared stealth and heat dissipation. Artificially designed superstructure film (SF) provides several advantages for controlling and modulating infrared radiation, making them a promising solution for these applications. The research described in this work has successfully produced broadband selective infrared radiation by using a surface made up of circular patches that are combined. Numerical simulations show that this SF can achieve broadband selective radiation with 3–5 μm mid-wave infrared (MWIR) suppression and 8–14 μm long-wave infrared (LWIR) emission. The spectral selectivity can be easily switched to high emissivity in MWIR and low emissivity in LWIR by simply changing the basal layer. The resonance mechanism for achieving broadband spectral selectivity in the SF may be due to a combination of multimode plasmon resonances that are induced by the structural nonrotational symmetry of the circular patches. By applying the selective radiation SF on the tail nozzle or the vehicle, the effect of thermal management is very significant. Selective radiation SF can reduce radiant energy in the 3−5 μm band by a significant amount at 500 °C, resulting in a 46 °C cooler temperature than that at the body without the SF. At 80 °C, radiated energy in the 8–14 μm band is also considerably reduced and the temperature is 10 °C lower than that of the body without the SF. There will be obvious advantages in potential applications for infrared stealth and heat dissipation by the designed SF, a simple and convenient manufacturing process.

A Shish-Kebab Superstructure Film for Personal Radiative Cooling.

Due to global warming and the energy crisis, incorporating passive radiative cooling into personal thermal management has attracted extensive attention. However, developing a wearable textile that reflects incoming sunlight and allows mid-infrared radiation transmission is still a tough challenge. Herein, a shish-kebab superstructure film was produced via a flow-induced crystallization strategy for personal radiative cooling. The resulting film endowed a high infrared transmittance (87%) and improved sunlight reflectivity (83%). A device was developed to simulate the human body skin, and the temperatures of the shish-kebab film were 2.5 and 2.6 °C lower than that of traditional textile in outdoor and indoor tests, respectively. In order to make the shish-kebab film more wearable, a series of modifications were then carried out. This study demonstrates the substantial potential to personal thermal management textiles.

Direct Electrodeposition of Phosphorus-Doped Nickel Superstructures from Choline Chloride–Ethylene Glycol Deep Eutectic Solvent for Enhanced Hydrogen Evolution Catalysis

Hydrogen produced by electrochemical water splitting offers a hopeful and renewable solution to address the global energy crisis; however, development of highly efficient hydrogen generation electrocatalysts remains a big challenge. Herein, self-supported P-doped nickel superstructure films (NiPx) developed on Cu foil were prepared via a facile one-step electrodeposition route from the choline chloride–ethylene glycol (Ethaline)-based deep eutectic solvent (DES). Two depositional patterns including potentiostatic deposition and a consecutive potential cycling approach were compared, and the latter model with a potentiodynamic control was found to be a valid electrochemical protocol to create crack-free NiPx films which were highly active for catalyzing hydrogen evolution reaction (HER) under an alkaline condition. The optimal deposited sample with a Ni/P ratio of 1:0.056 achieved a low overpotential of 105 mV to deliver a current density of 10 mA cm–2 with a small Tafel slope of 44.7 mV dec–1 and excellen...

Colloid-Interface-Assisted Laser Irradiation of Nanocrystals Superlattices to be Scalable Plasmonic Superstructures with Novel Activities.

High-efficient charge and energy transfer between nanocrystals (NCs) in a bottom-up assembly are hard to achieve, resulting in an obstacle in application. Instead of the ligands exchange strategies, the advantage of a continuous laser is taken with optimal wavelength and power to irradiate the film-scale NCs superlattices at solid-liquid interfaces. Owing to the Au-based NCs' surface plasmon resonance (SPR) effect, the gentle laser irradiation leads the Au NCs or Au@CdS core/shell NCs to attach each other with controlled pattern at the interfaces between solid NCs phase and liquid ethanol/ethylene glycol. A continuous wave 532 nm laser (6.68-13.37 W cm-2 ), to control Au-based superlattices, is used to form the monolayer with uniformly reduced interparticle distance followed by welded superstructures. Considering the size effect to Au NCs' melting, when decreasing the Au NCs size to ≈5 nm, stronger welding nanostructures are obtained with diverse unprecedented shapes which cannot be achieved by normal colloidal synthesis. With the help of facile scale-up and formation at solid-liquid interfaces, and a good connection of crystalline between NCs, the obtained plasmonic superstructured films that could be facilely transferred onto different substrates exhibit broad SPR absorption in the visible and near-infrared regime, enhanced electric conductivities, and wide applications as surface enhanced Raman scattering (SERS)-active substrates.

Highly Ordered Single Crystalline Nanowire Array Assembled Three-Dimensional Nb3O7(OH) and Nb2O5 Superstructures for Energy Storage and Conversion Applications.

Three-dimensional (3D) metal oxide superstructures have demonstrated great potentials for structure-dependent energy storage and conversion applications. Here, we reported a facile hydrothermal method for direct growth of highly ordered single crystalline nanowire array assembled 3D orthorhombic Nb3O7(OH) superstructures and their subsequent thermal transformation into monoclinic Nb2O5 with well preserved 3D nanowire superstructures. The performance of resultant 3D Nb3O7(OH) and Nb2O5 superstructures differed remarkably when used for energy conversion and storage applications. The thermally converted Nb2O5 superstructures as anode material of lithium-ion batteries (LiBs) showed higher capacity and excellent cycling stability compared to the Nb3O7(OH) superstructures, while directly hydrothermal grown Nb3O7(OH) nanowire superstructure film on FTO substrate as photoanode of dye-sensitized solar cells (DSSCs) without the need for further calcination exhibited an overall light conversion efficiency of 6.38%, higher than that (5.87%) of DSSCs made from the thermally converted Nb2O5 film. The high energy application performance of the niobium-based nanowire superstructures with different chemical compositions can be attributed to their large surface area, superior electron transport property, and high light utilization efficiency resulting from a 3D superstructure, high crystallinity, and large sizes. The formation process of 3D nanowire superstructures before and after thermal treatment was investigated and discussed based on our theoretical and experimental results.

Hydrothermal synthesis, growth mechanism, and properties of three-dimensional micro/nanoscaled hierarchical architecture films of hemimorphite zinc silicate

A simple hydrothermal route has been developed for the fabricating hemimorphite zinc silicate, Zn4Si2O7(OH)2·H2O (ZSO), 3D hierarchical architecture films deposited on the Si substrate. Individual ZSO hierarchical architectures are assembled by many well-aligned and highly ordered rod bundles. The morphologies of the rod bundles within the ZSO hierarchical superstructures can be varied with the different surfactants and Zn sources; it realizes parts or all of the assembled rod bundles transforming into a single non-hierarchical prism. A possible mechanism for the formation of the ZSO hierarchical architectures is carefully investigated. The luminescence property of the ZSO architectures was dependent on the morphologies of the rod bundles within the ZSO hierarchical superstructures; also, as-prepared ZSO hierarchical superstructure films exhibits a hydrophobic feature.

Amphiphilic molecule controlled synthesis of CuO nano/micro-superstructure film with hydrophilicity and superhydrophilicity surface

This paper described how we obtained cupric oxide (CuO) nano/micro superstructure film with hydrophilicity and superhydrophilicity surfaces by a controllable synthesis of amphiphilic molecule, cetyltrimethylammonium bromide (CTAB) and polyethylene glycol-6000(PEG), via a simple solution-immersion process on Cu foil at room-temperature. A series of control experiments indicated that the concentration of NaOH, the concentration and the species of the amphiphilic molecule had directly influenced the morphology and wettability of the products. Because of their novel structure and wettability, the CuO films could be a promising material for fabricating optical switches, solar cells and catalyst or could be used as a gas-sensing medium. And the wettability of the CuO films may be used in some areas.

Piezoelectricity and visible light luminescence in tetravalent‐metal‐doped poled silica thin films

AbstractIt is known that poling treatment in germanium‐doped silica (Ge:SiO2) glass raises their optical nonlinearity and produces the Pockels effect. This means that the poling treatment in Ge:SiO2 produces asymmetry in the glass. We generated piezoelectricity in poled Ge:SiO2 glass thin films. Tetravalent‐metal‐doped SiO2 (M4:SiO2) films were prepared on Si substrates by RF magnetron sputtering. We used germanium, titanium, and tin as doping materials. However, less than a week later, piezoelectricity disappeared almost completely in all of the samples. To prevent piezoelectricity from disappearing, we attempted to pin the doping ions. We developed a pinning technique based on the superstructure of a Ge‐Ti‐Sn:SiO2 and Ge‐Ti‐Zr:SiO2. The superstructure was very effective in preventing piezoelectricity from disappearing. Furthermore, broadband visible light emission was observed in the proposed superstructure film. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 168(3): 28–37, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20777

Observation of Stimulated Emission in Short Wavelength Band from Silica-Based Superstructure Films

We report Ultraviolet (UV)-induced visible light luminescence in artificial-lattice thin films of ion-doped silica glass (silica superstructure thin films). The film was composed of periodic nanometer layers of germanium-doped silica (Ge: SiO2), titanium-doped silica (Ti: SiO2), and tin-doped silica (Sn: SiO2). The thickness of each layer was between 10 and 30nm. Despite the small thickness of the film (few microns), a relatively bright luminescence of white light was observed, along with cathode-ray luminescence in the superstructure film. In addition, irradiation of the superstructure film with UV light led to light amplification by stimulated emission at 405nm. The experimental results suggest the potential application of silica superstructure thin films as optical amplifiers.

Visible Light Luminescence in Silica-Based Superstructure Films

We measured the visible luminescence, under various conditions, of two different silica based superstructure films mounted on a silica substrate. One superstructure film was made up of alternate nanometer layers of Ge:SiO 2 , Ti:SiO 2 and Sn:SiO 2 and the other of Ge:SiO 2 , Ti:SiO 2 and Zr:SiO 2 . We used UV irradiation (wavelength: 254 nm) to cause the luminescence. The luminescent color changed depending on the doping material. The luminescent intensity increased as samples were cooled from room temperature to −196 °C, and luminescence disappeared in samples heated to 150 °C. Further investigation of the silica based superstructure film will likely lead to a new optical material.

Piezoelectricity and Visible Light Luminescence in Tetravalent-Metal-Doped Poled Silica Thin Films

It is known that poling treatment in germanium-doped silica (Ge:SiO2) glass raises their optical nonlinearity and produces the Pockels effect. This means that the poling treatment in Ge:SiO2 produces asymmetry in the glass. We generated piezoelectricity in poled Ge:SiO2 glass thin films. Tetravalent-metal-doped SiO2 (M4:SiO2) films were prepared on Si substrates by RF magnetron sputtering. We used germanium, titanium, and tin as doping materials. However, less than a week later, piezoelectricity disappeared almost completely in all of the samples. To prevent piezoelectricity from disappearing, we attempted to pin the doping ions. We developed a pinning technique based on the superstructure of a Ge-Ti-Sn:SiO2 and Ge-Ti-Zr:SiO2. The superstructure was very effective in preventing piezoelectricity from disappearing. Furthermore, broadband visible light emission was observed in the proposed superstructure film. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 168(3): 28–37, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20777

Natural Polarization Phenomenon of Superstructure Film Composed of Metal-Doped Silica Layers

The piezoelectricity and its related characteristics of a superstructure of silica-based thin films were investigated. Thin films with a periodic structure of nanometer-ordered silica layers containing metal dopants performed like c-axis oriented piezoelectric thin films. Piezoelectricity, pyroelectricity, and an anomalous photovoltaic effect were observed in poled superstructure silica films. The polarization was stabilized by this structure to prevent aging. We found that under some deposition conditions, piezoelectricity was observed in as-deposited films that were not poled.

Architecture of Polymeric Superstructures Constructed by Mesoscopically Ordered Cubic Lattices

AbstractHighly monodisperse crosslinked core‐shell polymer microspheres could be prepared easily by introducing special crosslinking reagents into the segregated core in block copolymer assembly films. The crosslinked core was stabilized sterically by highly branched shell chains in solution. These microspheres moved like pseudo‐latex. The microspheres formed a lattice with a body‐centered cubic (BCC) structure near the overlap threshold (C*). This structure changed to a face‐centered cubic (FCC) lattice in the bulk region of the films. Photofunctionalized core‐shell microspheres were prepared by introducing dithiocarbamate (DC) groups into shell parts by means of polymer reactions, where DC groups could be propagated using vinyl monomers such as methyl methacrylate (MMA) with living radical mechanism. Polymeric superstructure (three microphase‐separated structure) films were constructed by graft copolymerization of MMA initiated with photofunctionalized microspheres such as macroinitiators under UV irradiation, exhibiting self‐coloring due to Bragg diffraction. These materials can be used for the construction of optical devices such as for the fabrication of light modulators. Photograph of a solution of the microsphere in MMA.magnified imagePhotograph of a solution of the microsphere in MMA.

Architecture of polymeric superstructures: Locking of cubic lattices by graft polymerization from photofunctional core-shell polymer microspheres

It is well known that submicron-size colloidal spheres form a body-centered cubic (BCC) or face-centered cubic (FCC) lattice in an aqueous solution [1–5]. More recently, Asher et al. [6] have developed an approach to permanently lock in the crystalline colloidal array ordering in a hydrogel matrix. We have also constructed polymeric superstructures by free radical polymerization of N-vinylpyrrolidone (VP) monomer as a matrix, after polypyrrole microspheres were arranged on a BCC lattice in VP monomer solution [7]. More recently, we demonstrated that the core-shell polymer microspheres [8] and highly armed star polymers [9] led to hierarchical structure transformation of the cubic lattices. That is to say, these radial branched polymers formed a lattice with a BCC structure near the overlap threshold (C∗). In the bulk of the film, this structure changed to a FCC lattice. After such branched polymers formed a cubic lattice in polymerizable vinyl monomer, the polymeric superstructures were locked permanently into an ordered lattice in a solid matrix by means of free-radical polymerization [10, 11]. This technique is one of the best methods for creating nanoscopic polymeric superstructures composed of three or two phase-separated microdomains. However, the microspheres exhibiting relatively large particle diameter were packed with irregular arrangement in places due to polymerization-induced phase separation. In this communication, we report the architecture of polymeric superstructure films formed by locking of polymer matrix by means of graft polymerization from photofunctional core-shell polymer microspheres. The well-defined polystyrene-block-poly(4-vinylpyridine) (PS-block-P4VP) diblock copolymer (SV: Mn = 7.27× 104, P4VP block 26.7 mol%) was prepared by the sequential anionic polymerization technique. The details concerning the synthesis, purification and characterization of diblock copolymers have been given elsewhere [12]. Fig. 1a shows the transmission electron microscopy (TEM) photograph of SV specimen cast from toluene. The dark portions are the P4VP phases selectively stained with OsO4. The morphological structure showed the dispersed P4VP spheres in a PS matrix. Core-shell polymer microspheres (SV-M) were synthesized by crosslinking the segregated chains in P4VP spherical microdomains with 1,4-dibromobutane (DBB) vapor at room temperature. The details concerning the synthesis and the characterization of such microspheres have been given previously [13]. Characteristics of the SV-M microsphere are listed in Table I. The crosslink density of P4VP cores was 30.3 mol%. Fig. 1b shows a TEM photograph of SV-M cast from 1.0 wt% toluene solution. This specimen corresponds to the restructural film from the core-shell microspheres. It is found from this photograph that dark crosslinked P4VP cores (average diameter Dc = 30.2 nm) with a narrow size distribution are dispersed in a PS matrix. It was also mentioned previously from small-angle Xray scattering (SAXS) measurements that P4VP cores were packed with a FCC arrangement in a bulk film [8]. The hydrodynamic diameter (DH = 96.9 nm) of microspheres was determined by means of dynamic light scattering (DLS). The C∗ [14] of the SV-M in benzene was calculated to be 11.9 wt% from the DH and total molecular weight of the microsphere. Photofunctional core-shell microspheres (SV-MP) were prepared as follows. The PS shell of parent

Annealing behavior of Ar ion irradiated Bi2Sr2Can-1CunO4+2n superlattice and intergrowth films

Artificially layered Bi2Sr2Can−1CunO4+n films were synthesized by sequential sputter deposition of BiO, SrCu0.5O1.5 and CaCuO2 layers. Annealing behavior of these films which were irradiated by Ar ions was studied. Defect assisted improvement of their crystalline perfection is expected which might results in the improvement of the superconducting properties of these films. An artificial film, such as an intergrowth of 2223 and 2234 phases, and superstructure films of (2245)1(2201)1 and (2234)1(2212)1, were irradiated by Ar ions (150 keV, 2−10×1012 ions/cm2) and annealed at 730 °C. An improvement of superconducting transition temperatures were observed.

Artificially engineered pyroelectric Sr1−xBaxTiO3 superstructure films

Artificially engineered superstructure films of SrTiO3/BaTiO3 were deposited layer by layer via pulsed laser deposition onto substrates of sapphire with and without Pt/Ti electrodes. Secondary-ion-mass-spectroscopy and x-ray diffraction measurements were performed to explore the nature of the multilayered structure. Dielectric measurements versus temperature revealed a broad peak near the extrapolated Curie temperature.

Magnetic Properties of Co(Fe)-based super structured films

The change of saturation magnetostriction(λs), saturation magnetization(Bs), and soft magnetic properties(permeability μ' and coercivity Hc) were investigated for Co-based super structured films with Fe content up to 5at%. The films were prepared by using reactive RF sputtering method with N2 gas periodically mixed into Ar gas. The ratio of N2 gas partial pressure to the total gas pressure(η) was 20%, 26% and 33%. Thermal annealing of the films was performed at 515°C for an hour with a rotating magnetic fild applied in the film plane. Bs does not change within the experimental error whereas λs increases as the content of Fe increases and changes its sign from negative to positive. For the range of 86∼90at% of Co, |λs| of the films with 1∼2.5at% of Fe becomes less than 1×10-5. The anisotropy of μ', namely, the ratio of μ' along the hard axis to that along the easy axis tends to increase with Fe content. This ratio for the films prepared with η =33% is greater than that for the prepared with η =20% and 26%.

Preparation and Magnetism of CuO/A12O3 and CuO/MgO Artificial Superstructured Films

AbstractThree kinds of copper oxide (CuO) films, that is, CuO mono-layer films (MLFs), CuO/A12O3 artificial superstructured films (ASFs) and CuO/MgO ASFs were prepared by a reactive vapor deposition method. Magnetic susceptibility of the MLFs is almost constant against temperature and the Neel temperature (TN) is a little lower than that of bulk CuO. There is paramagnetic contribution proportional to the number of the interfaces for both kinds of ASFs. It is considered to be caused by imperfect -Cu-O-Cu- antiferromagnetic superexchange interactions located in the vicinity of interfaces.

Magnetic and Magnetoresistive Properties of Au/Co Superlattices

Au/Co artificial superstructure films were prepared by an alternating deposition technique in ultra-high vacuum. A large perpendicular anisotropy was found to occur when the Co layers were thinner than 20 A. From torque measurements the maximum value of K ? at room temperature was estimated to be 9.6 × 106 erg/cm3. The surface anisotropy energy constant K s was about 0.4 erg/cm2. The magnetoresistivity was measured as a function of a perpendicular applied magnetic field. The magnetoresistivity curve obtained was hysteretic, showing a peak in the vicinity of H c . The maximum change in resistivity was about 4% at 77 K.