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In this study, the tannins extracted from the Pinus radiata bark were used to develop an active–passive dual paint scheme with intumescent (IN) and fire-resistant (FR) behaviors. The properties of the coating were observed to depend on the concentration of high-molecular-weight tannins (H-MWT) incorporated into the formulation. At high concentrations (13% w/w), the coating exhibits fire-retardant properties due to the generation of a carbonaceous layer, however, at low concentrations (2.5% w/w), it generates an intumescent effect due to the formation of a carbonaceous foam layer. The dual IN–FR scheme was evaluated against fire by flame advance tests, carbonization index, mass loss, and intumescent effect, and was also compared to a commercial coating. The dual scheme presented good mechanical properties with a pull-off adhesion value of 0.76 MPa and an abrasion index of 54.7% at 1000 cycles, when using a coating with a high solid content (&gt, 60%) and the same thickness as those of the commercial coatings. The results of the fire resistance test indicate that the dual scheme generates a protective effect for wood and metal, with an excellent performance that is comparable to that of a commercial intumescent coating.

The aim of this work was to prepare and characterize color-tunable luminescent nanocomposite fibers composed of CdTe quantum dots (CdTe-QDs) and polylactic acid (PLA) via nanoprecipitation. This method provides a simple procedure to incorporate QDs with various emission wavelengths onto nanofibers’ surfaces. A one-pot microwave irradiation method was employed to prepare green- to red-emitting 3-mercaptopropionic acid (MPA)-capped CdTe-QDs with high luminescence. Microfiber PLA membranes were produced via forcespinning. These nanofibers can integrate the luminescent properties of CdTe-QDs and extend their advantages to fiber-based structures. Ultraviolet-visible spectroscopy (UV–vis) and transmission electron microscopy (TEM) were used to characterize the CdTe-QDs. TEM images revealed that the CdTe-QDs were 4 nm in size. The CdTe-QDs’ effect on the microfibers were characterized morphologically via scanning electron microscopy (SEM), which showed that the average diameter of the CdTe-QDs/PLA nanofibers was 3.5 μm. They were optically analyzed by photoluminescence (PL), absorption spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and confocal fluorescence microscopy. FTIR revealed strong interactions between the MAP stabilizing agents and PLA fibers. These preliminary results demonstrate that these microfibers have potential for biological labeling and diagnostics based on their properties.

This work reports a new method for large scale production of ZnO nanowires (ZnO-NWs) by microwave assisted thermal decomposition (MATD). This method is simple, economical and reproducible; in addition, the production of material exceeds 95% without using preferential growth precursors. The reaction occurs in only 3 min with minimal energy expenditure. ZnO-NWs produced at 1200 W had diameters ranging between 20 and 70 nm and lengths that varied between 1 and 15 µm, were totally crystalline and showed preferential growth in the [001] direction. Using XRD and HRTEM, it was determined that ZnO presented a hexagonal, wurtzite structure. The relationship between graphite and ZnO, the power of the reaction system and the reactor humidity each played an important role in this method and need to be properly controlled to optimize the production of nanowires. The reactor used allowed for the separation of the reaction products; for that reason, the ZnO-NWs produced had a high degree of purity, as determined by XRD. The photocatalytic activity of ZnO-NWs in methyl orange (MO) decreased as the pH increased; this behavior is common in ZnO because basic pH increased the interaction between the MO and ZnO. The synthesis process, growth mechanisms and photocatalytic activity of ZnO-NWs are discussed in this work.

Nanocomposites and a composite based on poly(butylene adipate-co-terephthalate) (PBAT) were synthesized using commercial copper nanoparticles (Cu-NPs), copper/cuprous oxide nanoparticles (Cu|Cu2O-NPs), and copper sulfate (CuSO4), respectively. The Cu|Cu2O-NPs were synthesized using chemical reduction and characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The synthesis of Cu|Cu2O-NPs yielded a mixture of Cu and Cu2O, with metal Cu having a spherical morphology of approximately 40 nm in diameter and Cu2O with a diameter of 150 nm. To prepare the nanocomposites (NCs) and the composite material (MC), the NPs and the CuSO4 salt were incorporated into the PBAT matrix in concentrations of 1, 3, and 5% p/p via an ex situ method. Fourier transform infrared spectroscopy (FTIR), a tensile test, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and agar diffusion assays were used for structural, thermomechanical, and antimicrobial characterization. Results showed that the reinforcements did not modify the chemical structure of the PBAT and only slightly increased the percentage of crystallization. The mechanical and thermal properties of the PBAT did not change much with the addition of fillers, except for a slight increase in tensile strength and thermal stability, respectively. The agar diffusion antimicrobial assays showed that the NCs and MCs had good inhibitory responses against the nonresistant strains Enterococcus faecalis, Streptococcus mutans, and Staphylococcus aureus. The MCs based on CuSO4 had the highest biocidal effect, even against the resistant bacteria Acinetobacter baumannii. Electronic supplementary material The online version of this article (10.1186/s11671-019-2987-x) contains supplementary material, which is available to authorized users.

We report the study of ZnO nanorods (ZnO-NR) decorated with BiOI nanoplatelets by the simple precipitation of BiOI in aqueous solution containing ZnO-NR powders. Likewise, as a reference for the decoration of ZnO-NR, BiOI thin films were prepared by the SILAR technique on RF magnetron-sputtered ZnO thin films. The scanning electron microscopy analysis showed that BiOI grew on the ZnO-NR surfaces in nanoplatelet shape with an order of magnitude smaller in size, with respect to the platelets observed in BiOI thin films. Analysis by X-ray diffraction exhibited the hexagonal P63mc phase of ZnO and the tetragonal P4nmm crystal phase of BiOI. On the other hand, BiOI thin films are nonuniform and strongly adherent and, besides they exhibited the P4nmm tetragonal crystal structure of BiOI, they have highly preferential orientation along (001) direction (9.66°). Optical characterization of ZnO-NR/BiOI by absorbance showed a widened peak slightly shifted to infrared compared with the ZnO-NR absorbance peak, suggesting the increase of the absorption wavelength ranges from the ultraviolet to visible for ZnO-NR. Similarly, the results of the optical characterization by absorbance, for BiOI thin films, indicated the bandgap energy of the samples was between 1.78 eV and 1.88 eV, values previously reported for BiOI.

Mixing aqueous silver solutions with aqueous leaf aromatic plant extracts from basil, mint, marjoram and peppermint resulted in the synthesis of quasi-spherical silver nanoparticles in a range of size between 2 and 80 nm in diameter as analyzed by analytical high-resolution electron microscopy. The average size could be controlled by applying heat to the initial reaction system at different rates of heating, and by the specific botanical species employed for the reaction. Increasing the rate of heating resulted in a statistically significant decrease in the size of the nanoparticles produced, regardless of the species employed. This fact was more evident in the case of marjoram, which decreased the average diameter from 27 nm at a slow rate of heating to 8 nm at a high rate of heating. With regard to the species, minimum sizes of

Nanostructured TiN thin films were grown by reactive magnetron sputtering deposition on Si (100) substrate at room temperature. The nanostructured TiN thin films were characterized by X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), Scanning Tunneling Microscopy (STM), Atomic Force Microscopy (AFM), resistivity and hydrophobicity tests. The nanostructured TiN thin films had an average grain size 4.6 nm, an average roughness of 1.3 nm, a preferential orientation in the [111] direction and also they showed hydrophobicity Type I. Fil: Solis Pomar, F.. Universidad Autónoma de Nuevo León; México Fil: Nápoles, O.. Universidad de La Habana; Cuba Fil: Vázquez Robaina, Odin. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de La Habana; Cuba Fil: Gutierrez Lazos, C.. Universidad Autónoma de Nuevo León; México Fil: Fundora, A.. Universidad de La Habana; Cuba Fil: Colin, Angel. Universidad Autónoma de Nuevo León; México Fil: Pérez Tijerina, E.. Universidad Autónoma de Nuevo León; México Fil: Melendrez, M. F.. Universidad de Concepción; Chile

In this work, we report a highly adherent, and uniform deposition of nanostructured tellurium. The deposition of the nanostructured tellurium was realized by the dripping of a modified solution of NaHTe based on the dissolution of NaBH4 and tellurium powder in an aqueous solution of NH4OH. This method allowed the relatively simple manipulation of tellurium nanostructures under laboratory ambient, without requiring the use of organic stabilizers. Transmission electron microscopy (TEM) was realized on a powder sample obtained by the reaction between H2Te and aqueous solution of NH4OH. TEM analysis indicated that tellurium nanorods and Y-type nanostructures are grown from tellurium nanoparticles, such as in a hydrothermal system. Then, the nanoparticles serve as seeds for the growth of more extended tellurium nanostructures. Electron diffraction and X-ray diffraction analysis showed that depositions have the hexagonal structure of tellurium highly oriented on (101) direction.

In this work, a new method to obtain zinc oxide nanonails (ZnO-NNs) via microwave plasma-assisted chemical vapor deposition (MAP-CVD) is reported. The ZnO-NNs were grown on cobalt seeds using He as the carrier gas. The cobalt seeds were deposited onto alumina at different distances from the substrate to the precursor material via the sputtering technique. The ZnO-NNs were characterized by SEM, TEM, SAED, HRTEM and EDX. NNs growth was uniform on the substrate surface: the stem of these structures ranged between 250 and 450 nm, the cap ranged between 25–150 nm, and the necks ranged between 30–200 nm. The wide distribution of the NNs dimensions was due to the vapor from the thermal decomposition of ZnO, which is richer in gaseous species of Zn than oxygen, leading to the formation of oxygen vacancies. The rich Zn vapor triggers the growth in a different direction to the shank of the cap forming the NNs, which grows in the direction [1010]. Some structural and experimental aspects are discussed in this paper.

We propose a model of antenna-coupled microbolometer to be included in an array for receiving and detecting long wave infrared (LWIR) electromagnetic radiation. The antenna is joined to microstrip bandpass filters thus forming a single metal structure to define the operation frequency band. The antenna and microstrip filters are modeled in aluminum thin film. The microbolometer is modeled with superconducting niobium, all together on a silicon nitride membrane. The squared pixel structure is designed on a support frame of 20 μm in size. Simulation results for this antenna exhibit a frequency range of operation from 27 to 35 THz and is configured for two arrays, one of 10×10 and the other one of 50×50 elements. The device has been simulated by means of the commercial electromagnetic software (HFSS), which is based on the finite elements method. The predicted values for the figures of merit of this microbolometer are as follows: τ=5.8 ns, Rv=5.3×103 V/W, and D⁎ = 2.07×1010 cmHz/W, respectively.

This work presents results of the optical and structural characterization of oleic acid-stabilized cadmium telluride nanocrystals (CdTe-NC) synthesized by an organometallic route. After being cleaned, the CdTe-NC were dispersed in toluene to obtain an ink-like dispersion, which was drop-cast on glass substrate to deposit a thin film. The CdTe-NC colloidal dispersion as well as the CdTe drop-cast thin films were characterized with regard to the optical and structural properties. TEM analysis indicates that the CdTe-NC have a nearly spherical shape (3.5 nm as mean size). Electron diffraction and XRD diffraction analyses indicated the bulk-CdTe face-centered cubic structure for CdTe-NC. An additional diffraction line corresponding to the octahedral Cd3P2 was also detected as a secondary phase, which probably originates by reacting free cadmium ions with trioctylphosphine (the tellurium reducing agent). The Raman spectrum exhibits two broad bands centered at 141.6 and 162.3 cm−1, which could be associated to the TO and LO modes of cubic CdTe nanocrystals, respectively. Additional peaks located in the 222 to 324 cm−1 range, agree fairly well with the wavenumbers reported for TO modes of octahedral Cd3P2.

In this work, we study the synthesis of monodispersed Fe nanoparticles (Fe-NPs)in situfunctionalized with oleic acid. The nanoparticles were self-assembled by inert gas condensation (IGC) technique by using magnetron-sputtering process. Structural characterization of Fe-NPs was performed by transmission electron microscopy (TEM). Particle size control was carried out through the following parameters: (i) condensation zone length, (ii) magnetron power, and (iii) gas flow (Ar and He). Typically the nanoparticles generated by IGC showed diameters which ranged from ~0.7 to 20 nm. Mass spectroscopy of Fe-NPs in the deposition system allowed the study ofin situnanoparticle formation, through a quadrupole mass filter (QMF) that one can use together with a mass filter. When the deposition system works without quadrupole mass filter, the particle diameter distribution is around +/−20%. When the quadrupole is in line, then the distribution can be reduced to around +/−2%.

In this work cadmium telluride quantum dots (CdTeQDs) were prepared via one-pot synthesis microwave assisted. Afterwards, CdTeQDs/silica (SiO2)/nigrosine (nigro)/poly (styrene co-methyl methacrylate) (PSCMM) fluorescent nanocomposite (CSNP) powders were prepared via ultrasonic treatment and post drying at 60 °C. The samples were characterized by UV–vis absorbance, x-ray diffraction (XRD) and transmission electron microscopy (TEM). Finally, successful printing tests were performed on security paper at 130 °C. These results show the potential of this nanocomposite to be used as security toner. This printing toner configuration is reported for first time.

The fabrication of ZnO (80 nm) thin film was achieved by hybrid atomic layer deposition (ALD) to prevent the reaction between the reactants and conductive layer of the substrates. ZnO nanorods (ZnO-NRs) growth over the substrates was performed by wet chemical procedure in which Zn(NO3)2 and hexamethylenetetramine were used as the precursors. HR-TEM, SAED, FE-SEM, X-ray diffraction (XRD), and UV–Vis spectroscopy were employed to characterize the ZnO-NRs samples on the substrates. XRD and HR-TEM analyses confirmed that the ZnO nanorod structure is hexagonal wurtzite type with growth in the [0001] direction. Length and thickness of the ZnO-NRs ranged between 45 and 90 nm and 480 and 600 nm, respectively. It was observed that the growth rate of NRs in [0001] direction is 10 times higher than in [1000] direction. The growth mechanism and resulted dimensions of nanorods are function of the synthesis parameters (in hybrid ALD process) such as reaction time, temperature, precursor molar ratio, and thickness of ZnO film.

Zinc Oxide nanowires (ZnO-NWs) were grown by vapor-liquid-solid (VLS) through chemical vapor deposition (CVD) with Au/Pd nanoparticles (Au/Pd-NPs) as catalyst. (Au/Pd)-NPs of 5 nm were synthesized by inert gas condensation technique (IGC), deposited on silicon substrates and characterized by atomic force microscopy (AFM). The substrate with the catalytic seeds was introduced in the reaction system where the ZnO-NWs were grown under different conditions such as: system pressure, position of the substrates with respect to the precursor material source, growth time and temperature. The nanostructures obtained were characterized by scanning electron microscopy (SEM), energy dispersed x-ray spectroscopy (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The growth parameters and the effect of catalyst nanoparticles coalescence on the ZnO-NWs dimensions is also discussed in this work.

In this work nanostructured PbS thin films were deposited on glass substrates at room temperature by radio frequency sputtering technique varying the power from 50 to 150 W while the other parameters were kept constant (Argon flow at 80 sccm for 30 min). It was observed by x-ray diffraction that they have a preferential growth in the (200) direction. Through atomic force microscopy (AFM) it was proved that the films present a nanostructured growth, with particle size between 6 and 8 nm. So it can be said that nanostructured thin films of PbS have been obtained by physical methods at room temperature for future application in solar cells.

The design and optical characterization by UV–vis transmittance of ultrathin low-emissivity (low-e) windows by reactive sputtering are reported. Two heterostructures on a glass substrate were considered for the low-e windows. The first heterostructure is Si3N4/TiO2/ZnO/Ag/SnO2/Si3N4 and the second is Si3N4/Ag/Si3N4. The transmittance and reflectance of these heterostructures were simulated to determine the required thickness of each layer. The first heterostructure exhibited maximum transmittance of 85% at 550 nm, slightly higher than the one determined by simulation and less than 50% transmittance in the near-infrared region (900 nm). The second heterostructure exhibited transmittance greater than 86% at 550 nm and

A hydrothermal method to grow vertical-aligned ZnO nanorod arrays on ZnO films obtained by atomic layer deposition (ALD) is presented. The growth of ZnO nanorods is studied as function of the crystallographic orientation of the ZnO films deposited on silicon (100) substrates. Different thicknesses of ZnO films around 40 to 180 nm were obtained and characterized before carrying out the growth process by hydrothermal methods. A textured ZnO layer with preferential direction in the normal c-axes is formed on substrates by the decomposition of diethylzinc to provide nucleation sites for vertical nanorod growth. Crystallographic orientation of the ZnO nanorods and ZnO-ALD films was determined by X-ray diffraction analysis. Composition, morphologies, length, size, and diameter of the nanorods were studied using a scanning electron microscope and energy dispersed x-ray spectroscopy analyses. In this work, it is demonstrated that crystallinity of the ZnO-ALD films plays an important role in the vertical-aligned ZnO nanorod growth. The nanorod arrays synthesized in solution had a diameter, length, density, and orientation desirable for a potential application as photosensitive materials in the manufacture of semiconductor-polymer solar cells. PACS 61.46.Hk, Nanocrystals; 61.46.Km, Structure of nanowires and nanorods; 81.07.Gf, Nanowires; 81.15.Gh, Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

In this study, Pb-filled ZnO nanowires [Pb(core)/ZnO(shell)] were synthesized by a simple and novel one-step vapor transport and condensation method by microwave-assisted decomposition of zinc ferrite. The synthesis was performed using a conventional oven at 1000 W and 5 min of treatment. After synthesis, a spongy white cotton-like material was obtained in the condensation zone of the reaction system. HRTEM analysis revealed that product consists of a Pb-(core) with (fcc) cubic structure that preferentially grows in the [111] direction and a hexagonal wurtzite ZnO-(Shell) that grows in the [001] direction. Nanowire length was more than 5 μm and a statistical analysis determined that the shell and core diameters were 21.00 ± 3.00 and 4.00 ± 1.00 nm, respectively. Experimental, structural details, and synthesis mechanism are discussed in this study.

Silver nanowires (Ag-NWs) were obtained using microwave-assisted hydrothermal method (MAH). The main advantage of the method is its high NWs production which is greater than 90%. It is also easy, fast, and highly reproducible process. One of the drawbacks presented so far in the synthesis of nanostructures by polyol path is the high temperature used in the process, which is superior than the boiling point of solvent (ethylene glycol), and also its excessive reaction time. Here, Ag-NWs with diameters of 70 to 110 nm were synthesized in 5 min in large quantities. Results showed that dimensions and shape of nanowires were very susceptible to changes with reaction parameters. The reactor power and reactor fill capacity were important for the synthesis. It was found that the reaction time needs to be decreased because of the NWs which start to deform and break up due to significant increase in the pressure's system. Energy-dispersive X-ray spectroscopy and electron diffraction analysis (SAED) did not show corresponding phases of AgO. Some aspects about synthesis parameters which are related to the percent yield and size of nanowires are also discussed.