Coating and functionalization of high density ion track structures by atomic layer deposition

In this study flexible TiO 2 coated porous Kapton membranes are presented having electron multiplication properties. 800 nm crossing pores were fabricated into 50 m thick Kapton membranes using ion track technology and chemical etching. Consecutively, 50 nm TiO 2 films were deposited i nto the pores of the Kapton membranes by atomic layer deposition using Ti( i OPr) 4 and water as precursors at 250 °C. The TiO 2 films and coated membranes were studied by scanning electro n microscopy (SEM), X - ray diffraction (XRD) and X - ray reflectometry (XRR). Au metal electrod e fabrication onto both sides of the coated foils was achieved by electron beam evaporation. The electron multipliers were obtained by joining 3 two coated membranes separated by a conductive spacer. The results show that electron multiplication can be achie ved using ALD - coated flexible ion track polymer foils

Effect of Different Anions Upon the WO3 Morphology and Structure

In this study the effects of various anions (SO42-, ClO4- and PO43-) were investigated on the hydrothermal treatment of WO3 from Na2WO4 and HCl at 180 and 200 degrees C. The products were analyzed by XRD and SEM. With the usage of SO42- the obtained product was hexagonal (h-) WO3 in the form of nanorods at both temperatures. Applying ClO4- resulted in a mixture of WO3 center dot 0.33H(2)O and small amount of m-WO3 at 180 degrees C and pure WO3 center dot 0.33H(2)O at 200 degrees C. The morphology was consisted of cuboid shapes arranged into spherical structures at 180 degrees C and longitudinal ones at 200 degrees C. By the application of PO43- no product formed at either temperature. Using the combination of SO42-, and ClO4- the product was h-WO3 at both 180 and 200 degrees C with rod-like crystals; thus, the effect of ClO4- was overdominated by the SO42- ions. Utilization of PO43- together with SO42-, and/or ClO4- resulted again in no product, meaning that adding PO43- to the reaction mixture completely blocks the hydrothermal formation of solid products by forming water soluble phosphotungstic acids

Effect of pH in the hydrothermal preparation of monoclinic tungsten oxide

This paper presents the preparation of monoclinic WO3 by a one-step hydrothermal method. The effect of very acidic pH (0.1) and the significance of various additives (CH3COOH, NaClO4, Na2SO4) were investigated. To clarify the role of pH on the obtained crystal structure and morphology, every synthesis using pH 1 were repeated, and the effect of temperature, using 180 and 200 °C, was also studied. All samples prepared at pH 0.1 were pure, well crystallized monoclinic WO3 independently from the temperature, the presence and the quality of the additives. At 180 and 200 °C, applying CH3COOH and NaClO4 resulted nanosheets similar in size. With Na2SO4 additive at 180 °C sheets, at 200 °C sheets and also rods formed indicating that SO4 2− was a capping agent only at 200 °C. For comparison, at pH 1 at both temperatures the crystalline phases and the morphologies varied depending on the type of the additive. © 2019 The Author

Hydrothermal Synthesis of Sr-Doped Hydroxyapatite and Its Antibacterial Activity

In this study, we prepared hydroxyapatite (HAP) samples using hydrothermal method. We investigated the effect of reaction conditions such as phosphate excess applying 1.49 and 1.67 (as stoichiometric) Ca/P ratio, pH (9/ 10/ 11/ 12) and time (4/ 8/ 12/ 24 h). Sample characterization was carried out by XRD and SEM. The results showed, all samples had HAP structure, however, lower Ca/P ratio, larger reaction time and setting the pH to 10 increased the crystallinity. Then, we synthetized Sr-doped HAP samples, varying the Sr concentration using 2, 4, 6, 8 and 10 % Sr/ (Ca+Sr). The Sr content was revealed by EDX. Sr-incorporation did not change the obtained crystalline HAP phase but the unit cell parameters increased. We calculated lattice constants and found that a, b changed from 9.4310 Å to 9.4700 Å, c from 6.8819 Å to 6.9227 Å and the unit cell volume from 530.0951 Å3 to 537.6556 Å3 due to the larger ionic radius of Sr compared to Ca. The pure and doped samples had uniform, mostly needle-like morphology with 100-300 nm length and 25-100 nm. In vitro cytotoxicity tests revealed evident antibacterial activity in the case of doped samples compared to pure HAP against E. coli

Influence of the Microwaves on the Sol-Gel Syntheses and on the Properties of the Resulting Oxide Nanostructures

Among the chemical methods in the liquid phase, the sol–gel technique is a versatile and efficient method for pure or doped metal oxide films or powders preparation, showing some advantages over other preparation techniques (high homogeneity, the possibility to introducing dopants in large amount, low processing temperature and control over the stoichiometry). Combining the sol–gel (SG)method with the effect of ultrasounds(US) or microwaves (MW) leads to improving the sol–gel procedure. The microwave-assisted sol–gel method is most frequently used for obtaining nanocrystalline, monodispersed oxide nanoparticles, or to transform amorphous gels into well-crystallized nanopowders. Less studied is the influence of the microwaves on the sol–gel reactions in solutions. The benefit of using microwave-assisted sol–gel preparation highly depends on the reagents used and on the composition of the studied systems. In the present chapter, results on the influence of the microwaves on the chemical reactions that take place during the sol–gel synthesis and on the properties of the resulted samples are discussed

WOˇˇ3ˇˇˇ photocatalysts: Influence of structure and composition

Hexagonal (h-) and monoclinic (m-) WO 3 nanoparticles with controlled composition (oxidized/yellow color or partially reduced/blue color) were prepared through annealing (NH 4) x WO 3- y . The formation, structure, composition, morphology, and optical properties of the samples were analyzed by powder X-ray diffraction, scanning and transmission electron microscopy combined with electron diffraction, and Raman, X-ray photoelectron, 1H magic angle spinning nuclear magnetic resonance, diffuse reflectance ultraviolet-visual, and photoluminescence spectroscopy. Their photocatalytic properties were tested by decomposing methyl orange in the aqueous phase and acetone in the gas phase. Oxidized m-WO 3 (m-WO 3 ox) was the most active photocatalyst both in the aqueous and in the gas phase, followed by the oxidized h-WO 3 (h-WO 3 ox) sample. Reduced h-WO 3 (h-WO 3 red) and m-WO 3 (m-WO 3 red) exhibited much lower activity. Thus, in contrast to TiO 2, where crystalline structure (rutile or anatase) plays a key effect in photocatalysis, for WO 3, it is the composition that is of greatest importance: the more oxidized the WO 3 sample, the better a photocatalyst it is. The crystal structure of WO 3 has only an indirect effect, in that it influences the composition of WO 3 samples. While oxidized m-WO 3 is completely oxidized, oxidized h-WO 3 is always in a partially reduced state due to the presence of stabilizing positive ions in its hexagonal channels. Consequently, an oxidized monoclinic WO 3 material will always provide better photocatalytic activity than an oxidized hexagonal one. © 2012 Elsevier Inc. All rights reserved

Programming nanostructured soft biological surfaces by atomic layer deposition

Here, we present the first successful attempt to programme the surface properties of nanostructured soft biological tissues by atomic layer deposition (ALD). The nanopatterned surface of lotus leaf was tuned by 3-125 nm TiO2 thin films. The lotus/TiO2 composites were studied by SEM-EDX, XPS, Raman, TG-DTA, XRR, water contact angle and photocatalysis measurements. While we could preserve the superhydrophobic feature of lotus, we managed to add a new property, i.e. photocatalytic activity. We also explored how surface passivation treatments and various ALD precursors affect the stability of the sensitive soft biological tissues. As we were able to gradually change the number of nanopatterns of lotus, we gained new insight into how the hollow organic nanotubes on the surface of lotus influence its superhydrophobic feature