scholarly journals Structure, Surface Morphology, Chemical Composition, and Sensing Properties of SnO2 Thin Films in an Oxidizing Atmosphere

Sensors ◽  
2021 ◽  
Vol 21 (17) ◽  
pp. 5741
Author(s):  
Weronika Izydorczyk ◽  
Jacek Izydorczyk
Keyword(s):  
Oxygen Sensor ◽  
Gas Sensing ◽  
Surface Film ◽  
Chemical Characterization ◽  
Film Structure ◽  
Nitrogen Atmosphere ◽  
Thin Layers ◽  
Near Surface ◽  
Dc Reactive Magnetron Sputtering ◽  
Layer Resistance

We conducted experiments on SnO2 thin layers to determine the dependencies between the stoichiometry, electrochemical properties, and structure. This study focused on features such as the film structure, working temperature, layer chemistry, and atmosphere composition, which play a crucial role in the oxygen sensor operation. We tested two kinds of resistive SnO2 layers, which had different grain dimensions, thicknesses, and morphologies. Gas-sensing layers fabricated by two methods, a rheotaxial growth and thermal oxidation (RGTO) process and DC reactive magnetron sputtering, were examined in this work. The crystalline structure of SnO2 films synthesized by both methods was characterized using XRD, and the crystallite size was determined from XRD and AFM measurements. Chemical characterization was carried out using X-ray photoelectron (XPS) and Auger electron (AES) spectroscopy for the surface and the near-surface film region (in-depth profiles). We investigated the layer resistance for different oxygen concentrations within a range of 1–4%, in a nitrogen atmosphere. Additionally, resistance measurements within a temperature range of 423–623 K were analyzed. We assumed a flat grain geometry in theoretical modeling for comparing the results of measurements with the calculated results.

Evolution of natural sea surface film structure as a tool for organic matter dynamics tracing

2008 ◽  
Vol 74 ◽  
pp. S52-S64 ◽  
Author(s):  
Z. Adriana Mazurek ◽  
J. Stanisław Pogorzelski ◽  
Katarzyna Boniewicz-Szmyt
Keyword(s):  
Organic Matter ◽  
Surface Film ◽  
Film Structure ◽  
Sea Surface ◽  
Organic Matter Dynamics

scholarly journals Nanostructured Composites Based on Liquid-Crystalline Elastomers

Polymers ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 773 ◽  
Author(s):  
Vanessa Cresta ◽  
Giuseppe Romano ◽  
Alexej Kolpak ◽  
Boštjan Zalar ◽  
Valentina Domenici
Keyword(s):  
Liquid Crystalline ◽  
Carbon Nanomaterials ◽  
Chemical Characterization ◽  
Soft Materials ◽  
Thin Layers ◽  
Ferroelectric Ceramics ◽  
Magnetic Actuation ◽  
Magnetic Iron Oxide Nanoparticles ◽  
Graphene Layers ◽  
Optical Applications

Liquid-crystalline elastomers (LCEs) are the object of many research investigations due to their reversible and controllable shape deformations, and their high potential for use in the field of soft robots and artificial muscles. This review focuses on recent studies about polymer composites based on LCEs and nanomaterials having different chemistry and morphology, with the aim of instilling new physical properties into LCEs. The synthesis, physico-chemical characterization, actuation properties, and applications of LCE-based composites reported in the literature are reviewed. Several cases are discussed: (1) the addition of various carbon nanomaterials to LCEs, from carbon black to carbon nanotubes, to the recent attempts to include graphene layers to enhance the thermo-mechanic properties of LCEs; (2) the use of various types of nanoparticles, such as ferroelectric ceramics, gold nanoparticles, conductive molybdenum-oxide nanowires, and magnetic iron-oxide nanoparticles, to induce electro-actuation, magnetic-actuation, or photo-actuation into the LCE-based composites; (3) the deposition on LCE surfaces of thin layers of conductive materials (i.e., conductive polymers and gold nanolayers) to produce bending actuation by applying on/off voltage cycles or surface-wrinkling phenomena in view of tunable optical applications. Some future perspectives of this field of soft materials conclude the review.

Effects of Preparing Conditions on NO2-Sensing Properties of Sputtered WO3 Nano-Films

2013 ◽  
Vol 690-693 ◽  
pp. 1680-1684
Author(s):  
Feng Yun Sun ◽  
Ming Hu ◽  
Peng Sun
Keyword(s):  
Gas Sensing ◽  
High Sensitivity ◽  
Fast Response ◽  
Optimal Parameters ◽  
Working Pressure ◽  
Sensing Properties ◽  
Dc Reactive Magnetron Sputtering ◽  
Experiment Method ◽  
Discharge Gas ◽  
Gas Ratio

WO3 nano-films were deposited on Al2O3 substrate by dc reactive magnetron sputtering method. The effects of preparing conditions, such as the discharge gas ratio (Ar:O2), working pressure, sputtering time and annealing temperature on microstructure, crystalline state and NO2-sensing properties of WO3 nano-films were investigated by orthogonal trial experiment method. The optimum technological conditions were determined by orthogonal test and extreme difference analysis. The crystallization, morphology and composition of WO3 thin film obtained at the optimal parameters were studied by XRD, SEM and XPS. The gas sensing mechanism was also studied. WO3 nano-film shows high sensitivity, fast response, good selectivity at the best operating temperature 200°C.

Rupture and Reformation of Ultra-Thin Surface Films

2010 ◽  
Author(s):  
William W. F. Chong ◽  
Mircea Teodorescu ◽  
Homer Rahnejat
Keyword(s):  
Thin Film ◽  
Data Storage ◽  
Surface Film ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Surface Films ◽  
Disk Drives ◽  
Film Rupture ◽  
Near Surface ◽  
Ultra Thin Film

In lubricated contact conjunctions film ruptures close to the exit boundary. This significantly affects the load carrying capacity and can lead to direct surface interactions. Nano-scale films (several molecular diameters of the lubricant) are no exception, a fact that has been observed using ellipsometry studies for ultra-thin film conjunctions representative for high storage capacity hard disk drives. Immediately beyond the film rupture an area of cavitation occurs and the continuity of flow condition is breached. It has been shown that for molecularly smooth surfaces solvation effect becomes dominant. This means that the contact exit is subject to discrete drainage of lubricant and may be devoid of a sufficient lubricant for film reformation to occur. This can be a stumbling block in an increasing quest to increase the data storage density of hard disk drives. Wear can become a problem as well as non-uniformity of free surface film at the inlet meniscus. It has been noted that peaks of lubricant can gather in some places, a phenomenon referred to as lubricant mogul. These localized piles of lubricant can exceed the nominally aimed for lubricant film thickness necessary for a given data storage level. This paper carries out an in-depth prediction of ultra thin film lubricant behavior through the contact. Hydrodynamic as well as near surface effects and intermolecular interactions responsible for the supply, formation, cavitation and reformation of thin films in the slider-disk conjunction have been considered.

scholarly journals Enhancement of Acetone Gas-Sensing Responses of Tapered WO3 Nanorods through Sputtering Coating with a Thin SnO2 Coverage Layer

Nanomaterials ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 864 ◽  
Author(s):  
Yuan-Chang Liang ◽  
Yu Chao
Keyword(s):  
Gas Sensing ◽  
Microstructural Analysis ◽  
Xrd Analysis ◽  
Thin Layers ◽  
Elemental Distribution ◽  
Distribution Analysis ◽  
Acetone Vapor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Composite Nanorods

WO3–SnO2 composite nanorods were synthesized by combining hydrothermal growth of tapered tungsten trioxide (WO3) nanorods and sputter deposition of thin SnO2 layers. Crystalline SnO2 coverage layers with thicknesses in the range of 13–34 nm were sputter coated onto WO3 nanorods by controlling the sputtering duration of the SnO2. The X-ray diffraction (XRD) analysis results demonstrated that crystalline hexagonal WO3–tetragonal SnO2 composite nanorods were formed. The microstructural analysis revealed that the SnO2 coverage layers were in a polycrystalline feature. The elemental distribution analysis revealed that the SnO2 thin layers homogeneously covered the surfaces of the hexagonally structured WO3 nanorods. The WO3–SnO2 composite nanorods with the thinnest SnO2 coverage layer showed superior gas-sensing response to 100–1000 ppm acetone vapor compared to other composite nanorods investigated in this study. The substantially improved gas-sensing responses to acetone vapor of the hexagonally structured WO3 nanorods coated with the SnO2 coverage layers are discussed in relation to the thickness of SnO2 coverage layers and the core–shell configuration of the WO3–SnO2 composite nanorods.

scholarly journals Effect of Thermal and Oxidative Aging on Asphalt Binders Rheology and Chemical Composition

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4438
Author(s):  
Ingrid Gabrielle do Nascimento Camargo ◽  
Bernhard Hofko ◽  
Johannes Mirwald ◽  
Hinrich Grothe
Keyword(s):  
Thin Film ◽  
Asphalt Binder ◽  
Chemical Characterization ◽  
Nitrogen Atmosphere ◽  
Asphalt Binders ◽  
Effect Of Temperature ◽  
Ambient Atmosphere ◽  
Test Procedures ◽  
Oxidative Aging ◽  
Aging Test

Aging of asphalt binders is one of the main causes of its hardening, which negatively affects the cracking and fatigue resistance of asphalt binders. Understanding asphalt aging is crucial to improve the durability of asphalt pavements. In this regard, this study aims at understanding and differentiating the effect of temperature and oxygen uptake on the aging mechanisms of unmodified asphalt binders. For that, four laboratory aging procedures were employed. The two standardized procedures, rolling thin-film oven test (RTFOT) and pressure aging vessel (PAV), were considered to simulate the short-term and long-term aging of the asphalt binders, respectively. In addition, two thin-film aging test procedures, the nitrogen atmosphere oven aging test (NAAT) and ambient atmosphere oven aging test (OAAT) were employed to assess the effect of thermal and oxidative aging on unmodified asphalt binder properties. The NAAT procedure is based on the principle that the inert gas minimizes the oxidative aging. The rheological and chemical characterization showed that the high temperatures considered during the NAAT procedure did not change the properties of the unmodified asphalt binders. Therefore, it can be hypothesized that no significant thermal and oxidative aging was observed during NAAT aging procedure for the considered binders and that oxidative aging is the main cause for the hardening.

Simulation of Structural Transformations in Modified Near-Surface Layers of Crystals

2019 ◽  
Vol 970 ◽  
pp. 276-282
Author(s):  
Yury Borodin ◽  
Anastasia Mantina
Keyword(s):  
Quantum Wells ◽  
Riemannian Space ◽  
Structural Transformations ◽  
Thin Layers ◽  
Surface Layers ◽  
Near Surface ◽  
Internal Geometry ◽  
Structure Ordering

Superlattice formation in thin layers of oxidizing crystals and the effect of near-surface proton saturation on structure ordering, formation and periodical distribution of quantum wells have been discussed. The paper shows, it is necessary to develop non-Euclidean approach to the crystal’s internal geometry and consider, in consecutive order, the question of the four-dimentional Riemannian space into three-dimentional Eucliden space interpretation (RE interpretation).

Volatile Evolution from Polymer Materials Induced by Irradiation with Accelerated He++ Ions

2004 ◽  
Vol 851 ◽  
Author(s):  
Julian.J. Murphy ◽  
Christopher.J. Wetteland
Keyword(s):  
Ion Beam ◽  
Surface Region ◽  
Energetic Particles ◽  
Thin Layers ◽  
Polymer Materials ◽  
Particle Radiation ◽  
Chemical Changes ◽  
Near Surface ◽  
Particle Irradiation ◽  
Pass Through

ABSTRACTExperimentally investigating ageing caused by irradiation with energetic particles is very difficult. Radioactive sources can be employed but these are difficult to handle and contaminate the material being irradiated precluding subsequent chemical and physical characterisation. The penetration of energetic particles also tends to be small so any change is localised in the near surface region so only a small amount of material is irradiated. Analysing changes in such thin layers causes a number of problems. To simulate ageing induced by particle radiation polymer samples have been exposed to fast He++ ions in an accelerated ion beam. The ions pass through a 10μm thick window of Havar foil before impacting upon the sample. Volatile species evolved from the materials upon bombardment are contained within the irradiation chamber by the foil window. Analysis of such species is shown to be a highly sensitive probe for investigating chemical changes in the exposed materials. A number of important chemical changes induced in polymer materials have been identified. Trends in the relative rates of volatile evolution have been identified which correlate with chemical changes identified in other radiation experiments. As these experiments are performed at far slower irradiation rates the large acceleration factors used in ion beam irradiation are discussed along with the implications for using ion beams to simulate alpha particle irradiation.

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