scholarly journals Changing Contents of Carbon Hybridizations in Amorphous Hydrogenated Carbon Layers (a-C:H) on Sustainable Polyhydroxybutyrate (PHB) Exhibit a Significant Deterioration in Stability, Depending on Thickness

2019 ◽  
Vol 5 (3) ◽  
pp. 52 ◽  
Author(s):  
Torben Schlebrowski ◽  
Lucas Beucher ◽  
Hadi Bazzi ◽  
Barbara Hahn ◽  
Stefan Wehner ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Raw Materials ◽  
Chemical Vapor ◽  
Drift Spectroscopy ◽  
Significant Deterioration ◽  
X Ray ◽  
Diffuse Reflectance Infrared ◽  
X Ray Absorption ◽  
Amorphous Hydrogenated Carbon

PHB is a biodegradable polymer based on renewable raw materials that could replace synthetic polymers in many applications. A big advantage is the resulting reduction of the waste problem, as well as the conservation of fossil resources. To arrange it for various applications, the surface is arranged by plasma-enhanced chemical vapor deposition (PECVD) with amorphous hydrogenated carbon layers (a-C:H). Here, on a 50 µm thick PHB-foil, a-C:H layers of different thicknesses (0–500 nm) were deposited in 50 nm steps. Surface topography was investigated by scanning electron microscopy (SEM), chemical composition by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and wettability checked by contact angle. In addition, layers were examined by synchrotron supported X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS), which revealed thickness dependent changes of the sp2/sp3 ratio. With increasing thickness, even the topography changes show internal, stress-induced phenomena. The results obtained provide a more detailed understanding of the predominantly inorganic a-C:H coatings on (bio)polymers via in situ growth.

scholarly journals Refinement of Sustainable Polybutylene Adipate Terephthalate (PBAT) with Amorphous Hydrogenated Carbon Films (a-C:H) Revealing Film Instabilities Influenced by a Thickness-Dependent Change of sp2/sp3 Ratio

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1077 ◽  
Author(s):  
Torben Schlebrowski ◽  
Halima Acharchi ◽  
Barbara Hahn ◽  
Stefan Wehner ◽  
Christian B. Fischer
Keyword(s):  
Photoelectron Spectroscopy ◽  
Chemical Vapor ◽  
Carbon Films ◽  
Organic Polymer ◽  
X Ray ◽  
Angle Measurements ◽  
Dependent Change ◽  
Contact Angle Measurements ◽  
Diffuse Reflectance Infrared ◽  
Amorphous Hydrogenated Carbon

The increasing use of polymers is related to a growing disposal problem. Switching to biodegradable polymers such as polybutylene adipate terephthalate (PBAT) is a feasible possibility, but after industrial production of commercially available material PBAT is not suitable for every application. Therefore, surface refinements with amorphous hydrogenated carbon films (a-C:H) produced by plasma-assisted chemical vapor deposition (PE-CVD) changing the top layer characteristics are used. Here, 50 µm-thick PBAT films are coated with a-C:H layers up to 500 nm in 50 nm steps. The top surface sp2/sp3 bonding ratios are analyzed by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) both synchrotron-based. In addition, measurements using diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) were performed for detailed chemical composition. Surface topography was analyzed by scanning electron microscopy (SEM) and the surface wettability by contact angle measurements. With increasing a-C:H layer thickness not only does the topography change but also the sp2 to sp3 ratio, which in combination indicates internal stress-induced phenomena. The results obtained provide a more detailed understanding of the mostly inorganic a-C:H coatings on the biodegradable organic polymer PBAT via in situ growth and stepwise height-dependent analysis.

In Situ Plasma Analysis, Fluorine Incorporation, Thermostability, Stress, and Hardness Comparison of Fluorinated Amorphous Carbon and Hydrogenated Amorphous Carbon Thin Films Deposited on Si by Plasma Enhanced Chemical Vapor Deposition

1999 ◽  
Vol 565 ◽  
Author(s):  
A. D. Glew ◽  
M. A. Cappelli ◽  
M. N. Touzelbaev ◽  
Y. Hu
Keyword(s):  
Amorphous Carbon ◽  
Photoelectron Spectroscopy ◽  
Chemical Vapor ◽  
Film Stress ◽  
In Situ Observation ◽  
Plasma Properties ◽  
Thin Film Stress ◽  
The Relationship ◽  
Amorphous Hydrogenated Carbon

AbstractIn situ observation of the plasma properties during deposition of fluorinated amorphous hydrogenated carbon (FLAC) and unfluorinated amorphous hydrogenated carbon are performed. The relationship between film properties and impinging ion energy and incident ion momentum is discussed within the framework of existing models of diamond-like carbon (DLC) formation. The DLC films are deposited in a low pressure radio frequency discharge operating at 13.57 MHz with methane and carbon tetra-fluoride as the source gases. Thermostability, stress, and mechanical properties are investigated. The films are elevated to 400 degrees C in order to investigate thermostability. Thin film stress and nano-hardness are also studied. The film density is investigated by gravimetric methods. The fluorinated film stoichiometry is explored with x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy.

Preparation and Characterization of Chromium Containing amorphous Hydrogenated Carbon Films (A-C:H/Cr)

1995 ◽  
Vol 388 ◽  
Author(s):  
R. Gampp ◽  
P. Gantenbein ◽  
P. Oelhafen
Keyword(s):  
Chromium Carbide ◽  
Photoelectron Spectroscopy ◽  
Chemical Vapor ◽  
Carbon Films ◽  
Rf Plasma ◽  
Silicon Substrates ◽  
Amorphous Hydrogenated Carbon ◽  
High Chemical Stability

AbstractChromium containing amorphous hydrogenated carbon films (a-C:H/Cr) were prepared in a process that combines rf plasma activated chemical vapor deposition of methane and magnetron sputtering of a chromium target. During the deposition the silicon substrates were kept at 200°C and dc biased at -200 V in order to obtain films with high chemical stability which is required for the application as solar selective surfaces. the films with different Cr concentrations (5 to 49 at.%) were characterized by in situ x-ray photoelectron spectroscopy (XPS). Up to 40 at.%, chromium proves to be built into the cermet-like films in the form of chromium carbide clusters. above 40 at.%, chromium is partly metallic. a modification of the a-C:H matrix in the vicinity of the chromium carbide clusters has been observed.

A dispenser–reactor apparatus applied forin situXAS monitoring of Pt nanoparticle formation

2015 ◽  
Vol 22 (3) ◽  
pp. 736-744 ◽  
Author(s):  
Jocenir Boita ◽  
Marcus Vinicius Castegnaro ◽  
Maria do Carmo Martins Alves ◽  
Jonder Morais
Keyword(s):  
Photoelectron Spectroscopy ◽  
Metallic Nanoparticles ◽  
Pt Nanoparticles ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Two Stages ◽  
X Ray Absorption

In situtime-resolved X-ray absorption spectroscopy (XAS) measurements collected at the PtL3-edge during the synthesis of Pt nanoparticles (NPs) in aqueous solution are reported. A specially designed dispenser–reactor apparatus allowed for monitoring changes in the XAS spectra from the earliest moments of Pt ions in solution until the formation of metallic nanoparticles with a mean diameter of 4.9 ± 1.1 nm. By monitoring the changes in the local chemical environment of the Pt atoms in real time, it was possible to observe that the NPs formation kinetics involved two stages: a reduction-nucleation burst followed by a slow growth and stabilization of NPs. Subsequently, the synthesized Pt NPs were supported on activated carbon and characterized by synchrotron-radiation-excited X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS). The supported Pt NPs remained in the metallic chemical state and with a reduced size, presenting slight lattice parameter contraction in comparison with the bulk Pt values.

scholarly journals Photolysis of Fluorinated Graphites with Embedded Acetonitrile Using a White-Beam Synchrotron Radiation

Nanomaterials ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 231
Author(s):  
Galina I. Semushkina ◽  
Yuliya V. Fedoseeva ◽  
Anna A. Makarova ◽  
Dmitry A. Smirnov ◽  
Igor P. Asanov ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Photoelectron Spectroscopy ◽  
X Ray ◽  
Photon Irradiation ◽  
Nexafs Spectroscopy ◽  
White Beam ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene ◽  
X Ray Absorption

Fluorinated graphitic layers with good mechanical and chemical stability, polar C–F bonds, and tunable bandgap are attractive for a variety of applications. In this work, we investigated the photolysis of fluorinated graphites with interlayer embedded acetonitrile, which is the simplest representative of the acetonitrile-containing photosensitizing family. The samples were continuously illuminated in situ with high-brightness non-monochromatized synchrotron radiation. Changes in the compositions of the samples were monitored using X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The NEXAFS N K-edge spectra showed that acetonitrile dissociates to form HCN and N2 molecules after exposure to the white beam for 2 s, and the latter molecules completely disappear after exposure for 200 s. The original composition of fluorinated matrices CF0.3 and CF0.5 is changed to CF0.10 and GF0.17, respectively. The highly fluorinated layers lose fluorine atoms together with carbon neighbors, creating atomic vacancies. The edges of vacancies are terminated with the nitrogen atoms and form pyridinic and pyrrolic units. Our in situ studies show that the photolysis products of acetonitrile depend on the photon irradiation duration and composition of the initial CFx matrix. The obtained results evaluate the radiation damage of the acetonitrile-intercalated fluorinated graphites and the opportunities to synthesize nitrogen-doped graphene materials.

Chemical Vapor Functionalization of ZnO Nanocrystals

2010 ◽  
Vol 1260 ◽  
Author(s):  
Moazzam Ali ◽  
Marty D. Donakowski ◽  
Markus Winterer
Keyword(s):  
Gas Phase ◽  
Diffuse Reflectance ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Zno Nanocrystals ◽  
In Series ◽  
Lower Temperature ◽  
Diffuse Reflectance Infrared

AbstractChemical Vapor Functionalization (CVF) is a method in which nanocrystals undergo in situ functionalization in the gas phase. In CVF, two reactors are used in series. The first reactor consists of a hot quartz tube (1073 K) where ZnO nanocrystals are synthesized in the gas phase from diethylzinc and oxygen. The second reactor, connected at the exit of the first one and kept at lower temperature (673 K), is used as functionalization chamber. At the connecting point of the two reactors, vapors of organic functionalizing agents are injected which react with the surface of ZnO nanocrystals. ZnO nanocrystals have been functionalized by 1-hexanol, n-hexanoic acid, n-hexanal and 1-hexylamine. Functionalized ZnO nanocrystals have been characterized by Dynamic Light Scattering, X-ray Diffraction and Diffuse Reflectance Infrared Fourier Transform Spectroscopy.

One-step in situ synthesis and characterization of W18O49@carbon coaxial nanocables

2009 ◽  
Vol 24 (5) ◽  
pp. 1833-1841 ◽  
Author(s):  
Yuqin Zhou ◽  
Yong Zhang ◽  
Ruying Li ◽  
Mei Cai ◽  
Xueliang Sun
Keyword(s):  
Raw Materials ◽  
Tungsten Powder ◽  
Carbon Sources ◽  
Chemical Vapor ◽  
Deposition Process ◽  
In Situ Synthesis ◽  
X Ray ◽  
Coaxial Nanocables ◽  
Catalyst Systems

We demonstrate here in situ synthesis of bulk yield W18O49@carbon coaxial nanocables based on an easily controlled chemical vapor deposition process at relatively low temperature (760 °C) using metallic tungsten powder and ethylene (C2H4) as the raw materials. Transmission electron microscope (TEM), energy dispersive x-ray (EDX), and x-ray diffraction (XRD) analyses indicate that the resultant nanostructures are composed of single-crystalline W18O49 nanowires, coaxially covered with amorphous carbon walls. A vapor–solid (VS) mechanism is proposed to interpret the formation of the nanocables. The effect of carbon sources on the nanocable growth was investigated. The results revealed that the introduction of carbon species not only causes the production of W18O49@C nanocable structures, but also obviously modulates growth behaviors and core/shell diameter ratio of the nanocables. The obtained nanocables may find great applications in catalyst systems and optical and electronic nanodevices because of their enhanced surface properties, as well as in high chemical stability.

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