scholarly journals Structure of Plasma (re)Polymerized Polylactic Acid Films Fabricated by Plasma-Assisted Vapour Thermal Deposition

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 459
Author(s):  
Zdeněk Krtouš ◽  
Lenka Hanyková ◽  
Ivan Krakovský ◽  
Daniil Nikitin ◽  
Pavel Pleskunov ◽  
...  
Keyword(s):  
Polylactic Acid ◽  
Photoelectron Spectroscopy ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Molecular Structures ◽  
Plasma Polymers ◽  
Thermal Deposition ◽  
X Ray ◽  
Process Chemistry ◽  
Precursor Molecules

Plasma polymer films typically consist of very short fragments of the precursor molecules. That rather limits the applicability of most plasma polymerisation/plasma-enhanced chemical vapour deposition (PECVD) processes in cases where retention of longer molecular structures is desirable. Plasma-assisted vapour thermal deposition (PAVTD) circumvents this limitation by using a classical bulk polymer as a high molecular weight “precursor”. As a model polymer in this study, polylactic acid (PLA) has been used. The resulting PLA-like films were characterised mostly by X-ray photoelectron spectroscopy (XPS) and nuclear magnetic resonance (NMR) spectroscopy. The molecular structure of the films was found to be tunable in a broad range: from the structures very similar to bulk PLA polymer to structures that are more typical for films prepared using PECVD. In all cases, PLA-like groups are at least partially preserved. A simplified model of the PAVTD process chemistry was proposed and found to describe well the observed composition of the films. The structure of the PLA-like films demonstrates the ability of plasma-assisted vapour thermal deposition to bridge the typical gap between the classical and plasma polymers.

Article

1998 ◽  
Vol 76 (11) ◽  
pp. 1559-1563
Author(s):  
J Hugh Horton ◽  
Johann Rasmusson ◽  
Joseph G Shapter ◽  
Peter R Norton
Keyword(s):  
Chemical Vapour Deposition ◽  
Photoelectron Spectroscopy ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Organometallic Compounds ◽  
Vapour Phase ◽  
Scanning Tunnelling Microscopy ◽  
X Ray ◽  
Scanning Tunnelling ◽  
Tunnelling Microscopy

The adsorption of the organometallic compounds bis(hexafluoroacetylacetonato)zinc(II) (Zn(hfac)2) and bis(hexafluoroacetylacetonato)nickel(II) (Ni(hfac)2) on the surface of Si(111)-7×7 were studied by a combination of scanning tunnelling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). These compounds are analogues of the compound bis(hexafluoroacetylacetonato)copper(II), which is an important precursor for the chemical vapour deposition of copper that we have previously studied. Both XPS and STM results indicate that the Zn(hfac)2 is adsorbed intact on the surface, and remains intact on the surface at temperatures up to 300 K. The XPS shows a transition from a physisorbed state to a chemisorbed state at temperatures between 160 and 300 K. At higher temperatures Zn(hfac)2 decomposed to form Zn and fluorocarbon fragments. The metal component diffused into the substrate. The Ni(hfac)2 complex could not be successfully adsorbed on the Si surface: it was shown that this was due to decomposition of the molecule in the vapour phase, probably due to the higher temperatures needed to evaporate this relatively involatile compound.Key words: scanning tunnelling microscopy, chemical vapour deposition, zinc, copper.

scholarly journals Growth of lithium hydride thin films from solutions: Towards solution atomic layer deposition of lithiated films

2019 ◽  
Vol 10 ◽  
pp. 1443-1451
Author(s):  
Ivan Kundrata ◽  
Karol Fröhlich ◽  
Lubomír Vančo ◽  
Matej Mičušík ◽  
Julien Bachmann
Keyword(s):  
Thin Films ◽  
Atomic Layer Deposition ◽  
Surface Area ◽  
Photoelectron Spectroscopy ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Atomic Layer ◽  
Lithium Hydride ◽  
X Ray ◽  
Layer Deposition

Lithiated thin films are necessary for the fabrication of novel solid-state batteries, including the electrodes and solid electrolytes. Physical vapour deposition and chemical vapour deposition can be used to deposit lithiated films. However, the issue of conformality on non-planar substrates with large surface area makes them impractical for nanobatteries the capacity of which scales with surface area. Atomic layer deposition (ALD) avoids these issues and is able to deposit conformal films on 3D substrates. However, ALD is limited in the range of chemical reactions, due to the required volatility of the precursors. Moreover, relatively high temperatures are necessary (above 100 °C), which can be detrimental to electrode layers and substrates, for example to silicon into which the lithium can easily diffuse. In addition, several highly reactive precursors, such as Grignard reagents or n-butyllithium (BuLi) are only usable in solution. In theory, it is possible to use BuLi and water in solution to produce thin films of LiH. This theoretical reaction is self-saturating and, therefore, follows the principles of solution atomic layer deposition (sALD). Therefore, in this work the sALD technique and principles have been employed to experimentally prove the possibility of LiH deposition. The formation of homogeneous air-sensitive thin films, characterized by using ellipsometry, grazing incidence X-ray diffraction (GIXRD), in situ quartz crystal microbalance, and scanning electron microscopy, was observed. Lithium hydride diffraction peaks have been observed in as-deposited films by GIXRD. X-ray photoelectron spectroscopy and Auger spectroscopy analysis show the chemical identity of the decomposing air-sensitive films. Despite the air sensitivity of BuLi and LiH, making many standard measurements difficult, this work establishes the use of sALD to deposit LiH, a material inaccessible to conventional ALD, from precursors and at temperatures not suitable for conventional ALD.

scholarly journals Borocarbonitride Layers on Titanium Dioxide Nanoribbons for Efficient Photoelectrocatalytic Water Splitting

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5490
Author(s):  
Nuria Jiménez-Arévalo ◽  
Eduardo Flores ◽  
Alessio Giampietri ◽  
Marco Sbroscia ◽  
Maria Grazia Betti ◽  
...  
Keyword(s):  
Water Splitting ◽  
Photoelectron Spectroscopy ◽  
Vapour Deposition ◽  
Electrochemical Impedance ◽  
Chemical Vapour ◽  
Photoelectrochemical Cell ◽  
Flat Band ◽  
X Ray Diffraction ◽  
X Ray ◽  
Reflectance Measurements

Heterostructures formed by ultrathin borocarbonitride (BCN) layers grown on TiO2 nanoribbons were investigated as photoanodes for photoelectrochemical water splitting. TiO2 nanoribbons were obtained by thermal oxidation of TiS3 samples. Then, BCN layers were successfully grown by plasma enhanced chemical vapour deposition. The structure and the chemical composition of the starting TiS3, the TiO2 nanoribbons and the TiO2-BCN heterostructures were investigated by Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Diffuse reflectance measurements showed a change in the gap from 0.94 eV (TiS3) to 3.3 eV (TiO2) after the thermal annealing of the starting material. Morphological characterizations, such as scanning electron microscopy and optical microscopy, show that the morphology of the samples was not affected by the change in the structure and composition. The obtained TiO2-BCN heterostructures were measured in a photoelectrochemical cell, showing an enhanced density of current under dark conditions and higher photocurrents when compared with TiO2. Finally, using electrochemical impedance spectroscopy, the flat band potential was determined to be equal in both TiO2 and TiO2-BCN samples, whereas the product of the dielectric constant and the density of donors was higher for TiO2-BCN.

scholarly journals Graphene prepared on SiC by chemical vapor deposition process at low temperature

2019 ◽  
Vol 70 (4) ◽  
pp. 329-331
Author(s):  
Petr Machac
Keyword(s):  
Raman Spectroscopy ◽  
Low Temperature ◽  
Vapor Deposition ◽  
Photoelectron Spectroscopy ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Chemical Vapor ◽  
Deposition Process ◽  
X Ray ◽  
Layer Graphene

Abstract Graphene preparation by the method of chemical vapour deposition on SiC substrates is described. Despite very low growth temperature (1080 °C) and with use of methane atmosphere, carbon layers in the form of multi-layer graphene were prepared. Graphene quality was verified by means of available analytical methods: Raman spectroscopy, X-ray photoelectron spectroscopy, Van der Paw method.

scholarly journals Impact of Methanol Concentration on Properties of Ultra-Nanocrystalline Diamond Films Grown by Hot-Filament Chemical Vapour Deposition

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 5
Author(s):  
Lidia Mosińska ◽  
Robert Szczęsny ◽  
Marek Trzcinski ◽  
Mieczysław Karol Naparty
Keyword(s):  
Chemical Vapour Deposition ◽  
Photoelectron Spectroscopy ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Methanol Concentration ◽  
X Ray ◽  
Atomic Force ◽  
Wide Range ◽  
Innovative Material ◽  
Hot Filament

Diamond is a very interesting material with a wide range of properties, making it highly applicable, for example, in power electronics, chemo- and biosensors, tools’ coatings, and heaters. Due to the high demand for this innovative material based on the properties it is already expected to have, it is important to obtain homogeneous diamond layers for specific applications. Doping is often chosen to modify the properties of layers. However, there is an alternative way to achieve this goal and it is shown in this publication. The presented research results reveal that the change in methanol content during the Hot Filament Chemical Vapour Deposition (HF CVD) process is a sufficient factor to tune the properties of deposited layers. This was confirmed by analysing the properties of the obtained layers, which were determined using Raman spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and an atomic force microscope (AFM), and the results were correlated with those of X-ray photoelectron spectroscopy (XPS). The results showed that the increasing of the concentration of methanol resulted in a slight decrease in the sp3 phase content. At the same time, the concentration of the -H, -OH, and =O groups increased with the increasing of the methanol concentration. This affirmed that by changing the content of methanol, it is possible to obtain layers with different properties.

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