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Spectroscopic ellipsometry of interfacial phase transitions in fluid metallic systems: KxKCl1-x and Ga1-xBix [online]

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ISBN: 3937300082 Year: DOI: 10.5445/KSP/812004 Language: ENGLISH
Publisher: KIT Scientific Publishing
Subject: Chemistry (General)
Added to DOAB on : 2019-07-30 20:01:59

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The investigation of the interfacial phase transitions in fluid systems with short-range intermetallic interactions are of great interest. The phenomena were studied in two systems exhibiting a liquid-liquid miscibility gap: at the fluid/wall interface in fluid KxKCl1-x and at the fluid/vacuum interface of the Ga1 xBix alloys. To characterize the interfacial changes of the ultra thin films (composition, thickness and their evolution with time) the spectroscopic ellipsometry was performed over a wide spectral range. Whereas in the experiments on KxKCl1-x an existing ellipsometer could be used, a completely new UHV-apparatus including the in-situ phase modulation ellipsometer had to be developed for Ga1 xBix alloys. For the KxKCl1-x system new results on complete wetting at solid-liquid coexistence as well as in the homogenous liquid phase (prewetting) are presented. The spectra show the typical F center absorption which indicates that the film is a salt-rich phase. The thickness strongly increases approaching the monotectic from 30 to 440 nm, which is in agreement with the tetra point wetting scenario. For this interpretation a quantitative description of the excess Gibbs energy has been developed. For the Ga1 xBix system the results on complete wetting, surface freezing and oscillatory interfacial instabilities are presented. The high-precision spectra have been recorded approaching the liquid-liquid miscibility. These spectra have been modeled using a Ga-Bi effective medium approximation for the substrate covered by a film of liquid Bi. The measurements give evidence of tetra point wetting in the Ga-Bi system. First ellipsometric study of the surface freezing in Ga-Bi has been performed. Within the miscibility gap a very interesting effect of surface and bulk oscillatory instability was observed. The details of this process at present are not well understood, but a qualitative description is given.

Ceramic Conductors

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ISBN: 9783038979562 9783038979579 Year: Pages: 184 DOI: 10.3390/books978-3-03897-957-9 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Physics (General)
Added to DOAB on : 2019-06-26 08:44:06
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This Special Issue of Crystals contains papers focusing on various properties of conducting ceramics. Multiple aspects of both the research and application of this group of materials have been addressed. Conducting ceramics are the wide group of mostly oxide materials which play crucial roles in various technical applications, especially in the context of the harvesting and storage of energy. Without ion-conducting oxides, such as yttria-stabilized zirconia, doped ceria devices such as solid oxide fuel cells would not exist, not to mention the wide group of other ion conductors which can be applied in batteries or even electrolyzers, besides fuel cells. The works published in this Special Issue tackle experimental results as well as general theoretical trends in the field of ceramic conductors, or electroceramics, as it is often referred to.

Element-Doped Functional Carbon-based Materials

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ISBN: 9783039282241 9783039282258 Year: Pages: 188 DOI: 10.3390/books978-3-03928-225-8 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: General and Civil Engineering --- Technology (General)
Added to DOAB on : 2020-01-30 16:39:46
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Carbon materials are one of the most fascinating materials because of their unique properties and potential use in several applications. They can be obtained from residues or by using advanced synthesis technologies like chemical vapor deposition. The carbon family is very broad, ranging from classical activated carbons to more advanced species such as carbon nanotubes and graphene. The surface chemistry is one of the most interesting aspects of this broad family of materials, which allows the incorporation of different types of chemical functionalities or heteroatoms on the carbon surface, such as O, N, B, S, or P, which can modify the acid–base character, hydrophobicity/hydrophilicity, or the electronic properties of these materials and, thus, determine the final application. This book represents a collection of original research articles and communications focused on the synthesis, properties, and applications of heteroatom-doped functional carbon materials.

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