Download or read book Synthesis and Characterization of Ternary Carbide Thin Films written by Ola Wilhelmsson and published by . This book was released on 2007 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and characterization of magnetic nanolaminated carbides written by Andrejs Petruhins and published by Linköping University Electronic Press. This book was released on 2018-03-15 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: MAX phases are a group of nanolaminated ternary carbides and nitrides, with a composition expressed by the general formula Mn+1AXn (?? = 1 ? 3), where M is a transition metal, A is an A-group element, and X is carbon and/or nitrogen. MAX phases have attracted interest due to their unique combination of metallic and ceramic properties, related to their inherently laminated structure of a transition metal carbide (Mn+1Xn) layer interleaved by an A-group metal layer. This Thesis explores synthesis and characterization of magnetic MAX phases, where the A-group element is gallium (Ga). Due to the low melting point of Ga (T = 30 °C), conventional thin film synthesis methods become challenging, as the material is in liquid form at typical process temperatures. Development of existing methods has therefore been investigated, for reliable/reproducible synthesis routes, including sputtering from a liquid target, and resulting high quality material. Routes for minimizing trial-and-error procedures during optimization of thin film synthesis have also been studied, allowing faster identification of optimal deposition conditions and a simplified transfer of essential deposition parameters between different deposition systems. A large part of this Thesis is devoted towards synthesis of MAX phase thin films in the Cr-Mn-Ga-C system. First, through process development, thin films of Cr2GaC were deposited by magnetron sputtering. The films were epitaxial, however with small amount of impurity phase Cr3Ga, as confirmed by X-ray diffraction (XRD) measurements. The film structure was confirmed by scanning transmission electron microscopy (STEM) and the composition by energy dispersive X-ray spectroscopy (EDX) inside the TEM. Inspired by predictive ab initio calculations, the new MAX phase Mn2GaC was successfully synthesized in thin film form by magnetron sputtering. Structural parameters and magnetic properties were analysed. The material was found to have two magnetic transitions in the temperature range 3 K to 750 K, with a first order transition at around 214 K, going from non-collinear antiferromagnetic state at lower temperature to an antiferromagnetic state at higher temperature. The Neél temperature was determined to be 507 K, changing from an antiferromagnetic to a paramagnetic state. Above 800 K, Mn2GaC decomposes. Furthermore, magnetostrictive, magnetoresistive and magnetocaloric properties of the material were iv determined, among which a drastic change in lattice parameters upon the first magnetic transition was observed. This may be of interest for magnetocaloric applications. Synthesis of both Cr2GaC and Mn2GaC in thin film form opens the possibility to tune the magnetic properties through a solid solution on the transition metal site, by alloying the aforementioned Cr2GaC with Mn, realizing (Cr1-xMnx)2GaC. From a compound target with a Cr:Mn ratio of 1:1, thin films of (Cr0.5Mn0.5)2GaC were synthesized, confirmed by TEM-EDX. Optimized structure was obtained by deposition on MgO substrates at a deposition temperature of 600 ºC. The thin films were phase pure and of high structural quality, allowing magnetic measurements. Using vibrating sample magnetometry (VSM), it was found that (Cr0.5Mn0.5)2GaC has a ferromagnetic component in the temperature range from 30 K to 300 K, with the measured magnetic moment at high field decreasing by increasing temperature. The remanent moment and coercive field is small, 0.036 ?B, and 12 mT at 30 K, respectively. Using ferromagnetic resonance spectroscopy, it was also found that the material has pure spin magnetism, as indicated by the determined spectroscopic splitting factor g = 2.00 and a negligible magnetocrystalline anisotropy energy. Fuelled by the recent discoveries of in-plane chemically ordered quaternary MAX phases, so called i-MAX phases, and guided by ab initio calculations, new members within this family, based on Cr and Mn, were synthesized by pressureless sintering methods, realizing (Cr2/3Sc1/3)2GaC and (Mn2/3Sc1/3)2GaC. Their structural properties were determined. Through these phases, the Mn content is the highest obtained in a bulk MAX phase to date. This work has further developed synthesis processes for sputtering from liquid material, for an optimized route to achieve thin films of controlled composition and a high structural quality. Furthermore, through this work, Mn has been added as a new element in the family of MAX phase elements. It has also been shown, that alloying with different content of Mn gives rise to varying magnetic properties in MAX phases. As a result of this Thesis, it is expected that the MAX phase family can be further expanded, with more members of new compositions and new properties.

Download or read book Synthesis and transport properties of 2D transition metal carbides MXenes written by Joseph Halim and published by Linköping University Electronic Press. This book was released on 2018-09-28 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the isolation and characterization of graphene, there has been a growing interest in 2D materials owing to their unique properties compared to their 3D counterparts. Recently, a family of 2D materials of early transition metal carbides and nitrides, labelled MXenes, has been discovered (Ti2CTz, Ti3C2Tz, Mo2TiC2Tz, Ti3CNTz, Ta4C3Tz, Ti4N3Tz among many others), where T stands for surface-terminating groups (O, OH, and F). MXenes are mostly produced by selectively etching A layers (where A stands for group A elements, mostly groups 13 and 14) from the MAX phases. The latter are a family of layered ternary carbides and/or nitrides and have a general formula of Mn+1AXn (n = 1-3), where M is a transition metal and X is carbon and/or nitrogen. The produced MXenes have a conductive carbide core and a non-conductive O-, OH- and/or F-terminated surface, which allows them to work as electrodes for energy storage applications, such as Li-ion batteries and supercapacitors. Prior to this work, MXenes were produced in the form of flakes of lateral dimension of about 1 to 2 microns; such dimensions and form are not suitable for electronic characterization and applications. I have synthesized various MXenes (Ti3C2Tz, Ti2CTz and Nb2CTz) as epitaxial thin films, a more suitable form for electronic and photonic applications. These films were produced by HF, NH4HF2 or LiF + HCl etching of magnetron sputtered epitaxial Ti3AlC2, Ti2AlC, and Nb2AlC thin films. For transport properties of the Ti-based MXenes, Ti2CTz and Ti3C2Tz, changing n from 1 to 2 resulted in an increase in conductivity but had no effect on the transport mechanism (i.e. both Ti3C2Tx and Ti2CTx were metallic). In order to examine whether the electronic properties of MXenes differ when going from a few layers to a single flake, similar to graphene, the electrical characterization of a single Ti3C2Tz flake with a lateral size of about 10 μm was performed. These measurements, the first for MXene, demonstrated its metallic nature, along with determining the nature of the charge carriers and their mobility. This indicates that Ti3C2Tz is inherently of 2D nature independent of the number of stacked layers, unlike graphene, where the electronic properties change based on the number of stacked layers. Changing the transition metal from Ti to Nb, viz. comparing Ti2CTz and Nb2CTz thin films, the electronic properties and electronic conduction mechanism differ. Ti2CTz showed metallic-like behavior (resistivity increases with increasing temperature) unlike Nb2CTz where the conduction occurs via variable range hopping mechanism (VRH) - where resistivity decreases with increasing temperature. Furthermore, these studies show the synthesis of pure Mo2CTz in the form of single flakes and freestanding films made by filtering Mo2CTz colloidal suspensions. Electronic characterization of free-standing films made from delaminated Mo2CTz flakes was investigated, showing that a VRH mechanism prevails at low temperatures (7 to ≈ 60 K). Upon vacuum annealing, the room temperature, RT, conductivity of Mo2CTx increased by two orders of magnitude. The conduction mechanism was concluded to be VRH most likely dominated by hopping within each flake. Other Mo-based MXenes, Mo2TiC2Tz and Mo2Ti2C3Tz, showed VRH mechanism at low temperature. However, at higher temperatures up to RT, the transport mechanism was not clearly understood. Therefore, a part of this thesis was dedicated to further investigating the transport properties of Mo-based MXenes. This includes Mo2CTz, out-of-plane ordered Mo2TiC2Tz and Mo2Ti2C3Tz, and vacancy ordered Mo1.33CTz. Magneto-transport of free-standing thin films of the Mo-based MXenes were studied, showing that all Mo-based MXenes have two transport regimes: a VRH mechanism at lower temperatures and a thermally activated process at higher temperatures. All Mo-based MXenes except Mo1.33CTz show that the electrical transport is dominated by inter-flake transfer. As for Mo1.33CTz, the primary electrical transport mechanism is more likely to be intra-flake. The synthesis of vacancy ordered MXenes (Mo1.33CTz and W1.33CTz) raised the question of possible introduction of vacancies in all MXenes. Vacancy ordered MXenes are produced by selective etching of Al and (Sc or Y) atoms from the parent 3D MAX phases, such as (Mo2/3Sc1/3)2AlC, with in-plane chemical ordering of Mo and Sc. However, not all quaternary parent MAX phases form the in-plane chemical ordering of the two M metals; thus the synthesis of the vacancy-ordered MXenes is restricted to a very limited number of MAX phases. I present a new method to obtain MXene flakes with disordered vacancies that may be generalized to all quaternary MAX phases. As proof of concept, I chose Nb-C MXene, as this 2D material has shown promise in several applications, including energy storage, photothermal cell ablation and photocatalysts for hydrogen evolution. Starting from synthetizing (Nb2/3Sc1/3)2AlC quaternary solid solution and etching both the Sc and Al atoms resulted in Nb1.33C material with a large number of vacancies and vacancy clusters. This method may be applicable to other quaternary or higher MAX phases wherein one of the transition metals is more reactive than the other, and it could be of vital importance in applications such as catalysis and energy storage.

Download or read book Synthesis and Characterization of Hafnium Carbide Thin Films written by Wiriya Thongruang and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book SYNTHESIS AND CHARACTERIZATION OF TERNARY COMPOUND THIN FILMS written by Dr. Umeshkumar Prabhakarrao Khairnar and published by Laxmi Book Publication. This book was released on 2023-06-20 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt: The term “thin solid film” has been used in literature to imply a layer of a solid material. Further, there is neither any well-defined limit of its thickness to imply the end of the thin film stage nor one to indicate its transition to the thicker film region. All basic researches on thin films are generally confined to a limited range of thickness, say in the range from a few Å to about 5000 Å depending on the properties to be investigated. Whereas for technological applications where reliability of performance is the most important criterion the thickness limit at the lower range is generally higher than 1000 Å and can be as high as few microns. In order to cover this wide range of film thickness both for basic researches and applications, a “ thin film” may arbitrarily defined as a solid two dimensional layer having a thickness varying from a few Å to about 10 microns or even more. Since the thickness limitations are rather arbitrary even somewhat thicker films may also come within the scope of the above definition. Further subdivision of thickness is made under the categories 1) Ultra-thin 2) Thin (or very thin) and 3) Comparatively thicker ones.

Download or read book Synthesis and Characterization of Amorphous Carbide based Thin Films written by and published by . This book was released on 2015 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Characterization of Multifunctional Carbide and Boride based Thin Films written by and published by . This book was released on 2014 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Characterization of LPCVD Silicon Carbide Thin Films for X ray Lithography written by Mahalingam Bhaskaran and published by . This book was released on 1991 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Thin Films Preparation Characterization Applications written by Manuel P. Soriaga and published by Springer Science & Business Media. This book was released on 2002-09-30 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is about thin films; what they are, how they are prepared, how they are characterized, and what they are used for. The contents of this book not only showcase the diversity of thin films, but also reveals the commonality among the work performed in a variety of areas. The chapters in this volume are based on invited papers presented by prominent researchers in the field at a Symposium on "Thin Films: Preparation, Characterization, Applications" at the 221st National Meeting of the American Chemical Society held in San Diego, California. The coverage of the symposium was extensive; topics ranged from highly-ordered metal adlayers on well-defined electrode surfaces to bio-organic films on non-metallic nanoparticles. An objective of this book is for the readers to be able to draw from the experience and results of others in order to improve and expand the understanding of the science and technology of their own thin films systems.

Download or read book Thin Film Synthesis of New Nanolaminted Ternary Carbides written by and published by . This book was released on 2015 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Preparation and Characterization of Ternary Fe Ni Al Alloy Thin Films written by Shih Gan Kao and published by . This book was released on 1977 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Amorphous Silicon Carbide Thin Films written by Mariana Amorim Fraga and published by . This book was released on 2011 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: Silicon carbide (SiC) has been described as a suitable semiconductor material to use in MEMS and electronic devices for harsh environments. In recent years, many developments in SiC technology as bulk growth, materials processing, electronic devices and sensors have been shown. Moreover, some studies show the synthesis, characterization and processing of crystalline SiC films. However, few works have investigated the potential of amorphous silicon carbide (a-SiC) thin films for sensors applications. This book presents fundamentals of amorphous silicon carbide thin films and their applications in piezoresistive sensors for high temperature applications.

Download or read book MAX Phases written by Michel W. Barsoum and published by John Wiley & Sons. This book was released on 2013-11-13 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this comprehensive yet compact monograph, Michel W. Barsoum, one of the pioneers in the field and the leading figure in MAX phase research, summarizes and explains, from both an experimental and a theoretical viewpoint, all the features that are necessary to understand and apply these new materials. The book covers elastic, electrical, thermal, chemical and mechanical properties in different temperature regimes. By bringing together, in a unifi ed, self-contained manner, all the information on MAX phases hitherto only found scattered in the journal literature, this one-stop resource offers researchers and developers alike an insight into these fascinating materials.

Download or read book Transition Metal Carbides and Nitrides written by Louis Toth and published by Elsevier. This book was released on 2014-04-11 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Refractory Materials, Volume 7: Transition Metal Carbides and Nitrides discusses the developments in transition metal carbide and nitride research. This volume is organized into nine chapters that emphasize the mechanical and superconducting properties of these compounds. The introductory chapters deal with the general properties, preparation techniques, characterization, crystal chemistry, phase relationships, and thermodynamics of transition metal carbides and nitrides. The following chapter highlights the mechanical properties of these compounds, such as elastic and plastic deformation, fracture, strengthening mechanisms, and hardness. The discussion then shifts to specific electrical and magnetic properties, including electrical resistivity, Hall coefficient, and magnetic susceptibility. A separate chapter is devoted to carbides and nitrides as superconductors. The concluding chapters explore certain theories that explain the mechanisms of band structure and bonding in carbides and nitrides. This volume is of great value to research workers in metallurgy, ceramics, physics, chemistry, and related fields, as well as to advanced students investigating problems concerning high temperature materials or interstitial compounds.

Download or read book Synthesis and Characterization of Multiferroic Thin Films written by Sung Hwan Lim and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Characterization of RF PECVD Carbon Nitride Thin Films written by Shuang Fang Lim and published by . This book was released on 1999 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Characterization of Diamond like Carbon and DLC MoS2 Composite Thin Films written by Hamid Niakan and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: