Download or read book A Comparative Study of 3d intercalated Transition Metal Dichalcogenides by Magnetic Transport and Electronic Properties written by Deepak Sapkota (Researcher in physics) and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Intercalation of transition metal dichalcogendies (TMDCs) by 3d-transition metals has been studied systematically. We mainly focus on intercalation into two host TMDCs 2H-NbS2 and 2H-TaS2 which are layered materials where the metal ions are in trigonal prismatic environment of chalcogens, the layers are separated by weak van der Waals force. So, foreign atoms or molecules can be inserted in between the layers of the TMDCs. The un-intercalated NbS2 shows superconductivity below 6 K whereas TaS2 exhibits coexistence of the superconductivity (Tc̳=0.8 K) with charge density wave phase (TC̳D̳W̳=75 K). In this research, the NbS2 is intercalated by V atom with formula unit V0.3NbS2, while TaS2 by Cr with formula unit Cr1/3TaS2. Upon the intercalation, the electronic as well as magnetic structure of host materials are likely to be modified. It is believed that the charge transfer between the 3d-intercalant and host TMDC, specifically the d-band of Nb or Ta, just causes an increase in chemical potential without altering the band structure and shape and size of Fermi surface, also known as rigid band model. And, the local moment in magnetic ion gives rise to magnetism via RKKY interaction. In order to examine the effect of intercalation in V0.3NbS2 and Cr1/3TaS2, we investigated the magnetic, transport, and electronic properties. In V0.3NbS2, which crystallizes in P-31m space group, we observed canted antiferromag-netic (weak ferromagnetic) magnetic ordering with majority of charge carriers as hole type. From ARPES measurements, additional bands are appeared to cross the Fermi level and shape and size of the Fermi surface are modified as compared to NbS2. Also, V-3d states are present near the Fermi level. These findings demonstrate that the simple rigid band picture is not viable in V0.3NbS2 compound. Moreover, from the photon dependent ARPES measurements strong kz̳ dispersion is found in contrast to that of host NbS2. Similarly, intercalated Cr1/3TaS2 crystallizes in P6322 space group orders ferromagnetically. Surface structure is investigated by STM, LEED, and core level photoemmission experiments. The resonant photoemmission and ARPES measurements are performed to examine the effect of charge transfer between Cr and TaS2 layer.

Download or read book Magnetic Transport and Structural Properties of Intercalated Layer Compounds written by S. S. P. Parkin and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Electronic Structure and Magnetism of 3d Transition Metal Pnictides written by Kazuko Motizuki and published by Springer Science & Business Media. This book was released on 2009-12-08 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book on the magnetic properties of 3d-transition metal compounds focuses on 3d-metal pnictides. It couples experimental data with phenomenological discussions and explores how certain behaviors can be explained based on an itinerant electron picture.

Download or read book Two Dimensional Transition Metal Dichalcogenides written by Alexander V. Kolobov and published by Springer. This book was released on 2016-07-26 with total page 545 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book summarizes the current status of theoretical and experimental progress in 2 dimensional graphene-like monolayers and few-layers of transition metal dichalcogenides (TMDCs). Semiconducting monolayer TMDCs, due to the presence of a direct gap, significantly extend the potential of low-dimensional nanomaterials for applications in nanoelectronics and nano-optoelectronics as well as flexible nano-electronics with unprecedented possibilities to control the gap by external stimuli. Strong quantum confinement results in extremely high exciton binding energies which forms an interesting platform for both fundamental studies and device applications. Breaking of spatial inversion symmetry in monolayers results in strong spin-valley coupling potentially leading to their use in valleytronics. Starting with the basic chemistry of transition metals, the reader is introduced to the rich field of transition metal dichalcogenides. After a chapter on three dimensional crystals and a description of top-down and bottom-up fabrication methods of few-layer and single layer structures, the fascinating world of two-dimensional TMDCs structures is presented with their unique atomic, electronic, and magnetic properties. The book covers in detail particular features associated with decreased dimensionality such as stability and phase-transitions in monolayers, the appearance of a direct gap, large binding energy of 2D excitons and trions and their dynamics, Raman scattering associated with decreased dimensionality, extraordinarily strong light-matter interaction, layer-dependent photoluminescence properties, new physics associated with the destruction of the spatial inversion symmetry of the bulk phase, spin-orbit and spin-valley couplings. The book concludes with chapters on engineered heterostructures and device applications such as a monolayer MoS2 transistor. Considering the explosive interest in physics and applications of two-dimensional materials, this book is a valuable source of information for material scientists and engineers working in the field as well as for the graduate students majoring in materials science.

Download or read book Two Dimensional Transition Metal Dichalcogenides written by Narayanasamy Sabari Arul and published by Springer. This book was released on 2019-07-30 with total page 355 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents advanced synthesis techniques adopted to fabricate two-dimensional (2D) transition metal dichalcogenides (TMDs) materials with its enhanced properties towards their utilization in various applications such as, energy storage devices, photovoltaics, electrocatalysis, electronic devices, photocatalysts, sensing and biomedical applications. It provides detailed coverage on everything from the synthesis and properties to the applications and future prospects of research in 2D TMD nanomaterials.

Download or read book Magnetic and Electrical Properties of Various 3d Transition Metal and Rare Earth Chalcogenides written by Virginia Lea Miller and published by . This book was released on 2006 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Optical Properties Of Solids Proceedings Of The Taiwan japan Workshop On Solid state Optical Spectroscopy written by Hui Pak Ming and published by #N/A. This book was released on 1991-10-09 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: This proceedings volume contains review articles on solid-state spectroscopies by leading researchers in Japan and Taiwan. Topics include excitons and biexcitons, size effects in quantum dots and microcrystals, nonlinear optical properties, optical spectra of disordered systems, electronic and optical properties of metal-dielectric and semiconductor superlattices, photoemission, Raman spectroscopy, and photoreflectance studies on solids.

Download or read book Physics Briefs written by and published by . This book was released on 1989 with total page 1124 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book MODIFICATION OF TRANSITION METAL DICHALCOGENIDES OPTICAL ELECTRICAL AND MAGNETIC PROPERTIES THROUGH ALLOYING written by Mingzu Liu and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation focuses on two-dimensional (2D) transition metal dichalcogenides (TMDs), and studies the modification of their physical properties through the method of substitutional doping/alloying. The controlled synthesis and novel properties such as room-temperature ferromagnetism in doped/alloyed 2D TMD systems are investigated. Two notes are addressed here: 1) The general concept of TMDs contains a large family of binary compounds, while we are mainly concentrated on the semiconducting members (sTMDs) inside, including MoS2, WS2, MoSe2, and WSe2. 2) The term of alloying is applied here to denote the situation where impurity atoms are incorporated intentionally into the host 2D lattice, with a concentration greater than 1 at%, while conventionally, the term of doping is only adapted to describe similar cases but with significantly lower concentrations less than 1 at%, and even less than 1000 ppm = 0.1 at% in some literatures. However, a clear quantitative classification between the two concepts does not exist, and we will study cases with a wide range of impurity concentrations in this dissertation. Therefore, we will indiscriminately use both the terms of doping and alloying for convenience, regardless of the exact concentration/amount of impurity atoms. The main context of this dissertation is outlined as follows. In Chapter 1, we will introduce the fundamentals of 2D TMD materials and techniques for 2D surface characterizations. 2D magnetism is one of the most active fields in condensed matter physics, and will be a major topic of our research, thus a brief introduction in principles of magnetic materials will also be given. Controllable substitutional doping/alloying in monolayer 2D materials is a prerequisite to any further characterizations and applications. In Chapter 2, we will first introduce the liquid-phase precursor-assisted chemical vapor deposition (CVD) method we developed for universal substitutional doping with tunable dopant concentrations in sTMDs. Different dopant elements are successfully incoporated in sTMD monolayers, and the defect types and optical properties are studied. It is then discovered that the edge termination in single crystal sTMD monolayers will greatly affect the spatial distribution of dopant atoms, and this effect is elucidated through the synthesis of doped hexagonal sTMD monolayers that have as-grown domains with different dopant concentrations. Combined with the solution-based CVD method we developed, the edge termination can be utilized for engineering in-plane heterojunctions that display fascinating electronic, optoelectronic, and magnetic properties. Long-range ferromagnetic ordering has been considered as hard to achieve for a long time in 2D systems, especially at room temperature. In Chapter 3, we will demonstrate room-temperature ferromagnetism in vanadium-doped (V-doped) sTMD monolayers and its coupling with the thermal, optical, and electrical properties. The magnetization is dependent on both the dopant concentration and temperature, and an abnormal crossover in the hysteresis loop of monolayer V-WSe2 is described, which is attributed to a strong 2D thermally induced spin flip phenomenon. The ferromagnetism is induced by indirect exchange interactions between V moments, which are mediated by hole carriers. It is then revealed that optical excitations creating excess hole carriers can be used to control the magnetization. Finally, we attempt on applying the induced magnetization to break the degeneracy in the valley degrees of freedom through a circularly polarized photoluminescence (PL) experiment, and look into the effect of magnetization on the optical emissions. The 2D magnetic systems based on V-doped sTMD monolayers hold great promise for novel magneto-electronic or magneto-optical devices, as well as offering a platform for fundamental physical studies. Magnetic domain structure is an inherent phenomenon in finite-size ferromagnetic systems. In Chapter 4, we will discuss the direct visulization of magnetic domains in Vdoped sTMD monolayers. Magnetic force microscopy (MFM) is first used in the tentative observation of domain structures experimentally, and a mathematical model is proposed to estimate the signal level. Lorentz transmission electron microscopy (Lorentz-TEM) is then used, and the observation of an field-dependent reversible domain contrast is reported in monolayer V-WS2. The contrast signal is revealed to be highly affected by the sample magnetization orientation and charge doping, which are mainly determined by the dopant concentration, beam-sample interactions and the type of substrates. Atomic-resolution electron microscopy is finally performed to detect potential connections between lattice atomic motions and macroscopic magnetization. The observed contrast signals on V-doped sTMD provide primary knowledge in domain structures of 2D diluted magnetic systems, and is the first reported imaging of a monolayer magnetic material through Lorentz-TEM. Finally, Chapter 5 summarizes the studies discussed in this dissertation, and provides outlooks to potential continuing future works.

Download or read book Intercalated Layered Materials written by F.A. Lévy and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 580 pages. Available in PDF, EPUB and Kindle. Book excerpt: Materials with layered structures remain an extensively investigated subject in current physics and chemistry. Most of the promising technological applications however deal with intercalation compounds of layered materials. Graphite intercalation compounds have now been known for a long time. Intercalation in transition metal dichalcogenides, on the other hand, has been investigated only recently. The amount of information on intercalated layered materials has increased far beyond the original concept for this volume in the series Physics and Chemistry of Materials with Layered Structures. The large size of this volume also indicates how important this field of research will be, not only in basic science, but also in industrial and energy applications. In this volume, two classes of materials are included, generally investigated by different scientists. Graphite intercalates and intercalates of other inorganic com pounds actually constitute separate classes of materials. However, the similarity between the intercalation techniques and some intercalation processes does not justify this separation, and accounts for the inclusion of both classes in this volume. The first part of the volume deals with intercalation processes and intercalates of transition metal dichalcogenides. Several chapters include connected topics necessary to give a good introduction or comprehensive review of these types of materials. Organic as well as inorganic intercalation compounds are treated. The second part includes contributions concerning graphite intercalates. It should be noted that graphite intercalation compounds have already been mentioned in Volumes I and V.

Download or read book Metals Abstracts written by and published by . This book was released on 1983 with total page 1058 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book 2D Materials written by Phaedon Avouris and published by Cambridge University Press. This book was released on 2017-06-29 with total page 521 pages. Available in PDF, EPUB and Kindle. Book excerpt: Learn about the most recent advances in 2D materials with this comprehensive and accessible text. Providing all the necessary materials science and physics background, leading experts discuss the fundamental properties of a wide range of 2D materials, and their potential applications in electronic, optoelectronic and photonic devices. Several important classes of materials are covered, from more established ones such as graphene, hexagonal boron nitride, and transition metal dichalcogenides, to new and emerging materials such as black phosphorus, silicene, and germanene. Readers will gain an in-depth understanding of the electronic structure and optical, thermal, mechanical, vibrational, spin and plasmonic properties of each material, as well as the different techniques that can be used for their synthesis. Presenting a unified perspective on 2D materials, this is an excellent resource for graduate students, researchers and practitioners working in nanotechnology, nanoelectronics, nanophotonics, condensed matter physics, and chemistry.

Download or read book British Technology Index written by and published by . This book was released on 1981 with total page 954 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Solid State Properties written by Mildred Dresselhaus and published by Springer. This book was released on 2018-01-17 with total page 521 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book fills a gap between many of the basic solid state physics and materials sciencebooks that are currently available. It is written for a mixed audience of electricalengineering and applied physics students who have some knowledge of elementaryundergraduate quantum mechanics and statistical mechanics. This book, based on asuccessful course taught at MIT, is divided pedagogically into three parts: (I) ElectronicStructure, (II) Transport Properties, and (III) Optical Properties. Each topic is explainedin the context of bulk materials and then extended to low-dimensional materials whereapplicable. Problem sets review the content of each chapter to help students to understandthe material described in each of the chapters more deeply and to prepare them to masterthe next chapters.

Download or read book 2D Metal Carbides and Nitrides MXenes written by Babak Anasori and published by Springer Nature. This book was released on 2019-10-30 with total page 534 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the rapidly expanding field of two-dimensional (2D) transition metal carbides and nitrides (MXenes). It covers fundamental knowledge on synthesis, structure, and properties of these new materials, and a description of their processing, scale-up and emerging applications. The ways in which the quickly expanding family of MXenes can outperform other novel nanomaterials in a variety of applications, spanning from energy storage and conversion to electronics; from water science to transportation; and in defense and medical applications, are discussed in detail.

Download or read book Crystallography and Crystal Chemistry of Materials with Layered Structures written by F.A. Lévy and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last ten years, the chemistry and physics of materials with layered structures became an intensively investigated field in the study of the solid state. Research into physical properties of these crystals and especially investigations of their physical anisotropy related to the structural anisotropy has led to remarkable and perplexing results. Most of the layered materials exist in several polytypic modifications and can include stacking faults. The crystal structures are therefore complex and it became apparent that there was a great need for a review of the crystallographic data of materials approximating two-dimensional solids. This second volume in the series 'Physics and Chemistry of Materials with Layered Structures' has been written by specialists of different classes of layered materials. Structural data are reviewed and the most important relations between the structure and the chemical and physical properties are emphasized. The first three contributions are devoted to the transition metal dichalcogenides whose physical properties have been investigated in detail. The crystallographic data and crystal growth conditions are presented in the first paper. The second paper constitutes an incisive review of the phase transformations and charge density waves which have been observed in the metallic dichalcogenides. In two contributions the layered structures of newer ternary compounds are de scribed and the connection between structure and non-stoichiometry is discussed.