Download or read book Materials and Magnetic Studies of Cobalt doped Anatase Titanium Dioxide and Perovskite Strontium Titanate as Potential Dilute Magnetic Semiconductors written by Tiffany C. Kaspar and published by . This book was released on 2004 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book APS Science written by Advanced Photon Source (Research facility) and published by . This book was released on 2004 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Study of Titanium Dioxide Based Dilute Magnetic Semiconductors written by Bakhtyar Ali and published by ProQuest. This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Dilute magnetic semiconductors (DMSs) with high Curie temperature are highly desirable in spintronics applications. Transition metal doped oxides such as cobalt (Co), chromium (Cr), copper (Cu) doped TiO 2, ZnO, and SnO 2 are being studied for the last few years. Among other DMSs Co x Ti (1-x) O 2 anatase and rutile has been observed to have high T c (~400K). It is transparent in the visible and near infrared regions with a sizable band gap and appreciable conductivity. Therefore, it is believed to be very useful candidate for the fabrication of magnetic semiconductor devices. It has been shown that the achievement of magnetic percolation effect in DMSs is strongly linked to the nature of dopant and synthesis procedure which eventually leads to defects in the material. In this thesis we report the study of Co doped TiO 2 thin films and Cu:Co codoped TiO 2 nanopowders. Thin films of Co doped TiO 2 on silicon and quartz substrates are synthesized by pulsed laser deposition (PLD). Various oxygen partial pressures (P O2), ranging from 6.6 mPa to 53 Pa, are used to vary the oxygen content in the samples. Crystal structure and transport/ magnetic properties of Co x Ti 1-x O 2 (0.01 = x= 0.06) thin films are found to have a strong dependence on oxygen stoichiometry. X-ray diffraction (XRD) data reveal the presence of mixed phase material containing both anatase and rutile. However, the stability of each phase depends on the P O2 present in the chamber during the growth of the films. X-ray Photoelectron Spectroscopy (XPS) shows that Co is substituted in TiO 2 and is in the 2+ oxidation state. There is an enhancement in electrical conductivity and magnetization resulting from off stoichiometric (deficient) oxygen. The resistivity data fit well with the simple thermal activation model, giving activation energy values of 20 to 140 meV. In the second part we have studied the role of Cu codoping and oxygen vacancies in enhancing/stabilizing room temperature ferromagnetic interactions in Co doped TiO 2 nanopowder (cobalt being 5%, well bellow the cation percolation limit for TiO 2). Analyses of the XRD, TEM and XPS data reveal the cobalt incorporation into the lattice structure with no sign of phase segregations. The as-prepared paramagnetic Co-TiO 2 powder is rendered ferromagnetic by controlling the point defects (oxygen vacancies) in the sample. Interestingly, Cu codoping enhances the magnetization by an order of magnitude in the reduced Co doped TiO 2 . We believe that impurity band exchange mechanism is a plausible model in our Co-TiO 2 sample. The implication of the effect of Cu doping in Co doped sample is also discussed. We have also shown that the enhancement of ferromagnetism with additional doping in Co doped TiO 2 is a reversible effect.
Download or read book Growth and Ferromagnetic Semiconducting Properties of Titanium Dioxide Thin Films written by Byoung-Seong Jeong and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: However, chemical analysis of surface structure indicates that the cobalt segregates into a Co-enriched particles on the surface of films. From SADPs, we confirm that the nanoclusters observed on the surface of the Co0.07Ti0.93O2 are Co-enriched anatase. From the resistivity measurement as a function of magnetic field, the ordinary Hall effect is dominant in the undoped and Co0.02Ti0.98O2-delta thin films. For each film, the magnetoresistance was positive and increase monotonically with increasing magnetic field. The anomalous Hall effect contribution is observed for the Co0.10Ti0.90O2-delta films grown under lower water vapor pressure due to more oxygen deficiency.
Download or read book First principles Investigations of Electronic Structures of Pristine and Doped Anatase Titanium Dioxide written by Yushan Wang and published by . This book was released on 2007 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chapters 4 through 6 are mainly concerned with insights into the mechanism of optical excitation in anatase TiO2. Chapters 7 and 8 are concerned with TiO2-based dilute magnetic semiconductors (DMS).
Download or read book Synthesis and Characterisation of M doped Titanium Dioxide for the Potential Application in Electrochemical Devices written by Laura R. Sayers and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The chemistry of systems intended to produce metal-doped, nanostructured oxide materials containing titaniumffV) has been investigated. Manganese and iron were chosen as cheap, sustainable metal atom dopants with a view to possible use of product materials in electrochemical devices. In particular, the aim was to enhance electronic conductivity and to introduce psudocapacitance for investigation in supercapacitor devices. Previous literature in this area was found to be misleading; products of earlier synthetic studies have been incompletely characterised, with solid products being assumed to be single crystalline phases and metal atom contents being assumed on the basis of hypothetical doping levels rather than being determined analytically. Electrochemical properties of product materials in electrode films were determined in this study via use of EIS, CV and galvanostatic charge- discharge techniques. Conventional sol-gel and micro-emulsion synthetic methods were undertaken with the view to control of product particle sizes and yields for single phase, Mn-doped titaniumfl V) oxide (ideally within the anatase structure). Other than for the pure binary oxides of manganese or titanium, the products obtained were mixtures of oxides rather than single phases, with titaniumfl V) in the rutile polymorph within the I mixed-phase products. "Doped" product materials produced by the emulsion method showed no improvements in conductivity or specific capacitance when compared with a standard anatase (undoped) sample. The mixed-oxide materials produced by the sol-gel method, containing Mn02, had enhanced conductivities but no improvement in specific capacitance. Single-phase, anatase structured, Mn-doped titanium dioxide materials, were prepared using the continuous hydrothermal synthesis (CHS) method. The maximum amount of Mn successfully incorporated into the .anatase structure was found to be approximately 8%wt, as determined by AAS, ICP-MS and SEM-EDX analytical methods; high Mu-content resulted in phase segregation and irreversibility within cyclic voltammograms, as evident in observation of an oxidation peak but no reduction peak. The highest recorded specific capacitance value for these samples was that for the CHSMn008 sample (theoretical composition Tio.92Mno.os02), with a value of 4.5 F g'l (oxide specific surface area, 34.8 m2 g·l). This compared to a similarly prepared anatase (undoped) material with a specific surface area of 48.6 m2 g'l and a specific capacitance of 2.5 F g·l. No correlation between specific surface areas and specific capacitance values was observed, but the BET-determined ·specific surface areas were for powdered samples whereas capacitances refer to composite electrode films. Chapter 1 Introduction • ", The initial eHS product materials displayed no improvement in conductivity, but p H-adjusted synthesis led to samples (denoted CHS MnKOH) with higher conductivities consequent on higher Mn contents, and these samples also had the highest specific capacitance values. In view of the success of the eHS method in producing Mn-doped anatase materials, it was also used to synthesise Fe-doped titaniumffV) oxides. The products were a range of single phase materials, but syntheses aimed at high Fecontents led to mixtures, Ti02 + Fe oxides + Fe2Ti05; the maximum amount of Fe incorporated whilst still maintaining a pure single phase product was approximately 7%wt. The conductivity of these materials showed marked improvement relative to the standard (undoped) anatase sample, comparable to those for eHS MnKOH samples, but the Mn-doped samples had higher specific capacitances than Fe-doped counterparts . . The highest specific capacitance values recorded were between 25 and 32 F g'l, regardless of dopant (MnlFe) and/or phase purity, and were associated with a high specific surface area or a high concentration of "dopant" within the sample. 1.
Download or read book Functional Metal Oxides written by Satishchandra Balkrishna Ogale and published by John Wiley & Sons. This book was released on 2013-11-08 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt: Functional oxides are used both as insulators and metallic conductors in key applications across all industrial sectors. This makes them attractive candidates in modern technology ? they make solar cells cheaper, computers more efficient and medical instrumentation more sensitive. Based on recent research, experts in the field describe novel materials, their properties and applications for energy systems, semiconductors, electronics, catalysts and thin films. This monograph is divided into 6 parts which allows the reader to find their topic of interest quickly and efficiently. * Magnetic Oxides * Dopants, Defects and Ferromagnetism in Metal Oxides * Ferroelectrics * Multiferroics * Interfaces and Magnetism * Devices and Applications This book is a valuable asset to materials scientists, solid state chemists, solid state physicists, as well as engineers in the electric and automotive industries.
Download or read book Metalorganic Chemical Vapor Deposition of Titanium Dioxide and Strontium Titanate for Microelectronics Applications written by Kanchana Vydianathan and published by . This book was released on 1998 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rare Earth and Transition Metal Doping of Semiconductor Materials written by Volkmar Dierolf and published by Woodhead Publishing. This book was released on 2016-02-23 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rare Earth and Transition Metal Doping of Semiconductor Material explores traditional semiconductor devices that are based on control of the electron's electric charge. This book looks at the semiconductor materials used for spintronics applications, in particular focusing on wide band-gap semiconductors doped with transition metals and rare earths. These materials are of particular commercial interest because their spin can be controlled at room temperature, a clear opposition to the most previous research on Gallium Arsenide, which allowed for control of spins at supercold temperatures. Part One of the book explains the theory of magnetism in semiconductors, while Part Two covers the growth of semiconductors for spintronics. Finally, Part Three looks at the characterization and properties of semiconductors for spintronics, with Part Four exploring the devices and the future direction of spintronics.
Download or read book Modulating Dopant defect Interactions in Transition Metal Doped Colloidal Strontium Titanate Nanocrystals written by William Harrigan and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Perovskites such as strontium titanate, a wide band gap semiconductor have been widely studied due to the multitude of potential applications in photocatalysis, multiferroics, sensing, and microelectronics. Various novel optical, electrical and magnetic properties can be imparted through the introduction of different transition metal dopant ions. The introduction of these impurities has been shown to impart functionality for various applications. The use of Cr3+ has been shown to introduce defect levels into the band structure of SrTiO3 and increase visible light utilization for photocatalysis. Transition metal doped highly crystalline colloidal SrTiO3 nanocrystals (NC) were synthesized using two modified hydrothermal (HT) synthesis methods and subsequently characterized. Structural characterization techniques such as powder X-ray diffraction (XRD), tunneling electron microscopy (TEM) and high-resolution tunneling electron microscopy (HR-TEM) proved vital in confirming the successful synthesis of highly crystalline sub-10 nm nanocubes. The use of transition metal doped colloidal nanocrystals will look to better understand dopant incorporation and subsequent defect formation and their interactions on the nm scale. The use of dopant specific spectroscopies such as electron paramagnetic resonance (EPR) spectroscopy was crucial in determining both the transition metal dopant oxidation state and dopant position in the colloidal NCs. Through the use of EPR spectroscopy the dopants and defects were unambiguously identified and characterized. Various surface related oxygen defects were identified and correlated to emerge under specific synthetic conditions. Site-selective internal doping of Cr or Mn was achieved through either modified HT methods. The extent of the dopant-defect interactions was studied using a photodoping technique. Under anaerobic conditions and in the presence of a hole quencher, the interactions of the photoinduced electron with SrTiO3 were monitored. The photoinduced changes were tracked using electronic absorption spectroscopy and EPR spectroscopy. An in-depth EPR analysis showed the photoinduced electron localizes on titanium atoms and undergoes cross relaxation with neighboring Cr ions.
Download or read book Hierarchical Nanostructures for Energy Devices written by Seung H Ko and published by Royal Society of Chemistry. This book was released on 2014-10-29 with total page 323 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface area has a directly relationship with the efficiency of energy devices. Hierarchical nanostructuring has the potential to greatly increase surface area, and their electrical properties are favourable, not only to energy generation and storage, but also energy-consuming electronic circuits. This book provides systematic coverage of how nanostructured materials can be applied to energy devices, with an emphasis on the process of generation to storage and consumption. The fundamentals (including properties, characterisation and synthesis) are clearly presented across the first chapters of the book, providing readers new to the field with a clear overview of this expanding topic. The detailed discussion of applications will be an inspiration to those already well-versed in the field. The editors have more than a decade of experience in working on all aspects of energy generation and storage - in academia, national laboratories and industry. The book presents a balanced view from all sectors and is presented in a format accessible by postgraduate students and professional researchers alike.
Download or read book The Defect Chemistry of Metal Oxides written by Donald Morgan Smyth and published by Oxford University Press on Demand. This book was released on 2000 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Defect Chemistry of Metal Oxides is a unique introduction to the equilibrium chemistry of solid inorganic compounds with a focus on metal oxides. Accessible to students with little or no background in defect chemistry, it explains how to apply basic principles and interpret the related behavior of materials. Topics discussed include lattice and electronic defects, doping effects, nonstoichiometry, and mass and charge transport. The text distinctly emphasizes the correlation between the general chemical properties of the constituent elements and the defect chemistry and transport properties of their compounds. It covers the types of defects formed, the effects of dopants, the amount and direction of nonstoichiometry, the depths of acceptor and donor levels, and more. Concluding chapters present up-to-date and detailed analyses of three systems: titanium dioxide, cobalt oxide and nickel oxide, and barium titanate. The Defect Chemistry of Metal Oxides is the only book of its kind that incorporates sample problems for students to solve. Suitable for a variety of courses in materials science and engineering, chemistry, and geochemistry, it also serves as a valuable reference for researchers and instructors.
Download or read book Perovskite Photovoltaics written by Aparna Thankappan and published by Academic Press. This book was released on 2018-06-29 with total page 521 pages. Available in PDF, EPUB and Kindle. Book excerpt: Perovskite Photovoltaics: Basic to Advanced Concepts and Implementation examines the emergence of perovskite photovoltaics, associated challenges and opportunities, and how to achieve broader development. Consolidating developments in perovskite photovoltaics, including recent progress solar cells, this text also highlights advances and the research necessary for sustaining energy. Addressing different photovoltaics fields with tailored content for what makes perovskite solar cells suitable, and including commercialization examples of large-scale perovskite solar technology. The book also contains a detailed analysis of the implementation and economic viability of perovskite solar cells, highlighting what photovoltaic devices need to be generated by low cost, non-toxic, earth abundant materials using environmentally scalable processes. This book is a valuable resource engineers, scientists and researchers, and all those who wish to broaden their knowledge on flexible perovskite solar cells. - Includes contributions by leading solar cell academics, industrialists, researchers and institutions across the globe - Addresses different photovoltaics fields with tailored content for what makes perovskite solar cells different - Provides commercialization examples of large-scale perovskite solar technology, giving users detailed analysis on the implementation, technical challenges and economic viability of perovskite solar cells
Download or read book Spectroscopy of Complex Oxide Interfaces written by Claudia Cancellieri and published by Springer. This book was released on 2018-04-09 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book summarizes the most recent and compelling experimental results for complex oxide interfaces. The results of this book were obtained with the cutting-edge photoemission technique at highest energy resolution. Due to their fascinating properties for new-generation electronic devices and the challenge of investigating buried regions, the book chiefly focuses on complex oxide interfaces. The crucial feature of exploring buried interfaces is the use of soft X-ray angle-resolved photoemission spectroscopy (ARPES) operating on the energy range of a few hundred eV to increase the photoelectron mean free path, enabling the photons to penetrate through the top layers – in contrast to conventional ultraviolet (UV)-ARPES techniques. The results presented here, achieved by different research groups around the world, are summarized in a clearly structured way and discussed in comparison with other photoemission spectroscopy techniques and other oxide materials. They are complemented and supported by the most recent theoretical calculations as well as results of complementary experimental techniques including electron transport and inelastic resonant X-ray scattering.
Download or read book Microwave Absorbing Materials written by Yuping Duan and published by CRC Press. This book was released on 2016-10-14 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the phenomenal development of electromagnetic wave communication devices and stealth technology, electromagnetic wave absorbing materials have been attracting attention as antielectromagnetic interference slabs, stealth materials, self-concealing technology, and microwave darkrooms. This book starts with the fundamental theory of electromagnetic wave absorption in loss medium space, followed by a discussion of different microwave absorbents, such as manganese dioxide, iron-based composite powder, conductive polyaniline, barium titanate powder, and manganese nitride. Then, structural absorbing materials are explored, including multilayer materials, new discrete absorbers, microwave absorption coatings, cement-based materials, and structural pyramid materials. Many of the graphics demonstrate not only the principles of physics and experimental results but also the methodology of computing. The book will be useful for graduate students of materials science and engineering, physics, chemistry, and electrical and electronic engineering; researchers in the fields of electromagnetic functional materials and nanoscience; and engineers in the fields of electromagnetic compatibility and stealth design.
Download or read book Physics and Engineering of New Materials written by Do Tran Cat and published by Springer Science & Business Media. This book was released on 2009-01-01 with total page 387 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the majority of the contributions to the Tenth German-Vietnamese Seminar on Physics and Engineering (GVS10) that took place in the Gustav- Stresemann-Institut (GSI) in Bonn from June 6 to June 9, 2007. In the focus of these studies are the preparation and basic properties of new material systems, related investigation methods, and practical applications. Accordingly the sections in this book are entitled electrons: transport and confinement, low-dimensional systems, magnetism, oxidic materials, organic films, new materials, and methods. The series of German-Vietnamese seminars was initiated and sponsored by the Gottlieb Daimler- and Karl Benz -Foundation since 1998 and took place alt- nately in both countries. These bilateral meetings brought together top-notch senior and junior Vietnamese scientists with German Scientists and stimulated many contacts and co-operations. Under the general title “Physics and Engine- ing” the programs covered, in the form of keynote-lectures, oral presentations and posters, experimental and theoretical cutting-edge material-physics oriented topics. The majority of the contributions was dealing with modern topics of material science, particularly nanoscience, which is a research field of high importance also in Vietnam. Modern material science allows a quick transfer of research results to technical applications, which is very useful for fast developing countries like Vietnam. On the other hand, the seminars took profit from the strong cro- fertilization of the different disciplines of physics. This book is dedicated to the tenth anniversary of the seminars and nicely shows the scientific progress in Vietnam and the competitive level reached.
Download or read book Nanoscale Materials written by Luis M. Liz-Marzán and published by Springer Science & Business Media. This book was released on 2007-05-08 with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organized nanoassemblies of inorganic nanoparticles and organic molecules are building blocks of nanodevices, whether they are designed to perform molecular level computing, sense the environment or improve the catalytic properties of a material. The key to creation of these hybrid nanostructures lies in understanding the chemistry at a fundamental level. This book serves as a reference book for researchers by providing fundamental understanding of many nanoscopic materials.
