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Effect Of Oxide Additions On The Microstructure And Dielectric Properties Of Barium Titanate
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Book Synopsis Effect of Oxide Additions on the Microstructure and Dielectric Properties of Barium Titanate by : Karl E. Nelson
Download or read book Effect of Oxide Additions on the Microstructure and Dielectric Properties of Barium Titanate written by Karl E. Nelson and published by . This book was released on 1957 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Effect of Minor Phase Additions on the Microstructure and Dielectric Properties of Barium Titanate Ceramics by : Timothy Robert Armstrong
Download or read book Effect of Minor Phase Additions on the Microstructure and Dielectric Properties of Barium Titanate Ceramics written by Timothy Robert Armstrong and published by . This book was released on 1989 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: Grain growth in BaTiO$\sb3$ can be significantly inhibited by insoluble or slightly soluble second phase additions such as ZrO$\sb2$, or by fluxes in the CaO$\cdot$Al$\sb2$O$\sb3\cdot$B$\sb2$O$\sb3$ system. SEM and TEM observations revealed enhanced microstructural uniformity in these specimens. For the ZrO$\sb2$ modified BaTiO$\sb3$ system, Zr diffused into the BaTiO$\sb3$ lattice when sintered above 1320$\sp\circ$C, resulting in a chemical modification of the tetragonal structure and the development of core-shell grains. TEM analysis of ZrO$\sb2$ modified BaTiO$\sb3$ sintered at temperatures less than 1320$\sp\circ$C, revealed the presence of ZrO$\sb2$ at the grain boundaries as discrete particles ($\approx$0.03 $\mu$m). Modification of BaTiO$\sb3$ with organically derived ZrO$\sb2$ resulted in the formation of substantial chemical inhomogeneities in the microstructure. These inhomogeneities were observed by TEM as large ZrO$\sb2$ particles ($>$75nm) and as a Ti and Zr rich phase, Ba$\sb2$(ZrTi)$\sb5$O$\sb{12}$. In the CaO$\cdot$Al$\sb2$O$\sb3\cdot$B$\sb2$O$\sb3$ modified BaTiO$\sb3$, fluxed samples had an amorphous grain boundary phase, which became microcrystalline upon addition of ZrO$\sb2$. For these samples core-shell grains were observed in specimens sintered at 1175$\sp\circ$C for 2h. More noticeable in the samples were regions near the grain boundaries where significant diffusion of the flux constituents into the BaTiO$\sb3$ occurred, resulting in the formation of a fine domain structure. These fine-grained samples were accompanied by an increase in the internal stress level with decreasing grain size and increasing concentration of core-shell grains. The core-shell grains are comprised of a core of unmodified BaTiO$\sb3$ and a shell of Zr modified BaTiO$\sb3$, Ba(Zr$\sb{\rm x}$Ti$\sb{\rm 1-x}$)O$\sb3$. This condition leads to high internal stress levels, arising from the thermal expansion mismatch between the core and the shell. The stress was found to be compressive in nature and dependent on temperature, time and grain size. The combination of internal stress and core-shell grains resulted in a decrease in the axial ratio $(c/a)$ with decreasing grain size and an essentially flat permittivity response with temperature, a condition consistent with a distribution of Curie points within the ceramic. These modified dielectrics also show a decrease in the aging rate with increasing temperature, resulting from the internal stress condition.
Book Synopsis The Effects of Oxide Additions on the Dielectric Constant of BaTiO3 by : James William Congdon
Download or read book The Effects of Oxide Additions on the Dielectric Constant of BaTiO3 written by James William Congdon and published by . This book was released on 1973 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Structure and Dielectric Properties of Pure and Zinc Oxide-Doped Barium Titanate by : M. Hasan
Download or read book Structure and Dielectric Properties of Pure and Zinc Oxide-Doped Barium Titanate written by M. Hasan and published by . This book was released on 2013 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of zinc oxide addition and sintering parameters on the structure and dielectric properties of barium titanate are observed. Different percentage of ZnO ranging from 0.30 to 1 wt. % is doped in barium titanate. Both the doped and undoped samples are sintered at temperatures ranging from 1250°C to 1325°C at different soaking times. The amount of densification of the doped and undoped samples is measured in terms of percentage theoretical density. Grain size and microstructural analysis is performed by a scanning electron microscope (SEM). Lattice parameters and tetragonality of doped and undoped barium titanate are calculated from x-ray diffraction pattern obtained from x-ray diffractometer (XRD) test. Dielectric properties of the samples are measured by an impedance analyzer. It is found that all the doped samples obtain their maximum percentage theoretical density at a lower sintering temperature compared to the undoped sample. SEM study reveals that the doped samples always show smaller grains compared to the undoped sample. Significant grain growth is observed in all of the samples at sintering temperatures above 1300°C. The evidence of surface melting is observed in 1 wt. % ZnO-doped sample soaked at 1325°C for 2 h. The presence of liquid at that sintering condition is explained by the doping mechanism of Zn2+ in BaTiO3. Correlation among the grain size, tetragonality, and dielectric properties of the doped and undoped samples are also discussed.
Book Synopsis Ceramic Materials Research by : R. Brook
Download or read book Ceramic Materials Research written by R. Brook and published by Elsevier. This book was released on 1989-05-01 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt: The high expectations set on ceramic materials in recent years have always been balanced by the very considerable difficulties seen in reaching the required levels of reproducibility and cost. Indications of the significant progress, which can be seen in the papers presented in this volume, coupled with the recognition that considerable problems still lie between the state of the art and the full and confident exploitation of the many merits of ceramics, provide a healthy basis for the profitable selection of future research directions. The mastery of ceramic processing and the imaginative matching of the properties of these materials to diverse applications remain among the most promising sectors for technological development.
Book Synopsis Dielectric Materials for Wireless Communication by : Mailadil T. Sebastian
Download or read book Dielectric Materials for Wireless Communication written by Mailadil T. Sebastian and published by Elsevier. This book was released on 2010-07-07 with total page 689 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microwave dielectric materials play a key role in our global society with a wide range of applications, from terrestrial and satellite communication including software radio, GPS, and DBS TV to environmental monitoring via satellite. A small ceramic component made from a dielectric material is fundamental to the operation of filters and oscillators in several microwave systems. In microwave communications, dielectric resonator filters are used to discriminate between wanted and unwanted signal frequencies in the transmitted and received signal. When the wanted frequency is extracted and detected, it is necessary to maintain a strong signal. For clarity it is also critical that the wanted signal frequencies are not affected by seasonal temperature changes. In order to meet the specifications of current and future systems, improved or new microwave components based on dedicated dielectric materials and new designs are required. The recent progress in microwave telecommunication, satellite broadcasting and intelligent transport systems (ITS) has resulted in an increased demand for Dielectric Resonators (DRs). With the recent revolution in mobile phone and satellite communication systems using microwaves as the propagation media, the research and development in the field of device miniaturization has been a major challenge in contemporary Materials Science. In a mobile phone communication, the message is sent from a phone to the nearest base station, and then on via a series of base stations to the other phone. At the heart of each base station is the combiner/filter unit which has the job of receiving the messages, keeping them separate, amplifying the signals and sending then onto the next base station. For such a microwave circuit to work, part of it needs to resonate at the specific working frequency. The frequency determining component (resonator) used in such a high frequency device must satisfy certain criteria. The three important characteristics required for a dielectric resonator are (a) a high dielectric constant which facilitates miniaturization (b) a high quality factor (Qxf) which improves the signal-to-noise ratio, (c) a low temperature coefficient of the resonant frequency which determines the stability of the transmitted frequency. During the past 25 years scientists the world over have developed a large number of new materials (about 3000) or improved the properties of known materials. About 5000 papers have been published and more than 1000 patents filed in the area of dielectric resonators and related technologies. This book brings the data and science of these several useful materials together, which will be of immense benefit to researchers and engineers the world over. The topics covered in the book includes factors affecting the dielectric properties, measurement of dielectric properties, important low loss dielectric material systems such as perovskites, tungsten bronze type materials, materials in BaO-TiO2 system, (Zr,Sn)TiO4, alumina, rutile, AnBn-1O3n type materials, LTCC, ceramic-polymer composites etc. The book also has a data table listing all reported low loss dielectric materials with properties and references arranged in the order of increasing dielectric constant. Collects together in one source data on all new materials used in wireless communication Includes tabulated properties of all reported low loss dielectric materials In-depth treatment of dielectric resonator materials
Book Synopsis The Effect of Neodymium Oxide on the Dielectric Properties of a Barium Titanate Ceramic by : John A. Bonneville
Download or read book The Effect of Neodymium Oxide on the Dielectric Properties of a Barium Titanate Ceramic written by John A. Bonneville and published by . This book was released on 1977 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Influence of Microstructure on the Dielectric Properties of Barium Titanate by : A. K. Kulkarni
Download or read book Influence of Microstructure on the Dielectric Properties of Barium Titanate written by A. K. Kulkarni and published by . This book was released on 1968 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Metal Oxide Varistors by : Jinliang He
Download or read book Metal Oxide Varistors written by Jinliang He and published by John Wiley & Sons. This book was released on 2019-02-08 with total page 613 pages. Available in PDF, EPUB and Kindle. Book excerpt: Completely up-to-date, this is the first comprehensive monograph on metal oxide varistors with a focus on microstructure, conduction mechanisms, device failures, ageing, additive impacts and future varistor systems. As such, it covers the fundamentals and applications of metal oxide varistors, including their macro-characteristics, microstructural properties and the device-internal physical and electrical mechanisms. The author reflects on the achievements made in varistor research and propose new approaches to analyze and predict the macro-characteristics, employing such methods as micro-contact measurements and numerical simulations. In addition, he looks at future directions for varistor research, such as ZnO varistors with a high voltage gradient and low residual voltage and further varistor types based on TiO2 and SnO2.
Book Synopsis Ferroelectric Materials and Ferroelectricity by : T. F. Connolly
Download or read book Ferroelectric Materials and Ferroelectricity written by T. F. Connolly and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 692 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is a joint effort of the Research Materials Information Center (RMIC) of the Solid State Division at Oak Ridge National Laboratory and the Libraries and Information Systems Center at Bell Telephone Laboratories (BTL) Murray Hill, N. J. The Research Materials Information Center has, since 1963, been answering inquiries on the avail ability, preparation, and properties of inorganic solid-state research materials. The preparation of bibliographies has been essential to this function, and the interest in ferroelectrics led to the compila tion of the journal and report literature on that subject. The 1962 book Ferroelectric Crystals, by Jona and Shirane, was taken as a cutoff point, and all papers through mid-1969 received by the Center have been included. The Libraries and Information Systems Center of BTL has, over a period of years, developed a proprie tary package of computer programs called BELDEX, which formats and generates indexes to biblio graphic material. This group therefore undertook to process RMIC's ferroelectric references by BELDEX so that both laboratories could have the benefit of an indexed basic bibliography in this important research area.
Book Synopsis The Effect of the Microstructure on the Electrical Properties of Polycrystalline Barium Titanate Ceramics by : Stephen Wallace Derbyshire
Download or read book The Effect of the Microstructure on the Electrical Properties of Polycrystalline Barium Titanate Ceramics written by Stephen Wallace Derbyshire and published by . This book was released on 1965 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Chemical Control of the Polymorphic Phase Boundaries in Doped Barium Titanate by : Sarah Ann Turp
Download or read book Chemical Control of the Polymorphic Phase Boundaries in Doped Barium Titanate written by Sarah Ann Turp and published by . This book was released on 2013 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: Barium titanate (BaTiO3), a known ferroelectric material, is of great interest as a future lead-free piezoelectric if appropriately doped to tailor the electric properties for specific applications. This work focuses on the study and rationalisation of the dielectric properties of a series of A-site/B-site co-doped compositions: SrZrO3-BaTiO3, CaZrO3-BaTiO3, LaScO3-BaTiO3 and GdScO3-BaTiO3. The effect of sintering conditions and microstructure on ceramics is shown to have a significant impact on the physical properties of these materials. Pellet inhomogeneity, air sensitivity in pre-calcined powders and the presence of parasitic grain boundary capacitances are all shown to have adverse effects on properties, including the magnitudes of relative permittivity and TC calculated from total capacitance data. These can be overcome by careful control of synthesis conditions. Dielectric spectroscopy measurements on the optimised materials show that increasing addition of SrZrO3, CaZrO3 or LaScO3 causes the phase transitions between the various polymorphs of BaTiO3 to coalesce. In each case TC is reduced whilst each of the other phase transitions is shifted to higher temperatures, until the coalescence temperature is reached. When doped with GdScO3 TC is observed to fall, but so too are the rhombohedral/orthorhombic and orthorhombic/tetragonal transitions, resulting in a stabilisation of the tetragonal polymorphic phase. This is suggested to result from an antipolar displacement of small Gd3+ ions, resulting in 8-coordinate ion and stabilisation of the tetragonal polymorph. The addition of dopant species is shown to result in two different high temperature conduction regimes. Both mechanisms are observed within single compositions over different temperature ranges. It is suggested that this is due to a change between n- and p-type electronic conduction processes or mixed ionic/electronic processes. Finally, it is shown that trends observed in changes to TC cannot be accounted for by simple and widely used size-based arguments alone, but requires consideration of cation size variance and charge dilution effects in order to fully understand the impact on TC of dopant addition.
Book Synopsis Effect of Bismuth Titanate Additions on the Electrical Properties of Barium Titanate by : Robert A. Kowalczyk
Download or read book Effect of Bismuth Titanate Additions on the Electrical Properties of Barium Titanate written by Robert A. Kowalczyk and published by . This book was released on 1958 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Ferroelectrics Literature Index by : T. F. Connolly
Download or read book Ferroelectrics Literature Index written by T. F. Connolly and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 713 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research on ferroelectricity and ferroelectric materials started in 1920 with the discovery by Valasek that the variation of spontaneous polarization in Rochelle salt with sign and magnitude of an applied electric field traced a complete and reproducible hysteresis loop. Activity in the field was sporadic until 1935, when Busch and co-workers announced the observation of similar behavior in potassium dihydrogen phosphate and related compounds. Progress thereafter continued at a modest level with the undertaking of some theoretical as well as further experimental studies. In 1944, von Hippel and co-workers discovered ferroelectricity in barium titanate. The technological importance of ceramic barium titanate and other perovskites led to an upsurge of interest, with many new ferroelectrics being identified in the following decade. By 1967, about 2000 papers on various aspects of ferroelectricity had been published. The bulk of this widely dispersed literature was concerned with the experimental measurement of dielectric, crystallographic, thermal, electromechanical, elastic, optical, and magnetic properties. A critical and excellently organized cpmpilation based on these data appeared in 1969 with the publica tion of Landolt-Bornstein, Volume 111/3. This superb tabulation gave instant access to the results in the literature on nearly 450 pure substances and solid solutions of ferroelectric and antiferroelectric materials. Continuing interest in ferroelectrics, spurred by the growing importance of electrooptic crystals, resulted in the publication of almost as many additional papers by the end of 1969 as had been surveyed in Landolt-Bornstein.
Book Synopsis American Doctoral Dissertations by :
Download or read book American Doctoral Dissertations written by and published by . This book was released on 1995 with total page 896 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Effect of Oxide Additions Upon the Sintering of Barium Titanate Compacts by : John R. Thome
Download or read book The Effect of Oxide Additions Upon the Sintering of Barium Titanate Compacts written by John R. Thome and published by . This book was released on 1969 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Systems with Barium Oxide and Titanium Oxide Additions in the Near Stoichiometric Region by :
Download or read book Systems with Barium Oxide and Titanium Oxide Additions in the Near Stoichiometric Region written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Barium oxide and titanium oxide additions were made to modify base Ba-excess and Ti-excess BaTiO3 powders towards the near stoichiometric region, to understand and control microstructure evolution and PTCR properties in these materials during processing. Microstructure and properties exhibited by these systems were compared with stoichiometric blended systems in literature which exhibit high density uniform fine grained microstructures. TiO2 additions do not have any effect on the solution behavior of the system being insoluble in aqueous media in the observed pH ranges. BaO additions modify the solution behavior of the system increasing the pH of the solution. TEM studies on powders with TiO2 additions show double-layer formations on the particle surfaces suggesting Barium dissolution from the BaTiO3 particle surfaces. Powders with BaO additions exhibit a single layer formation on the particle surfaces suggestive of BaO dissolution and redeposition occurring during milling and drying. Dissolution of BaO additions in solution considerably reduces dissolution from BaTiO3 particle surfaces. Surface states were however found to play a lesser role on microstructure and property evolution with high temperature processes dominating grain growth and densification in these systems. Near stoichiometric systems prepared through oxide additions have bimodal microstructures with the absence of second phase regions across the range of sintering temperatures used in this study. Inhomogenities in the system coupled with modified surface states and localized variations in the material may be responsible for this behavior. These systems exhibit a minimal PTC rise (=2 orders) when compared with Ti-excess systems which exhibit a PTC rise of 4̃ orders. Higher porosity coupled with low grain boundary coherence and large amounts of second phase in the grain boundary regions appear to be responsible for the enhanced PTC properties suggesting these mechanisms and their control to be dominant in obtaining high-rise PTC systems.