Dielectric Properties of Lead Magnesium Niobate PDF Download
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Author: James Wilmarth Smith
Publisher:
ISBN:
Category :
Languages : en
Pages : 268
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Author: James Wilmarth Smith
Publisher:
ISBN:
Category :
Languages : en
Pages : 268
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Author: Daniel Joseph Beck
Publisher:
ISBN:
Category :
Languages : en
Pages : 71
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Author: Daniel Raiford Wilson
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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"It is well known that perovskite lead magnesium niobate (PMN) must undergo unusual processing techniques to be reproducibly synthesized. This research successfully used the Columbite precursor method to produce 98% pyrochlore-free perovskite PMN. Annealing of the samples to eliminate excess lead oxide from the grain boundary was rendered unnecessary when powders were properly dispersed and filtered. Thus, it was unnecessary to add excess PbO to achieve high density PMN with superior electrical properties. An excess of 0.5 wt% MgO was added to all compositions to reduce pyrochlore formation, to improve densification, and to improve electrical properties. Lead titanate (PT) was added to the PMN compositions in amounts ranging from 11 to 14 mole%. These additions resulted in improvement in both dielectric and pyroelectric properties. The temperature where the maximum dielectric constant occurred also increased, corresponding to an upward shift in the phase transition, while dielectric losses were unaffected. Improvements were also seen in the remnant polarization and maximum pyroelectric coefficient. Additions of lead tungstate (PW) were also studied in two of the PMN-PT solid solutions. These samples showed lower values of the maximum dielectric constant, as well as lower temperatures of this maximum. Likewise, remnant polarization and maximum pyroelectric coefficient decreased"--Abstract, leaf iii
Author: Michael Christopher Wagner
Publisher:
ISBN:
Category :
Languages : en
Pages : 41
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As the range of applications for electro-optic materials continues to grow, so does the need to identify and characterize new materials with improved electro-optic responses. A promising electro-optic material which has yet to be widely utilized is Lead Magnesium Niobate-Lead Titanate (PMN-PT) ceramic. In an effort to better characterize and understand the material, this work employed FTIR spectroscopy to calculate the refractive index of PMN-PT over a wide range of optical frequencies. Through analysis of interference fringes, the dispersion curve is calculated between 10,500 cm1 and 1200 cm1 (approximately 955 nm and 8.3 Îơm) containing nearly two thousand data points with an assumed accuracy of three decimal places. Additionally, capacitance bridge analysis is used to characterize the effect of temperature on the dielectric constant of PMN-PT. Special attention is given to the relationship of refractive index and dielectric constant so that a temperature study of the dielectric constant can be used to infer additional physical characteristics of PMN-PT.
Author:
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Category :
Languages : en
Pages : 11
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A chemical solution powder synthesis technique has been developed that produces first, uniform powders of lead magnesium niobate (PMN) with 60 to 80 nm crystallite size. The synthesis technique was based on the dissolution of lead acetate and alkoxide precursors in acetic acid followed by precipitation with oxalic acid/propanol solutions. Lead magnesium niobate ceramics fabricated from these chemically derived powders had smaller, more uniform grain size and higher dielectric constants than ceramics fabricated from mixed oxide powders that were processed under similar thermal conditions. Chem-prep PMN dielectrics with peak dielectric constants greater than 22,000 and polarizations in excess of 29 [mu]C/cm2 were obtained for 1,100 C firing treatments. Substantial decreases in dielectric constant and polarization were measured for chemically prepared PMN ceramics fired at lower temperatures, consistent with previous work on mixed oxide materials.
Author: Samuel Taylor
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Lead magnesium niobate-titanate, Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT), and lead indium niobate-magnesium niobate-titanate, Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) ferroelectric single crystals are widely used in current and next generation medical ultrasound devices for their high signal strength and high frequency capabilities. With technology innovations, single crystal elements in transducers have become small enough that geometry induced domain clamping can severely limit the dielectric properties of the material and must be taken into consideration. Previous work on single crystal PMN-PT and PIN-PMN-PT has demonstrated that a sample with geometries on the scale of the materials ferroelectric domain size will cause domain clamping. [1] Those studies only evaluated single crystals with polished surface finishes. During preparation of a crystal sample, machining stresses can cause permanent lattice distortions, inducing a surface dead layer, an area of distorted lattice near the surface that is no longer ferroelectric. [2] The geometry induced domain clamping study used samples with essentially no surface dead layer. In medical ultrasounds, the low acoustic impedance of human tissues requires impedance matching layers to be adhered to the crystal surface within the transducer in order to transition the sound wave from the high impedance crystal to the low impedance human tissue. Most bonding techniques require a crystal surface rougher than that obtained from a traditional polishing process. A rougher surface will have high stress introduced deeper into the part due to the machining process. This creates a surface dead layer where the lattice is permanently distorted and no longer exhibits ferroelectric behavior. This will reduce the percent volume of ferroelectric material in the part, reducing overall ferroelectric properties/behavior. In this study, commercial surface finish techniques, including ID saw, wire saw, rough surface grinding and fine surface grinding were used to prepare crystal samples of varying thickness to evaluate the thickness and surface roughness dependence of PMN-PT and PIN-PMT- PT single crystals dielectric properties and ferroelectric behavior. All the samples studied met current commercial matching layer adhesion requirements for surface roughness. The ferroelectric crystals were polarized under both DC and AC fields. Electrical properties were measured after DC poling and AC poling. AC poling response was measured to observe the polarization hysteresis behavior of each sample. The primary electrical properties of interest were the thickness mode electromechanical coupling coefficient (kt), strain free component of the relative dielectric permittivity ([epsilon]r) and the coercive field (Ec), as well as the general shape and evolution of the polarization hysteresis loop through multiple measurements. With the ID sawn, wire sawn and rough surface finishes, both PMN-PT and PIN-PMN-PT crystals exhibited thickness dependent domain impingement. PMN-PT samples showed decreased [epsilon]r and non-characteristic PE hysteresis below 350[mu]m thickness. Although PIN-PMN-PT samples showed degradation in the ferroelectric hysteresis loop at thicknesses just below bulk thickness, [epsilon]r was maintained for samples of at least 400[mu]m thickness. For both crystal compositions, the surface dead layer occupied enough volume to result in a measurable detrimental effect on poling and electrical properties. The effects of the surface dead layer on ferroelectric behavior of the crystal samples were similar to the dimensional pinning of domains in thin polished samples of PMN-PT. With similar surface preparation, PIN-PMN-PT crystals also exhibited low properties, unlike in a polished sample. Using a fine grind technique, thin samples of PIN-PMN-PT could be poled and still maintain normal bulk properties and polarization behavior. This research focused on crystals with compositions near the morphotrophic phase boundary (MPB). This study concluded that in commercially processed PIN-PMN-PT and PMN-PT crystal samples, the main contributing factor to domain impingement is the surface dead layer, not the part geometry. As the surface finish is improved, the lattice damage caused by machining stress is reduced, therefore reducing the depth of the surface dead layer into the sample and reducing the overall volume percent of the sample that cannot be poled. As surface machining techniques are refined, creating a smoother surface, geometry induced domain impingement starts to play a larger role in ferroelectric behavior.
Author: Z-G Ye
Publisher: Elsevier
ISBN: 1845694007
Category : Technology & Engineering
Languages : en
Pages : 1091
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Book Description
This comprehensive book covers recent developments in advanced dielectric, piezoelectric and ferroelectric materials. Dielectric materials such as ceramics are used to manufacture microelectronic devices. Piezoelectric components have been used for many years in radioelectrics, time-keeping and, more recently, in microprocessor-based devices. Ferroelectric materials are widely used in various devices such as piezoelectric/electrostrictive transducers and actuators, pyroelectric infrared detectors, optical integrated circuits, optical data storage and display devices.The book is divided into eight parts under the general headings: High strain high performance piezo- and ferroelectric single crystals; Electric field-induced effects and domain engineering; Morphotropic phase boundary related phenomena; High power piezoelectric and microwave dielectric materials; Nanoscale piezo- and ferroelectrics; Piezo- and ferroelectric films; Novel processing and new materials; Novel properties of ferroelectrics and related materials. Each chapter looks at key recent research on these materials, their properties and potential applications.Advanced dielectric, piezoelectric and ferroelectric materials is an important reference tool for all those working in the area of electrical and electronic materials in general and dielectrics, piezoelectrics and ferroelectrics in particular. - Covers the latest developments in advanced dielectric, piezoelectric and ferroelectric materials - Includes topics such as high strain high performance piezo and ferroelectric single crystals - Discusses novel processing and new materials, and novel properties of ferroelectrics and related materials
Author: K. M. Nair
Publisher: John Wiley & Sons
ISBN: 1118408179
Category : Technology & Engineering
Languages : en
Pages : 323
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Book Description
This proceedings contains papers presented at the Advanced Dielectric Materials: Design, Preparation, Processing and Applications; and Advanced Dielectrics for Wireless Communications symposia. Topics include design of material, materials synthesis and processing, processing-microstructure-property relationship, multilayer device materials, thin and thick films, device applications, low temperature co-fired ceramics (LTCC)for multilayer devices, microwave dielectric materials and much more.
Author: Mailadil T. Sebastian
Publisher: Elsevier
ISBN: 0080560504
Category : Technology & Engineering
Languages : en
Pages : 689
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Book Description
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
Author: Aneta Słodczyk
Publisher:
ISBN:
Category :
Languages : en
Pages :
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