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Author: Publisher: ISBN: Category : Languages : en Pages : 10
Book Description
The relatively poor efficiency of phosphor materials in cathodoluminescence with low accelerating voltages is a major concern in the design of field emission flat panel displays operated below 5 kV. The authors research on rare-earth-activated phosphors indicates that mechanisms involving interactions of excited activators have a significant impact on phosphor efficiency. Persistence measurements in photoluminescence (PL) and cathodoluminescence (CL) show significant deviations from the sequential relaxation model. This model assumes that higher excited manifolds in an activator de-excite primarily by phonon-mediated sequential relaxation to lower energy manifolds in the same activator ion. In addition to sequential relaxation, there appears to be strong coupling between activators, which results in energy transfer interactions. Some of these interactions negatively impact phosphor efficiency by nonradiatively de-exciting activators. Increasing activator concentration enhances these interactions. The net effect is a significant degradation in phosphor efficiency at useful activator concentrations, which is exaggerated when low-energy electron beams are used to excite the emission.
Author: Publisher: ISBN: Category : Languages : en Pages : 10
Book Description
The relatively poor efficiency of phosphor materials in cathodoluminescence with low accelerating voltages is a major concern in the design of field emission flat panel displays operated below 5 kV. The authors research on rare-earth-activated phosphors indicates that mechanisms involving interactions of excited activators have a significant impact on phosphor efficiency. Persistence measurements in photoluminescence (PL) and cathodoluminescence (CL) show significant deviations from the sequential relaxation model. This model assumes that higher excited manifolds in an activator de-excite primarily by phonon-mediated sequential relaxation to lower energy manifolds in the same activator ion. In addition to sequential relaxation, there appears to be strong coupling between activators, which results in energy transfer interactions. Some of these interactions negatively impact phosphor efficiency by nonradiatively de-exciting activators. Increasing activator concentration enhances these interactions. The net effect is a significant degradation in phosphor efficiency at useful activator concentrations, which is exaggerated when low-energy electron beams are used to excite the emission.
Author: Vikas Dubey Publisher: Elsevier ISBN: 0323886051 Category : Science Languages : en Pages : 410
Book Description
Rare-Earth-Activated Phosphors: Chemistry and Applications outlines important fundamentals and properties and explores successful application that address key problems across the sciences. Sections introduce phosphors and luminescence, explore their properties, characteristics, synthesis and degradation and highlight key applications across telecommunications, lighting, electroluminescent devices, (bio-)analytical sensors, bio-imaging set-ups, drug delivery and sustainable energy devices. Drawing on the knowledge of an expert team of contributors, the book provides useful insight into successfully harnessing the properties of rare earth activated phosphors for a range of important applications. Rare-earth nano-phosphors offer an interesting array of characteristics, including sharp emission bands, exceptional optical damage thresholds, low toxicity, high selectivity and stability, and long luminescence lifetimes. Understanding these properties can help researchers effectively manipulate them for a range of important applications. Provides a good introduction to the useful properties and characteristics of rare earth activated phosphors Analyzes the use of rare earth activated phosphors for a broad variety of important applications, bridging the gap between theory and application Encourages further discourse and development for improving the energy-efficiency of devices based on rare earth activated phosphors
Author: Mihail Nazarov Publisher: CRC Press ISBN: 9814310778 Category : Science Languages : en Pages : 468
Book Description
This book concentrates on the luminescence and structural properties of the new generation of europium and terbium activated phosphors, associated phenomena, and related topics, from basic principles to the most recent discoveries. It summarizes the present state of the art in this rapidly growing field. The authors describe recent developments in the areas of rare earth doped phosphors and of some new materials or well-known materials with improved properties that open up new possibilities. The areas of focus include X-ray phosphors, phosphors for light-emitting devices, emissive displays, and fluorescent lamps. The book comprises theoretical and experimental analysis of various properties of phosphors, research methods and preparation techniques, and some promising applications.
Author: Ratnesh Tiwari Publisher: Walter de Gruyter GmbH & Co KG ISBN: 3110676451 Category : Science Languages : en Pages : 258
Book Description
Phosphors are often consisting of transition-metal compounds or rare-earth compounds, with the most common application being displays and fluorescent light. This book will guide the reader through the latest developments in thermo-, electro-, mechano- and bioluminescence of rare earth phosphors and crystals. Also, the effect of doping will be discussed.
Author: Arunachalam Lakshmanan Publisher: Nova Publishers ISBN: 9781604560183 Category : Science Languages : en Pages : 326
Book Description
This new book highlights the link between the luminescence phenomena of phosphors used in different displays. Both fluorescence (used in display phosphors) and phosphorescence (used in after glow phosphors and storage phosphors) mechanisms and the efforts made in phosphor synthesis to reduce the interference of one on another are dealt with in detail.
Author: Emma Barrett Publisher: ISBN: Category : Languages : en Pages :
Book Description
1bis thesis is concerned with the luminescent properties ·of rare earth doped oxides and the IT-VI chalcogenide CaCdS. Both materials are luminescent by very different mechanisms. Luminescence from CaCdS is due to transitions between the conduction and valence band. Emission spectra were found to be much sharper than in previously reported work. The narrowness of the peak appears to coincide with a reduction in particle size. With increasing cadmium concentration, this short wavelength (370 nm) emission band became distorted in symmetry and exhibited a red shift. This was seen as being indicative of a solid solution in which Cd substituted into the Ca sublattice. The excitation and emission mechanisms of rare earth doped materials are distinctly different from those of the IT-VI chalcogenides. Rare earth emissions consist of narrow emission bands which are predominantly due to transitions within the sheilded 4f orbital The visible emission spectra measurements of rare earth doped Y£J3, YV04' Gd202S and Y202S phosphors under 244 nm and 257 nm excitation were undertaken in order to examine the mechanisms of their emission processes. 1bis makes possible a comparison with the upconversion visible emission spectra that are obtained from these phosphors when they are excited with red light of 632.8 nm. .The motivation for this research was to develop improved phosphors for lighting applications that can be excited in the ultraviolet region.
Author: William M. Yen Publisher: CRC Press ISBN: 1351835874 Category : Science Languages : en Pages : 414
Book Description
Drawing from the second edition of the best-selling Handbook of Phosphors, Fundamentals of Phosphors covers the principles and mechanisms of luminescence in detail and surveys the primary phosphor materials as well as their optical properties. The book addresses cutting-edge developments in phosphor science and technology including oxynitride phosphors and the impact of lanthanide level location on phosphor performance. Beginning with an explanation of the physics underlying luminescence mechanisms in solids, the book goes on to interpret various luminescence phenomena in inorganic and organic materials. This includes the interpretation of the luminescence of recently developed low-dimensional systems, such as quantum wells and dots. The book also discusses the excitation mechanisms by cathode-ray and ionizing radiation and by electric fields to produce electroluminescence. The book classifies phosphor materials according to the type of luminescence centers employed or the class of host materials used and interprets the optical properties of these materials, including their luminescence characteristics and mechanisms. Placing a strong emphasis on those materials that are important from a practical point of view, the coverage also includes those possessing no possibility for practical use but are important from a theoretical standpoint.
Author: Dr. B. M. Manohara Publisher: Nitya Publications ISBN: 8194550491 Category : Juvenile Nonfiction Languages : en Pages : 177
Book Description
Phosphor materials find wide applications ranging from fluorescent display to luminescence immunoassay. These materials essentially convert one type of energy in to visible radiation and hence, phosphor materials are called optical transducer. They are generally crystalline in nature. Phosphors with high quantum efficiency, effective excitation and absorption, colour parity, longer ifetime and lower cost, as well as better morphology are required. Surface properties have important function for hosphors.Spherical phosphors are optimum morphology in application. The spherical particles are easy to be packed density so that the screen and display can obtain high definition. In addition the dense packed small particles can prevent phosphors from aging.
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Author: Vikas Dubey
Author: Mihail Nazarov
Author: Ratnesh Tiwari
Author: Arunachalam Lakshmanan
Author: Simon John Alfred Iddenten
Author: Emma Barrett
Author: William M. Yen
Author: Dr. B. M. Manohara
Author: Ashley Sara Harvey