The importance of solid state science are summarized in the introductory chapters of this edition, and many of the chapters have been completely rewritten or revised.
Each chapter has a special contribution to make in the overall understanding of the solid state science of phosphors and luminescence.
- Introduces the reader to the science and art of preparing inorganic luminescent materials.
- Describes how and why luminescent materials exhibit such specific intrinsic properties.
- Describes the science of the solid state and presents the exact formulas and conditions required to make all of the phosphors known at that time.
Since the first date of publication of this book in 1991, the subject of phosphors and luminescence has assumed even more importance in the overall scheme of technological development. Many new types of displays have appeared which depend upon phosphors in their operation. Some of these were pure conjecture in 1991 but are a reality in 2004. Descriptions have been included of the newer (as well as the older) types of displays in this edition along with an annotated portrait of the phosphors used in each category. Many of these new light sources promise to displace and make obsolete our current light sources, such as incandescent lamps, fluorescent lamps and the ubiquitous colour Cathode Ray Tube now used in TV and computer monitors. The importance of solid state science are summarized in the introductory chapters of this edition, and many of the chapters have been completely rewritten or revised. Each chapter has a special contribution to make in the overall understanding of the solid state science of phosphors and luminescence. Introduces the reader to the science and art of preparing inorganic luminescent materials Describes how and why luminescent materials exhibit such specific intrinsic properties Describes the science of the solid state and presents the exact formulas and conditions required to make all of the phosphors known at that time
Cover 1
Studies in Inorganic Chemistry 21 2
Preface 5
Acknowledgement 7
Table of Contents 9
Introduction 17
Introduction to The Solid State 19
Changes of State 21
Energetics of Changes of State 23
Propagation Models and the Close-Packed Solid 26
The Structure of Solids 30
Determination of Structure of Compounds 43
The Defect Solid 48
Suggested Reading 55
The Point Defect 57
Types of Point Defects 57
The Point Defect in Homogeneous Solids 59
The Point Defect in Heterogeneous Solids 63
The Plane Net 67
Defect Equation Symbolism 75
Some Applications for Defect Chemistry 76
Phosphors 77
Lithium Niobate 78
Bubble Memories 80
Calcium Sulfide Phosphor 82
Thermodynamics of the Point Defect 83
Statistical Mechanics Approach 83
Schottkv and Frenkel Defects 84
Defect Thermodynamics 86
Combined Approach to Defect Formation 88
Interstitial Atoms 90
Frenkel Pairs 90
Schottkv Defects 91
Defect Equilibria 91
Defect Equilibria in Various Types of Compounds 93
Stoichiometric Binary Compounds of MXs 94
Defect Concentrations in MXs Compounds 96
Non-Stoichiometric Binary Compounds 98
Defect Concentrations in MXsPlusmnDelta 100
Ionization of Defects 103
Brouwer's Approximation Method 106
Analyses of Real Crystals using Brouwer's Methodcomparison to the Thermodynamic Method 113
The AgBr Crystal with a Divalent Impurity. Cd2+ 113
Let us Now Summarize What we have Covered to Date 118
Defect Disorder in AgBr- A Thermodynamic Approach 118
Summary and Conclusions 123
The Effects of Purity (and Impurities) 125
Nanotechnology and The Solid State 127
Suggested Reading 129
The Solid State: Mechanisms of Nucleation, Solid State Diffusion, Growth of Particles and Measurement of Solid State Reactions 131
Solid State Reactions and Nucleation Mechanisms 132
Types of Solid State Reactions 133
Solid State Nucleation Processes and Models 140
Diffusion Controlled Solid State Reactions 151
The Tarnishing Reaction 151
Fick's Laws of Diffusion 154
Role of Defects in Solid State Diffusion Mechanisms 157
Analysis of Diffusion Reactions in the Solid State 161
Analysis of Diffusion Reactions in Spinel 162
Phosphors Based on Spinels 165
Diffusion in Silicates and Silicate Phosphors 170
Diffusion Mechanisms Where the Cation Changes its Valence State 179
Homogeneous Nucleation Processes - Particle Growth 182
Nucleation in Precipitation Reactions 186
Sequences in Particle Growth 187
Ostwald Ripening of a Calcium Phosphate Product 189
Sintering and Sintering Processes 190
Grain Growth 192
Let us Now Summarize the Subjects we have Covered so Far in this Chapter 200
Methods of Measurement of Solid State Reactions 201
Differential Thermal Analysis 202
Differential Scanning Calorimetry 216
Utilization of DTA and DSC 218
Applications of DTA 218
Uses of DSC 221
Thermogravimetry 223
Determination of Rate Processes in Solid State Reactions 229
Types of Solid State Reactions 230
The Freeman-Carroll Method Applied to DTA 233
The Freeman-Carroll Method Applied to TGA 234
Recommended Reading 235
Measuring Particle Size and Growing Single Crystals 237
Measurement of Particle Sizes and Shapes 237
Particle Shapes 241
Measurement of Particle Size 246
Measurement of Particle Size 250
The Binomial Theorem-Particle Distributions 251
Measuring Particle Distributions 254
Analysis of Particle Size Distribution Parameters 261
The Histogram 261
Frequency Plots 262
Cumulative Frequency 263
Log Normal Probability Method 264
Types of Log Normal Particle Distributions 266
Unlimited Particle Distributions 266
Limited Particle Distributions 267
Log Normal Distributions- Discontinuous Limits 268
Multiple Particle Distributions 269
Using Particle Distribution Parameters in Industry 270
Fluorescent Lamp Phosphor Particles 270
Tungsten Metal Powder 271
A Typical PSD Calculation 272
Methods of Measuring Particle Distributions 275
Sedimentation Methods 276
Electrical Resistivity- The Coulter Counter 279
Laser Diffractometrv 282
Other Methods of Measuring Particle Size 284
Growth of Single Crystals 286
Heating Elements and Crucibles 287
Growth of Single Crystals From the Melt 291
Necking In a Seed 292
Melt Growth Using The Czochralski Method 294
Growing a Single Crystal 296
Effects of Rotation in the Czrochralski System 299
Design of a Crystal Pulling Apparatus 301
Heat Flows in the Czrochralski System 303
An Automated Czrochralski System 307
Growing Laser Crystals 309
Melt Growth Using the Bridgeman-Stockbarger Method 316
Melt Growth Using the Kvropoulos Method 318
Crystal Growth Using a Variation of the Kvopolous Method 319
Edge Defined Crystal Growth From the Melt 323
Zone Melting and Refining 325
Crystal Purification Using Zone Refining 326
The Impurity Leveling Factor 329
Crystal Growth from the Melt- The Verneuil Method 333
Melting and Stoichiometrv of the Crystal 337
Dvstectic Crystals 339
Defect-Free Single Crystal Silicon 340
Actual Imperfections of Crystals Grown from a Melt 342
Crystal Growth from a Liquid Phase 345
Growth of Single Crystals From a Molten Flux 345
Hvdrothermal Growth of Crystals 348
Vapor Methods Used for Single Crystal Growth 358
Suggested Reading 361
Optical and Electronic Properties of Solids 363
The Nature of Light 363
Absorbance, Reflectivity and Transmittance 369
Electronic Properties of Crystals 378
Band Models and The Reciprocal Lattice 378
Calculation of Energy Bands in Crystals 388
Point Defects and the Energy Band Model 400
Crystal Structures 400
Brillouin Zones 400
Energy Bands in Solids 401
Phonons as Quantized Lattice Vibrations 405
Phonon Dispersion Equations 407
The Case of the Impurity Activator Center in a Phosphor 413
Electronic Aspects of Phosphors 414
Energy Processes in a Phosphor 416
Properties Associated with Phosphors 424
Notation 425
Quantum Efficiency 426
Decay Times 427
Band Shapes 429
Spectroscopic Notation 431
Organic Phosphors and Their Luminescence Mechanisms 434
Factors Associated with Excitation Energy Conversion 436
Prediction of Electronic Transition Intensities 438
Multipole Interactions 438
Einstein Absorption and Emission Coefficients 439
Electronic Transition Moments 441
Concise Hamiltonian Calculation of Transition Moments 442
Detailed Calculation of Electronic Transition Moments 443
Dipole and Multipole Oscillator Strengths 446
Mechanisms of Energy Transfer in Solids 449
Radiative Transfer (Radiation Trapping) 450
Energy Transfer by Resonance Exchange 451
Energy Transfer by a Spatial Process 454
Energy Exchange by Spin Coupling 457
Energy Transfer by Non-Resonant Processes 460
Summary of Phonon Processes as Related to Phosphors 462
Excitation of the Activator Center 462
Phonon Process 462
Energy Flow 462
Excited State Relaxation 462
Phonon Process 462
Energy Flow 462
Center Ready to Emit 462
Direct Relaxation 462
Phonon Process 462
Energy Flow 462
Emission of a Photon 462
Phonon Process 462
Energy Flow 462
Resonant and Non-Resonant Processes 463
Actual Phonon Process 463
Energy Flow 463
Suggested Reading 464
Design of Phosphors 465
The Luminescent Center in Inorganic Phosphors 465
The Ground State Perturbation Factor 470
Design of a Phosphor 474
Choice of the Host Components 474
Choice of the Activator(s) 480
Quenchers, or "Killers" of Luminescence 486
Factors Affecting Phosphor Efficiencies (Brightness) 489
Preparation of Phosphors 498
Phosphor Parameters 498
Independent Variables 498
Dependent Variables 504
Selection of Materials 505
Assay 505
Weighing 505
Blending 506
Firing Cycle 506
Dispersion 506
Evaluation 506
The Firing Cycle as a Dependent Variable 506
Size and Mass Fired 510
Firing Atmosphere 511
Effect of Host Structure 511
Effect of Preparation Method Employed 517
Ratios of Components and Use of a Flux 518
Commercial Phosphors 519
Cathode Ray Phosphors 519
How Cathode-Rav Phosphors are Used 520
JEDEC Phosphors 524
Fluorescent Lamp Phosphors 529
Measurement of Optical Properties of Phosphors 534
Measurement of Phosphor Brightness 535
Measurement of Spectral Energy Distributions 536
Measurement of Quantum Efficiencies 538
Specification and Measurement of Color 538
The Human Eve 539
The Nature of Chroma 541
The Standard Observer 544
Color Measurement 550
Color Matching 559
Color Spaces 561
The Munsell Color Tree 562
Color Matching and MacAdam Space 566
Rare Earths and their Spectral Properties 570
History of the Lanthanides 570
Chemistry of the Lanthanides 572
Rare Earth Energy Levels and Electronic States 577
Calculating Lanthanide Energy Levels 583
The Concept of Fractional Parentage 586
Energy Transitions and Mixed States 591
Spectroscopic Rules for the Rare Earths 593
Experimental Stark States 595
The "Free-Ion" Approach to Rare Earth Energy Levels 600
Charge Transfer States and 5d Multiplets 603
Phonon Assisted Relaxation in Phosphors 605
Anti-Stokes Phosphors 612
The Solid State Laser 621
Suggested Reading 632
Current Phosphor Device Technology 633
Current Progress in CRT Display and Discharge Lighting 633
Cathode Ray Tubes fCRT) 633
Fluorescent Lamps 640
Current Display Devices Based upon Electron Creation 646
CRT's for Display. Measurement and Specialty Types 648
Oscilloscopes and Storage Tubes- Measurement 648
Flying Spot Scanner 650
Radar Displays 651
Image Intensifier Screens 653
Thin Film Technology 655
Evaporation 659
Chemical-Vapor Deposition 659
Mechanical Film Deposition 660
Sputtering 661
Ion Beam Deposition Methods 662
Electron Beam Deposition 663
Devices Using Internal Electron Beam Generation 663
Vacuum Fluorescent Displays 663
Field Emission Displays (FED) 666
Large Outdoor Displays 669
Light Emitting Diodes (LED) 670
Light Emitting Diode Lasers 677
Organic Light Emitting Diode Displays (OLED) 685
Electroluminescent Displays (EL) 691
Current Display Devices Based upon Photon Creation 694
Fluorescent Lamps for Special Purposes 695
Liquid Crystal Back-Light Displays 695
Lamps for Copying Machines 701
Blacklight Lamps for Water Treatment and Viewers 701
Medical Uses for Blacklight Lamps 702
Display Devices Based on Vacuum UV Photon Generation 702
Plasma Display Panels- Vacuum UV Photon Generation 703
Neon Signs 708
Devices Utilizing High Energy Photons 709
X-Ray Intensifying Screens 709
Scintillation Phosphors for Imaging 714
Long Decav Phosphors 719
Subject index 721
The Point Defect
R.C. Ropp 138 Mountain Avenue, Warren, NJ 07059, U.S.A.
There are two types of defects associated with phosphors. One involves controlled point defects in which a foreign activator cation is incorporated in the solid in defined amounts. The other involves line and point defects inadvertently formed in the solid structure because of impurity and entropy effects. This chapter will define and characterize the nature of all of these point defects in the solid, their thermodynamics and equilibria. It will become apparent that the type of defect present will depend upon the nature of the solid in which they are incorporated. That is, the characteristics of the point defects in a given phosphor will depend upon its chemical composition. Of necessity, this chapter is not intended to be exhaustive, and the reader is referred to the many treatises concerned with the point defect.
2.1 TYPES OF POINT DEFECTS
Let us now consider the defect solid from a general perspective. Consider the case of semi-conductors, where most of the atoms are the same, but the total of the charges is not zero. In that case, the excess charge (n- or p- type) is spread over the whole lattice so that no single atom, or group of atoms, has a charge different from its neighbors. However, most inorganic solids are composed of charged moieties, half of which are positive (cations) and half negative (anions). The total charge of the cations equals, in general, that of the anions. If an atom is missing, the lattice readjusts to compensate for this loss of charge. If there is an extra atom present, the charge-compensation mechanism again manifests itself. Another possibility is the presence of an atom with a charge larger or smaller than that of its neighbors. In a given structure, cations are usually surrounded by anions, and vice-versa (Remember what we said in Chapter 1 wherein it was stated that most structures are oxygen-dominated). Thus, a cation with an extra charge needs to be compensated by a like anion, or by a nearest neighbor cation with a lesser charge. An example of charge-compensation for a divalent cation sub-lattice would be the following defect equation:
2.1.1
2+⇋M++M3+
where the M3+ and M+ are situated on nearest neighbor cation sites, which were originally divalent.
Thus, the charge compensation mechanism represents the single most important mechanism which operates within the defect solid.
Because of this, the number and types of defects, which can appear in the solid, are limited. This restricts the number of defect types we need to consider, in both elemental (all the same kind of atom) and ionic lattices (having both cations and anions present). We have shown that by stacking atoms or propagation units together, a solid with specific symmetry results. If we have done this properly, a perfect solid should result with no holes or defects in it. Yet, the 2nd law of thermodynamics demands that a certain number of point defects (vacancies) appear in the lattice. It is impossible to obtain a solid without some sort of defects. A perfect solid would violate this law. The 2nd law states that zero entropy is only possible at absolute zero temperature. Since most solids exist at temperatures far from absolute zero, those that we encounter are defect solids. It is natural to ask what the nature of these defects might be, particularly when we add a foreign cation (activator) to a solid to form a phosphor.
Consider the surface of a solid. In the interior, we see a certain symmetry which depends upon the structure of the solid. As we approach the surface from the interior, the symmetry begins to change. At the very surface, the surface atoms see only half the symmetry that the interior atoms do. Reactions between solids take place at the surface. Thus, the surface of a solid represents a defect in itself since it is not like the interior of the solid.
In a three-dimensional solid, we can postulate that there ought to be three major types of defects, having either one-, two- or three- dimensions. Indeed, this is exactly the case found for defects in solids, as we briefly described in the preceding chapter. We have already given names to each of these three types of defects. Thus a one-dimensional defect of the lattice is called a "point" defect, a two-dimensional defect a "line" or "edge" defect and a three-dimensional defect is called a "plane" or "volume" defect. We have already described, in an elementary way, line and volume defects and will not address them further except to point out how they may arise when certain point defects are present. It is sufficient to realize that they exist and are important for anyone who studies homogeneous materials such as metals.
Point defects are changes at atomistic levels, while line and volume defects are changes in stacking of planes or groups of atoms (molecules) in the structure. The former affect the chemical properties of the solid whereas the latter affect the physical properties of the solid. Note that the arrangement (structure) of the individual atoms (ions) are not affected, only the method in which the structure units are assembled. That is, the structure of the solid remains intact in spite of the presence of defects. Let us now examine each of these defects in more detail, starting with the one-dimensional lattice defect and then with the multi-dimensional defects. We will find that specific types have been found to be associated with each type of dimensional defect which have specific effects upon the stability of the solid structure. It should be clear that the type of point defect prevalent in any given solid will depend upon whether it is homogenous (same atoms) or heterogeneous (composed of differing atoms).
I The Point Defect in Homogeneous Solids
We begin by identifying the various defects which can arise in solids and later will show how they can be manipulated to obtain desirable properties not found in naturally formed solids. Let us look first at the homogeneous type of solid. We will first restrict our discussion to solids which are stoichiometric, and later will examine solids which can be classified as "non-stoichiometric", or having an excess of one or another of one of the building blocks of the solid. These occur in semi-conductors as well as other types of electronically or optically active solids.
Suppose you were given the problem of identifying defects in a homogeneous solid. Since all of the atoms in this type of solid are the same, the problem is somewhat simplified over that of the heterogeneous solid (that is a solid containing more than one type of atom or ion). After some introspection, you could speculate that the homogeneous solid could have the following types of point defects:
2.1.2 Types of Point Defects Expected in a Homogeneous Solid
* Vacancies
* Self-interstitial
* Substitution Impurities
* Interstitial Impurities
On the left are the two types of point defects which involve the lattice itself, while the others involve impurity atoms (Note that interstitial atoms can involve either an impurity atom or the same atom that makes up the lattice structure itself). Indeed, there do not seem to anymore than these four, and indubitably, no others have been observed. Note that we are limiting our defect family to point defects in the lattice and are ignoring line and volume defects of the lattice. These four point defects, given above, are illustrated in the following diagram, given as 2.1.3. On the next page.
Note that what we mean by an "interstitial" is an atom that can fit into the spaces between the main atoms in the crystalline array. In this case, we have shown a hexagonal lattice and have labeled each type of point defect. Observe that we have shown a vacancy in our hexagonal lattice, as well as a foreign interstitial atom which is small enough to fit into the interstice between the atoms of the structure. Also shown are two types of substitutional atoms, one larger and the other smaller than the atoms composing the principal hexagonal lattice. In both cases, the hexagonal packing is disrupted due to a "non-fit" of these atoms in the structure. Additionally, we have illustrated another type of defect that can arise within the homogeneous lattice (in addition to the vacancy and substitutional impurities that are bound to arise). This is called the "self-interstitial". Note that it has a decisive effect on the structure at the defect. Since the atoms are all the same size, the self-interstitial introduces a line-defect in the overall structure. It should be evident that the line-defect introduces a difference in packing order since the close packing at the arrows has changed to cubic and then reverts to hexagonal in both lower and upper rows of atoms. It may be that this type of defect is a major cause of the line or edge type of defects that appear in most homogeneous solids. In contrast, the other defects produce only a disruption in the localized packing order of the hexagonal lattice, i.e. - the defect does not extend throughout the lattice, but only close to thespecific defect. It should be evident that metals or solid solutions of metals (alloys) show such behavior in contrast to heterogeneous lattices which involve compounds such as ZnS. This accounts for the tremendous...
| Erscheint lt. Verlag | 6.5.2004 |
|---|---|
| Sprache | englisch |
| Themenwelt | Sachbuch/Ratgeber |
| Naturwissenschaften ► Chemie ► Anorganische Chemie | |
| Naturwissenschaften ► Chemie ► Physikalische Chemie | |
| Naturwissenschaften ► Physik / Astronomie ► Festkörperphysik | |
| Technik | |
| ISBN-10 | 0-08-047323-7 / 0080473237 |
| ISBN-13 | 978-0-08-047323-9 / 9780080473239 |
| Haben Sie eine Frage zum Produkt? |
PDF (Adobe DRM)Größe: 71,7 MB
Kopierschutz: Adobe-DRM
Adobe-DRM ist ein Kopierschutz, der das eBook vor Mißbrauch schützen soll. Dabei wird das eBook bereits beim Download auf Ihre persönliche Adobe-ID autorisiert. Lesen können Sie das eBook dann nur auf den Geräten, welche ebenfalls auf Ihre Adobe-ID registriert sind.
Details zum Adobe-DRM
Dateiformat: PDF (Portable Document Format)
Mit einem festen Seitenlayout eignet sich die PDF besonders für Fachbücher mit Spalten, Tabellen und Abbildungen. Eine PDF kann auf fast allen Geräten angezeigt werden, ist aber für kleine Displays (Smartphone, eReader) nur eingeschränkt geeignet.
Systemvoraussetzungen:
PC/Mac: Mit einem PC oder Mac können Sie dieses eBook lesen. Sie benötigen eine
eReader: Dieses eBook kann mit (fast) allen eBook-Readern gelesen werden. Mit dem amazon-Kindle ist es aber nicht kompatibel.
Smartphone/Tablet: Egal ob Apple oder Android, dieses eBook können Sie lesen. Sie benötigen eine
Geräteliste und zusätzliche Hinweise
Zusätzliches Feature: Online Lesen
Dieses eBook können Sie zusätzlich zum Download auch online im Webbrowser lesen.
Buying eBooks from abroad
For tax law reasons we can sell eBooks just within Germany and Switzerland. Regrettably we cannot fulfill eBook-orders from other countries.
EPUB (Adobe DRM)Größe: 22,5 MB
Kopierschutz: Adobe-DRM
Adobe-DRM ist ein Kopierschutz, der das eBook vor Mißbrauch schützen soll. Dabei wird das eBook bereits beim Download auf Ihre persönliche Adobe-ID autorisiert. Lesen können Sie das eBook dann nur auf den Geräten, welche ebenfalls auf Ihre Adobe-ID registriert sind.
Details zum Adobe-DRM
Dateiformat: EPUB (Electronic Publication)
EPUB ist ein offener Standard für eBooks und eignet sich besonders zur Darstellung von Belletristik und Sachbüchern. Der Fließtext wird dynamisch an die Display- und Schriftgröße angepasst. Auch für mobile Lesegeräte ist EPUB daher gut geeignet.
Systemvoraussetzungen:
PC/Mac: Mit einem PC oder Mac können Sie dieses eBook lesen. Sie benötigen eine
eReader: Dieses eBook kann mit (fast) allen eBook-Readern gelesen werden. Mit dem amazon-Kindle ist es aber nicht kompatibel.
Smartphone/Tablet: Egal ob Apple oder Android, dieses eBook können Sie lesen. Sie benötigen eine
Geräteliste und zusätzliche Hinweise
Zusätzliches Feature: Online Lesen
Dieses eBook können Sie zusätzlich zum Download auch online im Webbrowser lesen.
Buying eBooks from abroad
For tax law reasons we can sell eBooks just within Germany and Switzerland. Regrettably we cannot fulfill eBook-orders from other countries.
aus dem Bereich
