Transparent Ceramics

ADRIAN GOLDSTEIN, PHD, has led the Israel Ceramics Institute for twenty years, also teaching electronic ceramics, for a few years in the Materials Engineering Department of the Technion. He has authored one book and published over 35 refereed papers in leading journals. ANDREAS KRELL, PHD, has served as the Journal Associated Editor at the American Ceramic Society. He was Head of Department at Fraunhofer Institute for Ceramic Technologies and Systems IKTS, and he chaired the first European Transparent Ceramics Symposium. ZEEV BURSHTEIN, PHD, is a part-time Scientific Consultant at the Soreq Nuclear Research Center, where he also teaches in the Materials Engineering department. He served as chief advisor of the Israeli Minister of Science and Technology from 1990 –1991.

"... this work can be unreservedly recommended to anyone who works or wants to become active in the field of transparent ceramics. Due to its autonomy in the relevant literature - in relation to both physics and materials science - it should definitely be purchased by libraries and companies in the field of technical ceramics. With its value as a source for facts, background information, connections and data, anyone doing research in this area will hardly be able to put this book down and should, thus, purchase it personally."—Prof. Rainer Telle, RWTH Aachen, cfi Ceramic Forum International / Ber. DKG 98 (2021) 4, D8-D9 (translated from the original article in German)

• Foreword xiiiAcknowledgments xvGeneral Abbreviations xvii1 Introduction 11.1 Importance of Transparent Ceramics: The Book’s Rationale Topic and Aims 11.2 Factors Determining the Overall Worth of Transparent Ceramics 21.2.1 Technical Characteristics 21.2.2 Fabrication and Characterization Costs 31.2.3 Overview of Worth 31.3 Spectral Domain for Ceramics High Transmission Targeted in This Book 31.3.1 High Transmission Spectral Domain 31.3.2 Electromagnetic Radiation/Solid Interaction in the Vicinity of the Transparency Domain 41.4 Definition of Transparency Levels 41.5 Evolution of Transmissive Ability Along the Ceramics Development History 61.5.1 Ceramics with Transparency Conferred by Glassy Phases 61.5.2 The First Fully Crystalline Transparent Ceramic 71.5.3 A Brief Progress History of All-Crystalline Transparent Ceramics 82 Electromagnetic Radiation: Interaction with Matter 112.1 Electromagnetic Radiation: Phenomenology and Characterizing Parameters 112.2 Interference and Polarization 132.3 Main Processes which Disturb Electromagnetic Radiation After Incidence on a Solid 132.3.1 Refraction 142.3.2 Reflection 172.3.3 Birefringence 202.3.4 Scattering 222.3.4.1 Scattering by Pores 222.3.4.2 Scattering Owed to Birefringence 242.3.5 Absorption 272.3.5.1 Transition Metal and Rare-Earth Cations in Transparent Ceramic Hosts 272.3.5.2 Absorption Spectra of Metal and Rare-Earth Cations Located in TC Hosts 282.3.5.2.1 Transition Metal and Rare-Earth Cations’ Electronic Spectra: Theoretical Basis 292.3.5.2.1.1 Electronic States of a Cation in Free Space 292.3.5.2.2 Absorption Spectra of Transition Metal and Rare-Earth Cations: Examples 502.3.5.2.2.1 The Considered Solid Hosts 502.4 Physical Processes Controlling Light Absorption in the Optical Window Vicinity 542.4.1 High Photon Energy Window Cutoff: Ultraviolet Light Absorption in Solids 542.4.2 Low Photon Energy Window Cutoff: Infrared Light Absorption in Solids 582.4.2.1 Molecular Vibrations 582.4.2.2 Solid Vibrations 592.4.2.3 Acoustic Modes 612.4.2.4 Optical Modes 622.5 Thermal Emissivity 662.6 Color of Solids 672.6.1 Quantitative Specification of Color 672.6.2 Coloration Mechanisms: Coloration Based on Conductive Colloids 713 Ceramics Engineering: Aspects Specific to Those Transparent 733.1 Processing 733.1.1 List of Main Processing Approaches 733.1.2 Powder Compacts Sintering 733.1.2.1 Configuration Requirements for High Green Body Sinterability: Factors of Influence 733.1.2.2 Powder Processing and Green-Body Forming 773.1.2.2.1 Agglomerates 773.1.2.2.2 Powder Processing 803.1.2.2.3 Forming Techniques 813.1.2.2.3.1 Press Forming 813.1.2.2.3.2 Liquid-Suspensions Based Forming 843.1.2.2.3.3 Slip-Casting Under Strong Magnetic Fields 863.1.2.2.3.4 Gravitational Deposition, Centrifugal-Casting, and Filter-Pressing 883.1.2.3 Sintering 893.1.2.3.1 Low Relevancy of Average Pore Size 893.1.2.3.2 Pore Size Distribution Dynamics During Sintering 893.1.2.3.3 Grain Growth 933.1.2.3.4 Methods for Pores Closure Rate Increase 933.1.2.3.4.1 Liquid Assisted Sintering 943.1.2.3.4.2 Pressure Assisted Sintering 943.1.2.3.4.3 Sintering Under Electromagnetic Radiation 963.1.2.3.4.4 Sintering Slip-Cast Specimens Under Magnetic Field 973.1.2.3.4.5 Reaction-Preceded Sintering 973.1.2.3.4.6 Use of Sintering Aids 983.1.3 Bulk Chemical Vapor Deposition (CVD) 983.1.4 Glass-Ceramics Fabrication by Controlled Glass Crystallization 983.1.4.1 Introduction 983.1.4.2 Glass Crystallization: Basic Theory 1003.1.4.2.1 Nucleation 1003.1.4.2.2 Crystal Growth 1023.1.4.2.3 Phase Separation in Glass 1023.1.4.2.4 Crystal Morphologies 1033.1.4.3 Requirements for the Obtainment of Performant Glass-Ceramics 1033.1.4.3.1 Nucleators 1033.1.4.4 Influence of Controlled Glass Crystallization on Optical Transmission 1043.1.4.4.1 Full Crystallization 1053.1.5 Bulk Sol–Gel 1053.1.6 Polycrystalline to Single Crystal Conversion via Solid-State Processes 1073.1.7 Transparency Conferred to Non-cubic Materials by Limited Lattice Disordering 1093.1.8 Transparent Non-cubic Nanoceramics 1093.1.9 Grinding and Polishing 1093.2 Characterization 1113.2.1 Characterization of Particles, Slurries, Granules, and Green Bodies Relevant in Some Transparent Ceramics Fabrication 1113.2.1.1 Powder Characterization 1123.2.1.2 Granules Measurement and Slurry Characterization 1133.2.1.3 Green-Body Characterization 1143.2.2 Scatters Topology Illustration 1153.2.2.1 Laser-Scattering Tomography (LST) 1163.2.3 Discrimination Between Translucency and High Transmission Level 1163.2.4 Bulk Density Determination from Optical Transmission Data 1173.2.5 Lattice Irregularities: Grain Boundaries, Cations Segregation, Inversion 1183.2.6 Parasitic Radiation Absorbers’ Identification and Spectral Characterization 1233.2.6.1 Absorption by Native Defects of Transparent Hosts 1233.2.7 Detection of ppm Impurity Concentration Levels 1243.2.8 Mechanical Issues for Windows and Optical Components 1264 Materials and Their Processing 1314.1 Introduction 1314.1.1 General 1314.1.2 List of Materials and Their Properties 1314.2 Principal Materials Description 1314.2.1 Mg and Zn Spinels 1314.2.1.1 Mg-Spinel 1314.2.1.1.1 Structure 1314.2.1.1.2 Fabrication 1364.2.1.1.3 Properties of Spinel 1464.2.1.2 Zn-Spinel 1524.2.2 γ-Al-oxynitride 1524.2.2.1 Composition and Structure 1524.2.2.2 Processing 1544.2.2.2.1 Fabrication Approaches 1544.2.2.2.2 Powder Synthesis 1554.2.2.2.3 Green Parts Forming. Sintering 1554.2.2.3 Characteristics of Densified Parts 1564.2.3 Transparent and Translucent Alumina 1574.2.3.1 Structure 1584.2.3.1.1 Utility of T-PCA 1584.2.3.2 Processing of Transparent Ceramic Alumina 1594.2.3.2.1 Raw Materials 1594.2.3.2.2 Processing 1594.2.3.3 Properties of Transparent Alumina 1634.2.4 Transparent Magnesia and Calcia 1634.2.4.1 Structure 1644.2.4.2 Raw Materials and Processing 1654.2.4.3 Properties 1674.2.4.4 Transparent Calcium Oxide 1694.2.5 Transparent YAG and Other Garnets 1694.2.5.1 Structure, Processing, and Properties of YAG 1704.2.5.1.1 Processing 1704.2.5.1.2 Properties of YAG 1744.2.5.2 LuAG 1774.2.5.3 Garnets Based on Tb 1784.2.5.4 Garnets Based on Ga 1794.2.5.5 Other Materials Usable for Magneto-Optical Components 1794.2.6 Transparent Yttria and Other Sesquioxides 1804.2.6.1 Structure of Y2O3 1804.2.6.2 Processing of Y2O3 1814.2.6.2.1 Y2O3 Powders 1814.2.6.2.2 Processing Approaches 1814.2.6.2.3 Discussion of Processing 1854.2.6.3 Properties of Y2O3 1874.2.6.4 Other Sesquioxides with Bixbyite Lattice 1874.2.6.4.1 Sc2O3 1884.2.6.4.2 Lu2O3 1894.2.7 Transparent Zirconia 1904.2.7.1 Structure: Polymorphism, Effect of Alloying 1904.2.7.2 Processing–Transparency Correlation in Cubic Zirconia Fabrication 1924.2.7.2.1 Zirconia Powders 1924.2.7.2.2 Forming and Sintering 1934.2.7.3 Properties 1944.2.7.3.1 Density of Zirconias 1944.2.7.4 Types of Transparent Zirconia 1954.2.7.4.1 TZPs 1954.2.7.4.2 Cubic ZrO2 1954.2.7.4.3 Monoclinic Zirconia 1964.2.7.4.4 Electronic Absorption 1974.2.8 Transparent Metal Fluoride Ceramics 1984.2.8.1 Crystallographic Structure 1994.2.8.2 Processing of Transparent-Calcium Fluoride 1994.2.8.3 Properties 2004.2.9 Transparent Chalcogenides 2014.2.9.1 Composition and Structure 2014.2.9.2 Processing 2014.2.9.3 Properties 2034.2.10 Ferroelectrics 2034.2.10.1 Ferroelectrics with Perovskite-Type Lattice 2034.2.10.2 PLZTs: Fabrication and Properties 2044.2.10.2.1 Electro-optic Properties of PLZTs 2074.2.10.3 Other Perovskites Including Pb 2074.2.10.4 Perovskites Free of Pb 2084.2.10.4.1 Ba Metatitanate 2084.2.10.4.2 Materials Based on the Potassium Niobate-sodium Niobate System 2094.2.11 Transparent Glass-Ceramics 2104.2.11.1 Transparent Glass Ceramics Based on Stuffed β-Quartz Solid Solutions 2104.2.11.2 Transparent Glass Ceramics Based on Crystals Having a Spinel-Type Lattice 2124.2.11.3 Mullite-Based Transparent Glass-Ceramics 2134.2.11.4 Other Transparent Glass-Ceramics Derived from Polinary Oxide Systems 2144.2.11.5 Oxyfluoride Matrix Transparent Glass-Ceramics 2144.2.11.6 Transparent Glass-Ceramics Including Very High Crystalline Phase Concentration 2164.2.11.6.1 Materials of Extreme Hardness (Al2O3–La2O3, ZrO2) 2164.2.11.6.2 TGCs of High Crystallinity Including Na3Ca Silicates 2164.2.11.6.3 Materials for Scintillators 2174.2.11.7 Pyroelectric and Ferroelectric Transparent Glass-Ceramics 2174.2.12 Cubic Boron Nitride 2224.2.13 Ultrahard Transparent Polycrystalline Diamond Parts 2224.2.13.1 Structure 2224.2.13.2 Fabrication 2244.2.13.3 Properties 2254.2.14 Galium Phosphide (GaP) 2254.2.15 Transparent Silicon Carbide and Nitride and Aluminium Oxynitride 2265 TC Applications 2275.1 General Aspects 2275.2 Brief Description of Main Applications 2275.2.1 Envelopes for Lighting Devices 2275.2.2 Transparent Armor Including Ceramic Layers 2295.2.2.1 Armor: General Aspects 2295.2.2.1.1 The Threats Armor Has to Defeat (Projectiles) 2295.2.2.1.2 The Role of Armor 2305.2.2.1.3 Processes Generated by the Impact of a Projectile on a Ceramic Strike-Face (Small Arm Launchers) 2315.2.2.1.4 Final State of the Projectile/Armor Impact Event Participants 2345.2.2.1.4.1 Armor Performance Descriptors 2355.2.2.1.5 Characteristics which Influence Armor Performance 2365.2.2.1.6 Ceramic Armor Study and Design 2365.2.2.2 Specifics of the Transparent-Ceramic Based Armor 2395.2.2.3 Materials for Transparent Armor 2435.2.2.3.1 Ceramics 2435.2.2.3.2 Single Crystals 2455.2.2.3.3 Glass-Ceramics 2465.2.2.3.4 Glasses 2485.2.2.4 Examples of Transparent Ceramics Armor Applications 2485.2.3 Infrared Windows 2495.2.3.1 The Infrared Region 2495.2.3.2 Background Regarding Heavy Duty Windows 2495.2.3.2.1 Threats to Missile IR Domes: Material Characteristics Relevant for Their Protection 2495.2.3.2.1.1 Impact of Particulates (Erosion) 2495.2.3.2.1.2 Thermal Shock 2505.2.3.3 Applications of infrared transparent ceramics 2515.2.3.3.1 Missile Domes and Windows for Aircraft-Sensor Protection 2515.2.3.3.2 Laser Windows: Igniters, Cutting Tools, LIDARs 2515.2.3.3.2.1 Igniters 2515.2.3.3.2.2 LIDAR-Windows 2525.2.3.3.3 Windows for Vacuum Systems 2525.2.3.4 Ceramic Materials Optimal for the Various IR Windows Applications 2525.2.3.4.1 Competitor Materials: Glasses and Single Crystals 2535.2.3.4.2 Glasses 2535.2.3.4.3 Single Crystals 2535.2.3.4.4 Sapphire 2545.2.3.4.5 Crystals for the 8–12 μm Window 2545.2.3.5 Radomes 2545.2.4 Transparent Ceramics for Design, Decorative Use, and Jewelry 2545.2.5 Components of Imaging Optic Devices (LENSES) 2585.2.6 Dental Ceramics 2605.2.7 Applications of Transparent Ferroelectric and Pyroelectric Ceramics 2625.2.7.1 Flash Goggles 2635.2.7.2 Color Filter 2635.2.7.3 Stereo Viewing Device 2645.2.7.4 Applications of Second-Generation (Non-PLZT) Ferroelectric Ceramics 2655.2.8 Applications of Ceramics with Magnetic Properties 2655.2.9 Products Based on Ceramic Doped with Transition and/or Rare-Earth Cations 2675.2.9.1 Gain Media for Solid-State Lasers 2675.2.9.1.1 Lasers: Definition and Functioning Mechanisms 2675.2.9.1.1.1 Lasing Mechanisms 2675.2.9.1.2 Laser Systems Efficiency: Characterizing Parameters 2775.2.9.1.3 Laser Oscillators and Amplifiers 2775.2.9.1.4 Device Operation Related Improvements Allowing Increase of Ceramic Lasers Performance 2785.2.9.1.4.1 Diode Lasers as Pumping Sources 2785.2.9.1.4.2 Cryogenic Operation 2785.2.9.1.4.3 Cavity-Loss Control 2795.2.9.1.4.4 Laser Output Signal Manipulation 2805.2.9.1.4.5 Lasing Device Configuration Optimization 2815.2.9.1.4.6 ThinZag Configuration 2815.2.9.1.4.7 Virtual Point Source Pumping 2825.2.9.1.5 Ceramic Gain Media (Host+Lasant Ion) Improvements 2835.2.9.1.5.1 The Hosts 2835.2.9.1.5.2 Principal Lasing Cations Operating in Ceramic Hosts 2895.2.9.1.6 Applications of Ceramic Lasers 2995.2.9.1.6.1 Materials Working 2995.2.9.1.6.2 Laser Weapons 3005.2.9.1.6.3 Combustion Ignitors: Cars and Guns 3005.2.9.1.6.4 Other Applications 3005.2.9.2 Q-switches 3035.2.9.2.1 General 3035.2.9.2.2 Transition Metal Cations Usable for Switching 3045.2.9.2.2.1 Co2+ 3045.2.9.2.2.2 Cr4+,5+ 3065.2.9.2.2.3 V3+ 3085.2.9.2.2.4 Cr2+ (d4), Fe2+ (d6) 3095.2.9.3 Ceramic Phosphors for Solid State Lighting Systems 3095.2.9.3.1 Artificial Light Sources: General Considerations 3095.2.9.3.1.1 Conventional Light Sources Powered by Electricity 3105.2.9.3.1.2 Incandescent Lamps 3115.2.9.3.1.3 Discharge Lamps 3115.2.9.3.1.4 Fluorescent Lamps 3135.2.9.3.1.5 Solid-State Lighting Sources 3135.2.9.3.2 Transparent Bulk Ceramics Based Phosphors for Light Sources Based on LEDs 3145.2.9.3.2.1 Ce3+:YAG and Ce3+, RE3+:YAG Phosphors 3145.2.9.3.2.2 Bathochrome Moving (Redshifting) of Ce3+ Emission by YAG Lattice Straining 3185.2.9.3.2.3 Summary of SSLSs 3215.2.9.4 Scintillators 3216 Future Developments 3257 Conclusions 327References 329Index 357