SINGAPORE Functional Materials Electrical, Dielectric, Electromagnetic, Optical and Magnetic Applications Deborah D. L Chung State University of New York at Buffalo, USAy^, NEW JERSEY LONDON ^ World Scientific BEIJING SHANGHAI HONG KONG TAIPEI CHENNAI
Contents Preface vii 1. Introduction to Functional Materials and their Applications 1 1.1 Types of materials 1 1.2 Composite materials 3 1.3 Carbon 6 1.4 Smart structures 8 1.5 Intrinsic smartness 9 1.5.1 Self-sensing cement-matrix composites 9 1.5.2 Self-sensing polymer-matrix composites 13 1.5.3 Self-actuating materials 21 1.5.4 Self-healing materials 21 1.6 Extrinsic smartness 22 1.6.1 Sensing using optical fibers 22 1.6.2 Sensing and actuation using piezoelectric devices 23 1.6.3 Actuation using electrostrictive and magnetostrictive devices 23 1.6.4 Actuation using the shape-memory effect 24 1.6.5 Actuation using magnetorheological fluids 25 1.7 Functional applications 26 1.7.1 Electronic applications 26 1.7.2 Thermal applications 29 1.7.3 Energy harvesting 31 1.7.4 Energy storage 32 1.7.5 Sensing and healing 33 1.7.6 Actuation 33 1.7.7 Thermal management 34 xi
xii Functional Materials 1.7.8 Electromagnetic applications 34 1.7.9 Charge dissipation 35 1.7.10 Microelectronic packaging 36 1.7.11 Datastorage 36 1.7.12 Environmental protection 36 Review questions 38 References 39 2. Electrical Conduction Behavior 41 2.1 Origin of electrical conduction 41 2.2 Volume electrical resistivity 42 2.3 Resistivity-density product 46 2.4 Sheet resistance 47 2.5 Surface resistance 47 2.6 Contact electrical resistivity 49 2.7 Electric power and resistance heating 49 2.8 Effect of temperature on the electrical resistivity 52 2.9 Electrical conduction evaluation methods 55 2.9.1 Volume electrical resistivity measurement 55 2.9.2 Surface electrical resistance measurement 63 2.9.3 Contact electrical resistivity measurement 66 2.9.3.1 Configuration A 66 2.9.3.2 Configuration B 67 2.10 Effect of strain on the electrical resistivity (piezoresistivity) 70 2.11 Seebeck effect (a thermoelectric effect) 71 2.12 Semiconductors and theirjunctions 77 2.12.1 Intrinsic and extrinsic semiconductors 77 2.12.2 The/m-junction 83 Example problems 86 Review questions 92 References 93 Supplementary reading 93
Contents xiii 3. Dielectric Behavior 95 3.1 Relative dielectric constant 96 3.2 Calculation of the relative dielectric constant of a composite 100 3.2.1 Parallel configuration 100 3.2.2 Series configuration 102 3.3 Origin of dielectric behavior 103 3.4 Lossy capacitor 108 3.4.1 Lossy capacitor modeled as a capacitor and a resistor in parallel 109 3.4.2 Lossy capacitor modeled as a capacitor and a resistor in series 119 3.5 Dielectric material evaluation 123 3.5.1 Measurement of the relative dielectric constant 123 3.5.2 Measurement of the impedance 126 3.5.3 Frequency dependence of the impedance 127 3.5.4 Effect of polarization on the electrical resistivity 130 3.6 Electrical insulation 133 3.7 Conversion between mechanical energy and electrical energy 134 3.7.1 Conversion of mechanical energy to electrical energy 135 3.7.1.1 Scientific basis 135 3.7.1.2 Effect of stress on the charge center separation 144 3.7.1.3 Effect of stress on the relative dielectric constant 145 3.7.2 Conversion of electrical energy to mechanical energy 146 3.7.2.1 Effect of electric field on the charge Center separation 147
uv Functional Materials 3.7.2.2 Effect of the electric field on the relative dielectric constant 149 3.7.3 Electromechanical coupling factor 149 3.7.4 Piezoelectric materials 150 3.7.5 Piezoelectric composites principles 164 3.8 Electrets 168 3.9 Piezoelectret effect 171 3.10 Pyroelectric effect 174 3.11 Electrostrictive behavior 176 3.12 Electrorheology '. 178 3.13 Solid electrolytes 182 3.14 Composite materials for dielectric applications 182 3.14.1 Composites for electrical insulation 182 3.14.1.1 Polymer-matrix composites 183 3.14.1.2 Ceramic-matrix composites 184 3.14.2 Composites for capacitors 184 3.14.2.1 Polymer-matrix composites 184 3.14.2.2 Ceramic-matrix composites 185 3.14.3 Composites for piezoelectric functions 185 3.14.3.1 Polymer-matrix composites 185 3.14.3.2 Ceramic-matrix composites 186 3.14.4 Composites for microwave switching and electric field grading 186 3.14.5 Composites for electromagnetic windows 187 Example problems 187 Review questions 198 Supplementary reading 200 4. Electromagnetic Behavior 201 4.1 Electromagnetic applications 201 4.2 Electromagnetic radiation 203 4.2.1 Electromagnetic waves 203 4.2.2 Photon energy, frequency and wavelength 205 4.2.3 Propagation of electromagnetic radiation 207 4.2.4 Skin effect 208 4.2.5 Faraday's Law and Lenz's Law 209
Contents xv 4.3 Applications of Faraday's Law and Lenz's Law 211 4.3.1 Metal detection 211 4.3.2 Eddy current inspection 211 4.3.3 Transformer 213 4.3.4 Conversion of mechanical energy to electrical energy 214 4.4 Electromagnetic shielding 216 4.5 Low observability 221 4.6 Composite materials for electromagnetic functions 223 4.6.1. Composite materials with discontinuous fillers 223 4.6.2 Composite materials with continuous fillers 225 4.6.3 Relationship of EMI shielding effectiveness, electrical resistivity and surface area 226 4.6.4 Summary 230 Example problems 230 Review questions 235 Supplementary reading 235 5. Optical Behavior 237 5.1 Optical behavior of materials 237 5.2 Reflection and refraction 242 5.3 Optical fiber 246 5.4 Light sources 255 5.4.1 Light emitting diodes 255 5.4.2 Lasers 256 5.4.3 Gas-discharge lamps 262 5.5 Light detection and photocopying 262 5.6 Liquid crystal display 266 5.7 Thermal emission 268 5.8 Compact disc 270 5.9 Composite materials for optical applications 272 5.9.1 Composite materials for optical waveguides 272 5.9.2 Composite materials for optical filters 272 5.9.3 Composite materials for lasers 273
xvi Functional Materials Example problems 273 Review questions 279 Supplementary reading 279 6. Magnetic Behavior 281 6.1 Force generated by the interaction of a magnetic field with moving charged particles 281 6.1.1 Hall effect 282 6.1.2 Motor and fly wheel 282 6.1.3 Magnetic pump for electrically conductive fluids 284 6.1.4 Loudspeaker 284 6.1.5 Mass spectrometer 285 6.2 Magnetic moment 286 6.3 Ferromagnetic behavior 289 6.4 Paramagnetic behavior 297 6.5 Ferrimagnetic behavior 298 6.6 Antiferromagnetic behavior 302 6.7 Hard and soft magnets 303 6.8 Magnetic shielding 305 6.9 Composite material with a magnetic filler and a non-magnetic matrix 309 6.10 Diamagnetic behavior 313 6.11 Magnetostriction and Villari effect 314 6.12 Ferromagnetic shape memory effect 318 6.13 Magnetoresistance and magnetic multilayer 321 6.14 Magnetorheology 324 6.15 Nondestructive evaluation using magnetic particles 326 6.16 Composites for magnetic applications 328 6.16.1 Magnetic composites for nondestructive evaluation 328 6.16.2 Metal-matrix composites for magnetic applications 329 6.16.3 Polymer-matrix composites for magnetic applications 330
Contents xvii 6.16.4 Ceramic-matrix composites for magnetic applications 331 Example problems 332 Review questions 336 Supplementary reading 337 Index 339