Experimental Micro/Nanoscale Thermal Transport

PREFACE xi 1 INTRODUCTION 1 1.1 Unique Feature of Thermal Transport in Nanoscale and Nanostructured Materials 1 1.1.1 Thermal Transport Constrained by Material Size 2 1.1.2 Thermal Transport Constrained by Time 6 1.1.3 Thermal Transport Constrained by the Size of Physical Process 8 1.2 Molecular Dynamics Simulation of Thermal Transport at Micro/Nanoscales 10 1.2.1 Equilibrium MD Prediction of Thermal Conductivity 11 1.2.2 Nonequilibrium MD Study of Thermal Transport 15 1.2.3 MD Study of Thermal Transport Constrained by Time 18 1.3 Boltzmann Transportation Equation for Thermal Transport Study 21 1.4 Direct Energy Carrier Relaxation Tracking (DECRT) 32 1.5 Challenges in Characterizing Thermal Transport at Micro/Nanoscales 44 References 45 2 THERMAL CHARACTERIZATION IN FREQUENCY DOMAIN 47 2.1 Frequency Domain Photoacoustic (PA) Technique 47 2.1.1 Physical Model 48 2.1.2 Experimental Details 50 2.1.3 PA Measurement of Films and Bulk Materials 52 2.1.4 Uncertainty of the PA Measurement 55 2.2 Frequency Domain Photothermal Radiation (PTR) Technique 57 2.2.1 Experimental Details of the PTR Technique 57 2.2.2 PTR Measurement of Micrometer-Thick Films 58 2.2.3 PTR with Internal Heating of Desired Locations 60 2.3 Three-Omega Technique 62 2.3.1 Physical Model of the 3omega Technique for One-Dimensional Structures 62 2.3.2 Experimental Details 65 2.3.3 Calibration of the Experiment 67 2.3.4 Measurement of Micrometer-Thick Wires 69 2.3.5 Effect of Radiation on Measurement Result 70 2.4 Optical Heating Electrical Thermal Sensing (OHETS) Technique 73 2.4.1 Experimental Principle and Physical Model 73 2.4.2 Effect of Nonuniform Distribution of Laser Beam 74 2.4.3 Experimental Details and Calibration 77 2.4.4 Measurement of Electrically Conductive Wires 79 2.4.5 Measurement of Nonconductive Wires 81 2.4.6 Effect of Au Coating on Measurement 83 2.4.7 Temperature Rise in the OHETS Experiment 84 2.5 Comparison Among the Techniques 85 References 86 3 TRANSIENT TECHNOLOGIES IN THE TIME DOMAIN 87 3.1 Transient Photo-Electro-Thermal (TPET) Technique 87 3.1.1 Experimental Principles 88 3.1.2 Physical Model Development 88 3.1.3 Effect of Nonuniform Distribution and Finite Rising Time of the Laser Beam 90 3.1.4 Experimental Setup 92 3.1.5 Technique Validation 93 3.1.6 Thermal Characterization of SWCNT Bundles and Cloth Fibers 95 3.2 Transient Electrothermal (TET) Technique 98 3.2.1 Physical Principles of the TET Technique 98 3.2.2 Methods for Data Analysis to Determine the Thermal Diffusivity 100 3.2.3 Effect of Nonconstant Electrical Heating 101 3.2.4 Experimental Details 102 3.2.5 Technique Validation 104 3.2.6 Measurement of SWCNT Bundles 105 3.2.7 Measurement of Polyester Fibers 107 3.2.8 Measurement of Micro/Submicroscale Polyacrylonitrile Wires 109 3.3 Pulsed Laser-Assisted Thermal Relaxation Technique 113 3.3.1 Experimental Principles 113 3.3.2 Physical Model for the PLTR Technique 114 3.3.3 Methods to Determine the Thermal Diffusivity 116 3.3.4 Experimental Setup and Technique Validation 117 3.3.5 Measurement of Multiwalled Carbon Nanotube (MWCNT) Bundles 118 3.3.6 Measurement of Individual Microscale Carbon Fibers 122 3.4 Super Channeling Effect for Thermal Transport in Micro/Nanoscale Wires 123 3.5 Multidimensional Thermal Characterization 128 3.5.1 Sample Preparation 129 3.5.2 Thermal Characterization Design 130 3.5.3 Thermal Transport Along the Axial Direction of Amorphous TiO2 Nanotubes 131 3.5.4 Thermal Transport in the Cross-Tube Direction of Amorphous TiO2 Nanotubes 133 3.5.5 Evaluation of Thermal Contact Resistance Between Amorphous TiO2 Nanotubes 136 3.5.6 Anisotropic Thermal Transport in Anatase TiO2 Nanotubes 137 3.6 Remarks on the Transient Technologies 139 References 139 4 STEADY-STATE THERMAL CHARACTERIZATION 141 4.1 Generalized Electrothermal Characterization 142 4.1.1 Generalized Electrothermal (GET) Technique: Combined Transient and Steady States 142 4.1.2 Experimental Setup 144 4.1.3 Experimental Details 145 4.1.4 Measurement of MWCNT Bundle with L = 3.33 mm and D = 94.5 mum 147 4.1.5 Measurement of MWCNT Bundle with L = 2.90 mm and D = 233 mum 153 4.1.6 Analysis of the Tube-to-Tube Thermal Contact Resistance 157 4.1.7 Effect of Radiation Heat Loss 158 4.2 Get Measurement of Porous Freestanding Thin Films Composed of Anatase TiO2 Nanofibers 159 4.2.1 Sample Preparation 160 4.2.2 R--T Calibration 162 4.2.3 TET Measurement of Thermal Conductivity and Thermal Diffusivity 163 4.2.4 Thermophysical Properties of Samples with Different Dimensions 167 4.2.5 The Intrinsic Thermal Conductivity of TiO2 Nanofibers 170 4.2.6 Uncertainty Analysis 172 4.3 Measurement of Micrometer-Thick Polymer Films 173 4.3.1 Sample Preparation 173 4.3.2 Electrical Resistance (R)-Temperature Coefficient Calibration 175 4.3.3 Measurement of Thermal Conductivity and Thermal Diffusivity 175 4.3.4 Thermophysical Properties of P3HT Thin Films with Different Dimensions 178 4.4 Steady-State Electro-Raman Thermal (SERT) Technique 182 4.4.1 Experimental Principle and Physical Model Development 183 4.4.2 Experimental Setup for Measuring CNT Buckypaper 187 4.4.3 Calibration Experiment 188 4.4.4 Thermal Characterization of MWCNT Buckypapers 190 4.4.5 Thermal Conductivity Analysis 192 4.4.6 Uncertainty Induced by Location of Laser Focal Point 195 4.4.7 Effect of Thermal and Electrical Contact Resistances and Thermal Transport in Electrodes 196 4.5 SERT Measurement of MWCNT Bundles 197 4.6 Extension of the Steady-State Techniques 202 References 202 5 STEADY-STATE OPTICAL-BASED THERMAL PROBING AND CHARACTERIZATION 205 5.1 Sub-10-nm Temperature Measurement 205 5.1.1 Introduction to Sub-10-nm Near-Field Focusing 206 5.1.2 Experimental Design and Conduction 208 5.1.3 Measurement Results 210 5.1.4 Physics Behind Near-Field Focusing and Thermal Transport 213 5.2 Thermal Probing at nm/SUB-nm Resolution for Studying Interface Thermal Transport 219 5.2.1 Introduction 219 5.2.2 Experimental Method 220 5.2.3 Experimental Results 221 5.2.4 Comparison with Molecular Dynamics Simulation 225 5.2.5 Discussion 226 5.3 Optical Heating and Thermal Sensing using Raman Spectrometer 234 5.3.1 Thermal Conductivity Measurement of Suspended Filmlike Materials 234 5.3.2 Thermal Conductivity Measurement of Suspended Nanowires 236 5.4 Bilayer Sensor-Based Technique 237 5.5 Further Consideration for Micro/Nanoscale Thermal Sensing and Characterization 238 5.5.1 Electrothermal Sensing in Thermal Characterization of Coatings/Films 239 5.5.2 Transient Photo-Heating and Thermal Sensing of Wirelike Samples 240 References 242 INDEX 247