Introduction to Nanotechnology

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4.5. METHODS OF SYNTHESIS 99 isopropoxide is added to the solution. The titanium acts as a catalyst for the reaction. The choice of catalyst determines the size of the particles produced. For instance, 80-nm particles have been made using titanium. A surfactant such as oleic acid can be added to the solution to coat the particles and prevent aggregation. 4.5.3. Thermolysis Nanoparticles can be made by decomposing solids at high temperature having metal cations, and molecular anions or metal organic compounds. The process is called thermolysis. For example, small lithium particles can be made by decomposing lithium azide, LiN3. The material is placed in an evacuated quartz tube and heated to 400°C in the apparatus shown in Fig. 4.26. At about 370°C the LiN3 decomposes, releasing N2 gas, which is observed by an increase in the pressure on the vacuum gauge. In a few minutes the pressure drops back to its original low value, indicating that all the N2 has been removed. The remaining lithium atoms coalesce to form small colloidal metal particles. Particles less than 5 nm can be made by this method. Passivation can be achieved by introducing an appropriate gas. The presence of these nanoparticles can be detected by electron paramagnetic resonance (EPR) of the conduction electrons of the metal particles. Electron paramagnetic resonance, which is described in more detail in Chapter 3, measures the energy absorbed when electromagnetic radiation such as microwaves induces a transition between the spin states m, split by a DC magnetic field. Generally the experiment measures the derivative of the absorption as a fimction of an increasing DC magnetic field. Normally because of the low penetration depth of the microwaves into a metal, it is not possible to observe the EPR of the conduction electrons. FURNACE VACUUM GAUGE MOLECULAR \ \ \ \ PUMP \ \ I \ I \ \ \ \ I I 77 / \ / I \ / / \ / / \ / / I \ / EVACUATED SAMPLE FORE QUARTZ TUBE in Ta foil PUMP Figure 4.26. Apparatus used to make metal nanoparticles by thermally decomposing solids consisting of metal cations and molecular anions, or metal organic solids. (F. J. Owens, unpublished.)
100 PROPERTIES OF INDIVIDUAL NANOPARTICLES m 2 u ..... ........... . - 600-1 I I I I I I I I I I I I I _ . - ......... 400 E . .. -400 ... 0. ....... 4 -600 " I I ' I 31 50 3200 ' ' 3250 ' ' ' 3300 -200 . - e . - MAGNETIC FIELD (G) Figure 4.27. Electron paramagnetic resonance spectra at 300K (a) and 77K (b) arising from conduction electrons in lithium nanoparticles formed from the thermal decomposition of LiN3. (F. J. Owens, unpublished.) However, in a collection of nanoparticles there is a large increase in surface area, and the size is of the order of the penetration depth, so it is possible to detect the EPR of the conduction electrons. Generally EPR derivative signals are quite symmetric, but for the case of conduction electrons, relaxation effects make the lines very asymmetric, and the extent of the asymmetry is related to the small dimensions of the particles. This asymmetry is quite temperature dependent as indicated in Fig. 4.27, which shows the EPR spectra of lithium particles at 300 and 77K that had been made by the process described above. It is possible to estimate the size of the particles from the g-factor shift and line width of the spectra. 4.5.4. Pulsed Laser Methods Pulsed lasers have been used in the synthesis of nanoparticles of silver. Silver nitrate solution and a reducing agent are flowed through a blenderlike device. In the blender there is a solid disk, which rotates in the solution. The solid disk is subjected to pulses from a laser beam creating hot spots on the surface of the disk. The apparatus is illustrated in Fig. 4.28. Silver nitrate and the reducing agent react at these hot spots, resulting in the formation of small silver particles, which can be separated from the solution using a centrifuge. The size of the particles is controlled by the (b)
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INTRODUCTION TO NANOTECHNOLOGY Char
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CONTENTS Preface xi 1 Introduction
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5.2 Carbon Molecules 103 5.2.1 Natu
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9.4 Excitons 244 9.5 Single-Electro
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PREFACE In recent years nanotechnol
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INTRODUCTION The prefix nano in the
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INTRODUCTION 3 he recognized the ex
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1000 (I) a 900 4 800 a 900 I 6 700
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INTRODUCTION 7 developed before the
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2.1. STRUCTURE 9 mechanics, the res
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X T 2.1. STRUCTURE 11 Figure 2.4. C
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2.1. STRUCTURE 13 Figure 2.6. Thirt
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Sodium Nanoparticle Na, Magic Numbe
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2.1. STRUCTURE 17 of the large anio
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2.1. STRUCTURE 19 other, and high-f
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2.2. ENERGY BANDS 21 Conduction Ban
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2.2. ENERGY BANDS 23 Figure 2.13. S
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2.2. ENERGYBANDS 25 band at point T
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A X ' Wavevector A Si c z 2.2. ENER
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2.2. ENERGY BANDS 29 bands of Figs.
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2.3. LOCALIZED PARTICLES 31 add ele
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1 meV 10 meV 100 meV FJ E W 1 eV 10
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3 METHODS OF MEASURING PROPERTIES 3
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3.2. STRUCTURE 37 Table 3.1. Crysta
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3.2. STRUCTURE 39 Figure 3.2. Two-d
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3.2. STRUCTURE 41 The widths of the
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44 METHODS OF MEASURING PROPERTIES
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46 METHODS OF MEASURING PROPERTIES
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Page 62 and 63: 3.3. MICROSCOPY 51 types of transit
Page 64 and 65: 3.3. MICROSCOPY 53 Actual diverging
Page 66 and 67: Tunneling current Tunneling current
Page 68 and 69: 3.3. MrCAOSCOPY 57 and the latter m
Page 70 and 71: 3.4. SPECTROSCOPY 59 From Eq. (3.8)
Page 72 and 73: 1 Average Panicle FWHM Size (nm) in
Page 74 and 75: CdSe colloidal NCs a = 1.2 nrn 3.4.
Page 76 and 77: El X-RAY TUBE 8000 - A 6000 - 4000
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Page 80 and 81: i 3.4. SPECTROSCOPY 69 NMR involves
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Page 84 and 85: NUMBER OF ATOMS RADIUS (nm) 1 10 1
Page 86 and 87: I L 7 3 5 7 9 11 13 15 17 NUMBER OF
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Page 90 and 91: 1.02 { 1.01 - 1 - 0.99 - 4.2. METAL
Page 92 and 93: 4.2. METAL NANOCLUSTERS 81 Figure 4
Page 94 and 95: 4.2. METAL NANOCLUSTERS 83 Figure 4
Page 96 and 97: -0 100 200 300 400 500 600 MASSICHA
Page 98 and 99: a 42. METAL NANOCLUSTERS 87 Figure
Page 100 and 101: . . . .. . - . D 111111111111111111
Page 102 and 103: 3 4 2.5 0 cn g 2 0 z d 1.5 t a 9 1
Page 104 and 105: 4.3. SEMICONDUCTING NANOPARTICLES 9
Page 106 and 107: 4.4. RARE GAS AND MOLECULAR CLUSTER
Page 108 and 109: 4.5. METHODS OF SYNTHESIS 97 d Figu
Page 112 and 113: PULSED LASER BEAM 1 1 1 1 1 I ROTAT
Page 114 and 115: 5.1. INTRODUCTION CARBON NANOSTRUCT
Page 116 and 117: 5.2. CARBON MOLECULES 105 methane d
Page 118 and 119: 5.3. CARBON CLUSTERS 107 -0 20 40 6
Page 120 and 121: PHOTON ENERGY (electron volts) 5.3.
Page 122 and 123: Figure 5.6. Structure of the CEO fu
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Page 126 and 127: (c) 5.4. CARBON NANOTUBES 115 Figur
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Page 132 and 133: 5.4. CARBON NANOTUBES 121 energy gr
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Page 144 and 145: BULK NANOSTRUCTURED MATERIALS In th
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6.1. SOLID DISORDERED NANOSTRUCTURE
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6.1. SOLID DISORDERED NANOSTRUCTURE
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6.2. NANOSTRUCTURED CRYSTALS 153 qu
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6.2. NANOSTRUCTURED CRYSTALS 155 Fi
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158 BULK NANOSTRUCTURED MATERIALS 6
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160 BULK NANOSTRUCTURED MATERIALS w
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162 BULK NANOSTRUCTURED MATERIALS 0
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164 BULK NANOSTRUCTURED MATERIALS n
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166 NANOSTRUCTURED FERROMAGNETISM f
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168 NANOSTRUCTURED FERROMAGNETISM i
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170 NANOSTRUCTURED FERROMAGNETISM M
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172 NANOSTRUCTURED FERROMAGNETISM h
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174 NANOSTRUCTURED FERROMAGNETISM d
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176 NANOSTRUCTURED FERROMAGNETISM o
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4 h $ 3 7.5. NANOCARBON FERROMAGNET
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7.6. GIANT AND COLOSSAL MAGNETORESI
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1.4 N 1 1.2 z " 1 0 v 5 h 0.8 0 0.6
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7.6. GIANT AND COLOSSAL MAGNETORESI
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7.7. FERROFLUIDS 187 Figure 7.22. M
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7.7. FECIROFLUIDS 189 Figure 7.25.
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7.7. FERRQFLUlOS 191 FerroRuids can
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FURTHER READING FURTHER READING 193
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10- IR f IA -1 8.1. INTRODUCTION 19
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8.2. INFRARED FREQUENCY RANGE 197 1
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8.2. INFRARED FREQUENCY RANGE 199 d
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s C CTI e 8 9 4( 8.2. INFRARED FREQ
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8.2.3. Raman Spectroscopy 8.2. INFR
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8.2. INFRARED FREQUENCY RANGE 205 a
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- r I 520 51 8 v 6 516 a" 51 4 51 2
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8.2. INFRARED FREQUENCY RANGE 209 i
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v) - C 3 8 600 400 100 0 e e 10 20
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i E (cm-’ ) 20 c I 1 ID 0 4x107 8
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- ? m v .- - z In C a, c C - .. . .
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Excitatior I [eV]: 2.175 2.214 2.25
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6 100 200 300 Time (ns) 8.3. LUMINE
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400 nm Laser / Free excitons Trappe
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8.4. NANOSTRUCTURES IN ZEOLITE CAGE
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FURTHER READING 225 P. Milani and C
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9.2. PREPARATION OF QUANTUM NANOSTR
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i 9.2. PREPARATION OF QUANTUM NANOS
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9.3. SIZE AND DIMENSIONALITY EFFECT
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w n 3 2 1 9.3. SIZE AND DIMENSIONAL
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WE) Quantum Dot Number of Electrons
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9.5. SINGLE-ELECTRON TUNNELING 245
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9.5. SINGLE-ELECTRON TUNNELING 247
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1 pair section ;- COT. .; . . I. .
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o.6 LWIR: T = 77 K 45" incidence AD
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9.7. SUPERCONDUCTIVITY 253 horizont
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9.7. SUPERCONDUCTIVITY 255 applied
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10.1. SELF-ASSEMBLY 10 SELF-ASSEMBL
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10.1. SELF-ASSEMBLY 259 factor of 2
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(a) (LI (dl 10.1. SELF-ASSEMBLY 261
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10.1. SELF-ASSEMBLY 263 atoms, as n
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- c v) ._ C 3 2 9 40 c - .- e m v w
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10.2. CATALYSIS 267 where the lengt
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10.2. CATALYSIS 269 are also other
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1600 2 1200 t p - Bi2M020, 10.2. CA
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7 - I 2,330 m .- c r 0 2 2,300 - u)
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10.2. CATALYSIS 275 with a top and
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10.2. CATALYSIS 277 based on the pr
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10.2. CATALYSIS 279 CnHlnfl, which
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I1 ORGANIC COMPOUNDS AND POLYMERS 1
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11.2. FORMING AND CHARACTERIZING PO
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1 1.3. NANOCRYSTALS 285 This expres
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-1 5 0) C a, -1 1 000 300 100 30 10
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11.3. NANOCRYSTALS 289 Table 11.1.
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11.3. NANOCRYSTALS 291 R’ groups
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11.4. POLYMERS 293 Figure 11.9. Ske
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11.5. SUPRAMOLECULAR STRUCTURES 295
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M Et3P OTf M=Pd M=Pt M=Pd, 41 % M=P
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11.5. SVPRAMOLECUUAR STRUCTURES 2s
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11 5. SUPRAMOLECULAR STRUCTURES 303
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BiodegradaWe surface 4 Functional g
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FURTHER READING 309 F. J. Owens and
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12.2. BIOLOGICAL BUILDING BLOCKS 31
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314 BIOLOGICAL MATERIALS which we w
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316 BIOLOGICAL MATERIALS Table 12.2
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318 BIOLOGICAL MATERtALS i J / Flgu
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320 BIOLOGICAL MATERIALS Pyrimidine
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322 BlOLMjlCAL MATERiALS (a) DNA do
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324 BIOLOGICAL MATERIALS so each wo
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326 BIOLOGICAL MATERIALS 12.4.2. Mi
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328 BIOLOGICAL MATERIALS tions they
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330 BIOLOGICAL MATERIALS hardened f
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13 NANOMACHINES AND NANODEVICES In
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334 NANOMACHINES AND NANODEVICES CA
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336 NANOMACHINES AND NANODEVICES Op
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338 NANOMACHINES AND NANODEVICES ti
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340 NANOMACHINES AN0 NANODEVICES PO
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342 NANOMACHINES AND NANODEVICES X
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344 NANOMACHINES AND NANODEVICES na
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346 NANOMACHINES AND NANODEVICES 31
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348 NANOMACHINES AND NANODEVICES -
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350 NANOMACHINES AND NANODEVICES re
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352 NANOMACHINES AND NANODEVICES 1
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354 NANOMACHINES AND NANODEVICES -1
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A.l. INTRODUCTION APPENDIX A FORMUL
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A.3. PARTIAL CONFINEMENT 359 limiti
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APPENDIX B TABULATIONS OF SEMICONDU
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TABULATIONS OF SEMICONDUCTING MATER
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Table B.8. Effective masses m+ rela
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372 INDEX amoeba, 3 16 amphiphilic,
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374 INDEX CdS, 9, 130, 213, 216, 36
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376 INDEX dispersion, 277 disulfide
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378 INDEX Ga (gallium) (continued)
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380 INDEX length (continued) critic
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382 INDEX multiple ionization, 93 r
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384 INDEX pi-conjugation, 282, 292
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silica, 269 silica-alumina, 269, 27
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388 INDEX wavefimction (continued)
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