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An introduction to nano-science and nanotechnology, now in English !!
I am sorry about mistakes like "Fisics" instead of "Physics" and "alone atoms" where should be "sinlge atoms".

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  1. 1. NANOSCIENCE NANOTECHNOLOGY Walkiria Eyre [email_address]
  2. 2. TOPICS <ul><li>Nanoscience and nanotechnology concepts </li></ul><ul><li>The begining of the nanoscience research </li></ul><ul><li>Abstract on some nanostructures and it´s aplications </li></ul><ul><li>Magnetic nanostructures </li></ul>Part 1 Part 2
  3. 3. Nanoscience Fisics Engeneering Biology Chemistry Basic life processes Chemical reactions Medicine Classical Fisics Quantum Fisics Smart materials Technological aplications
  4. 4. Nanotechnology <ul><li>Using nanoscience to create: </li></ul><ul><ul><li>Smart materials </li></ul></ul><ul><ul><li>Engines (in nanometric scale) </li></ul></ul><ul><ul><li>Devices (with an enormous amount of aplications) </li></ul></ul>
  5. 5. Nanostructures <ul><li>Between 1 a 100 nm </li></ul><ul><li>What is smaller than 1 nanometer ? </li></ul><ul><ul><li>Alone atoms </li></ul></ul><ul><ul><li>Small and simple molecules </li></ul></ul>
  6. 8. NANO = 10 -9 <ul><li>Why is this size so special ? </li></ul><ul><ul><li>Nanostructures are the smallest solid things we can do </li></ul></ul><ul><ul><li>Quantum effects start to appear </li></ul></ul><ul><ul><li>Root of fundamental properties of the materials </li></ul></ul>
  7. 9. Nanofabrication techniques <ul><li>Top-down : nanostructure is obtained by successive cuts </li></ul><ul><li>Bottom-up : nanostructure is build in an atom by atom deposition </li></ul>
  8. 10. Beginning of Nanoscience <ul><li>1959 – Richard Feynman </li></ul><ul><ul><li>“ there´s plenty of room at the bottom” </li></ul></ul><ul><li>New instruments: </li></ul><ul><ul><li>Tunneling microscopes </li></ul></ul><ul><ul><li>Atomic force microscopes </li></ul></ul><ul><ul><li>Near-field microscopes </li></ul></ul>
  9. 11. <ul><li>1981 – Gerd Binning e Heinrich Roher (laboratório IBM em Zurique) </li></ul><ul><li>STM </li></ul><ul><ul><li>SCANNING TUNNELING MICROSCOPE </li></ul></ul>
  10. 12. IBM Logo xenon atoms on nickel substract
  11. 13. <ul><li>Image obtained by scanning the exponencial decrease of the tunneling current </li></ul>
  12. 14. Instruments: <ul><li>STM: scanning tunneling microscope </li></ul><ul><li>AFM: atomic force microscope </li></ul><ul><ul><li>contact AFM </li></ul></ul><ul><ul><li>non contact AFM </li></ul></ul><ul><ul><li>dynamic contact AFM </li></ul></ul><ul><li>MFM: magnetic force microscope </li></ul><ul><li>EFM: electrostatic force microscope </li></ul><ul><li>SVM: scanning voltage microscope </li></ul><ul><li>KPFM: kelvin probe force microscope </li></ul><ul><li>SCM: scanning capacitance microscope </li></ul><ul><li>FMM: force modulation microscope </li></ul><ul><li>SThM: scanning thermal microscope </li></ul><ul><li>NSOM: near-field scanning optical microscope </li></ul><ul><li>SNOM: scanning near-field optical microscope </li></ul>From:
  13. 15. STM From:
  14. 16. Piezoelectric effect <ul><li>The piezoel ec tric effect was discovered by Pierre e Jacques Curie in 1880 and consist s on varia tion of fisical dimens ions of cert ain materia l s subjected to an externally applied voltage. O pposite also occurs , e.g., when a mechanical stress is applied, a voltage is generated in response. </li></ul><ul><li>The quartz and the t ourmaline, natural crystals , are piezoel ec tric. </li></ul>
  15. 17. Images creation process <ul><li>A tip scan the surface at a distance of few atomic diameters </li></ul><ul><li>The tunneling current decreases exponentially with increasing distance </li></ul>From:
  16. 18. Continue... <ul><li>Colors are added taking in account different properties like height, curvature, etc... </li></ul>From:
  17. 19. <ul><li>Impurity on copper </li></ul>From:
  18. 20. <ul><li>Sodium and iodine on copper </li></ul>From:
  19. 21. <ul><li>Iron on copper </li></ul>From:
  20. 22. <ul><li>“ atom” </li></ul><ul><li>Iron on copper </li></ul>From:
  21. 23. <ul><li>Carbon monoxide on platinum (111) </li></ul>From:
  22. 24. Process: From:
  23. 25. Examples: From:
  24. 26. Nanostructures: <ul><li>The nanostructures can be divided in some classes, like: </li></ul><ul><li>Nanoparticles </li></ul><ul><li>Nanofilms </li></ul><ul><li>Nanowires </li></ul><ul><li>Nanotubes </li></ul>
  25. 27. Nanostructures and potencial aplications: <ul><li>At atomic scale: </li></ul><ul><ul><li>Quantum wells </li></ul></ul><ul><ul><ul><li>Extreme - thin layers of semiconductor material ( the well ) grown between barriers (gr ids ). The gr ids imprison electrons in the extreme- thin layers . </li></ul></ul></ul><ul><ul><ul><li>CD devices, telecomunication, optics </li></ul></ul></ul>From:
  26. 28. A typical configuration for a quantum well (AlIn)GaN LED on a sapphire substrate. Epitaxial layer thicknesses are exaggerated for clarity and are not to scale. From:
  27. 29. <ul><ul><li>Quantum dots </li></ul></ul><ul><ul><ul><li>F luorescent nanoparticles . Depending on its composition, these particles can show many different colors . </li></ul></ul></ul><ul><ul><ul><li>Telecommunications, optics . </li></ul></ul></ul><ul><ul><li>Polymers </li></ul></ul><ul><ul><ul><li>Some organic materials emit light under electric c urrent action . </li></ul></ul></ul><ul><ul><ul><li>informatics </li></ul></ul></ul>From:
  28. 30. “ Lead selenide (PbSe) quantum dots like the ones in this image, <10nm in size, emit light in the visible regime (~1 to 3eV). The nanoparticles in this scanning tunneling electron micrograph are similar to those in the colorful photograph of CdSe quantum dot containing material. (Micrograph courtesy of Mick Thomas, Cornell University) ” From:
  29. 31. The emission from quantum dots is tuned by changing the particle size. These quantum dot solids, containing CdSe nanocrystals dispersed in a polymer matrix, span the visible spectrum when excited with ultraviolet light. For scale, containers are ~ 1 cm in diameter. From:
  30. 32. <ul><li>Part icles smaller than 100 nm : </li></ul><ul><ul><li>Nanoc a psul e s </li></ul></ul><ul><ul><ul><li>Buckminsterfullerenes are the most known . D i sco vered in 1985, these part i c le s have 1 nm width. </li></ul></ul></ul><ul><ul><ul><li>Dry Lubri cant . </li></ul></ul></ul><ul><ul><li>C atal y tic n anopart icles </li></ul></ul><ul><ul><ul><li>In a 1-10 nm range , these particles, when manipulated, shows a great superf i cial area, improving its reactivity </li></ul></ul></ul><ul><ul><ul><li>M aterials, fuels and foods production </li></ul></ul></ul>From:
  31. 33. “ Scanning tunneling microscope (STM) image of a silver surface with adsorbed potassium atoms and two C-60 buckyballs. Using the STM tip to drag one of the buckyballs around the surface, UC Berkeley researchers were able to pick up single potassium atoms at a time, subtly altering the buckyball's electronic properties with each addition. Credit: Michael Crommie/UC Berkeley. (Image courtesy of Science) ” From:
  32. 34. <ul><li>Wires with less than 100 nm di a met e r </li></ul><ul><ul><li>Carbon Nanotubes </li></ul></ul><ul><ul><ul><li>Two types exist: single wall nanotub e s, call ed “ buckytubes ” , and multi-wall nanotub e s. Described as the most important material in nanotec h nolog y , t hey can have big mechanical resistance , 50-100 times that steel in one sixth of its weight. </li></ul></ul></ul><ul><ul><ul><li>S pace and electronic industries, aviation and innumerable other areas . </li></ul></ul></ul>From:
  33. 35. <ul><li>Films with less than 100 nm thickness </li></ul><ul><ul><li>Self-assembled Mono layers </li></ul></ul><ul><ul><ul><li>Organic or inorg a nic substances that, spontane ously , form a layer of the thickness of a molecule </li></ul></ul></ul><ul><ul><ul><li>A large amount of applications based on the chemical and physical properties . </li></ul></ul></ul>From:
  34. 36. <ul><li>Self-assembled monolayer </li></ul>From:
  35. 37. <ul><ul><li>N anopartic les coverings </li></ul></ul><ul><ul><ul><li>Stainless steel layers applied by nanocr y stalin powder confer greater hardness in comparison with conventional applications. </li></ul></ul></ul><ul><ul><ul><li>Sensors. Fabrica tion of liquid cr y stal. M olecular wires . Lubrication, protection and anticorrosive layers . Stronger and hard er cut tools. </li></ul></ul></ul>From:
  36. 38. CNT
  38. 45. Topics <ul><li>Magnetism concepts </li></ul><ul><li>Magnetic materials </li></ul><ul><li>Magnetic nanostructured systems </li></ul><ul><li>Thin films </li></ul><ul><li>Giant Magnetoresistence </li></ul>
  39. 46. Spin <ul><li>Classic point of view: </li></ul><ul><ul><li>Rotation m ovement of the electron around a n axle, it means , an angular moment </li></ul></ul>
  40. 47. Magnetic moment SPIN ( angular moment) *charge* Magnetic Moment
  41. 48. Magnetic Moment
  42. 49. Magnetization <ul><li>It is the total magnetic moment of a certain amount of the substance for unit of volume </li></ul><ul><li>Due to this , electrons tend to line up when submitted to a n external magnetic field </li></ul>
  43. 50. MAGNETIZATION Alignment of electrons due to the field
  44. 51. <ul><li>In the majority of atoms total spin is null </li></ul><ul><ul><li>Due to the occupation of the orbital s </li></ul></ul><ul><ul><ul><li>Linus Pauling principle </li></ul></ul></ul><ul><li>For some elements total spin is not null </li></ul><ul><ul><li>These elements have permanent magnetic moment </li></ul></ul><ul><ul><ul><li>Examples: Iron, Cobalt, Nickel, Manganese, Gadolinium, Europium. </li></ul></ul></ul>
  45. 52. Magnetic Behaviors <ul><li>In accordance with its behavior in the presence of a n external magnetic field, the magnetic materials can be classified in: </li></ul>Metamagnetic *Superparamagnetics* Spin glass Speromagnetic Helimagnetic Diamagnetic Paramagnetic Ferromagnetic Ferrimagnetic Antiferromagnetic
  46. 53. Magnetic Susceptibility <ul><li>For a large amount class of isotropic and linear materials, we have : </li></ul><ul><li>Where M is the magnetization and H the magnetic intensity. </li></ul>
  47. 54. Diamagnetism <ul><li>It is Lenz law at atomic level </li></ul><ul><ul><li>The material charges in movement tend to cancel the effect of the variation of the magnetic flow (applied external field) </li></ul></ul><ul><ul><li>magnetic susceptibility < 1 </li></ul></ul>
  48. 55. Examples of diamagnetic substances: <ul><li>water </li></ul><ul><li>lead </li></ul><ul><li>so di um chloride </li></ul><ul><li>quartz </li></ul><ul><li>sulphur </li></ul><ul><li>diam o n d </li></ul><ul><li>gra phi te </li></ul><ul><li>li quid nitrogen </li></ul><ul><li>copper = -9,8 × 10 −6 </li></ul>
  49. 56. Interesting effects: From:
  50. 57. Paramagnetism <ul><li>The presence of a n external magnetic field produces a torque that tends to line up the magnetic moments in the same direction of the field. </li></ul>
  51. 58. Examples of paramagnetic substances <ul><li>sodium </li></ul><ul><li>aluminium = 2,3 × 10 −5 </li></ul><ul><li>copper chloride </li></ul><ul><li>nickel sulphate </li></ul><ul><li>Liquid oxygen </li></ul>
  52. 59. Ferromagnetism <ul><li>Ferromagn e tic materials have a permanent magnetization </li></ul><ul><ul><li>atoms with electrons not pair uped whose spins are guided in the same direction </li></ul></ul>It generates regions called DOMAINS
  53. 60. Ferromagnetic materials examples <ul><li>Iron = 5.500 </li></ul><ul><li>Magnetite (Fe 3 O 4 ) </li></ul><ul><li>Cobalt </li></ul><ul><li>Nickel </li></ul><ul><li>Gadolinium </li></ul>
  54. 61. FERROMAGNETISM <ul><li>Magnetic Domains </li></ul>
  55. 62. Magnetic Domains The domains are delineated with colloidal iron oxide particles FOTOMICROGRAFY (Bell Telephone Laboratories) From:
  56. 63. <ul><li>“ Estructura de dominios magneticos en laberinto observada mediante microscopia Bitter en una cinta amorfa de base Fe ” </li></ul>MICROSCOPY From:
  57. 64. CURIE TEMPERATURE <ul><li>Ferromagn e tic materials acquire paramagnetic behavior. </li></ul><ul><ul><li>Alignment with external field </li></ul></ul>16 o C Gadolinium 358 o C Nickel 1131 o C Cobalt 770 o C Iron Curie point Element
  58. 65. Hysteresis loop <ul><li>It determines the characteristics of a magnetic material. </li></ul><ul><li>It is the graph of magnetization M of the material in function of the external magnetic field applied H. </li></ul>
  59. 66. Hysteresis Loop <ul><li>It shows how much a material magnetizes under the influence of a magnetic field and how much of magnetization remains in it after the field is off. </li></ul>
  60. 67. Hysteresis Loop From:
  61. 68. Definitions: From:
  62. 69. <ul><li>Granulars: magnetic nanoparticles dispersed in a solid or liquid medium: </li></ul><ul><ul><li>Solid: granular solids </li></ul></ul><ul><ul><li>Liquid: magnetic fluids </li></ul></ul>Magnetic nanostructured systems:
  63. 70. Magnetic Behavior Configuration of minimum potential energy Magnetic domains with random orientation size temperature
  64. 71. <ul><li>Critical size </li></ul><ul><li>A set of ten nanometers </li></ul>Random orientation is not energetically favorable **Spontaneous permanent magnetization** SINGLE-DOMAIN
  65. 72. Temperature variation: <ul><li>Magnetic nanoparticles </li></ul><ul><ul><li>small magnets </li></ul></ul>Temperature increase Rotation in the magnetization direction
  66. 73. Thus... <ul><li>Magnetic moment direction change constantly </li></ul><ul><li>Single vector (giant magnetic moment) </li></ul>Quantum force superparamagnetism
  67. 74. Thin films <ul><li>Materials of small thickness that can be made with one or more layers </li></ul>
  68. 75. Some aplications: <ul><li>Electronic semiconductors devices </li></ul><ul><li>Optic devices </li></ul><ul><li> In the ceramic thin films : </li></ul><ul><ul><ul><li>Coverings against corrosion </li></ul></ul></ul><ul><li> In the ferromagnetic films: </li></ul><ul><ul><ul><li>Computer memories </li></ul></ul></ul>
  69. 76. Fabrication Techniques <ul><li>Sputtering </li></ul><ul><li>Chemical vapor deposition </li></ul><ul><li>Molecular beam epitaxy </li></ul><ul><li>Sol-Gel process </li></ul><ul><li>Spin coating </li></ul><ul><li>Pulsed laser deposition </li></ul>
  70. 77. <ul><li>“ Ni grows in a layer-by-layer fashion on Cu(001) with the first monolayer nearly complete before second-layer growth commences. If the substrate temperature is raised to ~450K interdiffusion occurs”. </li></ul>From:
  71. 78. Ph otomicrogra phy of SBN -s trontium b arium n iobate - thin films .
  72. 79. From:
  73. 80. Thin films and giant magnetoresistance <ul><li>Thin films: </li></ul><ul><ul><li>Gradual deposition of atoms in a substract </li></ul></ul><ul><ul><li>Simple and multilayers </li></ul></ul>[ iron – cobalt – nickel ] [ chromium – copper – ruthenium ] Giant magnetoresistance
  74. 81. <ul><li>multilayer </li></ul>Transmission Electron Microscopy on an Fe/Si multilayer (photo courtesy of EPFL) From:
  75. 82. Giant Magnetoresistance: <ul><li>Discovered in 1988. </li></ul><ul><li>Thin films multilayer structures intercalating iron and chromium. </li></ul>
  76. 83. Experiment: <ul><li>Mesure of electrical resistance of the system for different applied magnetic fields. </li></ul>
  77. 84. Results: <ul><li>When the ferromagnetics layers are with contrary alignment </li></ul><ul><ul><li>Device shows high electric resistance </li></ul></ul><ul><li>When the ferromagnetics layers are with paralel alignment </li></ul><ul><ul><li>The resistance falls, around 40% to 50% </li></ul></ul>
  78. 85. Applications of the giant magnetoresistance effect: <ul><li>Magnetic writing </li></ul><ul><li>Spintronics </li></ul>
  79. 86. <ul><li>Investiments </li></ul>From: e US$milions
  80. 87. T H E E N D !