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An introduction to nano-science and nanotechnology, now in English !!

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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Nano-Science Nano-Science Presentation Transcript

  • NANOSCIENCE NANOTECHNOLOGY Walkiria Eyre [email_address]
    • Nanoscience and nanotechnology concepts
    • The begining of the nanoscience research
    • Abstract on some nanostructures and it´s aplications
    • Magnetic nanostructures
    Part 1 Part 2
  • Nanoscience Fisics Engeneering Biology Chemistry Basic life processes Chemical reactions Medicine Classical Fisics Quantum Fisics Smart materials Technological aplications
  • Nanotechnology
    • Using nanoscience to create:
      • Smart materials
      • Engines (in nanometric scale)
      • Devices (with an enormous amount of aplications)
  • Nanostructures
    • Between 1 a 100 nm
    • What is smaller than 1 nanometer ?
      • Alone atoms
      • Small and simple molecules
  • NANO = 10 -9
    • Why is this size so special ?
      • Nanostructures are the smallest solid things we can do
      • Quantum effects start to appear
      • Root of fundamental properties of the materials
  • Nanofabrication techniques
    • Top-down : nanostructure is obtained by successive cuts
    • Bottom-up : nanostructure is build in an atom by atom deposition
  • Beginning of Nanoscience
    • 1959 – Richard Feynman
      • “ there´s plenty of room at the bottom”
    • New instruments:
      • Tunneling microscopes
      • Atomic force microscopes
      • Near-field microscopes
    • 1981 – Gerd Binning e Heinrich Roher (laboratório IBM em Zurique)
    • STM
  • IBM Logo xenon atoms on nickel substract
    • Image obtained by scanning the exponencial decrease of the tunneling current
  • Instruments:
    • STM: scanning tunneling microscope
    • AFM: atomic force microscope
      • contact AFM
      • non contact AFM
      • dynamic contact AFM
    • MFM: magnetic force microscope
    • EFM: electrostatic force microscope
    • SVM: scanning voltage microscope
    • KPFM: kelvin probe force microscope
    • SCM: scanning capacitance microscope
    • FMM: force modulation microscope
    • SThM: scanning thermal microscope
    • NSOM: near-field scanning optical microscope
    • SNOM: scanning near-field optical microscope
    From: http://en.wikipedia.org/wiki/Scanning_probe_microscopy
  • STM From: http://en.wikipedia.org/wiki/Scanning_tunnelling_microscope
  • Piezoelectric effect
    • 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.
    • The quartz and the t ourmaline, natural crystals , are piezoel ec tric.
  • Images creation process
    • A tip scan the surface at a distance of few atomic diameters
    • The tunneling current decreases exponentially with increasing distance
    From: http://www.almaden.ibm.com/vis/stm/gallery.html
  • Continue...
    • Colors are added taking in account different properties like height, curvature, etc...
    From: http://www.almaden.ibm.com/vis/stm/gallery.html
    • Impurity on copper
    From: http://www.almaden.ibm.com/vis/stm/gallery.html
    • Sodium and iodine on copper
    From: http://www.almaden.ibm.com/vis/stm/gallery.html
    • Iron on copper
    From: http://www.almaden.ibm.com/vis/stm/gallery.html
    • “ atom”
    • Iron on copper
    From: http://www.almaden.ibm.com/vis/stm/gallery.html
    • Carbon monoxide on platinum (111)
    From: http://www.almaden.ibm.com/vis/stm/gallery.html
  • Process: From: http://www.almaden.ibm.com/vis/stm/gallery.html
  • Examples: From: http://www.almaden.ibm.com/vis/stm/gallery.html
  • Nanostructures:
    • The nanostructures can be divided in some classes, like:
    • Nanoparticles
    • Nanofilms
    • Nanowires
    • Nanotubes
  • Nanostructures and potencial aplications:
    • At atomic scale:
      • Quantum wells
        • Extreme - thin layers of semiconductor material ( the well ) grown between barriers (gr ids ). The gr ids imprison electrons in the extreme- thin layers .
        • CD devices, telecomunication, optics
    From: http://www.mct.gov.br/index.php/content/view/index.php
  • 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: http://www.mtmi.vu.lt/pfk/funkc_dariniai/diod/led.htm
      • Quantum dots
        • F luorescent nanoparticles . Depending on its composition, these particles can show many different colors .
        • Telecommunications, optics .
      • Polymers
        • Some organic materials emit light under electric c urrent action .
        • informatics
    From: http://www.mct.gov.br/index.php/content/view/index.php
  • “ 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: http://instruct1.cit.cornell.edu/courses/comm494-nano/working_version/3article.htm
  • 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: http://instruct1.cit.cornell.edu/courses/comm494-nano/working_version/3article.htm
    • Part icles smaller than 100 nm :
      • Nanoc a psul e s
        • Buckminsterfullerenes are the most known . D i sco vered in 1985, these part i c le s have 1 nm width.
        • Dry Lubri cant .
      • C atal y tic n anopart icles
        • In a 1-10 nm range , these particles, when manipulated, shows a great superf i cial area, improving its reactivity
        • M aterials, fuels and foods production
    From: http://www.mct.gov.br/index.php/content/view/index.php
  • “ 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: http://www.nanotech-now.com/ucb-release-03112004.htm
    • Wires with less than 100 nm di a met e r
      • Carbon Nanotubes
        • 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.
        • S pace and electronic industries, aviation and innumerable other areas .
    From: http://www.mct.gov.br/index.php/content/view/index.php
    • Films with less than 100 nm thickness
      • Self-assembled Mono layers
        • Organic or inorg a nic substances that, spontane ously , form a layer of the thickness of a molecule
        • A large amount of applications based on the chemical and physical properties .
    From: http://www.mct.gov.br/index.php/content/view/index.php
    • Self-assembled monolayer
    From: http://www.mtl.kyoto-u.ac.jp/english/laboratory/nanoscopic/nanoscopic.htm
      • N anopartic les coverings
        • Stainless steel layers applied by nanocr y stalin powder confer greater hardness in comparison with conventional applications.
        • Sensors. Fabrica tion of liquid cr y stal. M olecular wires . Lubrication, protection and anticorrosive layers . Stronger and hard er cut tools.
    From: http://www.mct.gov.br/index.php/content/view/index.php
  • CNT
  • Topics
    • Magnetism concepts
    • Magnetic materials
    • Magnetic nanostructured systems
    • Thin films
    • Giant Magnetoresistence
  • Spin
    • Classic point of view:
      • Rotation m ovement of the electron around a n axle, it means , an angular moment
  • Magnetic moment SPIN ( angular moment) *charge* Magnetic Moment
  • Magnetic Moment
  • Magnetization
    • It is the total magnetic moment of a certain amount of the substance for unit of volume
    • Due to this , electrons tend to line up when submitted to a n external magnetic field
  • MAGNETIZATION Alignment of electrons due to the field
    • In the majority of atoms total spin is null
      • Due to the occupation of the orbital s
        • Linus Pauling principle
    • For some elements total spin is not null
      • These elements have permanent magnetic moment
        • Examples: Iron, Cobalt, Nickel, Manganese, Gadolinium, Europium.
  • Magnetic Behaviors
    • In accordance with its behavior in the presence of a n external magnetic field, the magnetic materials can be classified in:
    Metamagnetic *Superparamagnetics* Spin glass Speromagnetic Helimagnetic Diamagnetic Paramagnetic Ferromagnetic Ferrimagnetic Antiferromagnetic
  • Magnetic Susceptibility
    • For a large amount class of isotropic and linear materials, we have :
    • Where M is the magnetization and H the magnetic intensity.
  • Diamagnetism
    • It is Lenz law at atomic level
      • The material charges in movement tend to cancel the effect of the variation of the magnetic flow (applied external field)
      • magnetic susceptibility < 1
  • Examples of diamagnetic substances:
    • water
    • lead
    • so di um chloride
    • quartz
    • sulphur
    • diam o n d
    • gra phi te
    • li quid nitrogen
    • copper = -9,8 × 10 −6
  • Interesting effects: From: http://en.wikipedia.org/wiki/Diamagnetism
  • Paramagnetism
    • 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.
  • Examples of paramagnetic substances
    • sodium
    • aluminium = 2,3 × 10 −5
    • copper chloride
    • nickel sulphate
    • Liquid oxygen
  • Ferromagnetism
    • Ferromagn e tic materials have a permanent magnetization
      • atoms with electrons not pair uped whose spins are guided in the same direction
    It generates regions called DOMAINS
  • Ferromagnetic materials examples
    • Iron = 5.500
    • Magnetite (Fe 3 O 4 )
    • Cobalt
    • Nickel
    • Gadolinium
    • Magnetic Domains
  • Magnetic Domains The domains are delineated with colloidal iron oxide particles FOTOMICROGRAFY (Bell Telephone Laboratories) From: http://www.feiradeciencias.com.br/sala13/13_38.asp
    • “ Estructura de dominios magneticos en laberinto observada mediante microscopia Bitter en una cinta amorfa de base Fe ”
    MICROSCOPY From: http://www.icmm.csic.es/eng/gallery/gall_omtp.htm
    • Ferromagn e tic materials acquire paramagnetic behavior.
      • Alignment with external field
    16 o C Gadolinium 358 o C Nickel 1131 o C Cobalt 770 o C Iron Curie point Element
  • Hysteresis loop
    • It determines the characteristics of a magnetic material.
    • It is the graph of magnetization M of the material in function of the external magnetic field applied H.
  • Hysteresis Loop
    • 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.
  • Hysteresis Loop From: http://hyperphysics.phy-astr.gsu.edu/Hbase/solids/imgsol/hyloop.gif
  • Definitions: From: http://hyperphysics.phy-astr.gsu.edu/Hbase/solids/imgsol/coercivity.gif
    • Granulars: magnetic nanoparticles dispersed in a solid or liquid medium:
      • Solid: granular solids
      • Liquid: magnetic fluids
    Magnetic nanostructured systems:
  • Magnetic Behavior Configuration of minimum potential energy Magnetic domains with random orientation size temperature
    • Critical size
    • A set of ten nanometers
    Random orientation is not energetically favorable **Spontaneous permanent magnetization** SINGLE-DOMAIN
  • Temperature variation:
    • Magnetic nanoparticles
      • small magnets
    Temperature increase Rotation in the magnetization direction
  • Thus...
    • Magnetic moment direction change constantly
    • Single vector (giant magnetic moment)
    Quantum force superparamagnetism
  • Thin films
    • Materials of small thickness that can be made with one or more layers
  • Some aplications:
    • Electronic semiconductors devices
    • Optic devices
    • In the ceramic thin films :
        • Coverings against corrosion
    • In the ferromagnetic films:
        • Computer memories
  • Fabrication Techniques
    • Sputtering
    • Chemical vapor deposition
    • Molecular beam epitaxy
    • Sol-Gel process
    • Spin coating
    • Pulsed laser deposition
    • “ 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”.
    From: http://www.surfaces.lsu.edu/nioncu.html
  • Ph otomicrogra phy of SBN -s trontium b arium n iobate - thin films .
  • From: http://www.liec.ufscar.br/ceramica/index.html
  • Thin films and giant magnetoresistance
    • Thin films:
      • Gradual deposition of atoms in a substract
      • Simple and multilayers
    [ iron – cobalt – nickel ] [ chromium – copper – ruthenium ] Giant magnetoresistance
    • multilayer
    Transmission Electron Microscopy on an Fe/Si multilayer (photo courtesy of EPFL) From: http://www.gencoa.com/tech/f_multilayer.html
  • Giant Magnetoresistance:
    • Discovered in 1988.
    • Thin films multilayer structures intercalating iron and chromium.
  • Experiment:
    • Mesure of electrical resistance of the system for different applied magnetic fields.
  • Results:
    • When the ferromagnetics layers are with contrary alignment
      • Device shows high electric resistance
    • When the ferromagnetics layers are with paralel alignment
      • The resistance falls, around 40% to 50%
  • Applications of the giant magnetoresistance effect:
    • Magnetic writing
    • Spintronics
    • Investiments
    From: http://nano.gov/ e http://www.mct.gov.br/ US$milions
  • T H E E N D !