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Sol-gel Synthesis

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Sol-gel Synthesis & Characterization of Luminescent Quantum Dots Laura Ingalls Huntley ... Sol-gel process to produce silica glasses doped with SnO2 and Tb3+. – PowerPoint PPT presentation

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Title: Sol-gel Synthesis


1
Sol-gel Synthesis Characterization of
Luminescent Quantum Dots
  • Laura Ingalls Huntley
  • Prof. Christie LaRochelle
  • PHY490 Senior Independent Study
  • 04 May 2007

2
Quantum Dots
  • Semiconductor crystals of less than 10 nm in
    size. I.e. nanocrystals.
  • Of particular interest due to their many
    applications in the fields of optoelectronics and
    quantum computing.
  • Synthesis Sol-gel process to produce silica
    glasses doped with SnO2 and Tb3.
  • Characterization optical spectroscopy, XRD, and
    TEM.

3
Sol-gel Synthetic Method
  • TEOS is hydrolyzed with water, ethanol, and acid.
  • SnCl2 is dissolved in ethanol and added with
    stirring.
  • Tb nitrate is dissolved and added after .5 hrs.
  • Water/Ethanol/Acid mixture is added to complete
    hydrolyzation.
  • Solution is transferred into plastic test tubes.

4
Synthetic Method Cont.
  • Solution in test tubes gels within 3-5 days as
    ethanol evaporates and crystals start to form.
  • After gel is formed, pellet is removed from test
    tube and placed in 90 C oven for a period of
    approximately 2 days. Pellets will form small
    glasses.
  • Glasses are then fired in tube furnace
    temperature is ramped from 90 C to 450 C in 9
    hours, then to 650 C in 20 minutes, and finally
    to 800 C in 5 hours. This temperature is
    maintained for 2 hours subsequently, the glasses
    are allowed to cool to room temperature.

5
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7
Optical Spectroscopy
8
Optical Spectroscopy, Cont.
9
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10
XRD TEM
  • XRD analysis showed only the SiO2 network. A
    higher concentration of tin may be needed for the
    SnO2 crystals to register on the XRD.
  • TEM is the next step in characterizing the
    glasses. The TEM machine needs an extremely thin
    sample in order to work, this may be achieved by
    grinding the glasses into a powder, adding a
    resin, and then shaving off a small layer.
  • However, the synthetic method could also be
    altered such that the glasses formed as a thin
    film.
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