KFUPMME Nanofocus Group

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KFUPM/ME Nano-focus Group Lecture Series Sheikh
Akbar (akbar.1_at_osu.edu) Center for Industrial
Sensors and Measurements (CISM) Ohio State
University, Columbus, OH, USA

• Housekeeping Matters
• - Acknowledgements to
• KFUPM invitation support
• Prof. Z. Ahmad, Prof. A. Al-Qutub A. Aleem
  (logistics)
• Overview-type lectures with multidisciplinary
  flavor
• Questions, comments and discussions are vital
• - For additional discussions, see me later
  (ME-233)
• - An evaluation form to be filled out by all
  attendees

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Lecture Topics

• Introduction to Nano-materials and
  Nano-structures (Dec. 10 1000 Room 14/108)
• Deposition Techniques for Thin-films and
  Nano-Materials (Dec. 11 315 Room 24/121)
• Gas-phase Driven Nano-structures (Dec. 12 315
  Room 24/128)
• Gas Sensors for Environmental Monitoring I
• (Dec. 13 315 Room 24/121)
• Gas Sensors for Environmental Monitoring II
• (Dec. 16 3.15 Room 24/121)
• Sol-gel Technique for Nano-particles
• (Dec. 17 3.15 Room 24/128)

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Nano-materials and Nano-structures Introduction
Hype?
Or
Real?
4
Fabrication Techniques

• Nano-particles
• Sol-gel high-energy ball milling
• Nano-tube, nano-wire, and nano-belt
• Evaporation (Science 291 (2001) p 1947)
• Laser ablation (Science 279 (1998) p 208)
• Anodization (J. Mater. Res. 16 (2001) p 3331)
• Electro-spinning (Nano lett. 3 (2003) p 555)
• Gas-phase reaction (Adv. Matls., 163 (2004) p
  260)
• Nano-porous structures
• Emulsion templating (J. Mater. Res. 18 (2003) p
  156)
• Photo-electrochemical etching (Electrochem.
  Solid-State. Lett. 1 (1998) p 175)

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Sol-gel sub-micron and nano-particles
Sol-gel SnO2
Sol-gel silica spheres
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High-energy ball milling
xSnO2-(1-x)aFe2O3 are fabricated by mechanical
alloying
Sens. Actuators B 65 (2000) 361
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Nano-belts (Evaporation Technique)
Source Science, 291 (2001) 1947

• Typical widths of nano-belts are in the range of
  50-200 nm
• The length is several hundred micrometer or
  more.
• It has rectangular cross-section
• Each nano-belt is a single crystal without
  dislocations
• Nano-belts of ZnO, SnO2, In2O3, CdO, Ga2O3, PbO2
  can be easily
• produced by evaporation

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Nano-tubes (Anodization)
Source Adv. Mater. 15 (2003) 624

• TiO2 nano-tubes fabricated by anodization
• Diameter of nano-tubes 10 80 nm
• Nano-tubes are oriented and perpendicular to
  the surface
• Nano-tube length increases with anodization
  time (400 nm in 20 min)
• As-received nano-tubes are amorphous and oxygen
  deficient
• Annealing in oxygen atmosphere is required

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Photo-electrochemical Etching
Nano-honeycomb structure
TiO2 SO42- 2h ? TiOSO4 1/2O2
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Invention of Titania Nano-fibers

• Process

Adv. Matls., 163, 260 (2004) Patent
appl. 2003-678772
Sintering
H2 heat treatment
1200 C for 6hrs
700C for 8hrs in 5 H2/N2
heat-treatment
- Nano-fibers are parallel, oriented in the same
direction - Diameter of nano-fibers 15 50 nm
Length of nano-fibers up to 5 µm
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Ceramic Nano-machining?
Wide variety of possibilities by gas-phase
reaction - CISM
Nano-fibers
Nano-channels (different sintering)
Nano-whiskers (doped with Fe2O3)
Nano-lamellar (two-phase)
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Patterned TiO2 Nanowires
Planar view
Tilted view
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TiO2 nano-wire on Ti64 alloy in Ar
Nano-wire diameter 50-100 nm Length of
nano-wire 3-5 ?m
Magnified image for the circled area
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Gas-Phase Growth in SnO2

• Experimental Conditions
• Sintered 1300 ?C for 24 hours
• Heat treat in a humid 5 H2 95 N2 atmosphere
  at 700 ?C for 4 hours
• 1 L/min gas flow
• Au-coated SnO2

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Challenges and Opportunities
Mass-scale synthesis and fabrication Materials
RD, manufacturing Assembling into devices and
structures Nano-packaging, bonding,
adhesion Stability in hostile environments
Surface and interface chemistry and
physics Fundamental understanding of
properties Mechanism and modeling Potential
applications Sensing, catalysis, bio-medical,
nano-electronics nano-composites, TBC, corrosion
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RD Tetrahedron Applies to Nano RD
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Success Code RTDAD

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