Synthesis and Processing of Metal Tabular Materials

1
Synthesis and Processing of Metal Tabular
Materials Ying Yuan and James H. Adair Starting
June 03
Passivation Dispersion
Dispersion Issues 1. Base metal ?
thermodynamically unstable in water or
water/ethanol. 2. Possible differential charging
? tabular shape materials.
Figure 1. Multilayer ceramic capacitors (MLCC)
Figure 3. (a) Electron micrograph of a mixture of
a kaolinite and a negative gold solution, showing
clay particles have a positive edge even though
the net electrophoretic charge of the clay is
negative.1 (b) Schematic illustration of
individual clay particle and aggregated particle
network formed due to the attraction of negative
faces and positive edges.2

• Template Directed Particle Synthesis
• Polyoxyethylene (POE, C12H25(OCH2CH2)4OH) was
  chosen as the surfactant to form bilayer template
  for platelets synthesis.

Dispersion Approach Complex ligand is
investigated as a dual passivation and dispersion
agent to form a chemically stable layer at the
surface of base metal to prevent the oxidation
and provide steric potential between particles.
Three stage oxidation of Cu nanoplatelets
Figure 4. Zeta potential of Cu platelets
suspension as a function of pH with the addition
of oxalic acid
Cu platelet average dimension d 43nm, t 6nm
Nedge Nside Ntop-bottomNbulk 1 7 29 954
Figure 5. TEM micrographs of Cu platelets with
the addition of oxalic acid as a dual passivation
and dispersion agent. Cu platelets were washed
three times in 10-2M oxalic acid
30water/70ethanol suspension at pH9.

• Conclusions
• Cu, Ni, and Cu0.81Ni0.19 were synthesized in
  POE/water bilayer system.
• Oxalic acid was evaluated as passivation
  dispersion agent for Cu nanoplatelets suspension.

Figure 2. Cu nanoplatelets synthesized using 0.5
M Cu(NO3)2 precursor in water-polyoxyethylene
bilayer template
1.Van. H. Olphen, An introduction to clay colloid
chemistry for clay technologists, geologists,
and soil scientists, Wiley, c1977, ISBN
047101463X, pp95
2. J. a. Lewis, J. Am. Ceram. Soc.,83 10
pp2341-59 (2000)