Nanoscale MOD Synthesis of Cermet Film Sensors

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Nanoscale MOD Synthesis of Cermet Film Sensors
Relva C Buchanan (PI), University of Cincinnati,
NSF-DMR-0407569

Nanostructured thin films and nanoparticle
systems, which exhibit high sensitivity to
temperature, flow, pressure or strain changes,
are in high demand for a variety of automotive,
consumer and electronic sensing applications.
Such films can be advantageously produced on
silicon or like substrates using metallo-organic
deposition (MOD) methods. The nanopowder
structures shown in figure A and B were prepared
from Zr and Ni trimetylacetate (TMA) precursors.
To prepare the composite thin films, the powders
were dissolved in a unique (propionic
acid/amylamine) solvent system, then spin coated
onto the silicon substrate, followed by pyrolysis
in air at 425?C to produce optimal film thickness
of 0.8-1.4?m. This technique allows for sintering
temperatures as low as 650-700?C (10-30 min) in
reducing atmospheres. The resultant
microstructure (figure C) consists of a Ni
conducting particulate phase, precipitated from
the amorphous deposited film, and uniformly
dispersed in zirconia matrix phase. Understanding
the materials chemistry, along with developing
analytical expressions for the kinetics of phase
evolution and film morphology, as related to
sensor properties, is a significant focus of this
research.
C
Figures Microstructure of A) zinconyl-TMA
showing nanoparticles in large agglomerates B)
Nickel-TMA showing fibrous morphology of
connected submicron platelets C) SEM of sintered
Ni-ZrO2 composite cermet film on Si substrate
with uniform nanoparticle distribution
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Connecting Students to Composite Materials
Research. Relva C Buchanan (PI), University of
Cincinnati, NSF-DMR-0407569

Several undergraduate students have done senior
projects in this ongoing area of sensor and
related electroceramics research. The experience
not only enhances their professional growth and
co-op program work experience but also broadens
their understanding of Materials Engineering,
and their interest in graduate education.
Students regularly participate in the
presentation of posters and talks describing
their results. The picture on right (above) shows
a graduating senior, who is graduate school
bound, giving a poster presentation on his
research on nanocomposite structures. Research
demonstration are regularly given to visitors to
increase interest in Materials Science and to
aid in recruitment. These visitors include high
school and junior high students, their teachers
and parents. The picture at lower right shows
high school students carrying out experiments on
hardness and impact testing of composite
materials. These students were part of a week
long Summer Materials Camp organized by the
Department of Chemical and Materials Engineering.
Special groups including minority and women
pre-engineering students are continuously
recruited and encouraged to tour the labs as
prospective students and for general science
awareness.