Shrinking from the Heat: Negative Thermal Expansion Materials
Cora Lind
Department of Chemistry, University of Toledo
Abstract
Negative thermal expansion (NTE) materials have
received considerable scientific interest because of
their potential for use as fillers in composites.
Mixing of a positive thermal expansion material with a
NTE filler should reduce the overall expansion coefficient
of the composite while maintaining other desirable properties
of the matrix material. Dedicated research on NTE materials
started only during the last decade. Much progress has been
made in the synthesis and characterization of NTE compounds,
but many show properties like irreversible phase transitions
under pressure that could interfere with the processing of
composites. In addition, a number of NTE oxides are metastable,
thus requiring synthetic approaches that use kinetic control.
In this talk, a brief overview of important aspects relating to
the field of NTE research will be given. We will then focus on
synthetic approaches and characterization of metastable NTE
materials, with special emphasis on factors that are important
for potential applications. Finally, some preliminary results
on the preparation of NTE/polymer composites will be discussed.