Impedance/Dielectric Spectroscopy of Electroceramics in the Nanograin Regime.
Impedance/Dielectric Spectroscopy of Electroceramics in
the Nanograin Regime.
Kidner, N. J.; Ingram, B. J.; Homrighaus, Z. J.; Mason,
T. O.; Garboczi, E. J.
Solid-State Ionics 2002. Materials Research Society Fall
Meeting. Proceedings. Volume 756. 2002, Boston, MA,
EE4.6.1-12 pp, 2002.
impedance spectroscopy; dielectric spectroscopy;
In the microcrystalline regime, the behavior of grain
boundary-controlled electroceramics is well described by
the brick layer model (BLM). In the nanocrystalline
regime, however, grain boundary layers can represent a
significant volume fraction of the overall
microstructure and simple layer models are no longer
valid. This work describes the development of a
pixel-based finite-difference approach to treat a nested
cube model (NCM), which more accurately calculates the
current distribution in polycrystalline ceramics when
grain core and grain boundary dimensions become
comparable. Furthermore, the NCM approaches layer model
behavior as the volume fraction of grain cores
approaches unity (thin boundary layers) and it matches
standard effective medium treatments as the volume
fraction of grain cores approaches zero. Therefore, the
NCM can model electroceramic behavior at all grain
sizes, from nanoscale to microscale. It can also be
modified to handle multi-layer grain boundaries and
property gradient effects (e.g., due to space charge