Js. Capurso et Wa. Schulze, PIEZORESISTIVITY IN PTCR BARIUM-TITANATE CERAMICS - I, EXPERIMENTAL FINDINGS, Journal of the American Ceramic Society, 81(2), 1998, pp. 337-346
Positive temperature coefficient of resistance (PTCR) barium titanate
is the active material in a ceramic sensor which employs piezoresistiv
ity to detect changes in applied stress. High-purity, chemically prepa
red barium titanate is donor-doped with 0.30 at.% lanthanum, and <0.10
at.% of a transition-metal counterdopant may be added to enhance the
PTCR effect. Tape-cast sheets of undoped and PTCR BaTiO3 are laminated
to produce a three-layer ''trilaminate''-a sintered structure which h
as two semiconducting PTCR layers separated by an insulating layer. Th
e trilaminate is stressed in a four-point bend configuration (placing
one semiconducting layer completely in tension, the other in compressi
on), and the resistivities for both stress states are measured concurr
ently as functions of applied stress and temperature. Results are pres
ented for various semiconducting layer compositions and sintering cond
itions.