This paper describes a new smart material system using intercalated graphite as the material and using exfoliation as the phase transition that gives rise to the electromechanical switching action. In this action, a stress of up to 3 MPa (400 psi) or a strain of up to 4500% results reversibly from an applied electric field of only 7 V/cm. This high-stress high-strain low- electric-field type of electromechanical switching is in sharp contrast to the electromechanical switching provided by piezoelectric materials. The exfoliation is a phase transition involving the vaporization of the intercalate between the graphite layers to form bubbles. For bromine as the intercalate, the bubbles remain mostly closed and exfoliation is reversible. The resulting stress or strain is along the c-axis of the graphite, so highly oriented pyrolytic graphite and graphite flakes are both possible for achieving electromechanical switching.

Date Published: 23 July 1993
PDF: 7 pages
Proc. SPIE 1916, Smart Structures and Materials 1993: Smart Materials, (23 July 1993); doi: 10.1117/12.148468

Published in SPIE Proceedings Vol. 1916:
Smart Structures and Materials 1993: Smart Materials
Vijay K. Varadan, Editor(s)