Y. Tajitsu et al., FERROELECTRIC BEHAVIOR OF THIN-FILMS OF VINYLIDENE FLUORIDE TRIFLUOROETHYLENE/HEXAFLUOROPROPYLENE COPOLYMER/, JPN J A P 1, 36(9B), 1997, pp. 6114-6117
Ferroelectricity in vinylidene fluoride (VDF), trifluoroethylene (TrFE
) and hexafluoropropylene (HFP) copolymers (P(VDF/TrFE/HFP)) with a lo
w HFP content (lower than 11mol%) has been investigated primarily thro
ugh switching measurements using P(VDF/TrFE) as a comparison. Switchin
g phenomena as a result of ultimately 180 degrees rotations of individ
ual molecular chains around their axes in crystalline regions were obs
erved in P(VDF/TrFE/HFP) with an HFP content lower than 2.5 mol%. With
increasing HFP content in P(VDF/TrFE/HFP), the amount of reversed pol
arization decreases, and the dielectric permittivity at the Curie poin
t becomes smaller. However, the switching times have very low dependen
ce on the HFP content of P(VDF/TrFE/HFP). These results suggest that n
oncrystalline regions in P(VDF/TrFE/HFP) are similar to those in P(VDF
/TrFE), and the disorder in crystalline regions of P(VDF/TrFE/HFP) inc
reases compared to that in crystalline regions of P(VDF/TrFE).