TY  - JOUR
A1  - Qiu, Xunlin
A1  - Wirges, Werner
A1  - Gerhard, Reimund
T1  - Polarization and Hysteresis in Tubular-Channel Fluoroethylenepropylene-Copolymer Ferroelectrets
JF  - Ferroelectrics
N2  - Polarization-vs.-applied-voltage hysteresis curves are recorded on tubular-channel fluoroethylene-propylene (FEP) copolymer ferroelectrets by means of a modified Sawyer-Tower circuit. Dielectric barrier discharges (DBDs) inside the cavities are triggered when the applied voltage is sufficiently high. During the DBDs, the cavities become man-made macroscopic dipoles which build up an effective polarization in the ferroelectret. Therefore, a phenomenological hysteresis curve is observed. From the hysteresis loop, the remanent polarization and the coercive field can be determined. Furthermore, the polarization can be related to the respective piezoelectric coefficient of the ferroelectret. The proposed method is easy to implement and is useful for characterization, further development and optimization of ferro- or piezoelectrets.
KW  - Ferroelectrets
KW  - piezoelectrets
KW  - tubular-channel polymer systems
KW  - dielectric barrier discharge (DBD)
KW  - fluoroethylenepropylene (FEP) copolymer
KW  - piezoelectricity-polarization relation
Y1  - 2014
U6  - https://doi.org/10.1080/00150193.2014.964603
SN  - 0015-0193
SN  - 1563-5112
VL  - 472
IS  - 1
SP  - 100
EP  - 109
PB  - Routledge, Taylor & Francis Group
CY  - Abingdon
ER  - 
TY  - JOUR
A1  - Altafim, Ruy Alberto Pisani
A1  - Rychkov, Dmitry
A1  - Wirges, Werner
A1  - Gerhard, Reimund
A1  - Basso, Heitor Cury
A1  - Altafim, Ruy Alberto Pisani
A1  - Melzer, Martin
T1  - Laminated tubular-channel ferroelectret systems from low-density Polyethylene Films and from Fluoroethylene-propylene Copolymer Films - A comparison
JF  - IEEE transactions on dielectrics and electrical insulation
N2  - A template-based lamination technique for the manufacture of ferroelectrets from uniform electret films was recently reported. In the present work, this technique is used to prepare similar ferroelectret structures from low-density polyethylene (LDPE) films and from fluoro-ethylene-propylene (FEP) copolymer films. A comparative analysis of the pressure-, temperature-, and frequency-dependent piezoelectric properties has been performed on the two ferroelectret systems. It is observed that the FEP ferroelectrets exhibit better piezoelectric responses and are thermally more stable. The difference between the piezoelectric d(33) coefficients of the two ferroelectret systems is partially explained here by their different elastic moduli. The anti-resonance peaks of both structures have been investigated by means of dielectric resonance spectroscopy and electroacoustic sound-pressure measurements. A difference of more than 10 kHz is observed between the anti-resonance frequencies of the two ferroelectret systems.
KW  - Ferroelectrets
KW  - piezoelectrets
KW  - piezoelectricity
KW  - electro-mechanical transducers
KW  - static-pressure dependence
KW  - temperature dependence
KW  - frequency response
Y1  - 2012
SN  - 1070-9878
VL  - 19
IS  - 4
SP  - 1116
EP  - 1123
PB  - Inst. of Electr. and Electronics Engineers
CY  - Piscataway
ER  -