High electric field resistivity and pyroelectric properties of vinylidene fluoride-trifluoroethylene copolymer

Abstract

Copolymers of vinylidene fluoride-trifluoroethylene P(VDF-TrFE) exhibit large piezoelectric and pyroelectric effects. In addition to the most common application of the pyroelectric effect (radiant detection) it is possible to convert heat directly into electrical energy by pyroelectric conversion. This study reports the first measurements of high (constant) field pyroelectric effects of P(VDF-TrFE) which are relevant to pyroelectric conversion. Electric displacement changes which result from temperature changes of the copolymer were measured for thermal cycling from room temperature to 90 °C at fields up to 1 MV/cm. The displacement changes (0.1–0.3 μ C/cm2) were dependent upon the molar ratio of the constituent monomers. The resistivity of the copolymer was also measured in the temperature range 20 to 90 °C and was found to vary from 1012 to 1016Ω cm depending on monomer ratio, temperature, field, and time. The resistivity and displacement change data are discussed in terms of predicted pyroelectric energy conversion performance.

Polarization of block textured films of ferroelectric copolymers of vinylidene fluoride with tetrafluoroethylene in an external field

“…The active investigation of these compounds is due to their special properties, which permitted the creation of new piezoelectric and pyroactive sensors with char acteristics that cannot be obtained with the use of clas sical inorganic ferroelectrics [1,2,5]. The possibility of producing a very large area of the active element of a pyrodetector (at a sufficiently high value of the pyro electric coefficient) makes it possible to propose such materials as thermoelectric converters of solar energy [6]. A hydrophone for registering the acoustic response due to the ablation of tissue sites during exposure to an ultraviolet excimer laser was created on the basis of the piezoactivity of polarized PVDF films [7].…”

Electrical and Crystallographic Study of an Electrothermodynamic Cycle for a Waste Heat Recovery

“…This simple method can modify the electrothermodynamic cycle from ABCD to ABC 1 D and the entire area, which means that the electric energy is increased. During the operation of the electrothermodynamic cycle, temperature variation and application of E affect the variations in P S , which in turn vary the electric [26] and Kim et al (ABC 1 D). The PZT (A) is belonging to a soft PZT, but its properties such as Curie temperature T C and dielectric permittivity are closer to the hard PZT.…”

“…[21] If a pyroelectric material is heated, there is an increase in the number of free charges on surfaces due to a change in its P S level because the material loses its electrical momentum due to thermal vibration. [26] The principle of the Olsen cycle is to charge a capacitor via cooling under low E and to discharge it by heating at a higher E. These steps can yield an enclosed clockwise loop in the electric displacement versus electric field (D-E) curve, which represents electric energy. Similarly, a reverse current flow can be established if the pyroelectric material is cooled.…”

“…This increase leads to a current flow under a short circuit condition. [26] Many attempts have been made to utilize PE based on the Olsen cycle in terms of theoretical investigations, materials, and systems. [21] In the 1980s, Olsen et al reported an electrothermodynamic cycle using PE and an external electric field (E).…”

A review of energy harvesting technology and its potential applications

“…A large advancement was obtained in the field of pyroelectric conversion by Olsen's Group [38,39]. They proposed the first pyroelectric conversion cycle named 'Olsen cycle' or 'Ericsson cycle' (electric analogous of the Ericsson heat engine cycle).…”