Thermally Stimulated Discharge of Electrets

Turnhout, J. van

doi:10.1007/978-3-540-34846-7_3

Cited by 164 publications

(197 citation statements)

References 349 publications

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“…But if these materials are heated at constant temperature, it produces an electrochemical potential difference between metallic electrode and the biopolymer. This effect is very well observed in case of many polymers by several researchers [21][22].…”

Section: Resultssupporting

confidence: 70%

Spontaneous Current Study in Wheat Starch Nano Powder

Gaur

Gaur²

2010

Acta Phys. Pol. A

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Spontaneous current study has been carried out in 70 nm particle size of wheat starch nano powder. The starch nano powder was prepared by mechanical grinding method. The spontaneous current was found to be induced and flowing in external circuit under short circuit condition by heating a sandwitched system. Sandwitched system consist of a starch nano powder (i.e. powder in different weight ratio of distilled water) between similar (Al-Al) and dissimilar (Al-Zn, Al-Cu, Al-Ag) electrode combination. The Spontaneous current spectra show two peaks lies in 46 ± 4 • C and 72 ± 4• C, respectively, in the first heating run. However, only single peak was observed in second heating run. In the dissimilar electrode combination the first peak shifts to lower temperature side, while second peak shifts to higher temperature side. Spontaneous current mechanism could be explained on the basis transitional changes of starch nano powder caused by influence of water. The temperature dependent open circuit voltage Voc was recorded. A linear relationship was observed between dissimilar electrodes system due to difference in electrode work functions. It has been observed that spontaneous current is influenced by water and depends on the choice of electrode material.

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Section: Resultssupporting

confidence: 70%

Spontaneous Current Study in Wheat Starch Nano Powder

Gaur

Gaur²

2010

Acta Phys. Pol. A

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“…as well. This indicates that the TSC α peak of polymer electrets is mainly due to the reorientation of dipolar main-chain segments [6]. Note that the location of the α peak corresponds to the glass-rubber transition of PVC-unplasticized.…”

Section: Resultsmentioning

confidence: 83%

Dielectric and Pyroelectric Properties of the Composites of Ferroelectric Ceramic and Poly(vinyl Chloride)

Olszowy¹

2003

Condens. Matter Phys.

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The dielectric and pyroelectric properties of lead zirconate titanate/poly(vinyl chloride) [PZT/PVC] and barium titanate/poly(vinyl chloride) [BaTiO 3 / PVC] composites were studied. Flexible composites were fabricated in the thin films form (200−400 µm) by hot-pressed method. Powders of PZT or BaTiO 3 in the shape of 75 µm ceramics particles were dispersed in a PVC matrix, providing composites with 0−3 connectivity. Distribution of the ceramic particles in the polymer phase was examined by scanning electron microscopy. The analysis of the thermally stimulated currents (TSC) have also been done. The changes of dielectric and pyroelectric data on composites with different contents of ceramics up to 40% volume were investigated. The dielectric constants were measured in the frequency range from 600 Hz to 6 MHz at room temperature. The pyroelectric coefficient for BaTiO 3 /PVC composite at 343 K is about 35 µC/m 2 K which is higher than that of β-PVDF (10 µC/m 2 K).

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“…As is well known, a master curve m a y be drawn from a set of functions after appropriated re-scaling of the quantities involved 39,57,58,59 . From the dielectric theory, i t i s k n o wn that Eq.54 results from a distribution of relaxation times with a single activation energy.…”

Section: V2-4 Master Curvesmentioning

confidence: 99%

Time dependent conductivity in disordered systems

Ferreira

Costa

1999

Braz. J. Phys.

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The time dependent current in disordered systems under a step applied voltage for a planar symmetry is deduced according to the continuous time random walk approximation. Known dielectric response functions like Cole-Cole, Davidson-Cole, Havriliak-Negami and a few others are used as hopping time distribution functions in order to generate conductive responses. A theoretical relation exists between the dielectric and the conductive response which is the same one prevailing between the time derivative of the creep and the relaxation function, as found long ago by Gross J.Appl. Phys.,18, 212 1947 . A truncated version of the Widder method, in connection with MapleTM software facilities, was employed to obtain graphical primitives of Laplace transforms. I IntroductionIn the opening talk Electret Research -Stages in its Development" 1 of the 5th International Symposium on Electret, ISE 5, held at Heidelberg, honoring his 80th birthday, Prof Gross reviewed the electret research at its very early stages. This testimony is particularly relevant on account of the role Prof Gross played in the development of the eld. He succeeded experimentally in distinguishing between hetero and homocharges appearing in poled dielectrics 2 . Heterocharge is the charge with opposite polarity to that residing on the nearby electrode, while the homocharge has the same sign. The former is attributed to polarization and the latter to space charge injection. Polarization in most cases is a linear e ect while space charge is not. See also 3 , and for the latest developments in this topic, see 4 .In dielectrics, polarization obeys a superposition principle 1,5 , by which the material presents a delayed response to changes of the poling electric eld. The simplest response of the polarization to a step variation in the electric eld is characterized by an exponential increase the so called Debye response , but this is rarely observed experimentally. A n yway the delayed response of the polarization to an alternating applied voltage gives rise to dielectric losses. In this kind of measurement the real and the imaginary components are related through the Kramers-Kronig 3 relations. To these relations Prof. Gross arrived working independently 6 .Here we will be concerned with a new type of delayed response: that a orded by current o wing in disordered materials. That is, absorption currents appear not only due to dipoles during the localized orientation process but also to the unbound motion of a drifting carrier in a disordered medium.The theoretical study of transport in a disordered medium was considerably advanced in a series of works which culminated with the famous article by S c her and Montroll SM 7-10 , using the Continuous Time Random Walk approach CTRW . In this treatment, the carrier performs a random walk in a regular lattice, biased by an electric eld, and the disordered character of the medium re ects itself in the hopping time distribution function HTDF , which n o w deviates from a simple exponential. For time dependent electric eld...

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Thermally Stimulated Discharge of Electrets

Cited by 164 publications

References 349 publications

Spontaneous Current Study in Wheat Starch Nano Powder

Spontaneous Current Study in Wheat Starch Nano Powder

Dielectric and Pyroelectric Properties of the Composites of Ferroelectric Ceramic and Poly(vinyl Chloride)

Time dependent conductivity in disordered systems

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