scholarly journals Thermal-Induced Dielectric Response In Mechanically Durable Polyvinylidene Fluoride/Tubular Kapok Fiber Encapsulated Polyethylene Glycol Composite Films

2021 ◽  
Author(s):  
Wenqi Wu ◽  
Xianglin Pei ◽  
Hairong Li ◽  
Junyang Tu ◽  
Qiong Li ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Dielectric Response ◽  
Polyvinylidene Fluoride ◽  
Composite Films ◽  
Dielectric Materials ◽  
Dielectric Susceptibility ◽  
Stable Operation ◽  
Kapok Fiber ◽  
Thermally Responsive ◽  
Mechanical Durability

Abstract Dielectric materials with thermally responsive property are being pursued in fields such as next-generation sensors, smart switches, and novel actuators. These applications require that the dielectric materials have mechanical durability and stable serviceability besides thermally responsive dielectric behavior. Herein, we report a novel thermally responsive, mechanically durable, and low-cost dielectric composite simply fabricated by vacuum impregnating polyethylene glycol (PEG) into Kapok fiber (KF) and compounding them with polyvinylidene fluoride (PVDF). A remarkable dielectric susceptibility, controlled dielectric transition temperature and obvious thermal hysteresis of the composite films induced by the solid-liquid phase transition of PEG are demonstrated. The effect of molecular weights of PEG on the dielectric response behaviors is evaluated. Such thermally responsive dielectric materials with satisfactory mechanical durability will offer a chance toward constructing thermally responsive systems for safe and stable operation.

scholarly journals Jonscher indices for dielectric materials

2019 ◽  
Vol 09 (06) ◽  
pp. 1950046
Author(s):  
C. L. Wang
Keyword(s):  
Experimental Data ◽  
Asymptotic Behavior ◽  
Dielectric Relaxation ◽  
Time Domain ◽  
Dielectric Response ◽  
Relaxation Function ◽  
Dielectric Materials ◽  
Dielectric Response Function ◽  
Barium Stannate ◽  
Two Parameters

Two parameters are proposed as Jonscher indices, named after A. K. Jonscher for his pioneering contribution to the universal dielectric relaxation law. Time domain universal dielectric relaxation law is then obtained from the asymptotic behavior of dielectric response function and relaxation function by replacing parameters in Mittag–Leffler functions with Jonscher indices. Relaxation types can be easily determined from experimental data of discharge current in barium stannate titanate after their Jonscher indices are determined.

Polarization Dynamics in La5/3Sr1/3NiO4

1999 ◽  
Vol 602 ◽  
Author(s):  
N. Hakim ◽  
Z. Zhai ◽  
C. Kusko ◽  
P.V. Parimi ◽  
S-W. Cheong ◽  
...  
Keyword(s):  
Dielectric Loss ◽  
Dielectric Response ◽  
Charge Ordering ◽  
Dielectric Susceptibility ◽  
Dynamic Susceptibility ◽  
Loss Peak ◽  
Relaxation Rates ◽  
Relaxation Mode ◽  
Microwave Frequencies ◽  
Charge Stripe

AbstractDynamic susceptibility measurements at microwave frequencies (2 – 10GHz) are a sensitive probe of charge dynamcis in La5/3Sr1/3NiO4. Below the charge ordering temperature of 240K, a dielectric loss peak due to a relaxation mode with a large dielectric susceptibility is observed, and is associated with charge stripe formation. The dielectric response for Hω∥b (Eω ⊥ b) is well represented by ε(T) = εo/(1 – iωτ(T)), with εo, ∼ 50, and τ(T) = 2 × 10−9(sec) exp(−T/37K). Parallel conductivity σ(T) contributions dominate at higher temperatures and for Hω∥c (Eω ⊥ c). The dielectric loss peak observed indicates that the charge relaxation rates lie in the GHz frequency ranges.

A distinct mutual phase transition in a new PVDF based lead-free composite film with enhanced dielectric and energy storage performance and low loss

2017 ◽  
Vol 5 (10) ◽  
pp. 2531-2541 ◽  
Author(s):  
Dong Guo ◽  
Kai Cai ◽  
Yunli Wang
Keyword(s):  
Phase Transition ◽  
Energy Storage ◽  
Polyvinylidene Fluoride ◽  
Composite Films ◽  
Lead Free ◽  
Low Loss ◽  
Ceramic Filler ◽  
Environment Friendly ◽  
High Permittivity ◽  
Storage Performance

Environment-friendly polyvinylidene fluoride (PVDF) based composite films were fabricated by using a high permittivity lead-free Ba(Sn,Ti)O3–(Ba,Ca)TiO3 (BCTS) ceramic filler with a special ‘tricritical’ phase structure.

TEMPERATURE DEPENDENCE OF THE n PARAMETER IN THE DISSADO–HILL MODEL

2013 ◽  
Vol 27 (06) ◽  
pp. 1350040 ◽  
Author(s):  
A. DOFF ◽  
J. C. GENTILINI ◽  
O. CAMBRUZZI
Keyword(s):  
Temperature Dependence ◽  
Quantum Electrodynamics ◽  
Dielectric Response ◽  
Dielectric Material ◽  
Dielectric Materials ◽  
Energy Scale ◽  
Dielectric Polarization ◽  
Hill Model ◽  
Running Coupling ◽  
Many Body Interactions

The response of a dielectric material to the application of an external electric field is characterized by the dependence of the complex dielectric polarization susceptibility on frequency ω and external factors such as temperature T. Even today, we do not have a universal model that describes the behavior for all materials. However, Dissado and Hill (DH) have proposed a model based on many-body interactions that is able to explain the dielectric response observed in many dielectric materials. By considering an analogy between the description given in the cluster approach to the structure of imperfect materials and the formalism developed in quantum field theory (QFT), particularly the scale invariance behavior displayed by the dependence of the running coupling constant of quantum electrodynamics (QED) on the energy scale Λ, we will include temperature dependence in the (n) and (m) parameters of the DH model to consider the effects of temperature on the dielectric response of some materials.

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