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Tuning the Relaxor–Ferroelectric Properties of Poly(vinylidene fluoride–trifluoroethylene–chlorofluoroethylene) Terpolymer Films by Means of Thermally Induced Micro- and Nanostructures
Macromolecules ( IF 5.5 ) Pub Date : 2022-06-21 , DOI: 10.1021/acs.macromol.2c00302
Thulasinath Raman Venkatesan 1, 2 , David Smykalla 3 , Bernd Ploss 3 , Michael Wübbenhorst 2 , Reimund Gerhard 1
Affiliation  

The effects of thermal processing on the micro- and nanostructural features and thus also on the relaxor–ferroelectric properties of a P(VDF–TrFE–CFE) terpolymer were investigated in detail by means of dielectric experiments, such as dielectric relaxation spectroscopy (DRS), dielectric hysteresis loops, and thermally stimulated depolarization currents (TSDCs). The results were correlated with those obtained from differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and Fourier-transform infrared spectroscopy (FTIR). The results from DRS and DSC show that annealing reduces the Curie transition temperature of the terpolymer, whereas the results from WAXD scans and FTIR spectra help to understand the shift in the Curie transition temperatures as a result of reducing the ferroelectric phase fraction, which by default exists even in terpolymers with relatively high CFE contents. In addition, the TSDC traces reveal that annealing has a similar effect on the midtemperature transition by altering the fraction of constrained amorphous phase at the interphase between the crystalline and the amorphous regions. Changes in the transition temperatures are in turn related to the behavior of the hysteresis curves on differently heat-treated samples. During heating, evolution of the hysteresis curves from ferroelectric to relaxor–ferroelectric, first exhibiting single hysteresis loops and then double hysteresis loops near the Curie transition of the sample, is observed. When comparing the dielectric–hysteresis loops obtained at various temperatures, we find that annealed terpolymer films show higher electric-displacement values and lower coercive fields than the nonannealed sample, irrespective of the measurement temperature, and also exhibit ideal relaxor–ferroelectric behavior at ambient temperatures, which makes them excellent candidates for applications at or near room temperature. By tailoring the annealing conditions, it has been shown that the application temperature could be increased by fine tuning the induced micro- and nanostructures.

中文翻译:

通过热诱导微纳米结构调整聚(偏二氟乙烯-三氟乙烯-氯氟乙烯)三元共聚物薄膜的弛豫-铁电性能

通过介电实验,例如介电弛豫光谱 (DRS),详细研究了热处理对 P(VDF-TrFE-CFE) 三元共聚物的微观和纳米结构特征以及弛豫铁电性能的影响、介电磁滞回线和热刺激去极化电流 (TSDC)。结果与从差示扫描量热法 (DSC)、广角 X 射线衍射 (WAXD) 和傅里叶变换红外光谱 (FTIR) 获得的结果相关。DRS 和 DSC 的结果表明,退火降低了三元共聚物的居里转变温度,而 WAXD 扫描和 FTIR 光谱的结果有助于理解由于降低铁电相分数而导致的居里转变温度的变化,默认情况下,即使在 CFE 含量相对较高的三元共聚物中也存在。此外,TSDC 迹线表明,通过改变结晶区和非晶区之间界面处的约束非晶相的比例,退火对中温转变具有类似的影响。转变温度的变化又与不同热处理样品的滞后曲线的行为有关。在加热过程中,观察到磁滞曲线从铁电到弛豫-铁电的演变,首先呈现出单磁滞回线,然后在样品的居里跃迁附近出现双磁滞回线。当比较在不同温度下获得的介电磁滞回线时,我们发现退火的三元共聚物薄膜比未退火的样品显示出更高的电位移值和更低的矫顽场,无论测量温度如何,并且在环境温度下也表现出理想的弛豫-铁电行为,这使其成为在室内或附近应用的理想候选者温度。通过调整退火条件,已经表明可以通过微调诱导的微结构和纳米结构来提高应用温度。
更新日期:2022-06-21
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