人工调控微结构压电驻极体的热稳定性和电荷动态特性

利用表面带有周期性结构的硬质模板,通过冷压工艺将周期结构图案复制到多孔聚四氟乙烯(PTFE)薄膜表面,再经过热黏合工艺与致密氟化乙丙烯共聚物(FEP)薄膜复合,制备出了高度有序的微孔结构复合膜,并用电晕充电的方法对复合膜进行极化处理,最终获得氟聚合物复合膜压电驻极体.借助对这类复合膜压电驻极体介电谐振谱的测量,得到了材料的杨氏模量.并利用等温热老化工艺对它们的压电系数d33的热稳定性进行了考察.最后通过短路热刺激放电谱的测量和分析,讨论了该复合膜在热老化处理后的电荷动态 关键词： 有序结构 压电驻极体 压电性 电荷动态特性

Thermal stability and charge dynamics of piezoelectrets with tailored micro-structure

The laminated fluoroethylenepropylene (FEP) and porous polytetrafluoroethylene (PTFE) films with regular void structure are prepared by using a rigid template with a periodic-structured surface. The porous PTFE film is firstly patterned with the rigid template surface by applying force on the stack of porous PTFE film and the template, then followed by the fusion bonding process to bond the FEP and patterned porous PTFE together. The corona charging technique is used to make the laminated film piezoelectric, i.e., to become piezoelectrets. The Young’s modulus of the laminated FEP/PTFE films is determined by dielectric resonance spectra. The thermal stability of the piezoelectric d₃₃ coefficients are characterized by measuring the decay of d₃₃ at elevated temperatures. The charge dynamics in such FEP/PTFE piezoelectrets is investigated by analying the thermally stimulated discharge current spectra in short circuit. The results show that laminated FEP/PTFE films with very regular void structure can be made by using rigid template and fusion bonding process. The Young's modulus of such films is about 0.53 MPa. The maximum quasi-static piezoelectric d₃₃ coefficient up to 500 pC/N is achieved. The laminated FEP/PTFE films show improved thermal stability. For example, the remnant d₃₃value is around 22% of the initial value for the sample annealed at 150 ℃ for 5000 min. For the samples after annealing treatment, the main drift path of the detrapped charges is through the solid dielectric layer.