- 學位論文
鋯鈦酸鉛/聚偏氟乙烯/銀壓電奈米複合材料之介電和壓電性質研究
Piezoelectric and Dielectric Properties of Lead Zirconate Titanate/Polyvinylidene Fluoride/Silver Piezoelectric Nanocomposites
摘要
本論文在探討鋯鈦酸鉛/聚偏氟乙烯/銀(PZT/PVDF/Ag)壓電複合材料之介電和壓電性能研究，並將其複合材料進行高壓極化與熱退火處理過程，觀察其電學性能的變化，並利用掃描式電子顯微鏡(SEM)與X射線繞射儀(XRD)觀測，進而與電性量測結果對應分析。 在PZT/PVDF壓電複合材料中，當PZT混合比例為80 wt%及熱退火溫度400oC處理之後會有最佳的相對介電常數和壓電係數。此外，當PZT/PVDF壓電複合材料混入不同重量比例的Ag時，由於空間電荷極化效應和導電網絡的形成，進而提高整體極化效果，其相對介電常數和壓電係數將會隨著Ag混合比例的增加而上升。 當PZT/PVDF壓電複合材料混入約23 wt%的銀粉時(粒徑大小為150nm和100nm)，其相對介電常數會增加為原值約5.5倍和6.8倍，而壓電係數(d_31)可高達-934 pm/V和-984 pm/V。當Ag混合比例約為28 wt%時，樣品會開始出現展透轉變(percolation transition)，複合材料的電學性質在此範圍中將會有大幅度的改變。然而，雖然在PZT/PVDF壓電複合材料中添加銀粉可以增加介電和壓電性能，但不可避免地其複合材料的介電損耗也會隨之提高。 最後，在本實驗中將PZT/PVDF/Ag壓電複合材料做變溫電性的量測，觀察在低溫下其I-V曲線之變化。
並列摘要
In this thesis, the dielectric and piezoelectric properties of lead zirconate titanate/polyvinylidene fluoride/silver (PZT/PVDF/Ag) nanocomposites were investigated. After polarization and annealing treatment, the nanocomposites were characterized by scanning electron microscope (SEM) and x-ray diffraction (XRD). The results are discussed and compared with the electrical characteristics of the composites. The PZT/PVDF composites without Ag content have maximum dielectric constant and piezoelectric coefficient when the composites have 80 wt% PZT and were annealed at 400°C. In the case of that Ag nanoparticles were added into the specimens to form PZT/PVDF/Ag nanocomposites, the dielectric constant and piezoelectric coefficient of the nanocomposites increase with increasing Ag content. This effect is possibly due to the enhanced space charge polarization and the formation of conductive network by the Ag content. After the specimen with 23 wt% Ag was polarized and annealed at 400°C (the mean particle size of the Ag powder is about 150 nm and 100 nm), its dielectric constant is above 5.5 and 6.8 times higher than the original value, and its transverse piezoelectric coefficient is up to -934 and -984 pm/V. However, when the Ag content reaches 28 wt%, a percolation transition occurs in the specimens, the electrical properties of composites would be a significant change in this range. Additionally, the dielectric and piezoelectric properties of the PZT/PVDF/Ag nanocomposites not only increase significantly with increasing Ag content, but also increases the dielectric dissipation factor significantly, causing a large energy loss. Finally, the PZT/PVDF/Ag nanocomposites were i nvestigated through variable temperature electrical measurements, and observed the change of the I-V curve at low temperature.