PMN-PT微型壓電能量擷取器之製作及其厚膜製程最佳化之研究

Abstract

本論文主要利用氣膠沉積法，於301不銹鋼基板上製備以PMN-PT主軸的壓電懸臂樑式能量擷取元件，並比較PMN-PT元件與PZT元件之輸出功率。本論文之元件可透過壓電材料PMN-PT，將環境中的機械震動能轉換為電能，而為了順利沉積出緻密的PMN-PT厚膜，論文中將探討氣膠沉積法的關鍵參數，透過不同粉末球磨時間與熱處理溫度的實驗，發現粉末經球磨3小時且再經過450 oC後為最佳噴塗參數，接著為了提升元件之壓電特性，其需經過退火及極化步驟，10 μm的PMN-PT元件之製程最佳參數分別為退火525 oC、極化電場30 V/μm、極化溫度150 oC、極化時間20分鐘。實驗結果顯示，本論文製備的能量擷取元件於0.5 g的震動環境下，共振頻為98 Hz，掛載最佳阻抗時輸出電壓可達7.7 Vpp而輸出功率可達90.4 μW，此輸出表現優於過去本團隊所研發的PZT元件，其於同樣0.5 g的震動環境中，最佳阻抗下之輸出電壓為6.2 Vpp、輸出功率為48.5 μW。本論文所製備的PMN-PT元件有較佳的輸出功率，主要原因是PMN-PT具有較佳的壓電常數(d31)以及介電常數(ε33)，導致最後有較佳的輸出功率表現，這也顯示了PMN-PT材料於能量擷取器的研究上，具有很高的價值。

In the past studies, the vibration energy harvesting technologies have been studied intensively and based on material of lead zirconate titanate (PZT). The power outputs of piezoelectric MEMS generators were steadily improved year by year. Until now, the performance of energy harvesters(EH) had gradually reached the limit of the chosen materials. In our previous research, a significant increase in power output was achieved by altering the EH substrate material. In view of this, we introduce innovative piezoelectric material in this dissertation to expect a breakthrough in the limit of EH energy output. According to recently published literature, attention has been given to lead magnesium niobate–lead titanate (PMN-PT) material because of its high piezoelectric constant and electromechanical coupling factor. In this dissertation, 10 m of PMN-PT film was successfully deposited on stainless steel substrate by aerosol deposition. First part of this dissertation is to investigate critical parameters of aerosol deposition method and we found the pre-process for starting powder is a key to deposit PMN-PT layer. Powder milled for 3 hours and heated at 450 oC were chosen as the best deposition condition. Then, in order to increase piezoelectric properties of the device, annealing and poling process were necessary and optimal parameters were described as below: annealed at 525 oC, electric field was 30 V/μm, poling temperature was 150 oC, and poling time was 20 minutes. The experimental results show that the fabricated device excited at 0.5 g vibration level can generate a maximum output voltage of 7.7 VPP and corresponding power of 90.4 μW at the resonant frequency of 98 Hz. When given a comparison with previous work, the output performance is better than the PZT-based EH with same thickness, which had maximum output voltage of 6.2 VPP and corresponding power of 48.5 μW under 0.5 g acceleration.