無鉛壓電陶瓷發展已數十年，發展主要分為鈣鈦礦結構與非鈣鈦礦結構。鉍層狀結構(BLS)為非鈣鈦礦結構具有優良的鐵電性，適用於高溫及疲勞特性好的鐵電儲存器、濾波器與共振器領域，具有競爭力的材料。鉍層狀結構材料利用碳酸鈉與碳酸鉀溶解與再結晶原理先製作碳酸鈉鉀，優點可降低燒結溫度、製程快速、低溫、成本低。鉍層狀結構陶瓷體(Na0.85K0.15)Bi5Ti5O18由碳酸鈉鉀、氧化鉍、氧化鈦經固態反應法製作，製程中會因碳酸物殘留造成結晶性與電性不佳，需在800 ℃煆燒。本文有系統地在不同燒結條件下，找出燒結溫度990℃、持溫8 小時為最佳條件，陶瓷密度7.08 kg/m3。(Na0.85K0.15)Bi5Ti5O18由電子顯微鏡(SEM、TEM)知為典型板狀結構，利用繞射圖形(DP)與高解析TEM(HRTEM)有螢石結構Bi-O層與之間類鈣鈦礦結構層，具有4層A-site夾雜在雙層Bi-O其中之證據。使用TOPAS計算空間群為I4/mmm，晶軸常數a=3.846 Å、c=40.806 Å且Rwp=9.51，Tc溫度點大於600℃、介電常數214、介電損失0.019、壓電特性d33值=16、Qm值=1375。0.1–3.0 wt.% ZnO添加至NBT鈣鈦礦結構壓電材料使用傳統燒結法，壓電特性與微結構將會被探討，ZnO添加≥2 wt.%時Na0.5Bi0.5TiO3有Zn2TiO4結晶相產生。NBT 添加1.0 wt.% ZnO 於1050℃燒結壓電特性為 d33 =95 pC/N, kp = 0.13, Qm = 250, εr =574。且NBT添加0.5 wt.% ZnO 於1140℃燒結會有較好的壓電特性d33 = 110 pC/N, kp = 0.17, Qm = 201, εr = 57。
壓電材料最早的應用感測器，有別於水下環境應用，目前有發展出空氣傳輸之超音波感測器，車用系統的倒車雷達即為應用例，商業化感測器為含鉛電材料。本研究完整製作無鉛壓電感測器為具有非對稱指向性的封閉式超音波感測器，研究範圍包括理論模擬、製程實作與實驗量測。無鉛壓電片使用平行板改良極化法，可提供比傳統方式較高良率及極化特性之壓電片。根據理論與ANSYS模擬來設計組裝超音波感測器，再以高溫填膠法縮短元件殘響時間，並成功開發無鉛壓電空氣傳輸之超音波感測器。

Lead-free piezoelectric ceramics have been developed for decades. Lead-free piezoelectric ceramics can be classified into two main types: perovskite and non-perovskite structures. Generally, bismuth layer structure have an excellent ferroelectricity and can be utilized in high-temperature and fatigue-resistant ferroelectric random-access memories, filters, and oscillators. Original compound-(Na,K)2CO3 and uniform mixing is the key to a successful experiment. Original compound can be synthesized by dissolving and re-crystallizing Na2CO3 and K2CO3, which can help to low-cost, low-temperature synthesis process and deliquesce is worse than sodium carbonate and potassium carbonate. The (Na0.85K0.15)Bi5Ti5O18 ceramic body can be synthesized from original compound, Bi2O3 and TiO2 via a solid state-reaction method. During the synthesis process, residual carbonate can result in poorer ceramic crystallinity and electrical properties; hence, calcination at 800℃ was necessary. The optimal conditions are: sintering temperature of 990℃ for 8 h; and the ceramic parameters are density 7.08 kg/m3 and Curie Temperature Tc >600℃. The ceramic’s micro-structure was found to be a typical plate-like (layered) structure, and DP and HRTEM provided evidence for the presence of a perovskite-like structure between the fluorite-structured Bi-O layers. Four layers of A sites were found to be sandwiched between two Bi-O layers. TOPAS software was employed to calculate the space group of the ceramic body, which was I4/mmm, a=3.846 Å, c=40.806 Å and Rwp=9.51. At the room temperature, dielectric constant=214 and dielectric loss tanδ=1.9%. The piezoelectric characteristics measured after poling were d33=16 and mechanical couple factor Qm=1375. NBT based piezoelectric ceramics doped with ZnO were synthesized using a conventional solid state reaction. The mechanism through which Zn doping altered the piezoelectric properties and microstructures of NBT ceramics was investigated and discussed. NBT based piezoelectric ceramics doped with 0.1–3.0 wt.% ZnO were investigated. An X-ray diffraction examination of the products indicates that they consist mainly of a Na0.5Bi0.5TiO3 crystalline phase with Zn2TiO4 as a secondary phase. The secondary phase is formed due to the addition of ZnO (≥2 wt.%). At room temperature, NBT ceramics with 1.0 wt.% ZnO dopant sintered at 1050℃ exhibit d33 = 95 pC/N, kp = 0.13, Qm = 250, εr = 574 (at a frequency of 1 MHz). Moreover, NBT ceramics with 0.5 wt.% ZnO dopant sintered at 1140℃ show quite good performance: d33 = 110 pC/N, kp = 0.17, Qm = 201, εr = 570 (at a frequency of 1 MHz).
Piezoelectric ultrasonic sensors basic operating principle is the operating frequency of the driving voltage is applied to the element. Lead-free piezoelectric ultrasonic sensor with asymmetric directivity device was produced. and can be applied in vehicle parking sensors. Self-made lead-free piezoelectric material was used to produce the piezoelectric plate, which was combined with relevant parts to assemble the piezoelectric ultrasonic sensor. The parallel plates method was employed to improve the polarization of the piezoelectric plate, which led to better polarization characteristics than those achieved using traditional methods. A comparison of the results between the ANSYS simulation and practical device found that both results are in agreement, with a minimal error, which indicates that the simulation and practical device correlated and can be used as a basis in designing lead-free piezoelectric ultrasonic sensors.

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