本文選題：鈮酸鉀鈉 + 晶體生長(zhǎng)　； 參考：《上海應(yīng)用技術(shù)大學(xué)》2017年碩士論文

【摘要】：壓電材料廣泛應(yīng)用于日常生活中,其中PZT基壓電陶瓷的市場(chǎng)占有率超過90%。隨著環(huán)境保護(hù)意識(shí)日益深入人心,現(xiàn)有壓電材料中大量的鉛對(duì)環(huán)境產(chǎn)生巨大危害,應(yīng)用將逐步受到限制,發(fā)展無鉛壓電材料近年來成為研究的熱點(diǎn)。在眾多無鉛壓電材料中,KNN基壓電材料以其相對(duì)較高的壓電系數(shù)、機(jī)電耦合系數(shù),特別是較高的居里溫度,使其在應(yīng)用中具有一定優(yōu)勢(shì),被認(rèn)為是最有希望替代PZT的無鉛壓電材料體系。本論文以KNN基單晶為研究對(duì)象,從晶體的生長(zhǎng)、加工到其結(jié)構(gòu)和性能的關(guān)系等方面進(jìn)行系統(tǒng)的研究。采用頂部籽晶助溶劑提拉法(TSSG)生長(zhǎng)KNN基單晶。在生長(zhǎng)初期沒有籽晶的情況下,選擇鉑絲作為籽晶,初步生長(zhǎng)了 KNN晶體。并且通過控制合適的工藝參數(shù),成功生長(zhǎng)大尺寸,高質(zhì)量的(KxNa1-x)Nb03 (簡(jiǎn)稱為KNN)單晶以及摻雜MnO_2的(KxNa1-x)NbO3x%MnO_2 (簡(jiǎn)稱為KNN-x%MrnO_2)單晶。通過定向、切片等后續(xù)加工得到了尺寸較大的(001)晶片。通過粉末XRD對(duì)晶體的結(jié)構(gòu)進(jìn)行分析,測(cè)試結(jié)果表明所生長(zhǎng)的KNN和KNN-x%MnO_2單晶均為純的鈣鈦礦結(jié)構(gòu),室溫下為正交相,無雜相生成。對(duì)單晶的(001)的介電、壓電、鐵電等電學(xué)性能進(jìn)行研究。通過單晶的升溫介電溫譜研究,結(jié)果表明晶體在升溫過程中主要存在兩個(gè)介電異常峰,分別對(duì)應(yīng)正交鐵電相到四方鐵電相轉(zhuǎn)變和四方鐵電相到立方順電相相變。純的KNN單晶的室溫下的介電常數(shù)約為168,介電損耗tanδ為0.2,晶體更趨向于正常鐵電體;而摻雜MnO_2后,室溫下的介電常數(shù)增大,介電損耗降低,晶體更趨向于弛豫鐵電體。并且摻雜一定量的MnO_2后,晶體的壓電系數(shù)KNN-0.5%MnO_2單晶d33由161pC/N升高到191pC/N;若在600℃下對(duì)晶體進(jìn)行退火處理,其壓電常數(shù)有所增大,d33為261pC/N。燦雜MnO_2后,晶體的矯頑場(chǎng)降低,剩余極化強(qiáng)度有所增大。采用升溫拉曼散射研究了 KNN單晶的晶格振動(dòng)變化,研究了溫度變化對(duì)晶格振動(dòng)模的影響。通過升溫過程中峰的個(gè)數(shù),以及峰形的變化確定相變,從常溫下的正交相(Amm2)到四方相(P4bm)再到順電相即立方相,這和介電溫譜的結(jié)果一致。通過改變實(shí)驗(yàn)光路配置,將四方相單晶不同的振動(dòng)模式峰分離,確定每個(gè)峰所對(duì)應(yīng)的振動(dòng)模。
[Abstract]:Piezoelectric materials are widely used in daily life, among which PZT-based piezoelectric ceramics have more than 90% market share. With the increasing awareness of environmental protection, a large amount of lead in the existing piezoelectric materials will cause great harm to the environment, and its application will be restricted gradually. The development of lead-free piezoelectric materials has become a hot topic in recent years. In many lead-free piezoelectric materials, KNN based piezoelectric materials have some advantages in application because of their relatively high piezoelectric coefficient, electromechanical coupling coefficient, especially the higher Curie temperature. It is considered to be the most promising alternative to PZT. In this paper, KNN-based single crystals are studied systematically, from the growth and processing of crystals to the relationship between structure and properties. KNN based single crystals were grown by the top seed cosolvent Czochralski method (TSSG). In the case of no seed crystal at the beginning of growth, the KNN crystal was grown with platinum wire as seed crystal. By controlling the appropriate technological parameters, large size (KxNa1-x) Nb03 (KNN) single crystals and (KxNa1-x) Nb3xMnO2 (KNN-xMrnO2) single crystals have been successfully grown by controlling appropriate technological parameters, as well as (KxNa1-x) NbO3xMnO2 (KNN-xMrnO2) single crystals doped with MnO _ (1-x) NbO _ 3xMnO _ 2. The larger (001) wafer was obtained by the following processing such as orientation, slicing and so on. The crystal structure was analyzed by powder XRD. The results showed that the KNN and KNN-xx MNO _ 2 single crystals were pure perovskite structure at room temperature. The dielectric, piezoelectric and ferroelectric properties of single crystal (001) were studied. The results show that there are mainly two abnormal dielectric peaks in the process of heating, which correspond to the transition from quadrature ferroelectric phase to tetragonal ferroelectric phase and tetragonal ferroelectric phase to cubic paraelectric phase transition. The dielectric constant of pure KNN crystal is about 168 at room temperature, the dielectric loss tan 未 is 0.2, and the crystal tends to be normal ferroelectrics, but after doping MNO 2, the dielectric constant increases at room temperature, the dielectric loss decreases, and the crystal tends to relaxor ferroelectrics. After doping a certain amount of MnO-2, the piezoelectric coefficient of the crystal KNN-0.5and MnO-2 single crystal d33 is increased from 161pC / N to 191pC / N, and if annealed at 600 鈩，

本文編號(hào)：2079788