【摘要】：鈮酸鉀鈉(KNN)無鉛壓電薄膜憑借高居里溫度,優(yōu)良的壓電性以及良好的生物相容性,可廣泛地應(yīng)用于驅(qū)動器、傳感器及致動器等領(lǐng)域。本文采用溶膠凝膠法制備KNN薄膜,探究了熱裂解溫度和退火溫度,離子(Li~+,Mn~(2+))摻雜及引入緩沖層(Nb_2O_5,SiTiO_3)對KNN薄膜結(jié)構(gòu)和性能的影響。主要研究結(jié)果如下:熱裂解溫度過低,薄膜內(nèi)有機物不完全分解,產(chǎn)生大量孔洞;熱解溫度過高導(dǎo)致堿金屬離子揮發(fā)嚴重,薄膜氧空位增多。退火溫度較低,晶粒不完全長大,薄膜結(jié)晶性差;退火溫度過高,堿金屬離子大量揮發(fā)。當熱裂解溫度為400℃,退火溫度為600℃時,薄膜性能最優(yōu):在1k Hz下,ε_r為712,在200 kV/cm電場下,2P_r和2E_c分別為6.2μC/cm~2、118.6 kV/cm。Li離子主要取代KNN薄膜的A位離子,可以細化晶粒,改善薄膜的結(jié)晶性,使薄膜更加致密均勻。當Li離子摻雜量為1.5 mol%時,薄膜結(jié)晶性好,電學性能最優(yōu):在1 k Hz,ε_r為449.7,在200 kV/cm電場下,2P_r和2E_c分別為10.3μC/cm~2、107.2 kV/cm;Mn離子通過變價降低薄膜中載流子空穴濃度,從而提高薄膜的質(zhì)量和性能。當Mn離子摻雜量為2 mol%時,KNLN薄膜具有最佳的性能:在1 kHz下,ε_r為875、tanδ為0.030;在200 kV/cm電場下,2P_r為22.5mC/cm~2;2E_c為130 kV/cm。Nb_2O_5緩沖層起到良好的過渡作用,降低了薄膜和襯底的相互擴散,減少了晶格失配引起的界面缺陷。當Nb_2O_5緩沖層為2層時,KNN薄膜的性能最優(yōu):在1 k Hz下,ε_r為265,在108.5kV/cm電場下,2P_r為7.8mC/cm~2;2E_c為75.8 kV/cm。SrTi O_3緩沖層能降低薄膜和襯底間的晶格失配,抑制界面非鐵電活性層的出現(xiàn),改善薄膜的質(zhì)量和性能。當SrTi O_3緩沖層為2層時,KNN薄膜的性能最優(yōu):在1 k Hz下,ε_r為446,在200 kV/cm電場下,2P_r為10.8mC/cm~2;2E_c為121 kV/cm。
[Abstract]:Potassium niobate (KNN) lead-free piezoelectric film is widely used in actuators sensors and actuators due to its high Curie temperature excellent piezoelectric properties and good biocompatibility. In this paper, KNN thin films were prepared by sol-gel method. The effects of pyrolysis temperature and annealing temperature, doping of Li~ mn ~ (2) and introducing buffer layer (Nb_2O_5,SiTiO_3) on the structure and properties of KNN thin films were investigated. The main results are as follows: the pyrolysis temperature is too low, the organic matter in the film is not completely decomposed, a large number of pores are produced, and the excessive pyrolysis temperature leads to the evaporation of alkali metal ions and the increase of oxygen vacancies in the films. The annealing temperature is low, the grain is not fully grown, the crystallinity of the film is poor, and the annealing temperature is too high, the alkali metal ions volatilize a lot. When the pyrolysis temperature is 400 鈩，

本文編號：2202034