随着环境和健康问题的日益严峻，寻找可以取代现有锆钛酸铅薄膜的无铅压电薄膜材料是近几年压电薄膜研究的热点。钛酸铋钠体系压电材料作为具有高压电性能的无铅压电材料之一备受瞩目。但目前该体系的薄膜工作较少，缺乏调控其薄膜相结构，提高压电性能的深入研究。本论文通过对钛酸铋钠-钛酸钡（BNT-BT）多晶、织构、外延薄膜到最后的厚膜逐步、系统地研究了成分、温度、取向、应力等对钛酸铋钠-钛酸钡薄膜的影响，通过这些因素相结合来有效调控其相结构并提高其压电性能。通过对A位元素补偿量、热解和退火工艺进行优化，得到了最优的BNT-BT薄膜沉积工艺。制备了不同成分的BNT-BT薄膜，通过XRD和变温拉曼等研究了其随成分和温度的结构变化。借助介温谱、压电响应回线、电滞回线测试以及压电力显微镜扫描进一步验证了其结构相变，提出了BNT-BT薄膜的相图，并得到了性能最优的成分。进一步通过引入LaNiO3晶种层在Pt/Ti/SiO2/Si衬底上制备了高（001）取向的织构BNT-BT6薄膜。相比于随机取向薄膜，（001）取向薄膜具有显著提升的压电性能（d33,eff=43pm/V）和退极化温度（约140℃）。解释了（001）取向薄膜中压电性能和退极化温度提高的原因。随后制备了不同厚度和组分的BNT-BT外延薄膜。通过倒易空间扫描、选区电子衍射、压电力显微镜等得到了不同组分BNT-BT薄膜随厚度的结构变化。原位和宏观压电性能表征发现其压电性能变化和其受衬底应力的变化相关。其中，BNT-BT2薄膜低厚度时受衬底应力作用变为单斜Mb相，随厚度增加应力释放恢复到菱方相。在150nm厚度存在两相共存，极大提升了压电性能，d33。local=100pm/V, d33,eff=60pm/V。最后制备了适用于MEMS器件的BNT-BT厚膜，其具有较好铁电和压电性能（Pr=20μC/cm2，d33,eff=40pm/V）。制备了悬臂梁结构，测试了其的尖端振动，并得到了厚膜的横向压电系数。e31= 4.7C/m2，d31=-34pC/N。
With the increasingly serious environmental and health problems, finding a lead free piezoelectric film material that can replace the existing lead zirconate titanate film is a hot research topic in recent years. As one of the lead-free piezoelectric materials with high piezoelectricity, the sodium bismuth titanate system piezoelectric material has attracted a lot of attentions. However, there has been little research focus on the sodium bismuth titanate films. This paper systematically studies the effects of composition, temperature, orientation and stress on polycrystalline, textured and epitaxial films of sodium bismuth titanate-barium titanate (BNT-BT). Through the combination of these factors, we effectively control the phase structure and improve the piezoelectric properties.By optimizing the compensation of A-site elements, pyrolysis and annealing process, the optimal deposition process of BNT-BT thin films was obtained. Different compositions of BNT-BT films were prepared, and their phase transitions with composition and temperature were studied by XRD and temperature-dependent Raman spectra. The phase transitions were further confirmed by the dielectric temperature spectrum, piezoelectric response loop, ferroelectric hysteresis and piezoresponse force microscopy. The best composition were obtained.A high (001)-textured BNT-BT6 film was further prepared on the Pt/Ti/SiO2/Si substrate by introducing a LaNiO3 seed layer. The (001)-textured thin film has a significantly enhanced piezoelectric property (d33,eff = 43pm/V) and an enhanced depolarization temperature (about 140 °C), compared to the randomly oriented film..Subsequently, BNT-BT epitaxial films of different thicknesses and compositions were prepared. The structural changes of BNT-BT films with different thicknesses were obtained by reciprocal space mapping, selected area electron diffraction, and piezoresponse force microscopy. Characterization of in-situ and macro-piezoelectric properties reveals that the change in piezoelectric properties is related to the changes in the stress from substrate. It’s need to be mentioned that at small thickness, the BNT BT2 film changed to the monoclinic Mb phase due to the substrate stress, and as the stress released with increasing thickness, it turned back to the rhombohedral phase. There are two phases coexisting at a thickness of 150 nm, which greatly improves the piezoelectric performance, d33,local=100pm/V and d33, eff=60pm/V.Finally, a BNT-BT thick film suitable for MEMS devices was prepared, which has good ferroelectric and piezoelectric properties (Pr=20μC/cm2, d33, eff=40pm/V). The cantilever beam structure was prepared and its tip vibration was tested, and the transverse piezoelectric coefficient of the thick films was evaluated, e31 = -4.7C/m2, and d31 = -34 pC/N.
