State Key Laboratory of New Ceramics and Fine Processing, School of Materials, Science and Engineering, Tsinghua University, 100084 Beijing, P. R. China.
Phys Chem Chem Phys. 2018 Jun 6;20(22):15236-15243. doi: 10.1039/c8cp01830h.
High-quality (1 - x)(Bi0.5Na0.5)TiO3-xSrTiO3 lead-free piezoelectric thin films (x = 0, 0.1, and 0.25) on Pt(111)/Ti/SiO2/Si(100) substrates were prepared by a sol-gel method. The microstructures of the thin films as a function of SrTiO3 doping level and temperature were investigated by X-ray diffraction and Raman spectroscopy. Their temperature- and frequency-dependent piezoelectric properties were studied on the nanoscale using switching spectroscopy piezoresponse force microscopy (SS-PFM). A rhombohedral ferroelectric to pseudocubic relaxor phase transition was observed when either ST content or temperature increased. The significant frequency dependence of both ferroelectric and piezoelectric properties was also disclosed by analyzing polarization hysteresis loops on the macroscopic scale and local switching dynamics at various frequencies. It was determined that the short-range order clusters came out through the long-range ferroelectric order, thus the nanoscale approaches are consistent with macroscopic data at elevated temperatures and various frequency ranges.
在 Pt(111)/Ti/SiO2/Si(100) 衬底上，通过溶胶-凝胶法制备了高质量的(1 - x)(Bi0.5Na0.5)TiO3-xSrTiO3 无铅压电薄膜(x = 0、0.1 和 0.25)。通过 X 射线衍射和拉曼光谱研究了薄膜的微结构随 SrTiO3 掺杂水平和温度的变化。使用开关光谱压电力显微镜(SS-PFM)在纳米尺度上研究了其温度和频率相关的压电性能。当 ST 含量或温度升高时，观察到菱形铁电相到赝立方弛豫相的转变。通过在宏观尺度上分析极化滞后回线和在不同频率下的局部开关动力学，揭示了铁电和压电性能的显著频率依赖性。确定了通过长程铁电有序出现的短程有序簇，因此在高温和不同频率范围内，纳米级方法与宏观数据一致。
