Bi5Ti3FeO15薄膜的结构和多铁性研究

采用脉冲激光沉积的方法, 在Pt/Ti/SiO₂/Si衬底上生长Bi₅Ti₃FeO₁₅ (BTFO15)多铁性薄膜, 并对其结构、磁性、铁电性、铁电畴等进行了研究。通过X射线衍射、扫描电镜以及高角环形暗场像-扫描透射电镜测试, 结果表明, 薄膜具有高结晶度和完美层状晶格结构, 两层Bi原子层紧密堆积, 两层Bi₂O₂之间有三层Bi层和三层Ti(Fe)O₆八面体层, 构成三明治结构; 在室温下的磁滞回线和电滞回线证实了弱铁磁性和铁电性的共存; 采用压电响应力显微镜研究了薄膜的畴结构, 在面内和面外分别施加±3 V和±10 V的电压, 观测到了畴反转。这些研究结果对理解多铁性材料的微观结构和宏观特性的相互调制有重要意义。

Structure and Property of Bi5Ti3FeO15 Film

Bi₅Ti₃FeO₁₅ (BTFO15) thin films were grown on Pt/Ti/SiO₂/Si substrate by pulsed laser deposition (PLD) method. The structure, magnetic properties, ferroelectric properties, and ferroelectric domains were studied by using X ray diffraction, scanning electron microscopy and scanning TEM high-angle annular dark-field (HAADF STEM). Results showed that the BTFO15 film had high crystallization with perfect layered lattice structure. It stacked like a sandwich which three Bi layers and Ti(Fe)O₆ octahedra were sandwiched by two closely stacked Bi layers. In addtion, room-temperature magnetic hystersis loop and ferroelectric hysteresis loop confirmed that the BTFO15 film had weak ferromagnetism and ferroelectricity. The piezo response force microscope was used to study the domain and domain switching, the in-plane and out-of-plane PFM images were obtained by applying the voltage of ±3 V and ±10 V. These results are important to understand the relationship between microstructure and property of multiferroic materials.