Tuning of Optical Properties via Annealing of Bismuth Ferrite (BiFeO3) Thin Films

In this study we are reporting annealing induced optical properties of bismuth ferrite (BiFeO3) thin films deposited on glass substrate via spin coating at 5000 rpm. The structural, optical and surface morphology of BiFeO3 (BFO) thin films have been studied via X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Optical absorption (UV-Vis) and Photoluminescence (PL) spectroscopy. XRD spectra confirm annealing induced phase formation of BiFeO3 possessing a rhombohedral R3c structure. The films are dense and without cracks, although the presence of porosity in BFO/glass was observed. Moreover, optical absorption spectra indicate annealing induced effect on the energy band structure in comparison to pristine BiFeO3. It is observed that annealing effect shows an intense shift in the UV-Vis spectra as diffuse absorption together with the variation in the optical band gap. The evaluated optical band gap values are approximately equal to the bulk band gap value of BiFeO3.

界面影响BFO铁电薄膜极化翻转行为的原位电学研究

铁电薄膜在高密度存储器等微型功能器件具有巨大的应用前景,在外场下研究铁电薄膜极化翻转机制具有重要意义。本文用原位透射电镜技术对BFO薄膜电容器的铁电极化翻转动态行为及界面因素进行了研究。原位结果观察到“面内层状”与典型“成核生长”两种铁电极化翻转模式;HAADF高分辨与高斯拟合分析结果表明界面几何构型的影响作用,界面几何曲率的不同导致局部电荷密度不同,并进一步影响局部内建电场和成核势垒,使得铁电极化翻转呈现不同的行为模式。本研究为调控铁电成核与翻转方式以及器件界面设计提供了新的见解和参考。

多铁性BiFeO_(3)薄膜中复杂畴组态的亚埃尺度研究

本文利用透射电子显微镜对外延生长的BiFeO_(3)/DyScO_(3)[110]O薄膜中复杂畴组态进行了细致的研究。衬度分析表明薄膜中存在由锯齿状畴和界面纳米畴组成的复杂畴。像差校正电镜研究发现锯齿状畴的顶点通常位于180°畴壁、109°畴壁和71°畴壁的交点,纳米畴位于薄膜与衬底的界面位置。且界面处存在纳米尺寸缺陷,分析得出这种界面纳米缺陷促进了纳米畴的形成,进而诱导复杂畴结构的形成。

BiFe_(0.98-x)Ti_(0.02)Zn_xO_3薄膜结构与压电性能

采用金属有机分解法在ITO/玻璃衬底上制备出晶粒尺寸均匀且致密的BiFe0.98-xTi0.02ZnxO3薄膜。XRD结果表明,掺入适量Zn2+有助于薄膜(012)取向晶粒的生长。压电原子力显微镜测试结果显示,BiFe0.965Ti0.02Zn0.015O3薄膜具有最大的压电常数d33(123 pm/V),比BiFe0.98Ti0.02O3薄膜压电响应提高50%。