氮氢混合气氛对SrBi_2Ta_2O_9铁电薄膜和粉末性能的影响

Effect of Forming Gas on Properties of SrBi_2Ta_2O_9 Ferroelectric Thin Film and Powder

用金属有机物分解法分别制备了SrBi2Ta2O9(SBT)薄膜和粉末样品.XRD和SEM结果显示SBT粉末经历氮氢混合气氛400℃退火处理后发生了还原反应,金属Bi和δ-Bi2O3析出,成针状结构聚集在表面,晶体结构没有被破坏.SBT薄膜在500℃退火处理时,表面出现Bi的球形及针状结构聚集体,相对于薄膜结构,SBT粉末中的Bi元素在较低温度时更容易被还原.Bi的大量缺失严重影响薄膜的铁电性能,当退火时间为5.5min时,SBT薄膜剩余极化强度Pr下降了约43%,但是在109极化反转后仍然保持了良好的抗疲劳特性;退火时间超过8.5min时,薄膜被击穿,铁电性能消失.

SrBi2Ta2O9 （SBT） ferroelectric thin film and powder samples were fabricated by using metalorganic decomposition （MOD） method.XRD and SEM results show that SBT powders still remain polycrystalline perovskite structure and amounts of Bi and δ-Bi2O3 are reduced from SBT annealed in the forming gas at 400℃.Spherical and needle structures form on the surface of SBT thin films annealed in the forming gas at 500℃.Bi element in powders is more easily reduced at lower temperature compared with that of thin films and form needle structures on SBT surface.Bi deficiency derived from forming gas annealing causes serious ferroelectricity degradation on the SBT capacitors.Annealed in the forming gas ambient at 400℃ for 5.5min,the remnant polarization of SBT films drop about 43%.If annealing time is longer than 8.5min,films are breakdown and ferroelectricity disappears totally.However,no obvious polarization fatigue with 10^9 electric field cycling could be observed.