在单元分子晶体中,室温以上的铁电
Sachio Horiuchi1, Yusuke Tokunaga, Gianluca Giovannetti
1National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8562, Japan. s-horiuchi@aist.go.jp
Nature
|February 12, 2010
概括
研究人员通过将分子极性与电场对齐,在晶体酸中实现了铁电. 这种有机材料具有很高的自发极化,为新的电子应用铺平了道路.
科学领域:
- 材料科学 材料科学 材料科学
- 有机电子 有机电子
- 晶体学 晶体学是指结晶学.
背景情况:
- 铁电材料表现出独特的电活性特性,如可切换的极性,火电和压电.
- 有机铁电材料对于灵活的电子产品是可取的,但实现高自发偏振仍然是一个挑战.
- 克罗酸是一种五边形分子,在其晶体状态下具有与结合的极性结构.
研究的目的:
- 通过电场诱导的分子对齐来证明晶体酸中的铁电.
- 通过拓性pi-bond切换来研究极化切换的机制.
- 描述这种有机铁电的自发偏振和热稳定性.
主要方法:
- 应用电场来诱导克罗酸晶体中分子极性的一致对齐.
- 测量光学第二波生成以确认偏振对齐.
- 在室温下观察极化歇斯底里循环.
- 执行第一原则电子结构计算.
主要成果:
- 电场应用在克罗酸中连贯地调整了分子极性,由增加的光学第二波生成证明.
- 在室温下观察到一个明确的极化歇斯底里循环,证实了铁电.
- 分子晶体在有机铁电物中表现出最高的自发偏振 (约为20μC cm-2),这归因于同步的质子转移.
- 高极化一直保持到400K.
结论:
- 晶体克罗酸可以通过电场诱导的同步质子转移,切换pi键拓,使其铁电.
- 这种有机铁电材料对于其分子大小而言,具有异常高的自发极化.
- 强大的铁电特性高达400K表明在有机电子产品的活性电容器和非线性光学中的潜在应用.
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