Structural assignment of polarization in hydrogen-bonded supramolecular ferroelectrics
Structural assignment of polarization in hydrogen-bonded supramolecular ferroelectrics
复制标题
DOI：
10.1021/ja075406r
复制
发表时间：
2007-10-31
影响因子：
15
通讯作者：
Tokura, Yoshinori
中科院分区：
文献类型：
--
作者：
Kumai, Reiji;Horiuchi, Sachio;Tokura, Yoshinori
吩嗪 (Phz) 与氯苯甲酸 (H(2)ca) 和溴苯苯酸 (H(2)ba) 的 1:1 加合物，其中非极性中性分子通过分子间 O-(HN)-N-... 氢键连接，显示出铁电转变。这些材料的中子衍射分析表明，在铁电转变温度（Phz-H(2)ca 为 253 K，Phz-H(2)ba 为 168 K）以下存在两个不等价的氢键位点。通过同步加速器 X 射线衍射的最大熵法 (MEM) 分析也观察到了这种不对称性。结构分析结果表明，材料极化的根源是基于两个不等价氢键的对称性破缺。
A 1:1 adduct of phenazine (Phz) with chloranilic acid (H(2)ca) and bromanilic acid (H(2)ba), in which nonpolar neutral molecules are connected by the intermolecular O-(HN)-N-... hydrogen bonds, shows ferroelectric transitions. Neutron diffraction analysis of these materials reveals that there are two inequivalent hydrogen-bonding sites below the ferroelectric transition temperature (253 K for Phz-H(2)ca and 168 K for Phz-H(2)ba). This asymmetry was also observed by the maximum entropy method (MEM) analysis of the synchrotron X-ray diffractions. The structure analysis results suggest that the origin of the polarization of the material is the symmetry breaking based on the two inequivalent hydrogen bonds.