Observation of Quantum Paraelectricity in an Intermolecular Ionic Hydrogen-Bonded Crystal of a Squaric Acid Derivative
Observation of Quantum Paraelectricity in an Intermolecular Ionic Hydrogen-Bonded Crystal of a Squaric Acid Derivative
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DOI：
10.1021/jp030961a
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发表时间：
2004-04
影响因子：
3.3
通讯作者：
I. Takasu;A. Izuoka;T. Sugawara;T. Mochida
中科院分区：
文献类型：
--
作者：
I. Takasu;A. Izuoka;T. Sugawara;T. Mochida
用交流介电测量方法研究了方酸衍生物对亚苯基二（方酸）（PBSQ）水合晶体中的质子转移。该晶体由PBSQ单阴离子和质子化的水二聚体（H5 O2+）抗衡阳离子组成，通过去质子化的PBSQ部分之间强的OH· ·O-离子氢键形成高度对称的一维氢键链。水合晶体的介电常数几乎与温度无关（e'ε 9），但氘代晶体表现出居里-韦斯型温度依赖性，并在28 K时经历介电常数的降低，这是（反）铁电相变的特征。因此，我们得出结论，水合PBSQ晶体的介电响应起源于质子转移沿着分子间氢键和温度无关的介电行为可以解释在量子顺电。
Proton transfer in a hydrated crystal of a squaric acid derivative, p-phenylenebis(squaric acid) (PBSQ), was investigated by means of ac dielectric measurements. The crystal consisted of PBSQ monoanions and protonated water dimer (H5O2+) counter cations, and a highly symmetric, one-dimensional hydrogen-bonded chain was formed through strong OH· · ·O- ionic hydrogen bonding between deprotonated PBSQ moieties. The permittivity of the hydrated crystal was nearly temperature independent (e‘ ∼ 9), but the deuterated crystal exhibited a Curie−Weiss type temperature dependence and underwent depression of the permittivity at 28 K, which is the characteristic of an (anti)ferroelectric phase transition. Thus, we conclude that the dielectric response of the hydrated PBSQ crystal originates from proton transfer along the intermolecular hydrogen bond and that the temperature-independent dielectric behavior can be interpreted in terms of quantum paraelectricity.