Dynamical Properties of Protons in KH2PO4. I. –Proton Self-Trapped State and Its Incoherent Tunneling–
Dynamical Properties of Protons in KH2PO4. I. –Proton Self-Trapped State and Its Incoherent Tunneling–
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KH2PO4 中质子的动力学特性 I. –质子自俘获态及其非相干隧道 –
DOI：
10.1143/jpsj.63.3691
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发表时间：
1994
影响因子：
1.7
通讯作者：
S. Ikeda
中科院分区：
文献类型：
--
作者：
Y. Yamada;S. Ikeda
研究了氢键铁电晶体KH 2 PO 4（KDP）的质子-声子系统。作为一个合理的模型，“质子自陷态”模型已被提出。我们认为，通过与声子的耦合，氢键上的质子倾向于通过破坏周围原子的局部对称性而在移动的位置处自陷。相同的耦合导致简并自陷态之间的量子力学跃迁（声子辅助隧穿）。在更高的温度下，预计转变为热激活型（非相干隧穿）。利用该模型对KDP的中子非相干散射研究结果进行了分析。在T =150 K（T > Tc）时，当非相干隧穿弛豫时间取4×10 - 13秒时，散射函数与观测光谱符合得很好。研究了弛豫时间随温度的变化关系，证实了该方法的有效性。
We investigate a proton-phonon system which represents the hydrogen-bonded ferroelectric crystals, in particular KH 2 PO 4 (KDP). As a plausible model, `proton self-trapped state' model has been proposed. It is considered that, through the coupling to phonons, the proton on the hydrogen bond tends to be self-trapped at the shifted positions by breaking local symmetry of the surrounding atoms. The same coupling causes the quantum mechanical transition (phonon assisted tunneling) between the degenerated self-trapped states. At higher temperatures the transition is expected to become thermal activation type (incoherent tunneling). The results of neutron incoherent scattering study on KDP have been analyzed based on this model. The scattering function at T =150 K ( T > T c ) shows satisfactory agreement with the observed spectrum by taking the relaxation time to cause incoherent tunneling to be 4×10 -13 sec. The temperature dependence of the relaxation time is also investigated, which confirmed the validity o...