Abstract The solution structures in the tetra-n-butylammonium bromide (TBAB) aqueous solution relate closely with the memory effect. In the present study, the behavior derived from the existence of the residual solution structures after TBAB semiclathrate hydrate (TBAB SCH) decomposition was investigated with two methods. One is a high-precision differential scanning calorimetry. The heat capacity of a TBAB aqueous solution with memory effect was slightly larger than that after the memory effect disappeared. The larger heat capacity implies the existence of solution structures. The other is a small-angle X-ray scattering (SAXS). In the first cooling process, strong scattering derived from rapid crystallization was observed at 263.6 K. In the second cooling process where the TBAB aqueous solution exhibited the memory effect, the scattering intensity gradually increased and became remarkably strong at a temperature (approximately 277 K) higher than 263.6 K. In the second cooling process, the invariant Q, which corresponds to electron density fluctuation, increased gradually until crystallization, whereas, in the first cooling process, the change of the invariant Q was quite small until crystallization. The increase of invariant Q implies the existence of 10–100 nm density fluctuation, which is consistent with the cluster size (10–20 nm) previously observed with electron microscopy in the same system.

中文翻译：

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四正丁基溴化铵半包合物水合物体系中记忆效应的量热和小角 X 射线散射研究

摘要 四正丁基溴化铵(TBAB)水溶液中的溶液结构与记忆效应密切相关。在本研究中，使用两种方法研究了 TBAB 半包合物 (TBAB SCH) 分解后残留溶液结构存在的行为。一种是高精度差示扫描量热法。具有记忆效应的TBAB水溶液的热容比记忆效应消失后略大。较大的热容意味着存在溶液结构。另一种是小角度 X 射线散射 (SAXS)。在第一次冷却过程中，在 263.6 K 处观察到来自快速结晶的强烈散射。在第二次冷却过程中，TBAB 水溶液表现出记忆效应，散射强度逐渐增加并在高于 263.6 K 的温度（约 277 K）下变得非常强。在第二次冷却过程中，对应于电子密度波动的不变量 Q 逐渐增加直到结晶，而在第一次冷却中过程中，不变量 Q 的变化很小，直到结晶。不变 Q 的增加意味着存在 10-100 nm 的密度波动，这与先前在同一系统中用电子显微镜观察到的簇大小（10-20 nm）一致。在第一次冷却过程中，不变量 Q 的变化很小，直到结晶。不变 Q 的增加意味着存在 10-100 nm 的密度波动，这与先前在同一系统中用电子显微镜观察到的簇大小（10-20 nm）一致。在第一次冷却过程中，不变量 Q 的变化很小，直到结晶。不变 Q 的增加意味着存在 10-100 nm 的密度波动，这与先前在同一系统中用电子显微镜观察到的簇大小（10-20 nm）一致。