Temperature-dependent thermal conductivities are reported for one-dimensional (1D) hydrogen-bonding ferroelectric crystals of isostructural compounds NH₄HSO₄ and RbHSO₄. As the temperature was decreased from 300 K, at which point they were paraelectric in the P2₁/n space group, their thermal conductivities decreased, similar to those of glassy materials. At the ferroelectric transition points (T_1A = 270 K for NH₄HSO₄ and T_1R = 264 K for RbHSO₄), a change from P2₁/n to Pn space groups was observed, and the thermal conductivity of the NH₄HSO₄ crystal decreased without any anomalies, whereas that of RbHSO₄ increased, similar to that of crystalline materials. At the second ferroelectric-to-paraelectric transition point of NH₄HSO₄ (T_2A = 154 K), the thermal conductivity increased from 1.00 W m⁻¹ K to 1.32 W m⁻¹ K and increased with a subsequent decrease in temperature, similar to that of crystalline materials. Single-crystal x-ray structure analyses revealed that the thermal conductivity transition of RbHSO₄ at T_1R = 264 K corresponds to the rotational motion excitation of the HSO₄⁻ chains. The abrupt thermal conductivity jump of NH₄HSO₄ was likely related to the order–disorder type transition in NH₄⁺ ions, accompanied by lattice vibration excitation, coupled with internal rotation. At the T_2A ferroelectric-to-paraelectric phase transition of NH₄HSO₄, 2₁ crystal symmetry recovery was observed, similar to the Rochelle salt, and the space group at low temperatures was P2₁/n. For the RbHSO₄ crystals, the thermal conductivity parallel to the 1D chains was 1.5-times higher than the corresponding perpendicular orientation.

中文翻译：

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等效结构一维铁电晶体NH4HSO4和RbHSO4在热导率方面的对比温度依赖性

报道了同构化合物NH ₄ HSO ₄和RbHSO _4的一维（1D）氢键合铁电晶体的温度依赖性热导率。当温度从300 K降低时，此时在P 2 ₁ / n空间群中它们是顺电性的，它们的热导率下降，类似于玻璃材料。在铁电跃迁点（对于NH ₄ HSO ₄，T _1A = 270 K；对于RbHSO ₄，T _1R = 264 K ），从P 2 ₁ / n开始变化观察到Pn空间群的热导率，NH ₄ HSO ₄晶体的热导率下降而没有任何异常，而RbHSO ₄的热导率上升，类似于晶体材料。在NH ₄ HSO ₄的第二铁电-顺电转变点（T _2A = 154 K），热导率从1.00 W m ^-1 K增加到1.32 W m ^-1 K，并随温度的降低而增加，类似于晶体材料。X射线单晶结构分析表明，RbHSO ₄在T处的热导率跃迁_1R = 264个k对应于HSO的旋转运动激励₄ ^-链。NH ₄ HSO ₄的突然热导率跃迁可能与NH ₄ ⁺离子的有序-无序类型跃迁，晶格振动激发以及内部旋转有关。在NH ₄ HSO ₄的T _2A铁电-顺电相变中，观察到2 ₁晶体对称性恢复，类似于罗谢尔盐，并且在低温下的空间群为P 2 ₁ / n。对于RbHSO ₄ 晶体，与一维链平行的热导率比相应的垂直方向高1.5倍。