We present a study of thermal conductivity, $\kappa$, in undoped and doped strontium titanate in a wide temperature range (2–400 K) and detecting different regimes of heat flow. In undoped ${\mathrm{SrTiO}}_3$, $\kappa$ evolves faster than cubic with temperature below its peak and in a narrow temperature window. Such behavior, previously observed in a handful of solids, has been attributed to a Poiseuille flow of phonons, expected to arise when momentum-conserving scattering events outweigh momentum-degrading ones. The effect disappears in the presence of dopants. In ${\mathrm{SrTi}}_{1-x}{\mathrm{Nb}}_x{\mathrm{O}}_3$, a significant reduction in lattice thermal conductivity starts below the temperature at which the average inter-dopant distance and the thermal wavelength of acoustic phonons become comparable. In the high-temperature regime, thermal diffusivity becomes proportional to the inverse of temperature, with a prefactor set by sound velocity and Planckian time (${\tau }_p=(\hslash /k_{B}T)$).

中文翻译：

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钛酸锶的热输运和声子流体动力学

我们提出了导热系数的研究， $\kappa$在宽温度范围（2–400 K）中检测未掺杂和掺杂的钛酸锶，并检测不同的热流状态。在未掺杂${\mathrm{钛酸锶}}_3$， $\kappa$当温度低于其峰值且在狭窄的温度范围内时，其演化速度快于立方。以前在少数几种固体中观察到的这种行为已归因于声子的泊肃叶流，当保持动量的散射事件大于降低动量的散射事件时，预计会发生这种声子。在掺杂剂的存在下该作用消失。在${\mathrm{锶钛}}_{\mathrm{1个}-X}{铌}_X{\mathrm{Ø}}_3$，在低于平均掺杂剂间距离和声子的热波长可比的温度以下，晶格热导率开始显着降低。在高温状态下，热扩散率与温度的倒数成正比，其系数由声速和普朗克时间（${\tau }_p=（\hslash /{ķ}_{乙}Ť）$）。