Nanoscale structures can produce extreme strain that enables unprecedented material properties, such as tailored electronic bandgap^1,2,3,4,5, elevated superconducting temperature^6,7 and enhanced electrocatalytic activity^8,9. While uniform strains are known to elicit limited effects on heat flow^{10,11,12,13,14,15}, the impact of inhomogeneous strains has remained elusive owing to the coexistence of interfaces^{16,17,18,19,20} and defects^21,22,23. Here we address this gap by introducing inhomogeneous strain through bending individual silicon nanoribbons on a custom-fabricated microdevice and measuring its effect on thermal transport while characterizing the strain-dependent vibrational spectra with sub-nanometre resolution. Our results show that a strain gradient of 0.112% per nanometre could lead to a drastic thermal conductivity reduction of 34 ± 5%, in clear contrast to the nearly constant values measured under uniform strains^10,12,14,15. We further map the local lattice vibrational spectra using electron energy-loss spectroscopy, which reveals phonon peak shifts of several millielectron-volts along the strain gradient. This unique phonon spectra broadening effect intensifies phonon scattering and substantially impedes thermal transport, as evidenced by first-principles calculations. Our work uncovers a crucial piece of the long-standing puzzle of lattice dynamics under inhomogeneous strain, which is absent under uniform strain and eludes conventional understanding.

纳米级结构可以产生极端应变，从而实现前所未有的材料特性，例如定制电子带隙^1,2,3,4,5、升高的超导温度^6,7和增强的电催化活性^8,9。虽然已知均匀应变对热流的影响有限^{10,11,12,13,14,15}，但由于界面^{16,17,18,19,20}和缺陷^{21的共存，非均匀应变的影响仍然难以捉摸。 ,22,23}。在这里，我们通过在定制制造的微型器件上弯曲单个硅纳米带引入不均匀应变，并测量其对热传输的影响，同时以亚纳米分辨率表征应变相关的振动光谱，从而解决了这一差距。我们的结果表明，每纳米 0.112% 的应变梯度可能导致热导率急剧下降 34 ± 5%，这与均匀应变下测量的几乎恒定的值形成鲜明对比^10,12,14,15。我们进一步使用电子能量损失光谱绘制了局域晶格振动光谱，该光谱揭示了沿应变梯度的几毫电子伏特的声子峰位移。第一性原理计算证明，这种独特的声子谱展宽效应加剧了声子散射并极大地阻碍了热传输。我们的工作揭示了非均匀应变下晶格动力学长期存在的难题的一个关键部分，而该难题在均匀应变下是不存在的，并且回避了传统的理解。