The modified phonon dispersion is of importance for understanding the origin of the reduced heat conductivity in nanowires. We have measured the phonon dispersion for 50 nm diameter InSb (111) nanowires using time-resolved X-ray diffraction. By comparing the sound speed of the bulk (3880 m/s) and that of a classical thin rod (3600 m/s) to our measurement (2880 m/s), we conclude that the origin of the reduced sound speed and thereby to the reduced heat conductivity is that the C44 elastic constant is reduced by 35% compared to the bulk material.
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机译：改性的声子色散对于理解纳米线中热导率降低的起因至关重要。我们已经使用时间分辨X射线衍射测量了直径为50 nm的InSb（111）纳米线的声子色散。通过比较主体的声速（3880 m / s）和经典细棒的声速（3600 m / s）与我们的测量值（2880 m / s），我们得出结论，声速降低的原因是降低的热导率是与大块材料相比，C44弹性常数降低了35％。
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