Material Science and Technology Division, Oak Ridge National Lab, Oak Ridge, TN, 37831, USA.
Neutron Scattering Division, Oak Ridge National Lab, Oak Ridge, TN, 37831, USA.
Nat Commun. 2018 May 8;9(1):1823. doi: 10.1038/s41467-018-04229-1.
Controlling the thermal energy of lattice vibrations separately from electrons is vital to many applications including electronic devices and thermoelectric energy conversion. To remove heat without shorting electrical connections, heat must be carried in the lattice of electrical insulators. Phonons are limited to the speed of sound, which, compared to the speed of electronic processes, puts a fundamental constraint on thermal management. Here we report a supersonic channel for the propagation of lattice energy in the technologically promising piezoelectric mineral fresnoite (BaTiSiO) using neutron scattering. Lattice energy propagates 2.8-4.3 times the speed of sound in the form of phasons, which are caused by an incommensurate modulation in the flexible framework structure of fresnoite. The phasons enhance the thermal conductivity by 20% at room temperature and carry lattice-energy signals at speeds beyond the limits of phonons.
从电子上单独控制晶格振动的热能对于许多应用至关重要，包括电子设备和热电能量转换。为了在不短路电连接的情况下散热，热量必须在电绝缘体的晶格中传递。声子的速度受到限制，与电子过程的速度相比，这对热管理提出了根本性的限制。在这里，我们使用中子散射报告了在技术上有前途的压电矿物 fresnoite（BaTiSiO）中传播晶格能的超声通道。晶格能以相位的形式传播，速度是声速的 2.8-4.3 倍，这是由 fresnoite 柔性框架结构的不调和调制引起的。在室温下，相位将热导率提高了 20%，并且以超过声子极限的速度传递晶格能量信号。
