含红外发散的低温玻璃超声声速理论

本文采用红外发散和隧道态模型,讨论玻璃超声声速在3K温度以下的行为。我们把声速的改变看作两部分组成:无弛豫过程和有弛豫过程。前者采用“玻色型元激发”理论处理;后者采用“含红外发散的隧道弛豫”理论处理。我们不但得到与实验符合较好的声速-温度曲线,并且解释了一般频率下(10⁷Hz,T为0.3—1K),声速与频率无关的lnT规律和高频下(2GHz,T<0.1K)声速存在极小值的现象。 关键词：

THEORY OF VELOCITY OF ULTRASOUND WITH I NFRARED DIVERGENCE IN GIASSES AT LOW TEMPERATURES

The behavior of velocity of ultrasound in glasses below 3 K is analysed by combining the tunneling model and the infrared divergence theory. The variation of sound velocity is regarded as consisting of two parts, i.e., non-relaxation process and relaxation process. The former is analysed by the Bose elementary excitation theory and the latter by the theory of tun neling relaxation with infrared divergence. The theoretical curve of sound velocity vs temperature is consistent with the experimental data. The observed In T rule of sound velocity for normal frequency (10⁷Hz) at 0.3-1K, and the phenomenon of appearance of sound velocity minimum for ultrahigh frequency (2GHz) belowe 0.1 K are also explained.