【摘要】 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(10~7Hz,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。更多还原

【Abstract】 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~[1] and the latter by the theory of tun neling relaxation with infrared divergence~[2]. 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.更多还原