Velocity of sound wave is one of the most basic thermodynamic properties of materials.  Many thermophysical parameters may be derived from sound velocities.  Thirty years ago, scientists first presented the broadband spectroscopy technique for measuring the ultrasonic wave velocity under ambient conditions.  That method was much simpler than previous continuous-wave comparison technique with less instruments requirements.  One crucial advantage of the broadband pulse method was the ultra small duration time of sound pulse which could be utilized to measure specimen with thin thickness, another advantage of this method was that the frequency dependent phase velocity of specimen can be obtained directly.

Recently, Prof. LIU Yonggang and his graduate student WANG Zhigang from the Lab of Earth’s Deep Interior Materials and Fluid Interaction at Institute of Geochemistry, Chinese Academy of Science (IGCAS) applied this broadband spectroscopy method to measure the ultrasonic wave velocity of Z-cut quartz under high pressure up to 4.7 GPa. The sample was in a hydrostatic circumstance under high pressure, and longitudinal wave and shear wave signals could be got simultaneously in their work.  The experimental result was consistent with previous studies.  By this method, the spectrum of ultrasonic wave is easy to get, which is helpful for studying ultrasonic velocities and attenuation coefficient of materials.  The broadband spectroscopy method is also a valid method to obtain ultrasonic wave travel parameters and is worth being widely applied in elasticity study of thin specimens under high temperature and high pressure.

Their work was supported by the National Natural Science Foundation of China (Grant No. 40974052), the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No.KZCX2-YW-Q08–3-4), and the Mutual Foundation of Huge Scientific Equipment of National Natural Science Foundation of China and Chinese Academy of Science (Grant No. 10979053).  The paper about their work has been published on Review of Scientific Instruments 82, 014501 (2011).

(Provided by WANG Zhigang and LIU Yonggang)