An instrument for ultrasonic measurements of small specimens

An instrument which can be used to measure both sound velocity and attenuation in small specimens (about 5×5×5 mm3) is described. A dual path comparison method based on the ultrasonic pulse transmission method was used in the present work. For this measurement method, an easy-to-handle mercury delay line cell was devised. To test applicability of the instrument, sound velocities were measured at 10 MHz for synthetic silica glasses and a single crystal of sodium chloride along the [100] axis at room temperature. The accuracy of the measurements was better than 0.2%. As a further example, sound velocities and attenuation in the ceramic barium titanate, BaTiO3, were measured in the temperature range from room temperature to 200° C. A large peak was detected in the attenuation near the Curie temperature.