抄録
The internal friction of transparent natural quartz was measured at room temperature with longitudinal vibration in kilocycle range using a composite piezo-electric oscillator. Specimens were cylinders axes of which took various orientations in the crystallographic YZ-plane. The internal friction of specimens parallel to the Y- or Z-axis was small and almost independent of the strain amplitude of the vibration, while that of specimens with other orientations was rather large and showed marked dependence on the amplitude. The experimental results were analyzed with the theory of dislocation damping based on the pinned-down dislocation model. It could be concluded that the internal friction of quartz was mainly due to the vibration of dislocations in the slip plane parallel to the Y- or Z-axis. The dislocation density in a specimen was estimated to be 103–104 cm−2. It was also found that the dislocation density was reduced by annealing the specimen. The defects pinning down the dislocations were assumed to be aggregates of metallic impurities.
