Temperature dependence of attenuation of 3- and 9-GHz ultrasound in rutile (TiO2)

The attenuation of 3- and 9-GHz ultrasound in pure TiO2 (rutile) was measured as a function of temperature from 4°K to the highest temperature at which echoes were observed. Measurements were made of transverse waves and some longitudinal waves propagating in the [001], [110], and [100] directions. In general, it is observed that the attenuation increases rapidly with temperature beginning at a fairly low temperature (≅ 20 °K), but that for some modes this rapid increase is cut off before the attenuation is very large. For these modes, the subsequent increase is small so that the echoes are readily observed at room temperature. This behavior is discussed in terms of theories of ultrasonic attenuation. The high-temperature behavior may be related to the existence of low-lying optical modes to which acoustic thermal phonons may scatter. The attenuation in TiO2 is contrasted with that in Si where such optical modes are not present. © 1973 The American Physical Society.