Excess microwave ultrasonic attenuation in vacuum-heated rutile (TiO2)

It was observed by Lange that rutile (TiO2) appropriately heated in a vacuum showed an anomalous attenuation peak for 1-GHz ultrasound. He suggested that the cause of the attenuation was some lattice defects, and not conduction electrons. By comparing the attenuations of 3-GHz ultrasound in vacuum-heated TiO2 with that in Nb-doped TiO2 we find strong evidence for Lange's conclusion. © 1974 The American Physical Society.