An ultrasonic attenuation study of NH+4/H3O+-Rb+-β″-alumina

The attenuation of longitudinal ultrasound in NH+4/H3O+-Rb+-β″-Al2O3 ceramics has been studied. A double attenuation peak has been found, caused by NH+4/H3O+-Rb+ ion complexes rather than single protons. One half of this double peak has been identified as due to the NH+4 and/or H3O+ and is very similar to that of the H3O+ ion. Single protonic Grotthus-like transport was not detected. This result possibly resolves the controversy as to the conducting mechanism and species of NH+4/H3O+ β″-alumina.