Measurements of Relaxation Time of Sodium Ions in Sputtered Thin Film Beta-Alumina

Abstract

It has been reported by Almond and West that the temperature dependence curve of the acoustic attenuation in sodium-beta-alumina shows a broad peak compared with Debye theory. In the present experiment, the relaxation attenuation of rf-electric field accompanied by the surface elastic waves on a lithium-niobate transducer which is adjacent to the sputtered thin film sodium-beta-alumina deposited on a substrate with an air gap of a few μm has been measured (i.e.,by means of acousto-electric effect) as a function of temperature at frequencies 200, 400 and 600 MHz, respectively, and it has been clarified that the temperature dependence curve fits quite well with Debye theory in this system, and the activation energy was estimated to be approximately 0.13 eV. It should be emphasized that this method is very useful for the investigation of such thin film material.