Mechanical relaxation in SrBi2Ta2O9 ceramics

The internal friction (IF) of SrBi2 Ta2O9 ceramics was measured by using th e reed vibration method in the temperature range from 100 to 600 K with fre quency in kilohertz. A high IF peak appeared around 500 K, which was interp reted in terms of the migration of oxygen vacancies. Another low IF peak wa s found with a peak temperature of 200-250 K, which varied for tens of degr ees in different samples. This peak was assumed to be due to the depinning process of domain walls from oxygen vacancies. These results are helpful in the understanding of the excellent fatigue resistance property of SBT at r oom temperature. (C) 1999 American Institute of Physics. [S0003-6951(99)020 19-7].