The thermal behavior of charge properties and the polarization-retention of
a Sr0.8Bi2.2Ta2O9 thin film were investigated in a range from room tempera
ture to 558 K. The anomaly caused by the thermally stimulated space charge
was observed. The anomaly started at about 425 K and showed a peak at about
525 K. However, the thermal behavior of the charge properties of the film
in this temperature range is explained as being in a ferroelectric phase ac
cording to the Landau theory.