Degradation behavior in the remnant polarization of SrBi2Ta2O9 thin films by hydrogen annealing and its recovery by postannealing

The degradation behavior in the remnant polarization (P-r) of sol-gel-derived SrBi2Ta2O9 (SBT) thin films, with Pt top and bottom electrodes, by annealing under a 5% H-2/95% N-2 atmosphere is investigated. The hydrogen annealing is performed at temperatures ranging from 250 to 480 degrees C. By annealing, the P-r drops to almost zero for all temperatures. Postannealing at temperatures higher than 700 degrees C under an air atmosphere recovers the P-r. Interestingly, the recovery is most ineffective for the sample annealed at the Curie temperature of the SBT films. A phenomenological model that explains this anomalous recovery behavior is presented. (C) 1999 American Institute of Physics. [S0003-6951(99)02630-3].