Effect of Pyrolysis Atmosphere on Ferroelectric Properties of Bi3.25La0.75Ti3O12 Films Prepared by Sol-Gel Method

摘要

The effect of pyrolysis atmosphere is investigated for Bi3.25La0.75Ti3O12 (BLT) films prepared on Pt/TiO2/SiO2/pSi(100) substrates by sol-gel processes. The pyrolysis is carried out at 400 degrees C for 20 min under air or O-2 atmosphere and the successive anneal is performed at 700 degrees C for 30 min under O-2 atmosphere. The pyrolysis under O-2 is enough for complete removal of organic species, however after pyrolysis under air, carbon and hydrogen atomic species as organic fragment are partly remained in the film. This incomplete removal of organic fragments affects the grain growth and cause more defects in the film or between interfaces during the annealing for the crystallization of BLT film. The growth direction and grain size of the BLT film is revealed to affect ferroelectric properties. The remanent polarization P-tau for the BLT films of pyrolysis in O-2 and air are measured to be 18.85 mu C/cm(2) and 12.56 mu C/cm(2), respectively. The defects degrade the fatigue property dramatically for the film of pyrolysis in air. It can be concluded that the pyrolysis is an important procedure to control ferroelectric properties.