Effect of compositional variations on electrical properties in phase switching (Pb,La)(Zr,Ti,Sn)O_(3) thin and thick films

摘要

The composition-dependent electrical properties in (Pb,La)(Zr,Ti,Sn)O_(3) antiferroelectric-ferroelectric phase switching thin and thick films have been systematically studied and compared with bulk ceramics. The films were deposited on Pt-buffered silicon substrates by a sol-gel method. The results show that the dependence of low-field dielectric properties on compositions in the films is similar to that in bulk ceramics but the variation of high field properties (polarization or hysteresis loops) is quite different, which may be attributed to the special mechanical boundary condition of the films. While all the films with compositions in the antiferroelectric tetragonal region in the phase diagram demonstrate the existence of remanent polarization in the hysteresis loops, the films with zero remanent polarization can be obtained in the antiferroelectric orthorhombic region. This is because the films are under high tensile stress due to the thermal mismatch between the film and substrate, which tends to stabilize the ferroelectric phase and causes the retention of ferroelectric phase for the films in the antiferroelectric tetragonal region because of their relatively small free energy difference between the antiferroelectric phase and ferroelectric phase.