BaBi4Ti4O15 ferroelectric thin films grown by pulsed laser deposition

BaBi4Ti4O15 (BBiT) is an n = 4 member of the Bi-layer-structured ferroelectric oxide family (Aurivillius phases). BBiT thin films with preferred orientations have been grown on epitaxial conducting LaNiO3 electrodes on (001) SrTiO3 by pulsed laser deposition. Cross-section electron microscopy analysis reveals that the films consist of c(t)-axis oriented regions and mixed a(t)- and c(t)-axis oriented regions. The mixed a(t)- and c(t)-axis oriented regions show high surface roughness due to the rectangular crystallites protruding out of the surface, whereas the c(t)-axis oriented regions show a smooth surface morphology. In the mixed a(t)- and c(t)-axis oriented regions, the BBiT films exhibit saturated ferroelectric hysteresis loops with remnant polarization P-r of 2 mu C/cm(2) and coercive field E-c of 60 kV/cm and no polarization fatigue up to 10(8) cycles. The regions having c(t)-axis orientation with a smooth surface morphology exhibit a linear P-E curve. The results show that the ferroelectric properties of a planar capacitor consisting of BBiT depend on the crystalline orientation of the film. (C) 1999 American Institute of Physics. [S0003-6951(99)01201-8].