Ferroelectric Characterization of La∶BiFeO3/Bi0.5(Na0.85K0.15)0.5TiO3 Nano-composite Films

La0.1Bi0.9FeO3 (BFO), Bi0.5(Na0.85K0.15)0.5TiO3(BNKT) and BFO/BNKT nano-composite films were fabricated by pulsed laser deposition (PLD) method on Pt/Ti/SiO2/Si substrate. The ferroelectric properties were enhanced in BFO/BNKT compared to single layer film of BFO and BNKT. The ferroelectric domain structures were observed using piezoresponse force microscopy (PFM). The polarization reversal was time-dependent because the inhomogeneous domains with different coercivity. Evidence can also be seen in the fatigue results which showed unusual profile. The polarization increased as the increase of switching cycles because some of domains are difficult to switch using the applied field. Nano-scale piezoresponse hysteresis loops measured by PFM also revealed the local domain switching behavior in the BFO/BNKT film.