La∶BiFeO_3/Bi_(0.5)(Na_(0.85)K_(0.15))_(0.5)TiO_3纳米复合薄膜的铁电特性（英文）

Ferroelectric Characterization of La∶BiFeO_3/Bi_(0.5)(Na_(0.85)K_(0.15))_(0.5)TiO_3 Nano-composite Films

采用脉冲激光沉积技术(pulsed laser deposition,PLD),在Pt/Ti/SiO_2/Si基片上制备了La_(0.1)Bi_(0.9)FeO_3(BFO),Bi_(0.5)(Na_(0.85)K_(0.15))0.5TiO_3(BNKT)和BFO/BNKT纳米复合薄膜。结果表明,复合薄膜的铁电特性比单层的BFO、BNKT薄膜有所增强。利用压电力显微镜(piezoresponse force microscopy,PFM)观察到了铁电畴。由于畴结构内部矫顽力分布不均匀,导致极化反转随时间改变,疲劳测试结果也证实了该结论。随着转换周期的增加,极化随之增强。运用PFM测量了纳米级的压电响应,同样证实了BFO/BNKT复合薄膜中的畴反转现象。

La_(0. 1)Bi_(0. 9)FeO_3( BFO),Bi_(0. 5)( Na_(0. 85)K_(0. 15))_(0. 5)TiO_3( BNKT) and BFO/BNKT nano-composite films were fabricated by pulsed laser deposition( PLD) method on Pt / Ti / SiO_2/ 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.