Electric and Magnetic Properties of Bilayered Lead-Free Piezoelectric and Multiferroic Bi 0.9 Dy 0.1 FeO 3/K 0.5 Na 0.5 NbO 3 Thin Films

Composite lead-free piezoelectric and multiferroic thin films consisting of Bi 0.9 Dy 0.1 FeO 3 ( BDF ) and K 0.5 Na 0.5 NbO 3 ( KNN ) nanolayers were prepared on the Pt / TiO 2/ SiO 2/ Si substrates by pulsed laser deposition. The bilayered BDF / KNN films exhibited a preferential (100)-orientation and much enhanced ferroelectric properties (2P r = 26.5 mu C/cm2, 2E c = 369.2 kV/cm) as compared to those of single layer BDF or KNN thin film. In addition, the bilayered BDF / KNN films also showed ferromagnetic behavior at low temperature (2M r = 1.57 emu/cm3, 2H c = 3 kOe). The enhanced ferroelectric properties of the bilayered BDF / KNN thin films were attributed to the significantly reduced leakage current arising from the enhanced crystallinity and the interface reaction of the BDF and KNN nanolayers. An effective piezoelectric coefficient d 33 of 12 pm/V was measured on the bilayered films.