Multiferroic and nanomechanical properties of Bi1-xYxFeO3 polycrystalline films (x = 0.0–0.1)

In order to improve the multiferroic properties of BiFeO 3 and to clarify the Y substitution effect, we use an Nd:YAG laser to grow Bi 1-x Y x FeO 3 (BYFO) films on glass substrates at low deposition temperatures by pulsed laser deposition (PLD). Their phase structure, microstructure, ferroelectric and magnetic characteristics, and leakage mechanism are explored. The existence of the perovskite phase in BYFO films with x = 0.00–0.10 is confirmed. The structure is transformed from rhombohedral for x = 0.00 to pseudo-cubic for x = 0.05, and an additional phase, orthorhombic, is coexisted for x = 0.10. The microstructure and surface morphology analyses demonstrate a decrease in grain size and film roughness when the Y concentration is increased. The crystalline structure and grain size dominate the hardness of 6.5–10.1 GPa, as measured by nanoindenter. We attain good ferroelectric characteristics for BYFO films with x = 0.00–0.05, where the greatest remanent polarization (2P r ) of 102.6 µC/cm 2 is achieved for x = 0.05, connected to minimizing leakage and oxygen vacancy suppression. The typical ferromagnetic behavior with increased saturation magnetization from 4.4 emu/cm 3 to 6.5 emu/cm 3 by Y substitution possibly attributed to the suppressed spiral spin structure of G-type antiferromagnetism. The mechanisms of electric conduction behavior as functions of Y content and growth temperature are also discussed.