Structural evolution, ferroelectric, and nanomechanical properties of Bi1-xSmxFeO3 films (x = 0.05–0.16) on glass substrates

This study reports influences of Sm doping on the crystal structure, nanomechanical and ferroelectric properties of Bi_1-xSm_xFeO₃ (BSFO) thin films. BSFO films of perovskite phase were deposited on Pt/glass substrates by pulse laser deposition (PLD). The structural analysis shows that the BSFO transforms from rhombohedral structure into orthorhombic structure with the phase boundary near x = 0.16. The structure morphology of the thin films determined by using SEM and AFM exhibited that the grain size and surface roughness are reduced with increasing Sm content in BSFO. The hardness and Young's modulus are obtained in the range of 7.7–10.1 GPa and 154.6–167.5 GPa, respectively. Ferroelectric properties with remanent polarizations (2P_r) and coercive fields (E_c) occur respectively in the ranges of 41–150 μC/cm² and 327–450 kV/cm for x = 0.05–0.14. The enhanced ferroelectric properties can be attributed to the smooth interface and fine microstructure with small grain sizes in range of 30–200 nm. A double ferroelectric hysteresis P-E loop with a different nanomechanical properties is observed in the composition of x = 0.16 and is associated with the appearance of orthorhombic phase. The leakage behavior with mechanisms and nanomechanical characterizations are also studied as functions of Sm content.