Substrate-dependent ferroelectric and dielectric properties of Mn doped Na_0.5Bi_0.5TiO₃ thin films derived by chemical solution decomposition

Na_0.5Bi_0.5(Ti_0.98Mn_0.02)O₃ (NBTMn) thin films have been fabricated on Pt/TiO₂/SiO₂/Si and LaNiO₃ (LNO)/Si substrates via chemical solution decomposition. The microstructure, ferroelectric and dielectric properties were investigated. Both films on different substrates can be crystallized into the phase-pure perovskite structures. The NBTMn thin film deposited on Pt/TiO₂/SiO₂/Si substrate shows random orientation with (l00) and (110) diffraction peaks, while the sample on LNO/Si exhibits preferred orientation with strong diffraction peaks of (l00). The NBTMn thin film deposited on LNO/Si substrate exhibits a denser and smoother microstructure. Compared with the round shaped polarization-electric field hysteresis loops of NBTMn on Pt/TiO₂/SiO₂/Si substrate, the enhanced ferroelectric property can be observed in NBTMn thin film fabricated on LNO/Si with a remanent polarization (P_r) of 10.2 μC/cm² due to the reduced leakage current. The dielectric tunabilities of two films increase gradually with the increasing of applied voltage, and the sample on LNO/Si substrate has a relatively larger dielectric tunability with 20% at 14 V and 1 MHz. - Graphical abstract: Na_0.5Bi_0.5(Ti_0.98Mn_0.02)O₃ (NBTMn) thin films have been fabricated on Pt/Si and LaNiO₃ (LNO)/Si substrates. Compared with the NBTMn thin film deposited on Pt/Si substrate which shows poor P-E loops with a round shaped feature because of the high leakage current, the NBTMn thin film on LNO/Si substrate exhibits much improved P-E loops with a slim shaped feature and a remanent polarization of 10.2 μC/cm². - Highlights: • The phase-pure perovskite can be obtained with both adopted substrates. • Obviously reduced leakage current can be obtained in thin film on LNO/Si substrate. • A well-defined P-E loop is achieved in NBTMn thin film on LNO/Si substrate. • The dielectric properties of thin films is dependent on applied field and frequency.