Investigation On The Preparation And Properties Of Mn Doped NBT-BT-BFO Solid Solution Film

Ferroelectric materials with spontaneous polarization have great application prospect and potential market value.With the continuous application of microelectronic devices,ferroelectric thin-film materials and related thin-film devices have been gradually developed,which is the product of the combination of theory and high-tech,and has become the basic core technology of many application technologies.Ferroelectric thin film materials can be applied to different kinds of devices,such as energy storage capacitors?energy storage?,tuners?dielectric properties?and so on.In addition,in order to reduce the use of lead-containing materials and improve the level of social and economic development,the task of seeking new lead-free materials is very urgent and of great significance.Sodium bismuth titanate(Na_0.5Bi_0.5TiO₃,NBT)is an ABO₃ perovskite-structured ferroelectric.NBT is considered to be one of the strong competitors for lead-based materials.Its excellent properties such as moderate residual polarization intensity?P_r=38?C/cm²?and high Curie temperature?T_c=320??are widely studied in recent years.In view of the high leakage current of pure NBT thin films,the performance of the films is masked.The electrical properties of NBT materials were regulated by ion doping and the addition of other components in solid solution.In addition,the choice of high-performance substrate materials and the stoichiometric deviation of A-site elements due to volatilization have also attracted researchers'attention.In this paper,the chemical solution deposition method which is easy to control the uniformity of the films and the layer annealing process are used to prepare Mn doped NBT-BT-BFO thin films.The effects of ion doping,substrate material selection and Bi stoichiometric shift on the microstructures,morphologies and electrical properties of the films were systematically discussed..The main contents are as follows:1.Indium tin oxide?ITO?/glass was selected as substrate to fabricate NBT-BT-BFO thin films with different Mn ion content?0 mol%,0.6 mol%,1.2 mol%,1.8 mol%?.The effects of different ion dopants on the structure and electrical properties of the films were investigated.The results show that the thin films doped with 1.2mol%Mn have lower leakage current 2.31×10^-8 A/cm²?150 kV/cm?,lower residual polarization value?22.34?C/cm²?and higher breakdown resistance,higher energy storage density?25.32 J/cm³?and energy storage efficiency?44.52%?,higher dielectric constant?360? and lower dielectric loss?0.24?at 100kHz2.Solid solution films with good Mn content of 1.2 mol% were prepared on ITO,lanthanum nickelate and platinum respectively.The effects of substrates on the crystallinity and electrical properties of the films were investigated.The results show that the solid solution-based thin film on the platinum substrate has a low leakage current density of 8.96×10^-9 A/cm²?150 kV/cm?,a lower residual polarization value?7.15?C/cm²?,a higher breakdown strength,a higher energy storage density?24.68J/cm³? and an energy storage efficiency?63.23%?,a higher dielectric constant?410? and a lower dielectric loss?0.06?at 100 kHz.The film deposited on the nickel-acid-based substrate exhibits a single?l00?-direction orientation.And has a smaller grain size?29.91 nm?.3.A solid solution film with 1.2 mol%Mn doping on Pt substrates was selected as the research object,and the stoichiometric ratios of Bi elements?-5%,+0%,+5% and+10%?were changed to deviate from the stoichiometric ratios.The results show that solid solution based thin films?Bi stoichiometric+5%? have lower leakage current density and higher energy storage efficiency,and can be used as the preferred materials for this kind of materials.