Of Fe Doping And Magnetic Properties Of Ionic Groups Implantation Of The Electromagnetic Properties Of Bismuth Layered Thin Film

Ferroelectrics and ferroelectromagnets are currently the subject of intensive investigations because they exhibit interesting fundamental physics as well as promising application in future. However, for the application of ferroelectrics random access memories and ferroelectromagnets random access memories, the shortcomings are more or less existent in the ferroelectric materials and ferroelectromagnets materials which make them can not fully meet the requirements. The optimization of the materials is still a hot research on the ferroelectric memories and ferroelectromagnets memories in present. Therefore to find the well comprehensive performance materials and improve their properties are very important for accelerating their practical application.For SrBi₄Ti₄O₁₅ (SBTi) ferroelectric thin films can not always meet the needs of practical application, this article had made some research to improve their properties by A-site doped and give some possible reasons for their improvements; for the large leakage current and weak ferromagnetism of BiFeO₃ (BFO), which has attracted the greatest attention, we attempt to implant the BFO unit to the three-layered perovskite materials BIT to form the four-layered perovskite materials Bi₅FeTi₃O₁₅ (BFTO), using the space charge and the insulating layer of the bismuth oxide layer in BIT to reduce the electric-conductivity of the ferroelectromagnets materials, improve its leakage current behavior and explore the magnetic properties of layered materials by doping Co³⁺ into the BFTO thin films. The main results are as follows:1. For the first time, we have been synthesized the SrBi_4-xFe_xTi₄O₁₅ (SBFT-x) thin films (x = 0.00, 0.05, 0.08, 0.15) on Pt/Ti/SiO₂/Si (100) substrates by sol-gel method. It is found that Fe-doping does not change the crystal structure of SrBi₄Ti₄O₁₅ (SBTi). The coercive filed (E_c) and remnant polarization (P_r) increase at first, then decrease with the increase of Fe doping content. At a maximum applied field of 229 kV/cm, the 2Pr reaches a maximum value of 91.1μC/cm² when x is 0.05 and the corresponding Ec is 72kV/cm. The 2Pr increases by about 260% and the Ec decreases by about 6%, respectively. Obviously, the ferroelectric property of SrBi₄Ti₄O₁₅ is greatly enhanced by Fe doping. But when x is 0.05, the fatigue-endurance characteristic of the film is not improved. In this article, we clarified the possible reasons of the improvement of ferroelectric property and fatigue mechanism in detail.2. For the first time, we use the metal organic deposition (MOD) method successfully prepared the Bi₅FeTi₃O₁₅ (BFTO) thin films on Pt/Ti/SiO2/Si (100) substrates by implanting the BFO unit into the three-layered FE compound Bi₄Ti₃O₁₂. The microstructure, surface morphology and cross-sectional microstructure of the films are studied by the X-ray diffraction, atomic force microscope and field emission scanning electronics microscope, respectively. The remnant polarization (2P_r) and coercive field (E_c) of BFTO thin films under an electric field of ⁵70kVcm^-1 are determined to be 35.5μC/cm² and 171kV/cm, respectively. The normalized polarization of BFTO thin films under 285kV/cm decreased to 66% after being subjected to 5.2×10⁹ read/write cycles. A comparison between BFTO and Sr₄Bi₄Ti₃O₁₅ in Raman spectra and ferroelectric behavior is also presented. The leakage current density measurement reveals that the conduction mechanism of BFTO thin films in the intermediate electric field range from ⁵0 to ²00kVcm^-1 is dominated by Schottky emission.3. For the first time, we use the metal organic deposition (MOD) method successfully prepared the Co doped Bi₅FeTi₃O₁₅ (BFCTO) thin films on Pt/Ti/SiO₂/Si (100) substrates. The microstructure, surface morphology and cross-sectional microstructure of the films are studied by the X-ray diffraction, atomic force microscope and scanning electronics microscope, respectively. The remnant polarization (Pr) and coercive field (Ec) increase with the increases of applied electric field. At a maximum applied field of 547kV/cm, the 2P_r and E_c values are determined to be 62μC/cm² and 142kV/cm, respectively. The films show no significant change of P_sw and Pns up to 1.1×10⁹ read/write cycles at a frequency of 50 kHz, exhibit an excellent fatigue endurance property.