| Multiferroic materials have received considerable attention in the last few years due to their combination of ferroelectric order and ferromagnetic order and potential for applications such as data-storage, spin electronics, transducer and so on. BiFeO3(BFO) belongs to those few single-phase multiferroic materials which simultaneously show both ferroelectricity and ferromagnetism at room temperature. In this thesis, we optimized the fabrication process of BFO ceramic and thin film and further improved the film performance by introducing BFO/BLT bi-layer film structure.To overcome the obstacle that BFO is too temperature sensitive to attain pure phase, improved solid-state reaction technology was employed, in which process the BFO target was sintered at 820℃for about 20 min with a high heating rate of 100℃/s. As the temperature increased rapidly, the temperature range for the formation of impure phase was skiped, Which in turn avoid the impure phase. Based on the successful fabrication of pure phase BFO target, we further deposited BFO thin films using RF-magnetron sputtering, and obtained the optimal fabrication parameters. High-quality, pure phase BFO thin films were fabricated.The BLT thin films were deposited on Pt/TiO2/SiO2/ p-Si(100) substrate by Sol-Gel method. The films show random grain orientation, pure BFO phase and excellent ferroelectric properties with 2Pr of 36.4μC/cm2 and 2Ec of 246 kV/cm.The introduction of BFO/BLT bi-layer further improved the film performance. The impurity formation and the abnormal grain growth phenomenon in BFO thin films were inhibited by introducing BLT layer. The leakage current density of BFO/BLT bi-layer was reduced by one to two order compared to that of BFO thin films due to the improved grain uniformity and density. Therefore, the BFO/BLT thin films can withstand higher breakdown voltage than BFO thin films, showing much better ferroelectric property with a 2Pr as high as12.4μC/cm2. |
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