The Observation On Domain Switching Of ABO₃ Low Dimensional Ferroelectric Materials At Different Loading Force And Loading Electric

In recent years, with the rapid development of microelectronic integrated technology progress and the demand for preparation technology, low dimensional ferroelectric materials have attracted extensive interest because of their important role in Ferro-Electric Random Access Memory(FARM).The bismuth sodium titanate(Na0.5Bi0.5TiO3, NBT) series are considered as one type of the major lead-free ferroelectric materials due to the strong ferroelectricity, high Curie temperature and nontoxicity. In a memory device, the decrease of the dimension of material not only can save the addressing energy consumption, extend its life,but also can improve the storage density. One-dimensional ferroelectric materials have the potential for use in FARM. It is an effective means to study electric domain by using experimental method to observe and analyze the domain structure and domain switching at electric field.In this paper, nanoscale domain switching in(Na0.85K0.15)0.5Bi0.5TiO3(NBKT15)ferroelectric thin film and barium titanate(Ba TiO3) nanofiber have been studied by Piezoresponse Force Microscopy(PFM) at external fields. The main conclusions are as follows:(1) Here NKBT15 thin films were deposited on LaNiO3(LNO)/SiO2/Si(1 0 0) and Pt/Ti/SiO2/Si(1 0 0) substrates by metal–organic decomposition(MOD), and the effects of bottom electrodes LNO and Pt on the electric mechanical properties were investigated by ferroelectric tester, semiconductor analyzer and piezoresponse force microscopy, respectively.In comparison with the NKBT15 thin film deposited on Pt electrode, the NKBT15 thin film deposited on LNO electrode exhibits stronger remnant polarization, smaller leakage current,better crystallinity, larger grain size and column grain structure. When applied by electric fields, the domain configurations of single grain is easier to be reversed for the NKBT15 thin film deposited on LNO electrode due to the larger grain size. When the NKBT15 thin film deposited on LNO electrode was applied by a single loading force, the surface has grain deformation leading to 90°domain switching. It is found that the grain orientation and grain size due to the different bottom electrodes affect domain switching performance.(2) One-dimensional barium titanate nanofibers were synthesized by electrospinning and by using the calcinations technique at 500、600、700 and 800?C on Pt substrate. Scanning electron microscopy was used to verify that the diameters and lengths are in the range of80-140 nm and its length was over 0.1mm. Perovskite structure and crystalline structure were verified by X-ray diffraction and transmission electron microscopy. The high effectivepiezoelectric coefficient d33(60pm/V) was measured by piezoresponse force microscopy. We chose the adjacent two single nanofibers, and applied with different DC voltages on each of the two nanofibers by PFM, observing the domain evolutionary process under different applied electric field in a selected micro area. The single one-dimensional BTO nanofibers were selected to write the domain by external DC voltages successfully.