Papers by Keyword: Bi₄Ti₃O₁₂

Abstract: Nonvolatile of polycrystalline Bi4Ti3O12 thin films prepared by solgel method were studied, and the effect of annealing temperature on resistance switching behavior has been studied. The main point is accented on decrease the operation voltage. Two controllable resistance states were observed by applying voltage pulses. It was also found that the conduction mechanisms dominating the low and high resistance states are Ohmic behavior and Space Charge Limited Current(SCLC).

Abstract: Ferroelectric thin films containing the same volume fraction of the perovskite structure (Na_0.5Bi_0.5)TiO₃ (NBT) and layered structure Bi₄Ti₃O₁₂ (BIT) were prepared with different stacking sequence. Na_0.5Bi_4.5Ti₄O₁₅ thin film, solid solution of NBT and BIT, was also synthesized to compare with the alternative layered films. Their crystal structure, microstructure and electrical properties were investigated as a function of number of interface. It was found that the interface area as well as each material property is critical to the electrical properties. The alternative layer thin films between NBT and BIT showed positive effect on the dielectric behavior than the single NBIT compound film.

Abstract: In the last years oxide materials for electronics show significant progress. However, many details regarding technology control of the properties have to be solved. For electronics, thin films and heterestructures are important taking advantage of integration and synergetic concepts leading to new types of devices and functionalities. It is notable that, while fabrication of new devices and materials showing new phenomena are booming, the growth principles and concepts are somehow developing slowly within this general trend. This is because in many cases, growth of materials is very personalized. Understanding of the bi-directional relationship between the general and particular principles deserves attention. The immediate benefit is that knowledge on growth for one material can be transferred to another one. In our work we have analyzed such relationships for some oxide multicomponent perovskites. Materials used in our examples are Bi-Sr-Ca-Cu-O and YBa₂Cu₃O₇, (Ca, Sr)CuO₂, (Ca, Ba)CuO₂ and Bi₄Ti₃O₁₂. Presented thin films or heterostructures are with c-axis and non-c-axis orientations and based on these examples we discuss some of the growth principles.

Abstract: Bismuth titanate Bi₄Ti₃O₁₂ powders had been successfully prepared from different starting materials by chemical methods and characterized by XRD, SEM and DTA. Our efforts in this paper were directed to disclose the influence of precursors on the particle characterization. It was shown that different precursors affected the crystalline temperature, particle nucleation and growth rate greatly, leading to different particle size and morphology. Excess addition of Bi₂O₃ was found to be dominant in lowing crystalline temperature while spherical particles was probably attributed to large growth rate and use of glacial acetic acid as a solvent medium.

Abstract: Bismuth titanate nano-crystals were prepared successfully by sol-gel method and the critical particle size for phase transition was analyzed by Raman techniques. The results revealed the new Raman peaks at the wave number about 87, 227, 442, 467, 577 and 617cm-1 discerned gradually with increasing the particle size and abrupt increase in integrated intensity ratios of these modes, companied with strong decrease of half-widths happened at the particle size ranging from 18 to 33nm, which suggested an obvious size driven tetragonal-to-orthorhombic phase transition in Bismuth titanate nano-crystals.

Abstract: Na0.5Bi0.5TiO3 is one of the potential candidates for non-lead piezoelectric materials to replace existing lead-based ones. Properties of BNT could be enhanced by reactive templated grain growth (RTGG) technique through induction of grain orientation with crystals of Bi4Ti3O12. Controlling the size of Bi4Ti3O12 crystals during the synthesis with molten salt is a major factor in optimizing RTGG. It was found that molten salt synthesis of Bi4Ti3O12 crystals with NaCl-KCl yielded larger particles, compared with Na2SO4-3K2SO4. Varying the proportion of chloride salt did not produce noticeable changes in crystal size. Bi4Ti3O12 crystals were significantly affected by raw materials treatment. Non-milling of starting powders could approximately double the crystal size

Abstract: Bi4Ti3O12 based thick films were prepared by screen printing and firing using Pt bottom electrodes and ZrO2 substrates. The influence of excess Bi2O3 as sintering aid was investigated. Furthermore, substitution of Ti-site and Bi-site for V5+ and Nd3+ was performed. Screen-printable pastes were prepared by kneading the Bi4Ti3O12 based powder and Bi2O3 powder in a three-roll mill with an organic vehicle. The microstructures and ferroelectric properties of the thick films were examined in comparison with bulk ceramics. The remanent polarization of 9.6 μC/cm2 and coercive field of 64 kV/cm were obtained for the Bi3.0Nd1.0Ti2.99V0.01O12 thick film with 10 wt% of excess Bi2O3 fired at 1200OC.

Abstract: Nd-doped bismuth titanate Bi4-xNdxTi3O12 (BNT) thin films were fabricated on Pt/Ti/SiO2/Si substrates by sol-gel method and spin-coating technique. The structures and the ferroelectric properties of the films were investigated. Nd doping leads to a marked improvement in the remanent polarization (Pr) and the coercive field (Ec). At the applied electric field of 260 kV/cm, Pr and Ec of the BNT film with x=0.5 annealed at 650oC are 19 μC/cm2 and 135 kV/cm, respectively. Moreover, the BNT film with x=0.5 showed a fatiguefree behavior up to 3×1010 read/write cycles.

Abstract: Bi4Ti3O12 thin films were deposited on Pt/Ti/Si(p-100) substrate by RF magnetron sputtering at room temperature, and crystallized in a RTA furnace at temperature of 675°C for 10 minutes. SIMS analysis identifies that bismuth content in the Bi4Ti3O12 thin film reduced slightly from the surface into a depth of approximately 200 nm. XRD patterns revealed (117) phase was dominated regardless the film thickness, and the intensity of the other peaks increased with the increase of film thickness. (200) peak became dominant when the thickness of films were greater than 680 nm. SEM observation showed that the grains were stripe plate-like, and the grain size increased with the increase of film thickness. Dielectric constant increased with the increase of film thickness, and kept around a certain value with the thickness ranging from 300 to 640 nm, then it rose again as the film thickness above 680 nm. The leakage current and electrical breakdown also strongly depended on the film thickness.

Abstract: The present study is devoted to synthesis and investigation of photoluminescence in the nanosized Bi4Ti3O12 (BTO) thin films. The randomly oriented BTO thin films have been obtained by a modified hybrid sol-gel process. Bismuth nitrate and titanium (IV) butoxide were used as the starting materials. The thin films were deposited on silicon, glass and stainless steel by spin coating and crystallized by the conventional thermal annealing at temperature T=650°C. Formation of the layer perovskite-type structure of the orthorhombic symmetry was confirmed by X-ray diffraction method. Conservation of the chemical composition was investigated by energy dispersive spectroscopy. The UV luminescence has been observed in BTO thin films at room temperature. Results on luminescence excitation and emission in bismuth titanate thin films are given in the present paper.