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1.
Recently, Bi 4 m x La x Ti 3 O 12 (BLT) has received much attention because it enables low crystallization temperature with a large remanent polarization. BLT films were prepared using a metal organic decomposition technique followed by a rapid thermal annealing (RTA) and a furnace annealing. The annealing of BLT was performed in the temperature range from 550 to 700C. In particular, BLT film annealed at 600C using the RTA tool and the furnace shows good ferroelectric characteristics. The BLT film annealed at 600C exhibits a large value of remanent polarization (22 w C/cm 2 at 250kV/cm), and a low leakage current density (7 2 10 m 7 A/cm 2 at 250kV/cm), a good endurance characteristics for up to 3.2 2 10 11 cycles at 250kV/cm at 85C. From an accelerated imprint test, the lifetime of hysteresis integrity is estimated to be over 10 years at 85C. In conclusion, BLT is the one of the promising material to achieve the high density FeRAMs. 相似文献
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The dielectric properties of the Bi4–x
La
x
Ti3O12 (0 x 2) ceramics were characterized and discussed together with the P-E relation (polarization vs. electric field). With increasing x, the P-E relation changed from normal ferroelectric hysteresis loops to pure linear relation, which indicated that La3+ substitution for Bi3+ in Bi4Ti3O12 induced a phase transition from ferroelectric to paraelectric state at ambient temperature. Low loss dielectric ceramics with temperature stable dielectric constant were obtained for x > 1.2 in Bi4–x
La
x
Ti3O12 at 1 MHz. And the loss increased in all the compositions when the ceramics were measured at microwave frequencies. 相似文献
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Wataru Sakamoto Mio Yamada Naoya Iizawa Yu-Ki Mizutani Daichi Togawa Koichi Kikuta Toshinobu Yogo Takashi Hayashi Shin-Ichi Hirano 《Journal of Electroceramics》2004,13(1-3):339-343
Neodymium-modified Bi4Ti3O12, (Bi, Nd)4Ti3O12 (BNT) ferroelectric thin films have been prepared on Pt/TiOx/SiO2/Si substrates using metal-organic precursor solutions by the chemical solution deposition method. The BNT precursor films crystallized into the Bi layered perovskite Bi4Ti3O12 (BIT) as a single-phase above 600C. The synthesized BNT films revealed a random orientation having a strong 117 reflection, whereas non-substituted BIT thin films exhibited a random orientation with strong 00l diffractions. Among Bi4 – xNdxTi3O12 [x = 0.0, 0.5, 0.75, 1.0] thin films, Bi3.25Nd0.75Ti3O12 thin films showed a well-saturated P-E hysteresis loop with the highest Pr (22 C/cm2) and a low Ec (69 kV/cm) at an applied voltage of 5 V. The Nd-substitution with the optimum amount for the Bi site in the BIT structure was effective not only for promoting the 117 preferred orientation but also for improving the microstructure and ferroelectric properties of the resultant films. 相似文献
4.
《Integrated ferroelectrics》2013,141(1):1437-1443
Ruthenium films formed by metalorganic chemical vapor deposition were investigated, taking account of the application to the bottom electrode of ferroelectric capacitors. Ruthenium films were deposited using a liquid-type source of Ru[EtCp]2 in a cold-wall type reactor with infrared lamps. A smooth and flat Ru film was successfully formed on a SiO2-covered Si substrate without a seed layer. As the deposition temperature increased to 400°C, the crystallinity of the Ru film improved and the film exhibited high c-axis orientation. After forming a Bi4 ? x La x Ti3O12 (BLT) film by a sol-gel technique, a Pt/BLT/Ru capacitor was fabricated on the Ru film. Good hysteresis loops with 2P r = 20 μC/cm2 and 2V c = 3.4 V were successfully obtained and the ferroelectric property did not depend on the deposition temperature of Ru in the temperature range from 325°C to 400°C. On the contrary, the leakage current density was significantly suppressed down to 1/100 as the deposition temperature of Ru increased from 325°C to 400°C. 相似文献
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铁电薄膜具有良好的铁电、介电性能,在非挥发存储器件方面有很好的应用前景.本文介绍了钛酸铋(Bi4Ti3O12)铁电薄膜的研究现状,对目前Bi4Ti3O12铁电薄膜最常用的几种主要制备方法及其掺杂改性进行了评述,指出了Bi4Ti3O12铁电薄膜研究中亟待解决的几个问题. 相似文献
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Modification of Ba5NdTi3Ta7O30 dielectric ceramics was investigated through introducing Bi4Ti3O12. With increasing of Bi4Ti3O12 content, the dielectric constant increased, and the temperature coefficient of the dielectric constant changed from negative to positive. The small temperature coefficient ( < 50 ppm/°C) combined with high dielectric constant ( = 178) and low dielectric loss (tan = 0.007 at 1 MHz) was achieved in the composition x = 0.6. 相似文献
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Zhiguo Yi Yongxiang Li Jiangtao Zeng Qunbao Yang Qingrui Yin 《Journal of Electroceramics》2008,21(1-4):319-322
Bi5?x La x Nb3O15 (x?=?0–?1.25) ceramics prepared by conventional solid-state reaction were studied using X-ray diffraction (XRD), electron probe microanalysis (EPMA) and dielectric spectroscopy techniques. The XRD analysis indicated single phase solid solution of Bi5?x La x Nb3O15 is formed for x?≤?1.25. EPMA showed good densification and homogeneous microstructures for the ceramics. With increasing x, the dielectric constant decreases monotonously and can vary from 258 to 158 at 300 kHz. The frequency dependence of dielectric constants indicated these ceramics are promising candidates for high frequency applications. 相似文献
10.
Ba(Nd0.8Sm0.2)2Ti4O12 ceramics prepared by conventional solid-state sintering have a dielectric constant of about 80 and a nearly zero temperature coefficient of resonant frequency; however, the sintering temperature is above 1350_C. Doping with B2O3 (up to 5 wt%) promotes the densification and dielectric properties of BNST ceramics. It is found that coating BNST powder with thin B2O3 layer of about 180 nm reduces the sintering temperature to below 1020_C. The effects of B2O3 nano-coating on the dielectric microwave properties and the microstructures of BNST ceramics are investigated. Ninety-six percent of theoretical densities is obtained for specimens coated with 2 wt% B2O3 sintered at 960_C and the samples exhibit significant (002) preferred orientation and columnar structure. 相似文献
11.
采用喷雾干燥法制备尖晶石Li_4Ti_5O_(12)。将所得Li_4Ti_5O_(12)与纳米Sb_2O_3混合后高能球磨得到Sb_2O_3掺杂的Li_4Ti_5O_(12)。经X射线衍射(XRD)测试,结果表明Sb_2O_3未进入Li_4Ti_5O_(12)尖晶石结构。经扫描电子显微镜(SEM)测试,结果表明高能球磨法使颗粒更小、更分散。采用充放电测试、循环伏安法和交流阻抗测试研究了Sb_2O_3对Li_4Ti_5O_(12)电化学性能的影响。研究结果表明,Sb_2O_3的掺杂能提高Li_4Ti_5O_(12)的电化学性能。在15 C的高电流密度下,循环10次后其放电比容量仍保持在113.7 mAh/g,远高于未掺杂的Li_4Ti_5O_(12)电极放电比容量(62.7 mAh/g)。交流阻抗测试结果表明,Sb_2O_3/Li_4Ti_5O_(12)电极的电化学性能改善的主要原因是其R_(CT)值较小。 相似文献
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采用高温固相法制备Li4 Ti5 O12-Li3 VO4/C复合材料,利用XRD、SEM和电化学性能测试,分析样品的结构、形貌和性能.复合5%的Li3 VO4和引入少量的碳,均未改变Li4 Ti5 O12的尖晶石结构,但柠檬酸高温分解产生的CO2会造成复合材料中TiO2的残留.有机碳源柠檬酸热解产生部分还原性气体,造成复合材料含有氧空位,导致晶胞参数减小.碳的引入加剧了Li4 Ti5 O12与Li3 VO4的复合,降低了复合材料的扩散阻抗,提高了导电性,使Li3 VO4在小电流充放电时提供的容量较多.在1.0~2.2 V循环,Li4 Ti5 O12-Li3 VO4/C的0.2 C、10.0 C放电比容量分别为205.1 mAh/g、105.2 mAh/g. 相似文献
17.
Dae Min Kim Shin Kim Kwan Soo Kim Sang Ok Yoon Jong Guk Park 《Journal of Electroceramics》2009,23(2-4):164-168
Low-temperature sintering and dielectric properties of the Bi(Nb1?x Ta x )O4 (x?=?0.1, 0.3, and 0.5) system was investigated as a function of the zinc borosilicate (ZBS) glass content with a view to applying this system to LTCC technology. The addition of 7 wt% ZBS glass ensured a successful sintering below 900°C. The complete solid solution of Bi(Nb, Ta)O4 with an orthorhombic structure was formed and the high temperature form of Bi(Nb, Ta)O4 with a triclinic structure was not observed. The second phase of Bi2SiO5 was observed for all compositions. The non-relative liquid phase sintering (NLPS) occurred and the one-stage sintering was conducted. The Q?×?f values were improved by the addition of Ta. Bi(Nb0.7Ta0.3)O4 with 7 wt% ZBS glass sintered at 900°C demonstrated 35.8 in the dielectric constant (? r), 2,200 GHz in the quality factor (Q?×?f 0), and ?48 ppm/°C in the temperature coefficient of resonant frequency (τ f). 相似文献
18.
J. Frantti Y. Fujioka S. Eriksson V. Lantto M. Kakihana 《Journal of Electroceramics》2004,13(1-3):299-303
Raman spectroscopy was used to study the long wavelength vibrations of tetragonal perovskite (space group P4mm) Pb(HfxTi1–x)O3 (PHT) (0.10 x 0.50) samples at room temperature and at 20 K. For x 0.40, Raman spectra collected from the PHT samples were very similar to the previous spectra collected from the PZT samples with the same value of x, except the mode at around 190 cm–1, whose frequency was decreasing with increasing x in PHT ceramics. Correspondingly, the latter feature was taken as a sign of the mass effect (Hf versus Zr) while the similarity of the remaining parts of the Raman spectra was assumed to be due to the almost identical ionic radii difference between Ti4+ and Zr4+ and between Ti4+ and Hf4+ ionic radii. The behaviour of the mode at around 280 cm–1 revealed that a phase transition occurred once x was changing from 0.40 to 0.50. 相似文献
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