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991.
Xumei Zhao Xiaolian Chao Di Wu Pengfei Liang Zupei Yang 《Journal of the American Ceramic Society》2019,102(6):3498-3509
Transparent piezoelectric ceramic, as a lead-free multifunctional ceramic, is in dire need of development for future high-tech industries. However, excellent piezoelectricity and high transmittance are usually hard to achieve simultaneously, mainly due to the two mutual restricting factors (phase structure and grain size). In this work, we report that high piezoelectricity and transmittance can be obtained simultaneously in K0.5Na0.5NbO3 ceramics via Sr(Sc0.5Nb0.5)O3 (SSN) modification. The superior piezoelectric performance comes from the retain of orthorhombic phase structure at room temperature (RT); while the high transparency (>70% at 780 nm) can be attributed to the improved relative density and reduced grain size via SSN modification. Remarkably, in the sample with 0.05SSN modification, we realized a comprehensively high transmittance (73% at 780 nm) accompanied by a superior piezoelectric constant (d33 = 101 pC/N), which outperform other reported KNN-based transparent ceramics to our best knowledge. Our results may provide insight for further developing the transparent piezoelectric ceramics by controlling the grain size and phase structure. 相似文献
992.
Chuying Chen Zhijian Peng Luzhi Xie Ke Bi Xiuli Fu 《International Journal of Applied Ceramic Technology》2020,17(6):2545-2552
A series of 0.9625MgTiO3-0.0375(Ca0.5Sr0.5)TiO3 composite ceramics added with different amounts of B2O3 (1-5 wt%) were prepared via the solid state sintering method using the pre-synthesized raw MgTiO3 and (Ca0.5Sr0.5)TiO3 powders by molten-salt reaction. The sintering temperature of 0.9625MgTiO3-0.0375(Ca0.5Sr0.5)TiO3 composite ceramics can be reduced from 1275°C to 1175°C due to the liquid phase sintering effect of B2O3. When the adding amount of B2O3 was more than 2 wt%, a new phase MgTi2O5 could be detected by X-ray diffraction, which would substantially degrade the dielectric properties of the obtained ceramics. Resultantly, the quality factor (Q·f) and dielectric constant (εr) of the samples increase first and decrease later with increasing addition amount of B2O3. In addition, the temperature coefficient of resonant frequency (τf) progressively increases with increasing content of B2O3. By sintering at 1175°C for 4 hours, the obtained 0.9625MgTiO3-0.0375Ca0.5Sr0.5TiO3 composite ceramics with 2 wt% B2O3 possess the optimal microwave dielectric properties of εr = 18.9, Q·f = 57 000 GHz and τf = −1.2 ppm/°C. 相似文献
993.
Masashi Kotobuki 《Electrochimica acta》2010,55(22):6892-9819
To fabricate all-solid-state Li batteries using three-dimensionally ordered macroporous Li1.5Al0.5Ti1.5(PO4)3 (3DOM LATP) electrodes, the compatibilities of two anode materials (Li4Mn5O12 and Li4Ti5O12) with a LATP solid electrolyte were tested. Pure Li4Ti5O12 with high crystallinity was not obtained because of the formation of a TiO2 impurity phase. Li4Mn5O12 with high crystallinity was produced without an impurity phase, suggesting that Li4Mn5O12 is a better anode material for the LATP system. A Li4Mn5O12/3DOM LATP composite anode was fabricated by the colloidal crystal templating method and a sol-gel process. Reversible Li insertion into the fabricated Li4Mn5O12/3DOM LATP anode was observed, and its discharge capacity was measured to be 27 mA h g−1. An all-solid-state battery composed of LiMn2O4/3DOM LATP cathode, Li4Mn5O12/3DOM LATP anode, and a polymer electrolyte was fabricated and shown to operate successfully. It had a potential plateau that corresponds to the potential difference expected from the intrinsic redox potentials of LiMn2O4 and Li4Mn5O12. The discharge capacity of the all-solid-state battery was 480 μA h cm−2. 相似文献
994.
Autothermal reforming of methane (ATR) was studied over Rh catalysts supported on Ce0.5Zr0.5O2 solid solution, which were synthesized by four different routes, including reverse micro-emulsion (ME), co-precipitation (CP), urea-combustion (UC) and sol-gel (SG) method. The textural and structural properties of the as-prepared solid solutions were carefully examined by means of BET, TEM, XRD and Raman techniques. Results showed that the ME sample exhibited a single cubic phase, whereas tetragonal or mixed phases such as cubic CeO2-rich and tetragonal ZrO2-rich phases, were found in the case of CP, UC and SG. Vegard's rule revealed that the homogeneity of these as-prepared solid solutions followed the order of ME > CP > UC > SG. TPR and CO-pulse experiments were adopted to evaluate the reducibility and the oxygen storage capacity (OSC) of the catalysts. It was found that the more homogenous the solid solution is, the more reducibility it is, i.e. both the reducibility and OSC followed the same order as that of homogeneity.Rh/ME showed the highest activity and H2/CO ratio and such performance was maintained without significant loss during 10 h experiment. On the contrary, the other three catalysts having mixed phases showed remarkably deactivation in terms of H2/CO due to the loss of BET area. To elucidate the resistance toward carbon formation of these catalysts, methane decomposition experiments and following temperature-programmed-oxidation (TPO) were studied. As expected, the resistance toward carbon formation could be enhanced by the improved OSC of the catalyst. 相似文献
995.
996.
采用机械合金化结合冷等静压的方法制备了CoSb3和Co3.5Ni0.5Sb12化合物,并测量了其热电性能。利用基于密度泛函理论赝势平面波的方法对Ni掺杂前后的CoSb3的能带结构和态密度进行了计算,实验和理论计算结果表明:CoSb3的费密面位于导带和价带之间,其电阻率随温度的升高而降低,为非简并半导体;Co3.5Ni0.5Sb12的费密面进入导带,其电阻率随温度的升高而增大,为n型简并半导体;本实验条件下,Co3.5Ni0.5Sb12化合物的功率因子在550 K时出现最大值2 292.92μW/(m.K2),是未掺杂CoSb3化合物最大值的12倍。 相似文献
997.
采用流变相法结合高温热处理制备LiNi0.5Mn1.5O4-xFx(x=0,0.1)。用X射线衍射、扫描电镜和电化学测试等手段对合成材料进行了表征。结果表明,F的掺入抑制了LiNi0.5Mn1.5O4颗粒长大,增强了Li+在固相中的扩散能力,改善了电极与电解质溶液之间的界面性质,有效地提高了LiNi0.5Mn1.5O4的循环性能和倍率性能。0.2C放电时LiNi0.5Mn1.5O3.9F0.1的首次放电容量达到147.8mA.h/g,经80次循环后平均每次循环的容量衰减仅为0.0068%。而0.5C和2.0C放电时首次放电容量达到0.2C放电时的94.2%和83.8%。 相似文献
998.
Shiquan Lü Guohui Long Xiangwei Meng Yuan Ji Borui Lü Hongyuan Zhao 《International Journal of Hydrogen Energy》2012
PrBa0.5Sr0.5Co2O5+x (PBSC) oxides have been evaluated as cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs) with Ce0.9Gd0.1O1.95 (GDC) and La0.9Sr0.1Ga0.8Mg0.2O3−δ (LSGM) as electrolytes. XRD results show that PBSC cathode is chemically compatible with the intermediate-temperature electrolyte materials GDC and LSGM. The maximum electrical conductivity is 1522 S cm−1 at 100 °C and its value is higher than 581 S cm−1 over the whole temperature range investigated. Microstructures show that the contact between PBSC and LSGM is better than that between PBSC and GDC. The area-specific resistances (ASRs) of PBSC cathode on GDC and LSGM electrolytes are 0.048 and 0.027 Ωcm2 at 800 °C, respectively. The electrolyte-supported (thickness of electrolyte is 300 μm) fuel cells generate good performance with the maximum power densities of 617 mW cm−2 on GDC electrolyte and 1021 mW cm−2 on LSGM electrolyte at 800 °C. All results demonstrate that PBSC oxide is a very promising cathode material for application in IT-SOFCs and this cathode based on LSGM electrolyte obtained better performance than on GDC electrolyte. 相似文献
999.
Cobaltite-based perovskites based on Sm0.5Sr0.5CoO3−δ (SSC) are attractive as a cathode material with a barrier layer for solid oxide fuel cells (SOFC) due to their high electrochemical activity and electrical conductivity. SSC, synthesized by a complex method, is used as a cathode material in a composite cathode with Gd-doped ceria (GDC). A porous GDC layer is fabricated as a barrier to resist reactions of SSC with yttria-stabilized zirconia (YSZ). The effects of the ratio of SSC on GDC in composite cathodes and the thickness of the GDC barrier are characterized in this study. An SOFC with an SSC7–GDC3 composite cathode on a 4 μm GDC layer at 0.8 V yields the highest fuel cell performance: 1.24 W cm−2 and 0.61 W cm−2 at 780 °C and 680 °C, respectively. Impedance analysis indicates that the ohmic resistances are more dependent upon the GDC barrier thickness than the cathode composition. The polarization resistances at 780 °C and 730 °C exhibit similar values, but with decreasing temperature, the polarization resistances change dramatically according to the composition and barrier thickness. The ohmic and polarization resistances show different trends in different temperature ranges, due to the different charge transfer mechanisms of SSC and GDC within those temperature ranges. To obtain higher fuel cell performance, the addition of GDC into the porous SSC is effective, and the compositions of the composite cathode as well as the thickness of the barrier layer need to be optimized. 相似文献
1000.
Kyoichi Kinoshita Osamu NakatsukaShinichi Yoda Shigeaki Zaima 《Thin solid films》2012,520(8):3279-3282
Compositionally uniform Si0.5Ge0.5 bulk crystals were grown by the traveling liquidus-zone method which we developed for alloy crystal growth. Grown crystals were characterized as substrates for compressive-strained Ge thin films for high mobility p-channels of complementary metal oxide semiconductor transistors. Compositional uniformity was excellent and crystallinity was also excellent for 10 mm diameter crystals. However, crystallinity was degraded for 30 mm diameter crystals although compositional uniformity was excellent. Transmission electron microscope (TEM) observation showed high dislocation density at the interface between a Si seed and a grown crystal due to lattice mismatch. However, the dislocation density decreased as crystal growth proceeded. High quality 30 mm diameter crystals will be grown when the single crystal length is extended judging from TEM results. In this paper, we report on the growth and characterization of Si0.5Ge0.5 crystals as substrates for strained Ge thin films. 相似文献