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排序方式: 共有1349条查询结果,搜索用时 15 毫秒
71.
The effect of nano-sized PbO (10–30 nm) addition on the transport critical current density, Jc of (Bi1.6Pb0.4)Sr2Ca2Cu3O10 (PbO)x (x=0–0.15 wt%) was investigated. Jc of PbO added pellet samples showed the maximal value at x=0.05 wt%. Using this result, Ag-sheathed (Bi1.6Pb0.4)Sr2Ca2Cu3O10 (PbO)x/Ag tapes (x=0 and 0.05 wt %) were fabricated by the powder-in-tube (PIT) method. The tapes were sintered for 50 h and 100 h at 845 °C. The temperature dependence of Jc for the non-added and PbO added tapes in applied field was investigated. Jc of the non-added tapes was 4510 A/cm2 at 40 K and 949 A/cm2 at 77 K. Jc of (Bi1.6Pb0.4)Sr2Ca2Cu3O10 (PbO)0.05/Ag tape sintered for 100 h was 26,800 A/cm2 at 40 K and 10,700 A/cm2 at 40 K, which was higher than the tapes sintered for 50 h (8590 A/cm2 at 40 K and 1880 A/cm2 at 77 K). Nano-sized PbO added tapes sintered for 100 h showed a higher Jc (more than 10 times) under magnetic field (0–0.75 T) compared with the non-added tape. A combined effect of enhanced flux pinning and improved microstructure led to the significant increase in Jc of the nano-sized PbO added tapes. 相似文献
72.
《Journal of the European Ceramic Society》2014,34(12):3111-3117
Highly electrically conductive ceramic material based on aluminosilicate/graphene nanocomposite has been prepared by high pressure (400 MPa) compaction of montmorillonite intercalated with polyaniline followed with the high temperature (1400 °C) treatment in argon atmosphere. Tablets pressed from polyaniline/montmorillonite intercalate exhibits strong texture due to the disk-shaped montmorillonite particles and, consequently, the high anisotropy in conductivity. The high temperature induced phase transformation of montmorillonite into cristobalite and mullite preserved the aluminosilicate layered structure and created good conditions for formation of graphene sheets from polyaniline layers intercalated in montmorillonite. Therefore, the texture and anisotropy in conductivity remain preserved in resulting aluminosilicate/graphene tablets, while the in-plane conductivity in aluminosilicate/graphene tablets is 23,000× higher than the conductivity of uncalcined polyaniline/montmorillonite tablets. Simple fabrication method of aluminosilicate/graphene tablets is very promising for the manufacturing of the electrically conductive and tough ceramic material, which can be exposed to corrosive environment as well as to high temperatures. 相似文献
73.
Unlike insulating minerals, such as quartz or feldspar, the propensity of conductive minerals to heat using radiofrequency energy has not been particularly well quantified or documented in scholarly literature. A detailed knowledge of the RF properties of all minerals is required for RF energy to be effectively used in many potential applications. Electrical conductivity measurements were performed on selected sulphide minerals and magnetite between 100 kHz and 10 MHz using thin-film electrodes. However, reproducible measurements are challenging due both the high conductivity and semiconducting nature of the minerals. These measurements show variation between deposits and allude to favourable differences difference between minerals at radiofrequencies. 相似文献
74.
S. BahçeciB. Unal A. Baykal H. SözeriE. Karaoglu B. Esat 《Journal of Alloys and Compounds》2011,509(35):8825-8831
Polypropiolate sodium (PPNa)-Fe3O4 nanocomposites were successfully synthesized by the precipitation of Fe3O4 in the presence of sodium polypropiolate and followed by reflux route. Structural, morphological, electrical and magnetic properties evaluation of the nanocomposite were performed by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), vibrating scanning magnetometry (VSM) and conductivity measurements. Crystalline phase was identified as magnetite with an average crystallite size of 7 ± 3 nm as estimated from X-ray line profile fitting. Particle size estimated from TEM, by log-normal fitting, is ∼9 ± 1 nm. FT-IR analysis shows that the binding of PPNa on the surface of iron oxide is through bidentate linkage of carboxyl group. TGA analysis showed the presence of 20% PPNa around 80% magnetic core (Fe3O4)…PPNa-Fe3O4 nanocomposite show superparamagnetic characteristics at room temperature. It is found that the a.c. conductivity of the nanocomposites obeys the well-known power law of frequency in which it also depends on temperature. Additionally, its d.c. conductivity showed that two operating regions of the activation energy. Both real and imaginary parts of either permittivity exhibit almost the same attitudes which are the indication of the same ability in the stored energy, and dissipation of energy within the PPNa and PPNa-Fe3O4 nanocomposites. 相似文献
75.
Xia TongWeiming Zhu Qingyin Wu Xueyu QianZhen Liu Wenfu YanJian Gong 《Journal of Alloys and Compounds》2011,509(29):7768-7772
A new solid high-proton conductor, heptadecatungstovanadodiphosphoric heteropoly acid H7P2W17VO62·28H2O with Dawson structure was synthesized by the stepwise acidification and the stepwise addition of element solutions. The optimal proportion of component compounds in the synthesis reaction was given. The product was characterized by chemical analysis, potentiometric titration, IR, UV, XRD, 31P NMR, TG-DTA and electrochemical impedance spectroscopy (EIS). The results indicate that H7P2W17VO62·28H2O possesses the Dawson structure. EIS measurements show a high conductivity (3.10 × 10−2 S cm−1 at 26 °C and 75% relative humidity), with an activation energy of 32.23 kJ mol−1 for proton conduction. The mechanism of proton conduction for this heteropoly acid is Vehicle mechanism. 相似文献
76.
《应用陶瓷进展》2013,112(2):83-86
AbstractThe sintering characteristics of fly ash-pyrophyllite mixes containing 0-100 wt-% sericitic pyrophyllite have been studied, using 10 wt-% sodium hexametaphosphate as a binding agent and a firing temperature of 950°C. Increasing pyrophyllite content has been observed to increase the impact strength and apparent density and decrease the water absorption of sintered tile samples. Moreover, the presence of pyrophyllite imparted improved thermal shock resistance to the wall tile samples. 相似文献
77.
《国际聚合物材料杂志》2012,61(2):61-67
This paper reports the dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and ionic conductivity studies on nanosized Al2O3(aluminium oxide) filled PVA:NH4SCN:DMSO polymer composite dried gel electrolytes prepared by the wet chemistry route. Better mechanical stability and thermal behavior are noticed in the composite system. Multiple relaxation peaks seen in tangent loss measurements (in DMA studies) have been suitably correlated. Enhancement in ionic conductivity has been noticed with an optimum value of 4.02 × 10?3 Scm?1 for 4 wt% nano Al2O3 filled composite electrolytes. Temperature dependence of ionic conductivity shows a combination of Arrhenius and VTF (Vogel-Tamman-Fulcher) behavior. 相似文献
78.
Yazhou Kong Ying Li Jiawei Li Chuanbo Hu Xiaohua Wang Jiayao Lu 《Ceramics International》2018,44(4):3947-3950
In this work, perovskite-structured Li0.375Sr0.4375M0.25N0.75O3 (M=Ti, Sn, N=Nb, Ta) solid electrolytes were synthesized by conventional solid state reaction method. Phase compositions, fractured morphologies and conductivities of these compounds were investigated by X-ray diffraction, scanning electron microscope and AC-impedance spectroscopy, respectively. X-ray diffraction analysis confirms that all of Li0.375Sr0.4375M0.25N0.75O3 (M=Ti, Sn, N=Nb, Ta) ceramics present perovskite structure. Pure Li0.375Sr0.4375Ti0.25Ta0.75O3 and Li0.375Sr0.4375Sn0.25Ta0.75O3 perovskite ceramics were obtained. But impurities were detected in Li0.375Sr0.4375Ti0.25Nb0.75O3 and Li0.375Sr0.4375Sn0.25Nb0.75O3. Among all investigated compounds, Li0.375Sr0.4375Ti0.25Ta0.75O3 shows the highest total ionic conductivity of 2.60 × 10?4 S cm?1 at room temperature and the lowest activation energy of 0.347 eV. Conductivities of Li0.375Sr0.4375Sn0.25Ta0.75O3 and Li0.375Sr0.4375Sn0.25Nb0.75O3 were 4.4 × 10?5 S cm?1 and 1.82 × 10?6 S cm?1, respectively. Their conductivities were much lower than Li0.375Sr0.4375Ti0.25Ta0.75O3 and Li0.375Sr0.4375Ti0.25Nb0.75O3. 相似文献
79.
介绍了方波电压法测量液体介质tanδ的原理。分析了实现这一测量方法的技术关键。在测量系统的超稳时间、测量时间的控制、测量系统各参数的设置和电流测量仪器选用等方面,提出了通过实践验证的计算方法和解决方案,并证实该方法是测量液体介质低tanδ值,提高测量的分辨率和准确度一个有效途径。 相似文献
80.