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The vortex dynamics at microwave frequencies in YBa2Cu3O7-δ (YBCO) films have been studied. We observe a peak in the microwave (4.88 and 9.55 GHz) surface resistance in some films in
magnetic fields up to 0.8 T. This is associated with the ‘peak-effect’ phenomenon and reflects the order-disorder transformation
of the flux line lattice near the transition temperature. Introduction of artificial pinning centers like columnar defects
created as a result of irradiation with 200 MeV Ag ion (at a fluence of 4×1010 ions/cm2) leads to the suppression of the peak in films previously exhibiting ‘peak effect’. 相似文献
84.
首次报道了一种新型的基于铰链式六面顶压机的二级6-8模大腔体静高压装置的内置加热元件的设计与温度标定。此加热组装结构简单,升温快,保温效果好,并有效地解决了国外基于两面顶压机构架下的二级6-8模内加热组装中热电偶在施加压力时易断的问题。以低成本的碳管为加热元件,采用直接和间接两种加热方式,用双铂铑(Pt6%Rh-Pt30%Rt)B型热电偶进行温度测量,并根据实验过程中加热功率与腔内实际温度的关系,对不同压力下腔体内的温度进行了标定。实验结果表明:此加热系统的油压达到40 MPa(腔体压力约10 GPa)时,温度可以达到1 700 ℃以上;在油压为30 MPa、样品室温度为1 000 ℃时,保温时间可达2 h,甚至更长;实验中获得样品的直径可达3 mm,高度可达7 mm,实现了在高温超高压条件下大样品的制备,满足了实验对产生高温超高压条件的需要。 相似文献
85.
The rod-shaped Co-Ni-P shells were prepared by metalling Bacillus. The microstructures and composition of the shells were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive analysis (EDS). The electromagnetic parameters were measured by the coaxial line method in the frequency of 2-18 GHz. It was found that the Bacillus were successfully coated with Co-Ni-P, and the inner structure of the shells are hollow in structure. The shells exhibit excellent microwave absorption properties in 5-17 GHz frequency. The microwave reflection loss is above −10 dB in 5.38-16.6 GHz frequency. The maximum microwave reflection loss reaches −35.83 dB at 9.12 GHz for samples thickness 2.4 mm, and the widest bandwidth for microwave reflection loss above −10 dB is about ∼5.32 GHz for samples thickness 2.0 mm. These results confirm the feasibility of applying Bacillus as biotemplates for fabrication of the metallic shells as lightweight microwave absorption materials are very promising for applications. 相似文献
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88.
M. Igarashi K. KakimotoT. Hayashida Y. HanadaS. Fujita K. MoritaN. Nakamura S. HanyuY. Sutoh H. KutamiY. Iijima T. Saitoh 《Physica C: Superconductivity and its Applications》2010,470(20):1230-1233
We have studied a hot-wall heating system to produce GdBa2Cu3Oy (GdBCO) films with large critical currents (Ic) at a high production rate by a pulsed-laser-deposition (PLD) method. GdBCO films fabricated at a production rate of 30 m/h under the optimized conditions, especially a distance of 95 mm between the target and the substrate (T–S), exhibited high critical current densities (Jc) of about 3 MA/cm2 and Ic over 300 A at a thickness of 1–2 μm. Furthermore, long GdBCO tapes prepared by repeated depositions at each tape-passing speed of 80 m/h showed uniform Ic distribution along the longitudinal direction, because the hot-wall system enabled to stabilize temperature within a few degrees at 800 °C. A 170 m long tape with Ic over 600 A was successfully fabricated at a production rate of 16 m/h using a laser power of 360 W. 相似文献
89.
N. Foroughifar A. Mobinikhaledi H. FathinejadJirandehi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6):1241-1246
Pyrimidine derivatives, 4a-4m , were synthesized in high yield using a newly developed microwave-assisted cyclocondensation reaction of g -ketoester, aryl aldehyde, and (thio)urea. In all of these Biginelli reactions, a mixture of the appropriate g -ketoester, aryl aldehyde, and (thio)urea were subjected to microwave irradiation by using polyphosphate ester (PPE) as a reaction moderator. 1 H NMR and IR spectroscopies were used for characterization of compounds 4a-4m . 相似文献
90.
《高分子科学杂志,A辑:纯化学与应用化学》2013,50(4):351-363
ABSTRACT The influence of the presence of an inorganic carrier in the polymerization systems was investigated in this paper. Ten polymerization systems that contained different inorganic carriers such as Al2O3, SiO2 were studied. The ten polymerization systems are dibutyltin Maleate (DBTM) and allyl thiourea (AT), DBTM and stearic acid vinyl ester (SAVE), SAVE and maleic anhydride (MH), SAVE and acrylamide (AM), itaconic acid (IA) and AM, SAVE and IA, AM and MH, IA, sodium acrylate (AANa), AM. It was found that the activity of monomer can be changed in the presence of a carrier and furthermore, the different species of carrier influence the activity of same monomer differently in the polymerization. 相似文献