Tl-Ba-Cu-O体系高T_o超导体晶体结构本文用粉末烧结法合成了Tl-Ba-Ca-Cu-O体系一系列超导试样。用X射线粉末衍射法对它们进行了结构分析,发现了一组点阵常数α值相同,c值不同的四方超导相。超导相由隔层(Tl-O单隔层或双隔层)和缺氧类钙钛矿型结构单元Ba_2×Ca_(n-1)Cu_nO_(2n+1)(n为整数)所组成。从...
The resistive behaviour of Tl-Ca-Ba-Cu-O is found to be metallic while that of Pr-Tl-Sr-Ca- Cu-O shows a mixed metallic and semiconductive behaviour. The thermoelectric power of both superconductors is positive throughout the temperature interval. The thermoelectric power of the Tl-Ca-Ba- ...
Tl-Ca-Ba-Cu-O Thin Film Passive Microwave DevicesWe report results on several passive microwave devices fabricated and tested using epitaxial thin films of Tl 2 CaBa 2 Cu 2 O 8 grown on LaAlO 3 . We report microstrip resonators with unloaded Q's of 15,000 at 80K and 4.83 GHz, and ...
In order to establish the reproducible processing for high-Tc superconducting Tl-Ba-Ca-Cu-O phases, three kinds of superconductive samples with different starting compositions of Tl:Ba:Ca:Cu=2:2:2:3, 2.5:2:2:3 and 3:2:2:3 were heat treated under various conditions. The optimum starting...
A process of making high temperature Tl-based superconductors is disclosed. The process includes the steps of reacting solid Ba-Ca-Cu-oxides with Tl.sub.2 O.sub.3 vapor. The process allows high quality Tl-based superconductors to be easily fabricated.
The thermal conductivity of the Tl-Ba-Ca-Cu-O compound with nominal composition 2-2-2-3 has been investigated in the temperature range 4.2–300 K. An anomalous behaviour was observed near and above the superconducting transition. Time dependent effects were found below T c. They are ascribed...
In an effort to synthesize the high-Tc superconducting phase in the thallium system, two nominal compositions, Tl2Ca2Ba2Cu3O10 and Tl1Ca3Ba1Cu3O8.5, have been investigated for superconductivity as a function of the sintering temperature, time, atmosphere, and quench rate. Samples have been ...
It is interesting to note that there exist at least three superconducting phases in Tl-Ba-Ca-Cu-O system. All of them belong to the space group ${{D_{4h}^{17} - 4}}/{rm mmm}$. They have the same lattice constant a but different lattice constant c. The transition temperature Tc ...
Thin films of the (1223) phase (Tl-(1223), single Tl-O layer) and the (2223) phase (Tl-(2223), double Tl-O layers) of the Tl-Ba-Ca-Cu-O system were prepared using the laser ablation method. Both films had a high transport critical current density (J_c) of 1.5×10^5 A/cm...
The discovery of 30-K superconductivity in the La–Ba–Cu–O system1 and 90-K superconductivity in the Y–Ba–Cu–O system2 stimulated a worldwide search for even higher-temperature superconductors. Unfortunately, most of the higher-temperature transitio