Preparation And Properties Of The Modified Bscco Superconducting Materials

Superconductors are materials which have zero resistance and Messiner effect when they are in low temperature. They are divided into two kinds of materials, which are low temperature superconductor and high temperature superconductor, according to their different critical temperature. Copper oxide superconductor is an important part of high temperature superconductors, which includes YBCO, BSCCO, and so on. We prepared BSCCO blocks by dry method, and the effects of ZnO doping on superconductivity and crystal structure of (Bi, Pb)-2223 superconductor were investigated. The original works and valuable results of this dissertation are as follows:1. We prepared BSCCO superconductor pre-sinter powders by dry method, and then sintered at 845°C for 10h.They were then pressed into pellets under a pressure of 10MPa after repeatly sintering for three times. From the photograph of XRD and HRSEM, we could infer that superconductor phase was proved to be completely formed. In order to measure the Tc value of the superconductors, two series of measuring systems were designed, and the effect of sintering time and sintering temperature on superconductivity of BSCCO superconductor was investigated.2. The influence of different doping methods on the superconductivity and structure of BSCCO superconductor was investigated. Various samples were fabricated by different doping methods, such as nano-composite doping and nano-particle doping, and the ZnO content in each samples was 1(wt)%. The results of critical temperature test and HRSEM revealed that both the preparing conditions and superconductivity of superconductor changed with various doping methods.3. Uniformly distributed ZnO nano-defects were introduced into BSCCO superconductors, using nano-composite method. Then the influence of different factors on the preparing conditions and structure of superconductors was investigated. First, after sintering at high temperature for long hours, the BSCCO samples with ZnO doped were synthesized, and the content of ZnO ranged from 0.5% to 2%. The results of standard four probes indicated that Bi-2223 phase was already formed in the samples, and with the increase of ZnO content, the speed of resistance's dropping on superconductors was slowered down according to the falling of temperature. From the HRSEM photographs we could see nano-ZnO uniformly distributed both inside and outside of the superconductors.