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Since the beginning of 2008, the Japanese scientists in LaO1-xFxFeAs system the 26K superconductivity has been found to Chinese scientists led by other rare earth (Sm, Nd, Pr, Ce, Gd, Y) the La-bit alternative, F O electron doping Sr La hole doping, pressure synthesis and applied pressure, the ReOFeAs system (1111) superconducting critical temperature was raised to 56K, and an end to the monopoly of the copper oxide high-temperature superconductors , the new superconductors explore and Tc superconductivity research once again aroused attention. After nearly a year of hard work, people have been in another LaO1-xFxFeAs similar to the structure, also has F (?) The lattice layers: (Ba, K) Fe2As2, the of LiFeAs and Fe (Te, Se) and other three types of Fe discovery of superconductivity in the base compound, the formation of the four major categories of Fe-based superconductors. In the past year, a lot of theoretical and experimental studies carried out for the crystal structure of this class of superconductors, electronic structure, magnetic properties, the transport properties and superconductivity, their growing awareness. Especially compared with the copper oxide high-temperature superconductors, the similarities and differences of the physical properties of everyone interested. But they have a common feature, and its implied physical meaning is not clear, such as high temperature superconductivity is why only exists in the system with a two-dimensional structure? Why in the phase diagram, copper oxides and Fe-based superconducting phase near the antiferromagnetic ordered phase? antiferromagnetic fluctuations is conducive to the formation of high-temperature superconductivity, or just a competitive phase? Fe-based superconductors the electron - phonon interaction is very important, Fe-based superconductors antiferromagnetic fluctuations and superconductivity What is the relationship? relative to the commonality of Fe-based superconductors with copper oxide superconductors, the physical properties of the difference may be even more important. In a certain sense, the Fe-based superconductors easier understanding of their physical properties should be easier, despite its Fermi surface for multi-band, but its normal state properties does not seem like copper oxide so puzzling. The papers on the basis of summing up the work of the past, for the simplest structure FeSeo.85 system, and with FE02 surface Re2O3Fe2Se2 (Re = La, Ce) system, using Cu on Fe, F O part alternative, The structure, magnetic and transport properties were studied systematically. The paper is divided into three chapters: the first chapter introduces the basic nature of superconductivity research status of the Fe-based superconductors were reviewed and discussed, the motivation and meaning of this thesis. The second chapter describes the experimental methods used in the paper. Using conventional solid-state reaction prepared polycrystalline samples, using the standard four-probe method to measure the structure of the samples were characterized by X-ray powder diffraction (XRD), resistivity of the sample - temperature relationship, using SQUID (superconducting quantum interference device ) measurement sample magnetization. Chapter III reports the Fe1-xCuxSe0.85, Ce2O3-xFxFe2Se2 three systems the La2O3-xFxFe2Se2 and structure, magnetism and superconductivity research results. In Fe1-xCuxSe0.85 system, we found that the Cu Fe partial substitution will not only inhibit the superconductivity is more important is that the metal - insulator transition; in antiferromagnetic insulator La2O3Fe2Se2 system, by F part of the O Alternate introduction of the carrier, the system is not only transition metal, and rendering 10K superconductivity; at the same time the first synthesis of the compound having the the same antiferromagnetic with La2O3Fe2Se2 structure insulator Ce2O3Fe2Se2 single phase, and its F O part of the substitution effect to carry out a systematic study.
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