| In this dissertation, a systematically experimental study has been made on the structure, oxygen content, superconductivity and the etc. of the La2CuO4+δ, La2Cu1-xMxO4+δ (M = Zn, Ni) and La2-xNdxCuO4+δ system by means of powder X-ray diffraction, iodometric titration, DC susceptibility and so on. The main results are as follows,La2CuO4+δ was chemically oxidized by using NaClO as oxidizing reagent with oxidation time from 2 to 120h at room temperature (RT) and 50℃, respectively, for the first time. The effects of the oxygen doping have been studied on superconductivity and related physical properties of the La2CuO4+δ system. The results show that all the samples are single phase with orthorhombic structure, and the grain size and its morphology have no obvious change before and after oxidation. A large amount of extra oxygen can be intercalated into the lattice of the La2CuO4+δ with orthorhombic structure, the relation between the extra oxygen content and the oxidation time obeys the double exponential saturation law, thus we speculate that there may exist simultaneously two different kinds of diffusion mechanism, the vacancy mechanism and the interstitial mechanism, during the oxidizing process. All the samples oxidized at RT are bulk superconductors with onset superconducting transition at 45K. While all the samples oxidized at 50℃ are bulk superconductors, and the Tc's of which decrease gradually from 45K to 43K with increasing oxidation time. This result indicates that the higher oxidation temperature is unfavorable for the superconductivity of the La2CuO4+δ system. The experiments have been confirmed that NaCIO is a very efficient oxidizing reagent for La2CuO4+δ system, and the Tc at 45K has been obtained in chemically oxidized La2CuO4+δ for the first time. The most evident feature for the samples oxidized by KMnO4 is the appearance of the two-step superconducting transition. The SAED patterns confirm that there are two superconducting phases existing in the sample.The effects of the element substitution in the copper site in CuO2 plane have been studied on superconductivity and related physical properties of the La2CuO4+δ system by substituting Zn or Ni for Cu under chemical oxidation. The results show that all the samples La2Cu1-xMxO4+δ (M=Zn, Ni) are single phase with orthorhombic structure, and the grain size and its morphology have no obvious change before and after oxidation. The excess oxygen content of the element-substituted sample after oxidation is evidently larger than that of the oxidized sample of pure La2CuO4+δ. This indicates that the element-substituted sample is more favorable for the insertion of the extra oxygen. The onset superconducting transition temperature Tc and the superconducting phase content of the oxidized La2Cu1-xMxO4+δ (M = Zn, Ni) samples markedly decrease with increasing the Zn and Ni content. The average Tc suppression rates are -11.5K/%Zn and -6.8K/%Ni, respectively. The effective moment induced by Zn is 1μB order, which decreases with increasing the Zn content. The effective moment of per Ni is about 0.8μB, which doesn't obviously change with increasing the Ni content. By comparing the related properties of the chemically oxidized La2Cu1-xMxO4+δ system and the La2-xSrxCu1-yMyO4 system with the Sr optimal doping, we can conclude that the effects of Zn and Ni on superconductivity are basically the same in both of the two systems.
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