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- Type of Document: M.Sc. Thesis
- Language: Farsi
- Document No: 49222 (04)
- University: Sharif University of Technology
- Department: Physics
- Advisor(s): Akhavan, Mohammad
- Abstract:
- After the discovery of high temperature superconductivity in (LaM)2CuO4, different type of cuprate superconductors have been synthesized. Among them, YBCO compounds (e.g. YBa2Cu3O7-δ) have drawn more attention by researchers due to some advantages such as easier conditions of synthesis high quality samples in comparison with the other cuprate superconductors. However, superconductivity properties of these compounds are very sensitive to structural imperfections; hence it is important to study the effect of the microstructure on the behavior of the compounds. The compound YBaCu2Ox (Y112) is one of these microstructures that may form in YBa2Cu3O7-δ (Y123) samples. On the other hand, synthesis process of Y3Ba5Cu8Ox (Y358) (a new member of YBCO compounds) is difficult, because both the YBa2Cu3O7-δ and YBaCu2Ox phases can exist in it which can reduce the sample transition temperature. In spite of these, there have been few reports on YBaCu2Ox with different results about the formation of the superconducting phase. Some of them consider it as an independent superconducting phase, while others assume it to form as a multi-phase along with YBa2Cu3O7-δ. This study has made a general comparison of synthesis conditions, electrical resistance and X-ray diffraction patterns of YBaCu2Ox and YBa2Cu3O7-δ compounds. The analysis of these compound shows that preparation conditions of these samples are similar. Also, their transition temperatures are approximately equal. However, transition width of the YBaCu2Ox is more than YBa2Cu3O7-δ one. Two crystal structures were suggested for YBaCu2Ox, and the X-ray diffraction of the proposed structures have been compared with the experimental X-ray diffraction results of YBaCu2Ox. According to our results, although the behavior of YBaCu2Ox is similar to YBa2Cu3O7-δ superconducting phase, it seems this compound is not formed independently
- Keywords:
- Transition Temperature ; X Ray Diffraction ; Microstructure ; Crystal Structure Symmetry ; Y358 Supperconductor ; Cuprate Superconductors ; Independent Superconducting
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