Dissertation > Excellent graduate degree dissertation topics show

Study on the Epitaxial Growth and Its Mechanism of REBCO High Temperature Superconductor Bulks

Author: LiTianYu
Tutor: YaoXin
School: Shanghai Jiaotong University
Course: Condensed Matter Physics
Keywords: High-temperature superconducting Epitaxial growth Growth mechanism Isolated pollution
CLC: O469
Type: Master's thesis
Year: 2011
Downloads: 73
Quote: 0
Read: Download Dissertation

Abstract

High-temperature superconductors (HTSC) has excellent performance and great potential, has been subject to extensive concern in the scientific community. Especially the series RE1Ba2Cu3O7 (REBCO, RE123, where RE contains rare earth elements such as Y, Gd, Sm, Nd) superconducting bulk material has a bright future, very research value. So far, in the growth field of the preparation of bulk superconductors have made great progress, but still faces some difficulties: such as the growth long time; frozen field there is a loss at the grain boundaries; seed contamination of bulk materials; growth The highest temperature limit restrictions seed crystal. The main scientific significance of this paper is to discuss the means and methods of controlling the growth of high-performance REBCO superconducting bulk materials from the epitaxial control and growth mechanism. The main results are as follows: 1. Seed crystal melt-textured growth of YBCO superconducting bulk material in the grain boundary growth mechanism. Of YBCO and SmBCO film for the first time in the multi-seed melt-textured the law (MSMG) is used as a seed. The introduction of a new growth model for explaining the residual melt and the single-domain relationship of the angle between the seed crystallization method in the crystal boundaries. During the experiment, the film seed crystal showed a homogenous epitaxial, thermal performance, regular shape, ease of preparation etc.. And to verify the residual melt at the grain boundaries with the single domain between the increase of the angle is reduced. E.g., (110) / (110) (100) / (100) was significantly less than the residual melt of the grain boundaries at the grain boundaries. Intermediate isolation protective layer is applied to the growth of REBCO bulk superconductors. Intermediate protective layer between the first use in cold seed melt-textured Preparation of REBCO superconducting bulk materials, is about a mini-block placed between the seed and the bulk precursor. It is worth noting that most of the pollution caused by the seed crystal material is the protective layer absorbs. Therefore, we can get the seedless crystal contaminated samples. In addition, although the maximum temperature (Tmax) in the method of melt-textured process due to the limitations of the seed crystal material, there is a maximum value. However, by adding a protective layer, Tmax limit has improved. This is conducive to expanding the growth of the sample interval and inhibition of spontaneous nucleation. Overall, this work avoid seed contamination of the sample at the same time also increased the limit of Tmax. On the preparation of large-size, high-performance superconducting bulk materials, there are certain guiding significance. The paper orientation epitaxial growth of high-temperature superconducting bulk materials for REBCO and growth mechanism of providing new ideas and methods on preparing high-performance REBCO bulk superconductors have some help.

Study on the Epitaxial Growth and Its Mechanism of REBCO High Temperature Superconductor Bulks

Abstract

Related Dissertations