Process and Characterization of c-oriented Single Grain NdBaCuO/Ag High Temperature Superconductor

• Main Authors: Hsu, Shu-Hau, 許書豪
• Other Authors: Chen, In-Gann
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/86037423458050704292

碩士 === 國立成功大學 === 材料科學及工程學系 === 89 === Nd-Ba-Cu-O (NdBCO) high-temperature superconductor is known to form Nd1+xBa2-xCu3Oy solid solution because the ionic radius of Nd3+ is close to Ba2+. The substitution will degrade the superconducting properties, so the most melt-processes were conducted under the reduced oxygen atmosphere to depress the Nd-Ba solid solution. Besides, NdBCO exhibits the highest peritectic temperature (Tp) among REBCO oxides. Therefore, a stable seed with similar lattice parameters for melt-processed NdBCO has not been discovered to date. Recent studies showed that the peritectic temperatures (Tp) of NdBCO can be lowered by the addition of Ag. Based on this result, the melt-textured NdBCO/Ag can be seeded by Ag-free NdBCO at elevated temperature, which is referred as self-seeding (or hot-seeding) process. In this study, we attempted to synthesis c-oriented NdBCO/Ag superconductor in air by hot-seeding method. Additionally, a Ba-rich precursor (Nd2BaO4) has been added to enhance superconducting properties. The results showed that samples with the Nd210 addition and a proper post Ar heat-treatment, the high Tc (~90K) and Jc (2×104A/cm2 at 77K, 0T) can be achieved. And the c-oriented grain in present study can be up to 20mm in diameter. This is the first report about c-oriented single grain NdBCO with hot-seeding technique in air.