摘要
In our laboratory we successfully produced thin films on Al 2O3 by sputtering a target, which is made of a mixture of MgB2 (commercial powder) and Mg, and went post-annealing process under different conditions. However, the films were not axial oriented and their superconductivity was not as great as MgB2 powders. We study the B and Mg K-edge absorption spectra and find followings: 1. The sputtered film (before ex situ annealing treatment) contains small amount of B 2O3 due to residual oxygen in the vacuum chamber, and unknown Mg compound. No signal of MgO is observed. 2. Under annealing temperature at 900°C, B2O3 is reduced to B by reacting with Mg and MgO is formed. No superconductivity was found. 3. Under annealing temperature at 600° ∼ 700°C, the Tc increases from 11.5 K to 25.5 K. The chemical shift of the pre-edge of the Mg K-absorption edge is greater as compared with that of MgB2 powder (Tc = 39 K). The Mg K-absorption spectrum indicates that the sample contains some amount of MgO.
原文 | 英語 |
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頁(從 - 到) | 534-542 |
頁數 | 9 |
期刊 | Chinese Journal of Physics |
卷 | 42 |
發行號 | 4 II |
出版狀態 | 已發佈 - 2004 8月 |
ASJC Scopus subject areas
- 一般物理與天文學