纯MgB_2和碳掺杂MgB_2超导块材在酸浸过程中相成分和微观结构的演变(英文)

Investigation on Phase and Microstructure Comparison of Pure and Carbon-Doped MgB_2 Superconducting Bulks during Acid Exposure

采用X射线衍射仪和扫描电镜系统研究了纯MgB2和碳掺杂MgB2超导块材在的盐酸溶液中(pH=2)酸浸后的相成分和微观结构演变过程。XRD结果显示,纯MgB2和碳掺杂MgB2超导块材均迅速与盐酸反应而分解。分解反应在5h后完全结束,主要的固态产物是B(OH)3和MgCl2(6H2O)。SEM结果显示,纯MgB2和碳掺杂MgB2超导块材与酸反应都是从晶界处开始,与纯MgB2块材相比,碳掺杂MgB2块材在与酸反应后仍保持致密的结构特征。而对酸浸10min后纯MgB2和碳掺杂MgB2块材的临界超导转变温度测定结果显示,碳掺杂MgB2块材的临界超导转变温度保持不变,说明碳掺杂可提高MgB2在酸中的稳定性。

The phase composition and microstructure evolution of pure and carbon-doped MgB2 bulks exposed to hydrochloric acid （pH=2） for different time were investigated by X-ray diffraction （XRD） and Scanning electron microscopy （SEM） systematically. XRD.results show the decomposition of pure and carbon-doped MgB2 bulks exposed to acid is rapid decay with exposure time. The decomposition reaction will finish completely after 5 h exposure and the main solid products are B（OH）3 and MgC12（6H20）. The SEM results demonstrate that the reaction among pure and carbon-doped MgB2 as well as HC1 occurs at grain boundaries. But the grain connection of carbon-doped MgB2 is better than that of pure MgB2 after acid exposure. The Tc of MgB2 decreases after 10 min acid exposure, but Tc is almost unchanged in carbon-doped MgB2 after the same exposure. This result indicates that substitution of C for boron in MgB2 can improve of the resistance to the corrosion of acid.