Effect of Cu addition in reduction of MgO content for the synthesis of MgB2 through sintering
Effect of Cu addition in reduction of MgO content for the synthesis of MgB2 through sintering
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DOI：
10.1016/j.jallcom.2008.03.098
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发表时间：
2009-03
影响因子：
6.2
通讯作者：
Zongqing Ma;Yong-chang Liu;Q. Shi;Qian Zhao;Zhiming Gao
中科院分区：
文献类型：
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作者：
Zongqing Ma;Yong-chang Liu;Q. Shi;Qian Zhao;Zhiming Gao
微量Cu的加入（<3at%）可明显降低原位烧结MgB 2样品中MgO杂质的含量，并使其临界转变温度（Tc）由未掺杂样品的36.4K提高到3at% Cu的样品的38.6K。掺Cu的MgB_2中MgO杂质的减少主要归因于：（1）在485°C附近形成的局部Mg-Cu液相包裹住了相邻的Mg颗粒，从而保护了它们在Mg熔点之前不被氧化;（ii）当烧结温度升高到Mg的熔点以上时，微量Cu的加入降低了Mg液的蒸气压，减少了Mg液的挥发，抑制了气态Mg与Ar保护气中O2杂质反应生成MgO杂质。我们的研究结果提供了一个新的途径来控制纯或掺杂MgB 2样品在原位烧结过程中的Mg氧化通过改变微量的Cu添加。
The minor Cu addition (<3at%) could apparently reduce the amount of MgO impurity in the in situ sintered MgB2samples, accompanying with the improvement in the critical transition temperature (Tc) from 36.4K for the undoped sample to 38.6K for the samples with 3at% Cu addition. The decrease of MgO impurity within Cu-doped MgB2samples can be attributed to the following factors: (i) the formation of local Mg–Cu liquid at about 485°C wrapped the neighboring Mg particles and thus protected them from the oxidation before the melting point of Mg; (ii) when the sintering temperature increased above the melting point of Mg, the minor Cu addition could also decrease the vapor pressure of Mg liquid and then reduce the volatilization of Mg liquid, which can depress the reaction between gaseous Mg and O2impurity in the protective Ar gas forming MgO impurity. Our results provide a new route to govern the oxidation of Mg during the in situ sintering of pure or doped MgB2samples by altering the minor amount of Cu addition.