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B粉對分步法制備MgB2超導體的影響
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國家“973”計劃項目（2011CBA00104）；國家自然科學基金資助項目（50877067）


Effects of B Powder on the MgB2 Superconductor Prepared by Two-Step PIT
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    摘要:

    通過分步反應法，利用晶態(tài)B粉和無定形B粉分別與Mg粉反應制備了MgB2超導體。其中分步反應法的第1步采用不同狀態(tài)的B粉與Mg粉按原子比Mg:B=1:4混合，對于摻雜的樣品另加5%，8%（質(zhì)量分數(shù)）的SiC，采用900 ℃，30 min或800 ℃，1 h進行高溫熱處理。第2步是補充Mg粉，使Mg:B=1:2，均混的粉末經(jīng)裝管拉拔后進行第2步750 ℃，2.5 h熱處理。通過XRD、SEM研究樣品的相組成、微觀結構。采用標準四引線法測定了樣品的I-V曲線。結果表明：晶態(tài)B粉與Mg粉可在第1步的熱處理過程中生成大量低反應活性的MgB4。從微結構分析發(fā)現(xiàn)晶態(tài)B粉制備的樣品具有更好的晶粒連通性，從而也得到了更穩(wěn)定的I-V關系曲線。

    Abstract:

    MgB2 superconductors were prepared by two-step PIT with B (crystalline or amorphous) and Mg as starting materials. The first step was mixing B (crystalline or amorphous) and Mg with the molar ratio of Mg:B=1:4. For the doping samples, 5wt% and 8wt% SiC were added to the mixture. Pressed pellets were treated at 900 oC for 30 min or 800 oC for 1 h. The second step was adding Mg to get the molar ratio of Mg:B=1:2. The tubes filled with the ground powders were treated at 750 oC for 2.5 h. The phase identities and the microstructure were investigated by X-ray diffraction (XRD) and Scanning Electronic Microscopy (SEM), respectively. Voltage dependence of the current of MgB2 wire was measured by a standard four-probe method. The results demonstrate that lots of MgB4 in low energy is synthesized by crystalline B and Mg at the first step. The sample prepared from crystalline B exhibits an excellent grain connection and stable I-V characteristics.

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單 迪,王慶陽,劉國慶,熊曉梅,李金山,閆 果,周 廉. B粉對分步法制備MgB2超導體的影響[J].稀有金屬材料與工程,2013,42(6):1278~1281.[Shan Di, Wang Qingyang, Liu Guoqing, Xiong Xiaomei, Li Jinshan, Yan Guo, Zhou Lian. Effects of B Powder on the MgB2 Superconductor Prepared by Two-Step PIT[J]. Rare Metal Materials and Engineering,2013,42(6):1278~1281.]
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  • 收稿日期:2012-06-20
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