Thermal analysis on C<sub class="a-plus-plus">6sub>H<sub class="a-plus-plus">10sub>Ge<sub class="a-plus-plus">2sub>O<sub class="a-plus-plus">7sub>-doped MgB<sub class="a-plus-plus">2sub>

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• 作者：Gheorghe Aldica ; Carmen Matei ; Adelina Paun…
• 关键词：MgB2 ; C6H10Ge2O7 addition ; Thermal analysis ; Infrared spectroscopy ; X ; ray diffraction ; Phase transformations
• 刊名：Journal of Thermal Analysis and Calorimetry
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：127
• 期：1
• 页码：173-179
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Physical Chemistry; Analytical Chemistry; Polymer Sciences; Inorganic Chemistry; Measurement Science and Instrumentation;
• 出版者：Springer Netherlands
• ISSN：1588-2926
• 卷排序：127

文摘

Additives to MgB<sub>2sub> can improve the superconducting functional characteristics, such as critical current density (J<sub>csub>) and irreversibility field (H<sub>irrsub>). Recently, we have shown that repagermanium (C<sub>6sub>H<sub>10sub>Ge<sub>2sub>O<sub>7sub>) is an effective additive, enhancing both J<sub>csub> and H<sub>irrsub>. To look into details of the processes taking place during the reactive sintering, a thermal analysis study (0.167 K s−1, in Ar) is reported. We used differential scanning calorimetry between 298 and 863 K and simultaneous thermogravimetric—differential thermal analysis between 298 and 1233 K. Samples were mixtures of powders with composition 97 mol% MgB<sub>2sub> and 3 mol% C<sub>6sub>H<sub>10sub>Ge<sub>2sub>O<sub>7sub>. Up to 863 K, repagermanium decomposes by multiple steps and forms amorphous phases. A reaction with MgB<sub>2sub> is not observed. Above this temperature, partial decomposition of MgB<sub>2sub> occurs. Crystalline Ge and MgO are detected before formation of Mg<sub>2sub>Ge and MgB<sub>4sub>, when temperature approaches the melting point of Ge (1211 K). Carbon substitution for boron in the crystal lattice of MgB<sub>2sub> is observed for samples heated above 863 K. The amount of substitutional C does not significantly change with temperature.