Characterization of cubic 纬-phase uranium molybdenum alloys synthesized by ultrafast cooling

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• 作者：I. Tkach^a ; N.-T.H. Kim-Ngan^a ; ^b ; ^{tarnawsk@mag.mff.cuni.cz} ; ^{tarnawsk@up.krakow.pl} ; S. Ma&scaron ; ková ; ^a ; M. Dzevenko^c ; L. Havela^a ; A. Warren^d ; C. Stitt^d ; T. Scott^d
• 关键词：U-Mo alloys ; 纬-Uphase ; Superconductivity
• 刊名：Journal of Alloys and Compounds
• 出版年：2012
• 期刊代码：45_09258388
• 类别：ms
• 出版时间：5 September, 2012
• 卷：534
• 期：Complete
• 页码：101-109
• 文件大小：1561 K

摘要

U-Mo alloys with Mo concentration in the range of 0-15 at.%Mo were prepared using a splat-cooling technique. Phase analysis using X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron back-scatter diffraction (EBSD) revealed the presence of a small amount of 纬-U phase retained at room temperature alongside the majority 伪-U phase and opening the possibility of stabilizing the 纬-phase at room temperature in uranium metal by ultrafast cooling. The double-phase (伪 + 纬) structure with predominance of the 伪-phase was obtained in the alloys with 0-10 at.%Mo. Increasing further Mo doping leads to the 纬掳 phase (for 11-12 at.%Mo) and pure cubic 纬 phase (for 15 at.%Mo). The superconducting transition was investigated by low-temperature resistivity measurements down to 0.3 K in magnetic fields up to 5 T. All the splats become superconducting with T_c in the range from 1.24 K (pure U splat) to 2.11 K (U-15 at.%Mo). The superconductivity in the 纬-phase alloys exhibited a much higher upper critical field than for 伪-phase material. Electrical resistivity of the 纬-alloys (猢?1 at.%Mo) exhibited a negative temperature coefficient from room temperature down to the superconducting transition.