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首页> 外文期刊>Journal of Crystal Growth >Crystal growth of intermetallic clathrates: Floating zone process and ultra rapid crystallization
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Crystal growth of intermetallic clathrates: Floating zone process and ultra rapid crystallization

机译：金属间包合物的晶体生长：浮区过程和超快速结晶

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摘要

We studied the crystal growth process of type-Ⅰ transition metal clathrates in two different regimes: a regime of moderate cooling rate, realized with the floating zone technique, and a regime of ultra rapid cooling, realized by the melt spinning technique. In the former regime, bulk Ba_8Au_xSi_(46-x) and Ba_8Cu_(4.8)Ga_xGe_(41.2-x) single crystals were grown. We investigated segregation effects of the constituting elements by measurements of the composition profiles along the growth direction. The compositional non-uniformity results in a spatial variation of the electrical resistivity which is discussed as well. Structural features of clathrates and their extremely low thermal conductivities imply specifics in growth behavior which manifest themselves most pronouncedly in a rapid crystallization process. Our melt spinning experiments on Ba_8Au_5Si_(41) and Ba_8Ni_(3.5)Si_(42.5) (and earlier on some other clathrates) have revealed surprisingly large grains of at least 1 μm. Because of the anomalously high growth rate of the clathrate phase the formation of impurity phases is considerably kinetically suppressed. We present our scanning and transmission electron microscopy investigations of melt spun samples and discuss structural, thermodynamic and kinetic aspects of the unusual clathrate nucleation and crystallization.
机译：我们研究了两种不同类型的Ⅰ型过渡金属包合物的晶体生长过程：通过浮区技术实现的中等冷却速率机制，以及通过熔融纺丝技术实现的超快速冷却机制。在前一种状态下，生长了块状Ba_8Au_xSi_（46-x）和Ba_8Cu_（4.8）Ga_xGe_（41.2-x）单晶。我们通过测量沿生长方向的组成轮廓来研究构成元素的偏析作用。组成的不均匀性导致电阻率的空间变化，这也被讨论。包合物的结构特征及其极低的热导率暗示了生长行为的特征，这些特征在快速结晶过程中表现得最为明显。我们对Ba_8Au_5Si_（41）和Ba_8Ni_（3.5）Si_（42.5）（以及更早的其他包合物）的熔体纺丝实验发现，出人意料的大晶粒至少为1μm。由于包合物相的反常高的生长速率，大大地抑制了杂质相的形成。我们提出了熔融纺丝样品的扫描和透射电子显微镜研究，并讨论了异常包合物形核和结晶的结构，热力学和动力学方面。

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  • 来源
    《Journal of Crystal Growth》 |2014年第1期|627-632|共6页
  • 作者

    A. Prokofiev; X. Yan; M. Ikeda; S. Loeffler; S. Paschen;

  • 作者单位

    Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria;

    Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria;

    Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria;

    USTEM, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria;

    Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    A1. Segregation; A1. Crystallites; A2. Floating zone technique; B1. Nanomaterials;

    机译：A1。隔离;A1。晶体;A2。浮动区技术;B1。纳米材料;

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