Ag3In3Ca中的主要合金相是简单立方Ag42In45Ca13 (空间群为Pa3, a=2.496 nm), 它是Ag42In42Ca16二十面体稳定准晶的2/1立方近似相. 选区电子衍射(SAED)实验表明, 2/1立方近似相与二十面体准晶有相似的局部结构. X射线能谱(EDS)、电子能量损失谱(EELS)和X射线粉晶衍射分析表明, Ag3In3Ca合金中的立方相Ag42In45Ca13不稳定. 薄膜电镜样品在空气中易发生化学反应, 产物中主要是Ca和O, 还有少量C. 块状合金在空气中放置14 d后, 其中的立方相Ag42In45Ca13分解, 二元合金相AgIn2和In4Ag9的含量明显增加. 在550 ℃保温55 h 后, 立方近似相Ag42In45Ca13的含量显著减少. 在相同条件下, 二十面体准晶Ag42In42Ca16保持不变, 具有高的结构和化学稳定性.
The simple cubic Ag42In45Ca13 (Pa3, a=2.496 nm), which is the 2/1 crystalline approximant of the Ag42In42Ca16 icosahedral quasicrystal, has been found as the dominant phase in the ternary Ag3In3Ca alloy. Its close structural relation to the Ag42In42Ca16 icosahedral quasicrystal was shown by means of SAED (selected area electron diffraction). The decomposition of the cubic Ag42In45Ca13 after annealing or exposure in air was studied using EDS (energy dispersive X-ray spectroscopy), EELS (electron energy loss spectroscopy) and powder X-ray diffraction. Thin foils of the Ag3In3Ca alloy are easily oxidized in air and the product contains Ca, O and some C. In block samples of the Ag3In3Ca alloy exposed to air for 14 d, the cubic Ag42In45Ca13 gradually decomposes, while the amount of the binary AgIn2 and In4Ag9 phases increases. On the other hand, the Ag42In42Ca16 icosahedral quasicrystal is stable both chemically and structurally under the same conditions.
参考文献
| [1] | |
| [2] | |
| [3] | |
| [4] |
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%