A new phase in stoichiometric Cu6Sn5
A new phase in stoichiometric Cu6Sn5
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DOI：
10.1016/j.actamat.2012.08.024
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发表时间：
2012-11
期刊：
影响因子：
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通讯作者：
Yueqin Wu;J. Barry;Tomokazu Yamamoto;Q. Gu;S. McDonald;S. Matsumura;Han Huang;K. Nogita
中科院分区：
文献类型：
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作者：
Yueqin Wu;J. Barry;Tomokazu Yamamoto;Q. Gu;S. McDonald;S. Matsumura;Han Huang;K. Nogita
金属间化合物 Cu6Sn5 是许多电子器件的一个重要微观结构特征，它存在于焊料-基板界面处。 Cu6Sn5 随时间和温度变化的热机械性能取决于其晶体结构的性质和稳定性，已证明晶体结构至少存在四种变体（η、η'、η6 和 η8）。这项研究利用变温同步加速器 X 射线衍射 (XRD) 和透射电子显微镜详细介绍了直接合金化化学计量 Cu6Sn5 中另外一种新发现的单斜晶结构。该相与多晶型单斜-六方转变温度的平衡温度的偏离有关。新的单斜晶相可以被视为四个 η8-Cu5Sn4 晶胞加一个 η'-Cu6Sn5 晶胞的调制。它被标记为 η4+1，根据电子衍射图确定其电池参数为 a=92.241Å、b=7.311Å、c=9.880Å 和 β=118.95°。 XRD 结果可以很好地拟合使用新晶体参数的 Rietveld 精修。
The intermetallic compound Cu6Sn5is a significant microstructural feature of many electronic devices where it is present at the solder–substrate interfaces. The time- and temperature-dependent thermomechanical properties of Cu6Sn5are dependent on the nature and stability of its crystal structure, which has been shown to exist in at least four variants (η, η′, η6and η8). This research details an additional newly identified monoclinic-based structure in directly alloyed stoichiometric Cu6Sn5using variable-temperature synchrotron X-ray diffraction (XRD) and transmission electron microscopy. The phase is associated with a departure from the equilibrium temperature of the polymorphic monoclinic–hexagonal transformation temperature. The new monoclinic phase can be treated as a modulation of four η8-Cu5Sn4unit cells plus one η′-Cu6Sn5unit cell. It has been labeled as η4+1and has cell parameters of a=92.241Å, b=7.311Å, c=9.880Å and β=118.95° determined from electron diffraction patterns. The XRD results could be fitted well to a Rietveld refinement using the new crystal parameters.