Coexistence of rhcp and fcc phases in hard-sphere colloidal crystals
Coexistence of rhcp and fcc phases in hard-sphere colloidal crystals
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DOI：
10.1209/epl/i2005-10325-6
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发表时间：
2005-12-01
期刊：
影响因子：
--
通讯作者：
Lekkerkerker, HNW
中科院分区：
文献类型：
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作者：
Dolbnya, IP;Petukhov, AV;Lekkerkerker, HNW
我们提出了高分辨率小角度单晶X射线衍射硬球二氧化硅胶体晶体的结果。我们的研究结果表明，在强压缩样品中发现fcc堆积序列的堆积概率α只能有两个离散值，即0.5（对于rhcp）或1（对于fcc），这与以前在更稀的系统中观察到的亚稳硬球rhcp晶体可能有不同的α值相反。这表明，在浓缩样品中，从rhcp到fcc的转变并不是通过α的平滑变化，而是通过熔化的重排机制，这导致了完美的fcc微晶的形成。这些微晶不具有单一的堆垛层错证明了没有双fcc反射。
We present results for high-resolution small-angle single-crystal X-ray diffraction of hard- sphere silica colloidal crystals. Our results indicate that the stacking probability alpha of finding an fcc stacking sequence in a strongly compressed sample can only have two discrete values of either 0.5 ( for rhcp) or 1 ( for fcc) in contrast to previous observations on more dilute systems that metastable hard- sphere rhcp crystals may have various values of alpha. This suggests that, in a concentrated sample, the transition from rhcp to fcc does not go by a smooth variation of alpha, but through a rearrangement mechanism via melting, which leads to the formation of perfect fcc crystallites. These crystallites do not possess a single stacking fault as evidenced by the absence of twin fcc reflections.