arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0905.0326cond-mat.softcond-mat.other
收藏

重力作用下去离子荷电球二元混合物的相行为

Phase behavior of a deionized binary mixture of charged spheres in the presence of gravity

Nina J. Lorenz, Hans Joachim Schoepe, Thomas Palberg

摘要:

我们报告的相行为的水二元带电球悬浮液在彻底去离子条件下作为小颗粒的数量分数p和总的数密度n的函数。粒径比为0.557的混合物显示出复杂的相图。没有组成顺序的体心立方晶体的形成占主导地位。我们观察到在0.55 < p < 0.95处晶体稳定性急剧降低的区域,其中在高于n = 26 μ m-3的密度下,最小值位于p = 0.8 +/-0.05处。在p = 0.4时观察到稳定性增强的峰值区域。进一步的光散射实验进行表征的结晶时间尺度,密度分布和形成的相的组成。对于0.82 > p > 0.95,晶体形成部分地由重力辅助,即在共存范围内,两种物质的重力分离先于晶体形成样品。在对应于降低的晶体稳定性的组合物范围内,仅得到凝固线和熔化线的下限,但保留了相图的一般形状。在p = 0.93和n = 43 μ m-3时,两种不同的晶相共存,而在p = 0.4时,静态光散射实验中出现了额外的布拉格峰。这强烈表明,我们观察到的低共熔的稳定性降低的区域,而在p = 0.4的增强的稳定性似乎与化合物的形成。

英文摘要:

We report on the phase behavior of an aqueous binary charged sphere suspension under exhaustively deionized conditions as a function of number fraction of small particles p and total number density n. The mixture of size ratio 0.557 displays a complex phase diagram. Formation of bcc crystals with no compositional order dominates. We observe a region of drastically decreased crystal stability at 0.55 < p < 0.95 with the minimum located at p = 0.8 +/- 0.05 at densities above n = 26um-3. A peaked region of enhanced stability is observed at p = 0.4. Further light scattering experiments were conducted to characterize the crystallization time scales, the density profiles and the composition of formed phases. For 0.82 > p > 0.95 crystal formation is partially assisted by gravity, i.e. gravitational separation of the two species precedes crystal formation samples in the coexistence range. In the composition range corresponding to the decreased crystal stability only lower bounds of the freezing and melting line are obtained, but the general shape of the phase diagram is retained. At p = 0.93 and n = 43um-3 two different crystalline phases coexist in the bulk, while at p = 0.4 additional Bragg peaks appear in the static light scattering experiments. This strongly suggests that we observe a eutectic in the region of decreased stability, while the enhanced stability at p = 0.4 seems to correlate with compound formation.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑