The epitaxial growth of ice on single-crystalline substrates
The epitaxial growth of ice on single-crystalline substrates
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冰在单晶衬底上的外延生长
DOI：
10.1016/0022-3697(60)90036-6
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发表时间：
1960
影响因子：
4
通讯作者：
B. J. Mason
中科院分区：
文献类型：
--
作者：
G. Bryant;J. Hallett;B. J. Mason
在六方AgI、PbI2、cu、cdi2和水镁石的基面（0001）、新劈裂白云母的（001）面、正晶HgI2的（010）面、正晶碘的（001）面、v2o5的（100）面和方解石的菱形面上形成了冰晶外延沉积。在一种特定物质上首次出现冰晶的温度非常接近同一物质的气溶胶形成由过冷水滴组成的云的临界温度。当晶体高度超过~ 0.1μ时，晶体优先出现在衬底表面的解理和生长台阶上，并且与台阶的方向无关，它们都保持平行取向。生长在软岩基面上的薄的六角形冰板显示出干涉色，这可以衡量它们的厚度。通常，冰晶的直径明显增加，但厚度没有明显变化，这表明到达上表面的分子没有被吸收，而是在表面上迁移，并在晶体边缘内嵌。晶体接触邻近的晶体时通常会变厚；彩色的生长面从接触点开始在晶体表面展开。对AgI、PbI2、cu和cdi2的详细测量表明，对于给定的物质，存在一个定义明确的临界温度，超过这个温度，只有当空气相对于液态水超过饱和时才会出现冰晶，但低于这个温度，只要碘化银相对于冰的过饱和超过12%，而其他底物的数值略有不同，冰就会直接从气相形成。这些临界过饱和度是台阶边缘生长所必需的；冰只有在高得多的过饱和度（100 - 100%）下才会出现在基底的平坦部分。
Epitaxial deposits of ice crystals have been formed on the basal (0001) faces of hexagonal AgI, PbI2, CuS, CdI2and brucite, on the (001) face of freshly-cleaved muscovite, on the (010) face of orthorhombic HgI2, on the (001) face of orthorhombic iodine, on the (100) face of V2O5and on the rhombohedral faces of calcite. The temperature at which ice crystals first appear on a particular substance is very close to the threshold temperatures at which an aerosol of the same substance nucleates a cloud of supercooled water droplets.The crystals appear preferentially at cleavage and growth steps on the substrate surface, provided that these exceed ~ 0.1μ in height and preserve their parallel orientation irrespective of the direction of the step.Thin, hexagonal ice plates, growing on the basal plane of covellite (CuS), show interference colours which give a measure of their thickness. Commonly, the ice crystals increase appreciably in diameter with no discernible change of thickness, suggesting that molecules arriving on the upper surface are not assimilated but migrate over the surface and are built in at the crystal edges. Crystals usually thicken on touching a neighbouring crystal; coloured growth fronts are then seen spreading out across the crystal surface from the point of contact.Detailed measurements on AgI, PbI2, CuS and CdI2show that, for a given substance, there is a well-defined critical temperature above which ice crystals can appear only if the air exceeds saturation relative to liquid water, but below which ice forms directly from the vapour phase provided that the supersaturation relative to ice exceeds 12 per cent for silver iodide and slightly different values for the other substrates. These critical supersaturations are required for growth at the edges of steps; ice appears on the flat parts of the substrate only at much higher supersaturations (> 100 per cent).