The role of the twin planes in the rapid dendritic propagation of germanium crystals is examined on the basis of corner nucleation. A model is proposed, and it is shown that at least two twin planes must be present for continued easy propagation in <211> directions, in good agreement with experimental observations. The absence of the dendrite with only one twin is explained.

Ice single crystals grown from HCl solutions indicate a concentration-dependent partition coefficient. This departure from ideality may be tentatively attributed to bond defects generated by substitutional HCl molecules in the ice lattice.

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