Figure 8
Structural model for the ikaite-to-vaterite transformation (H: white atoms; Ca: blue atoms; CO3: black and red molecules): (a) ikaite structure, (b) ikaite structure without the water molecules, (c) alignment of Ca2+ atoms along the [001] direction in the dehydrated orthorhombic structure (black unit cell), and (d) vaterite with orthorhombic (blue) and hexagonal (green) cells outlined. The two orthorhombic lattices are drawn to indicate the relationship of the calcium arrays. Our model relating the ikaite and vaterite structures is described in the text (§4.2). |