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A crystallographic defect is an interruption of the regular patterns of arrangement of atoms or molecules in crystalline solids. The positions and orientations of particles, which are repeating at fixed distances determined by the unit cell parameters in crystals, exhibit a periodic crystal structure, but this is usually imperfect.
A crystal's crystallographic forms are sets of possible faces of the crystal that are related by one of the symmetries of the crystal. For example, crystals of galena often take the shape of cubes, and the six faces of the cube belong to a crystallographic form that displays one of the symmetries of the isometric crystal system. Galena also ...
Crystal formation requires two steps: nucleation and growth. [3] Nucleation is the initiation step for crystallization. [3] At the nucleation phase, protein molecules in solution come together as aggregates to form a stable solid nucleus. [3] As the nucleus forms, the crystal grows bigger and bigger by molecules attaching to this stable nucleus ...
Crystallization is the process by which solids form, where the atoms or molecules are highly organized into a structure known as a crystal.Some ways by which crystals form are precipitating from a solution, freezing, or more rarely deposition directly from a gas.
In crystallography, crystal structure is a description of ordered arrangement of atoms, ions, or molecules in a crystalline material. [1] Ordered structures occur from intrinsic nature of constituent particles to form symmetric patterns that repeat along the principal directions of three-dimensional space in matter.
In addition, physical properties are often controlled by crystalline defects. The understanding of crystal structures is an important prerequisite for understanding crystallographic defects. Most materials do not occur as a single crystal, but are poly-crystalline in nature (they exist as an aggregate of small crystals with different orientations).
Fundamentals of crystallography: crystal systems, Miller Indices, symmetry elements, bond lengths and radii, theoretical density; Crystal and glass structure prediction: Pauling's and Zachariasen’s rules; Phase diagrams and crystal chemistry (including solid solutions) Imperfections (including defect chemistry and line defects) Phase transitions
Axonal transport is also responsible for moving molecules destined for degradation from the axon back to the cell body, where they are broken down by lysosomes. [ 2 ] Dynein , a motor protein responsible for retrograde axonal transport, carries vesicles and other cellular products toward the cell bodies of neurons.