MNS--chapter3

释意

crystalline material:
A uniform substance made up of a three dimensional, grid-like repeating pattern.
(materials have long-range order arrangement of its atoms)

single crystal:
A crystalline material that is composed of only one crystal.

polycrystalline material:
A crystalline material which is composed of many smaller crystals or grains, randomly oriented.

Amorphous :
A material that displays only short range order.

assume的意思

Why do some materials assume(呈现，这里不是假设的意思) an amorphous structure?
The kinetics of the manufacturing process do not allow a regular or crystalline pattern to form.

crystal structure, lattice, basis, unit cell

A lattice is a collection of points arranged in a spatial pattern so each point has a relation its surrounding points that is valid for all other points as well.

A unit cell is the smallest part of a lattice that shows the repeating pattern of the lattice.

The basis is composed of atoms with a certain relationship spatial relationship.

The crystal structure is the combination of the lattice and basis and shows how the atoms of a crystal are arranged with respect to each other throughout the entire thing.

# of lattice points per cell:

(如果1atom/lattice, 就是#atoms/cell)
SC:1 BCC:2 FCC:4 HCP:2

coordination number:

SC:6 BCC:8 FCC:12 HCP:12

atomic radius与lattice parameters的关系：

![](http://latex.codecogs.com/gif.latex? BCC: \sqrt3 a_0 = 4r \ Fe, alkalis
)

\rho, PF

 = \frac {m}{v} = \frac {atoms/cell \cdot (M/NA)}{V_{unit cell}}) = \frac{atoms/cell \cdot V_{atom}}{V_{unit cell}})

7种晶格

cubic, hexagonal, tetragonal, orthorhombic, monoclinic, rhombohedral, triclinic

面和方向坐标的区别

[方向]<方向族> [100][-100]相反 [100][200]相同
(平面){平面族} (100)(-100)相同 (100)(200)不同

面：

planar destiny: 个数/面积
packing fraction: 面积/面积

线：

repeat distance: 1/LD
linear density (LD): 个数/长度
packing fraction: LD*直径

Diffraction tech for crystal structure analysis