Crystalline structures

1) Crystal:

It is a solid one whose atoms enjoy all the following property:

to)       they are in equivalent positions

b)       they see the same conditions to the contour

the structure enjoys therefore the traslazionale symmetry .

 

2) Relation between the crystalline directions and the characteristics of the crystal:

Reporting us to a cubical crystal, it is had that if the reticular parameter is to = 5A°, the D distance between two adjacent reticular plans aligns to you along (the 100) is D = 5A°, while if is aligns to you along (the 110) is D = 7.07A° while if is it aligns to you along (the 111) is D = 8.56A°. Naturally the how many the more plans are distant between they much minor are the force that joins them.

 

3) Indices of Miller:

Three entire ones enclosed between round parentheses (n₁ , n₂ , n₃) characterize the orthogonal plan to direction [ n₁ , n₂ , n₃].

 

4) unitary Cell:

The crystal can be subdivided in elementary blocks calls unitary cells to you all having the following property:

to)       same shape

b)       same content

c)       same volume

 

5) primitiva unitary Cell:

He is such to only contain a point of the reticulum.

 

6) Calcolo of the atom number for every cell:

To the points it comes associated a various weight to second of the number of cells with which they are you flavored yourself, in particular it is had:

to) 1/8 for the points that are found on you concern to us

b) ½ for the points that find to the center of one surface

c) 1 for the points contained to the center of the considered cell

 

7) Covalent bond:

It is had as an example in the Diamond, in and in GE, an atom brace is had everyone of which puts in game a its electron which are mostly come to find in the space comprised between two atoms. One has an attractive force of ione the C towards electrons and a repulsiva force of two electron clouds.

 

8) ionic Tie:

It is typical between two Ionian ones of opposite sign, in particular due to electron clouds is had a repulsiva force that stretch to reject itself and an attractive force between the Ionian ones of opposite sign.

 

9) metallic Tie:

The Ionian ones positi to you are attracted from the cloud electronic that already to ambient temperature is established.