Рефераты | Топики по английскому языку | Why the crystal structure of the element is such lattice but not another? |
volume-centered |
||||
|
Thallium |
Tl |
+0,24 |
4 |
9 |
volume-centered |
|
Lead |
Pb |
+0,09 |
4 |
18 |
face-centered |
|
Lead |
Pb |
+0,09 |
5 |
9 |
face-centered |
Where Rh is the Hall’s constant (Hall’s coefficient)
Z is an assumed number of electrons released by one atom to the conductivity zone.
Z kernel is the number of external electrons of the atomic kernel on the last shell.
The lattice type is the type of the metal crystal structure at room temperature and, in some cases, at phase transition temperatures (1).
In spite of the rough reasoning the table shows that the greater number of electrons gives the atom of the element to the conductivity zone, the more positive is the Hall’s constant. On the contrary the Hall’s constant is negative for the elements which have released one or two electrons to the conductivity zone, which doesn’t contradict to the conclusions of Payerls. A relationship is also seen between the conductivity electrons (Z) and valency electrons (Z kernel) stipulating the crystal structure.
The phase transition of the element from one lattice to another can be explained by the transfer of one of the external electrons of the atomic kernel to the metal conductivity zone or its return from the conductivity zone to the external shell of the kernel under the influence of external factors (pressure, temperature).
