Do all metals have the same Fermi energy level at constant temperature?

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Discussion Overview

The discussion revolves around whether all metallic substances have the same Fermi energy level at a constant temperature and the implications of fusing two metals with different Fermi levels, particularly in relation to electron flow and equilibrium, drawing parallels to a PN junction.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions if all metallic substances have the same Fermi energy level at constant temperature and speculates on the behavior of electrons when two metals with different Fermi levels are fused.
  • Another participant asserts that the Fermi energy levels are not the same and confirms that electrons will transfer between the two metals, referencing the Peltier effect.
  • A later reply introduces the concept of "contact potential," likening the situation to a PN junction and mentioning its relevance to the Kelvin Probe technique for measuring contact potential and Fermi energy.
  • One participant reiterates that electrons will transfer between the two metals and elaborates on the overlap of conduction and insulation bands in metals, suggesting this allows for electron mobility.

Areas of Agreement / Disagreement

Participants generally agree that the Fermi energy levels of different metals are not the same and that electron transfer occurs between them. However, the discussion includes varying explanations and implications of this phenomenon, indicating some disagreement on the details and mechanisms involved.

Contextual Notes

The discussion does not resolve the specifics of how the differences in Fermi levels affect electron flow or the precise nature of the contact potential in this context.

Assaf Peled
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Hi, a question please:

Do all metallic substances have an equal Fermi energy level (at a constant T) ?
If not, what will happen (before equilibrium) if one "fuses" together two bulks of metal with different Fermi
levels (as in a PN junction) ?

Since there's an abundance of energy states available around the Fermi level in metals, I would consequently expect electrons to flow between the bulks until an equilibrium is reached. On the other hand, I sense a hole in my little theory here.

Many thanks.

A.
 
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No, they don't. Electrons will indeed be transferred between the two metals. See Peltier effect.
 
Assaf Peled said:
Hi, a question please:

Do all metallic substances have an equal Fermi energy level (at a constant T) ?
If not, what will happen (before equilibrium) if one "fuses" together two bulks of metal with different Fermi
levels (as in a PN junction) ?

Since there's an abundance of energy states available around the Fermi level in metals, I would consequently expect electrons to flow between the bulks until an equilibrium is reached. On the other hand, I sense a hole in my little theory here.

Many thanks.

A.

There's something called a "contact potential" when such metals are in contact with each other, very much similar to a PN junction as you suspected.

This effect is made use of in the Kelvin Probe technique of measuring contact potential and Fermi energy in metals.

Zz.
 
nasu said:
No, they don't. Electrons will indeed be transferred between the two metals. See Peltier effect.
To be more explicit, the conduction band and insulation band overlap for two metals allowing for electrons to move freely in a metal.
 

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