Questions tagged [metals]

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Second-Order Perturbation in electron gas

I was trying to figure out the solution to exercise 1.4 on Quantum theory of many particles systems by Fetter & Walecka and I read through this question and its answer. But a point made in both ...
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Why do most metals have high thermal expansion coefficient although their thermal conductivity are generaly high?

the relationship between thermal conductivity and thermal expansion in metals. Why do most metals have high thermal expansion coefficient although their thermal conductivity are generaly high? Please ...
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Molten metal flow due to high currents

It is mentioned in the book "Ampere-Neumann Electrodynamics of Metals", Peter Graneau, that Carl Hering in 1923 operated furnaces by passing high currents through the molten metal pool. He ...
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Iridium carbides in stainless steel alloys

Has there ever been any high carbon stainless steel made with iridium as one of the alloy components? Is there any research in this direction? There is a paper from 2016 comparing various iridium ...
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What does the electric field from a off-center charge inside of a metal sphere look like?

Consider a uncharged metallic sphere with a charge inside of it but not in the center, e.g. $0.5$radius upwards. What does this electric field look like? Without the sphere it is easily calculated but ...
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Relation between Fermi surface and Fermi velocity

Is there a direct relation between the Fermi velocity and the Fermi surface? Can one reconstruct the Fermi surface if the full angular distribution of the Fermi velocity is known?
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Vanishing electric field inside a conductor implies vanishing charge density but there is a puzzle

If we place a metallic conductor in a static, external electric field, the free electrons inside the conductor will move opposite to the external field leaving the immobile positive ions (nucleus+core ...
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3 answers
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Permittivity vs resistance of metals and skin depth

I'm asked to estimate the skin depth of copper at a certain frequency, but in deriving the equation for skin depth we basically need to assume $-\omega^2\varepsilon+j\omega\sigma\approx j\omega\sigma$,...
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What would happen on an atomic level to mercury in a microwave?

I'm not sure why I was thinking of this, but I did and I couldn't think of an equivalent physical model to relate microwaved liquid Mercury to. Polar substances are heated by dielectric heating, the ...
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Are there charge fluctuations in band insulators?

Consider a one-dimensional non-interacting Hubbard Hamiltonian: $$ H=-t\sum_{\langle i, j \rangle}\sum_{\sigma=\uparrow,\downarrow} \left(c_{i,\sigma}^\dagger c_{j,\sigma} +\mathrm{h.c.} \right) $$ ...
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2 votes
1 answer
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Periodic boundary condition (Born-Von Karman): does the size of the cube matter?

Periodic boundary conditions are chosen to faithfully represent the dynamical situation of electrons flowing through the metal. It's a better picture than the stationary wave one. We imagine a cube of ...
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Valence and conduction band definition in metals

In the textbook examples, the band character (VB and CB) of semiconductors is explained by their location above (CB) or below (VB) the Fermi level. In metals however, the valence and conduction bands ...
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What is the difference between the superconducting energy gap, order parameter, and pair potential?

I often see these terms used interchangeably in literature. However, in papers that discuss the proximity effect in bilayers, I'll see statements saying the order parameter is spatially dependent but ...
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Penning Trap Anode

I am looking to confirm my logic around how the anode in a Penning trap is able to reflect/contain protons via an electric field. My logic is that the anode is an excitinged metal such as (Metal)2+, ...
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What differentiates an alloy from diffusion at an interface?

For the thin film deposition of some metal A onto another metal B, I understand it is possible for a bit of metal a to diffuse into grain boundaries of metal B. How are these diffused atoms of metal A ...
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Does a metal evaporate as single atoms or as molecules?

If I had a liquid metal, like Al, and I begin heating it so it evaporates, would the evaporating Al be in the form of atoms or as molecules?
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Will stainless steel heat up faster than a cordierite-based surface in a gas oven?

Background: As some may know, pizza stones, used to accumulate heat before the pizza dough is put into the oven, are often made of cordierite. If it's well heated it should provide the underside of ...
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Effect of reducing temperature on a concentric metallic hemisphere in terms of radius of the inner hollow hemisphere

This is more of a thought experiment from my end but was not sure on how to proceed. Let's say we have a solid metallic sphere with a hollow core and we split it exactly in half. Now we have a ...
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1 vote
1 answer
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Absolute Seebeck-Coefficient of Metals

Note: In litterature, the Seebeck-Coefficient is most often given to Platinum as a reference point, because it is challenging to measure the absolute Seebeck-Coefficient. It is however possible, this ...
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Electron transport in fluids VS solids ("structure factor" VS "phonons")

Assume to have a neutral plasma consisting of some ions $X^+$ in a neutralizing gas of electrons $e^-$. Imagine that the $X^+$ can be in a gaseous (G), liquid (L) or solid (S) phase. We want to ...
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What colour are metals? [duplicate]

I know that glass is actually green in that mirrors will always leave a green tint. This is because, although it's a small margin, green is the most absorbed wavelength for glass. Following on from ...
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Why does wiggling some thin metal objects back and forth cause them to snap?

Why does wiggling some thin metal objects back and forth cause them to snap? For example, a paperclip. Is this a property shared across all metals, or only some?
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Why dielectric waveguides support hybrid modes and metallic waveguides don't?

Can anyone explain me qualitatively, why dielectric waveguides (core and infinite cladding) support hybrid modes ($E_z$ and $H_z$ components in the guided wave) while metallic waveguides cannot. I am ...
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How to determine qualitatively the metallic/semimetallic conduction behaviour by comparing chemical potential and thermal energy?

Suppose a material has a semi-metallic dispersion and we want to study electronic transport with small applied electric and magnetic field. Let the chemical potential be positive-valued (i.e. the ...
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2 votes
2 answers
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Drude model - frequency dependent dielectric constant of the metal

This is from the slide used in class and I have a few questions to ask. First question: In the first line of equations of the phasor form, why is there a negative sign? Is this a sign error? How is ...
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1 vote
2 answers
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Would an electron move freely in a metal surface when it have different potential at different region?

I recently read that free electrons in a metal are free in the sense that they move inside the metal. So I wanted to know that will it won't move if the metal have different potentials in different ...
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1 vote
2 answers
195 views

How silver with greater number of free electrons has lower resistance?

My book(Concise Physics ICSE) mentions the following things about the dependence of resistance on the material of conductor:- Dependence on the material of conductor:Different materials have ...
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0 votes
3 answers
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How long does a large impulse take to travel through a solid?

If I had a 1000km long steel rod and I pushed one end of it, when would someone standing at the other end observe movement? Would it travel exactly the speed of sound in that material, or is the speed ...
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What does rainbow-colored-metal mean in the item that is supposed to be gold-plated silver?

There is item (it is high ranking decoration of one country) that is supposed to be made from gold-plated silver with some (white) enamel. Here is the picture: My question is - why there is this ...
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How does the conductivities of metals and semiconductors vary when placed in the presence of magnetic field?

Suppose you have two materials one is a metal and other is a heavily doped semiconductor and they are placed in a magnetic field. What experiment will you do to distinguish between them? Does the ...
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12 votes
1 answer
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Platinum seems to have higher kinetic friction coef. than static - how is this possible?

According to the Wiki Friction entry, Platinum on Platinum (dry and clean) has $\mu_s=1.2$ and $\mu_k=3$, which means that $\mu_s<\mu_k$. This seems impossible to me. The same phenomenon occurs in ...
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Why is silver such a good reflector of visible light?

In everyday mirrors, silver is used on the back of glass as a reflector (because it is highly efficient in reflecting visible light). But what are the characteristic properties that make silver a ...
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Does magnetism affect thermal conductivity of metals?

If you're going to answer my question I'm sort of asking for some examples or a good graph that shows how it affects different metals if at all. I'm aware that it affects ferro fluid. I've seen mixed ...
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Having more electrons than the Fermi energy allows

What happens when we have more electrons in a solid metal than the Fermi energy and Pauli exclusion allows? Let's say we reduce the temperature to a level where all the energy states are filled with ...
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At absolute zero temperature, we see that the electrical resistivity of a metal is not zero - Why? [closed]

I do know that for a perfect conductor, the electrical resistivity is zero at absolute zero temperature. But for an imperfect conductor (e.g. that we use in daily life) it is not zero even at $T=0^{\...
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Errors in Drude model for thermal conductivity in metals

According to the Drude model the thermal conductivity comes out to be $\kappa = \frac{1}{3}v^2\tau c_v$ the derivation of this is given in wikipedia also there it is mentioned about the errors made in ...
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Flash Emitted When Metal Violently Fractures: Triboluminescence or Sparking?

If a piece of steel emits visible light when it rapidly brittle fractures is that triboluminescence (TL), sparking, or something else? I have searched and searched but I have only found one reference ...
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Color Spectrum of Heated Metal [closed]

I have seen a few questions and answers according this subject. What troubles me, is that I saw somewhere that there is a difference between oxidation colors and incandescent colors when heating ...
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Why do “sparks” fly off of hot metal when compressed?

Link to video: https://www.instagram.com/p/B3T2iDQJePw/ Why, when this hot metal is crushed from the top down, do all these “sparks”, or whatever this may be, fly off? Please can someone explain what ...
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Laser-induced heat flow in metal

If you shine a laser on metal so the laser beam is perpendicular to the surface, will heat flow radially outward from the laser spot equally in all directions? If it hits the metal at an angle of ...
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Suppose you have given two identical materials one is a metal and another is semiconductor? How will you distinguish between them? [closed]

Suppose you have given two identical materials one is a metal and another is semiconductor? How will you distinguish between them?
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1 vote
1 answer
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Reflectance and Reflectance Color of Metals

I do not understand the layman's physics behind the reflectance curve of a metal based on the complex index of refraction. Figure 24 from Background: Physics and Math of Shading by Naty Hoffman graphs ...
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4 answers
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Can a metal sheet roof be vibrated at audio frequencies?

So I'm renting a cheap place for now due to certain circumstances. Problem is outside noise is excessive because there is no ceiling and the roof is only a metal sheet... Lately I play white noise to ...
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Dimensionality of bands in bulk materials: modeling interband transitions in Gold with 1D band structure

I'm currently dealing with interband transitions in metal nanoparticles. Geometry-wise they are considered to be a 3D material. Now I've found this paper, where they describe interband transitions in ...
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Poisson ratio in plastic deformation area

Can the Poisson ratio of metals in the plastic deformation range be assumed to be constant? If not, are there any alternative modeling approaches?
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Is there an alloy of iridium/tungsten or iridium / molybdenum?

I searched everywhere, but just couldn't find any iridium/tungsten or iridium / molybdenum alloy. What can be their properties if there any.
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Is there any alloy that has the same oxidation resistance at high temperature?

Iridium is a rare and expensive metal, for those reasons and others I was wondering if there an alternative to it.
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1 vote
1 answer
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Is sublimation of the metal filament in a vacuum tube the main reason for eventual failure?

I saw a question asking if metals sublimate, with some fascinating answers, which made me wonder if sublimation was the main cause of the eventual, and inevitable failure of vacuum tubes. High school ...
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Emission of photoelectrons by irradiating it with a sufficiently energetic photon beam

Let's say we irradiate a metal with a photon beam whose energy per quanta is 10 times the work function of the metal, say 10(k). So post absorption it will have the same energy, and say it collides ...
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2 votes
1 answer
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How does a materials modulus of elasticity (proportional zone ratio) relate to crystal defects?

I'm studying biomedical engineering and I'm about to take "Biomaterials" (basically materials science applied to medicine) final exam. In one recorded class, the professor mentions the ...
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