Questions tagged [material-science]

The study of how the properties of matter arise from its structure at all scales and of how processing can be used to modify those properties (often in pursuit of a specific application).

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1answer
62 views

What causes objects to appear “black”?

To my understanding, the reason objects appear of a certain color is because it is the color (in visible light) that is absorbed least by the electrons in the material's atoms, and the rest is ...
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30 views

How do materials absorb light

I'm curious how light is absorbed in materials. From what I understand, when an electron absorbs a photon, it gets excited to an energy level that is higher than the level it's in and the energy ...
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10 views

What is the effect of dopant on the crystalite size?

Crystal size decreases with doping and then increases with increase in dopant concentration, why? the ionic radii of dopant is greater than the host atoms.
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8 views

What is the effects on the electrical conductivity of a crystal structure if the Fermi sphere fits inside the first Brillouin zone

My explanation: If the Fermi sphere fits inside the first Brillouin zone then there are empty states between the 1st and 2nd Brillouin zone which electron can be excited into. Hence, the crystal ...
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11 views

How to get the principle stretches of compressible Neo-Hookean material under uniaxial extension?

As the title described, how the principal stretches of a compressible Neo-Hookean material undergoing uniaxial extension are derived from the constitutive model as below? $$ \lambda_1 = \lambda; \...
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14 views

Auger electron spectroscopy

I am doing Auger electron spectroscopy on a sample. I found the differential spectra is not symmetrical. For example, oxygen peak in as received sample looks symmetrical but that for carbon is not ...
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21 views

Electrostatic force and deformation

Can an electrostatic force cause plastic deformation of an object ? So if we two charged opposite sheets of paper and we hold with our hands the two plates will the electrostatic attraction cause ...
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3answers
70 views

Is “physical damage” proportional to momentum or kinetic energy? [duplicate]

If a rock is thrown at someone's head, or a car drives against a wall, or a meteor hits a planet, is the physical damage done to the object proportional to the projectile's momentum, or to its kinetic ...
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32 views

Why are we even assuming $\alpha Gb^2$+$\alpha Gb^2$ on one case and again $\alpha G(2b)^2$ on the other case?

My point of interest is to know where the energy of two edge dislocation system comes from ($\alpha Gb^2$+$\alpha Gb^2$).It not really the formula that I am looking for but essentially why are we ...
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17 views

What is the physical meaning of “critical crack length”?

There are two equations that are primarily used in context of the fracture stress one with $\sqrt{\frac{\gamma E}{a_0}}$and the other with $\sqrt{\frac{2\gamma E}{\pi C}}$.I do not understand which ...
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40 views

What's responsible for the different hardnesses between Steel and Aluminum?

Why is the aluminum in a tin can harder than aluminum can? What characterizes their different properties? Aluminum vs. Tin https://en.wikipedia.org/wiki/Aluminium Aluminium (aluminum in American ...
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17 views

How is the coefficient of thermal expansion of elastomers determined? (e.g. rubber, silicone resin)

I have been wondering: How is the coefficient of thermal expansion of elastomers determined? (e.g. rubber, silicone resin) Moreover, what are the 'DIY' methods of determining it without a need of a ...
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70 views

How quiet can a bouncing ball be when it hits the floor?

When non-elastic balls like a putty ball hit the ground they should waste their kinetic energy on heat and sound, much more than elastic balls. However putty balls hit the ground very quietly while ...
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38 views

Will a metastable solid convert to it's more stable form upon heating to the transition temperature of the more stable form?

Let's say a solid has a stable phase (A) that exists below some temperature, T, and A transitions to another stable phase B above that temperature. If you take a solid sample of B and rapidly quench ...
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43 views

What is the meaning of $\tau$=$Gb/l$

What is the physical meaning or intuition of the Shear Stress vs Shear Modulus and Burger Vector over length relation($\tau$=$Gb/l$). I have seen this formula being used to determine length in case ...
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1answer
40 views

Spring constant of tuning fork

I was playing with a tuning fork and got to wondering how to find it's spring constant (assuming damped oscillation). I can find plenty of resources about materials for springs, but not a whole lot ...
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21 views

Galfenol and internal pressure

Galfenol is cool stuff. It’s iron doped with gallium. When under several gigapascals of force it is able to convert applied pressure to electricity at 70% efficiency when under magnetic field. My ...
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1answer
99 views

I'm working on a project with infrared light and I need materials that are transparent to IR light

I'm going to be using infrared light of wavelength somewhere around $700-800 \space \text{nm}$ and I need cheap materials that can be easily found/bought which are transparent to infrared light. It ...
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11 views

How are the two Stacking Faults namely intrinsic(formed by vacancy agglomeration) and extrinsic(formed by interstitial agglomeration) different?

Stacking Faults and its association with partial dislocations seem to bother me day in and day out.With regard to this I do not understand how Partial dislocations lead to stacking faults and not the ...
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3answers
71 views

Why were icebreaker ships still made of wood, not metal, into the 20th century?

Shackleton's Endurance and Amundsen's Fram were made of wood, not metal. Yet I can find no explanation of why, even though most other ships had long since been built from iron and/or steel.....
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43 views

How can a metal be magnetic in this way?

I am reading a book about Skyrmions (Skyrmions in Condensed Matter, by Jung Hoon Han), and while reading about the interaction of Skyrmions with electrons (Chapter 5), the following statement was made:...
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19 views

Certain doubts in Lomer Cottrell dislocation

With regard to this particular phenomenon that occurs there are a couple of things that need to be addressed.Firstly,Why do I have a region of stacking fault in that particular junction. I mean why is ...
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36 views

Difference between permittivities eps-opt and eps-inf?

Very often in materials physics we are interested in the relative permittivity at optical frequencies, which is usually denoted by $\varepsilon_\text{opt}$ or $\varepsilon_\infty$. But I'm confused ...
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23 views

Is there a theoretical ground for ionic superconductivity?

I've been wondering for a while if there's a possible theoretical ground for ionic superconductivity, or whether it is at all possible from a thermodynamic and condensed matter physics standpoint. ...
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1answer
65 views

Does a metal with a strong positive charge decrease its strength?

Does a metal with a strong positive charge decrease its strength? According to the mainstream theory of metal bonds, free electrons form a link between lattices. If this is the case, the removal of ...
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31 views

Elastic (Young's) modulus and shear modulus derived from interatomic potential

Based on figure shown here, a theoretical elastic modulus can be derived by considering the interatomic potential and taking the derivative of the potential energy with respect to the distance (x-...
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2answers
59 views

What length can a metal wire (cable) hang vertically?

What length can a cable hang vertically with no additional weight attached to it. I tried figuring this out with 5/8 aircraft cable specs by dividing the rated weight capacity of the cable by the ...
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1answer
36 views

Measuring Tensile Strength in an alternative way

TL;DR: I make a cylindrical disc out of material X. Fill it with fluid and apply pressure on top of the disc which pushes the curved part of the cylinder outwards till fluid pressure breaks it. ...
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63 views

Thermodynamics: how does the deformation of partially elastic materials produce heat?

When a perfectly elastic material is deformed, the energy associated with the strain remains stored in the body as elastic potential energy, called strain energy. Upon the removal of the deforming ...
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28 views

How is quadratic form of miller index useful?

I have seen that we have used the $h^2+k^2+l^2$ value for finding whether the lattice is BCC,FCC or simple cubic.Where is this factor coming from?Why can I not use the structure factor theorem ...
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2answers
92 views

Is it possible that the speed of sound in some strange quantum material is faster than the speed of light in vacuum [closed]

If we believe the spacetime structure(including the limit of speed) could emerge from some vacuum structure(such as string-net condensation),then, is it possible that the speed of mode of excitation ...
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2answers
74 views

What's the explanation of 'paper pieces and comb experiment' about static electricity on atomic level?

I know that the charged comb induces static electricity in the paper pieces.how does that happen? Do the atoms in the paper get ionized,the same what happens when the comb was rubbed on hair?please ...
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1answer
32 views

What is the best material to be detected by hearing-wave sonar?

I would like to find a material which could very noticeably reflect or absorb a sound wave frequency between 20Hz and 22kHz, preferably in a grassy or organic nature environment. Preferably this would ...
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1answer
45 views

Why do concrete levees break? [closed]

I saw a picture of a breach in a levee that was constructed from vertical concrete slabs. I do not see why this should break when overflowed. Levee flood walls not as wide as normal levees build from ...
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1answer
70 views

Why does glass break at a given momentum?

My question is:Why is it more accurate to suppose that a sheet of glass will break, after being hit by a projectile with a given momentum, than suppose that it will break after receiving an impact ...
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44 views

What is the smallest stable grain size attainable when grinding an ionic crystalline compound?

If the compound could be ground to molecular size and if the resulting sample were kept in a 'pile' so that these molecules were in contact with each other, then the molecules would tend to bond ...
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1answer
24 views

Dielectric properties of polarizing beam splitter

Are all polarizing beam splitters made up of dielectric materials?If so, what kind of dielectric materials are actually used to make them?
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9 views

Effect of anodisation dye colour on absorptivity-to-emissivity ratio of aluminium

Anodised aluminium is a common material used in space, and it is commonly dyed black as this gives it an absorptivity-to-emissivity (a/e) ratio close to unity. This page says black anodic films have ...
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1answer
2k views

Is the specular reflection on a polished gold sphere white or gold in colour?

My understanding is that all specular reflection is due to Fresnel reflection at the interface which is a broadband effect. A classic example might be a white reflection on a polished ball (e.g. ...
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1answer
49 views

Tearing paper by creasing/folding

Why does folding/creasing loosen the fibre-fibre bonding in paper? Creasing makes tearing paper easier because it weakens the fibre-fibre bonds or makes the strong fibres easier to tear, it is said. ...
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1answer
45 views

Why does a metal wire breaks if it is continuously bent up and down?

Why does a metal wire breaks if it is continuously bent up and down ?
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16 views

Steinhardt order parameter and radial distribution function

Is there a relation between the probability distribution of Steinhardt order parameter for BCC and FCC and their radial distribution function? In the picture we see the probability distributions of ...
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27 views

Why infrared laser goggle looked orange?

So here's the thing, the laser goggle for UV light looked orange-yellow, which was sort of understandable, cause, if one want to block UV light, then the transmitted light ought to stay away from the ...
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1answer
101 views

How do knife blades become dull?

Knives are normally used to cut softer objects. So the edge of the knifes blade is harder than the substance it cuts through. A blades geometry is more complex, but let's simplify it to the blade ...
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29 views

Polarizing Beam splitter

What could be the effect of aging in Polarizing Beam Splitters? Is it possible that the Axes for s-polarization and p-polarization change due to some environmental effects on a polarizing beam ...
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2answers
24 views

Materials that change opacity under stress/strain?

I'm looking for a material that changes optical properties in response to changes in stress or density. The idea is to make a solid motor coupling to measure torque using photo emitter and detector ...
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1answer
52 views

Elastic potential energy per unit volume,stress-strain and strain-stress curve

From what I understand, when we calculate elastic potential energy per unit volume of a material which extends linearly, we calculate the area under the graph of stress- strain OR strain- stress graph,...
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27 views

What is a Material Called that Translates the Image of a Touching Object's Surface?

What is the name of a material that moves light through it in such a way that it appears that the surface of an object has translated through the material? Also, what is an example of this type of ...
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16 views

Do materials with greater density magnetise more readily?

I am interested in magnetic thin films, and was thinking about evaporated vs sputtered films. My understanding is that typically sputtered films are more dense than their evaporated counterpart. I ...
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10 views

Are there any techniques for calculating decomposition barriers for a set of crystals?

For a hypothetical crystal system ABO3, let's say there are two competing phases AO and BO2, which come from the decomposition of ABO3. Using DFT, I can calculate the energetic difference between ABO3,...