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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Types of semiconductor relaxation

Ok, so you've basically got tensile and compression strain in a lattice mismatched material right? So as you're epitaxially layering the material, the strained material is deforming more and more ...
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1answer
132 views

Pressure applied to flat plate

I have a question about the pressure placed on a plate of material X, how the force is distributed and what would be the material property that would determine its failure. To simplify things ...
2
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1answer
56 views

The resolution limit for lithography in practice?

For a given wavelength of light $\lambda$, and a given numerical aperture (NA), I always see the statement in papers/etc. that we can perform lithographic patterning at the Rayleigh limit given by ...
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1answer
65 views

in Science materials, what is difference b/w E and G?

I'm studying Science Materials on Callister's Materials Science and Engineering: An Introduction. I've never studied Mechanics (except for basic Physics courses), so I was wandering: when talking ...
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3answers
336 views

Are synthetically-produced diamonds as hard as natural diamonds?

I was having a discussion with my friend about the intrinsic worthlessness of diamonds (DeBeers and whatnot) and how synthetic diamonds haven't caught on, again because of the marketing/propoganda ...
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1answer
116 views

Is it possible for a material to shift the frequency of all light reflected off of it by a specific and constant value

Without reducing the energy more than necessary due to the frequency decrease? And if this happens/works, is there an index of such materials and their optic properties?
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1answer
25 views

Microscopic origin of optical transmission

When light interacts with matter, it is abosrbed, reflected and transmitted. With repect to the UV-Vis range, electronic abosrptions occur, where if the incident photon mode matches the energy ...
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33 views

Heat Sink considerations for thermionic generators

I recently read an article describing thermionic generation. I am considering building a TG for a science fair experiment. I was thinking about surrounding my heat source with a spherical emitter and ...
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2answers
97 views

Need an intermediate resistivity part/material

I need a part or material for a planned experiment (the experiment is similar to those described in my articles http://arxiv.org/abs/1208.0066 and http://arxiv.org/abs/1109.1626 ). The problem is that ...
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3answers
182 views

What is the difference between material fatigue test with 1 sec cycle and 1 hour cycle?

Assume I have two pieces of metal. I want to test the material fatigue (e.g. how many cycles can the material stand before it will break). Onto one of them I apply a tension force every second. Onto ...
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1answer
61 views

Determining of Fracture Toughness without fatigue pre cracking, is it possible? [closed]

Determining of Fracture Toughness without fatigue pre cracking, is it possible? I want to find the consistent method for determining fracture toughness values without fatigue test for creating ...
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0answers
82 views

Does graphene actually remain strong for macroworld engineering?

I heard that people envision strong structural materials made out of graphene, but I heard it may weaken when being stack in layers. Is graphene viable for macroworld structural engineering or is it ...
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1answer
284 views

Using Moments to influence the thickness of beams in structure?

Are moments relevant to the thicknesses of beams in a structure (ie. the larger the moment the thicker the beam)?
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1answer
314 views

Will density of a metal increases during forging?

This question is metallurgical engineering, but I had a similar doubt regarding density of liquids and what causing it. Forged parts refines defects, dislocations will be moved strengthening the ...
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2answers
153 views

Material breaking underneath its breaking point (due to repeated load)

I'm trying to recall some fact that I learned in my college materials science class, where we learned concepts like stress vs. strain. I remember that materials like metal have a breaking point, and ...
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2answers
132 views

Debye temperature for the steel?

I'm looking for data on Debye temperature of steel (ideally with a known carbon concentration, structure, and set of phases), but find only data on elements. Do You happen to meet the data in papers, ...
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0answers
97 views

Bubbling metal vapor through liquid Helium?

When a metal cools from its liquid state, part of the nucleation happens from pre-existing clusters (a group of unit cells of the crystal lattice) already present in the liquid. In the case of a ...
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3answers
4k views

Roughly how many atoms thick is the layer of graphite left by a pencil writing on paper?

Actually I can't expand much as the question pretty much explains the query. I would be interested in the method of estimating an answer as well as a potential way to measure it experimentally. ...
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2answers
328 views

How to determine what an object is composed of?

Heads up: This question has never been asked (here) before the way I will ask it here, so let's shed some light on it a bit. Prelude and anecdote(can be skipped): The other day I was walking home, ...
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2answers
141 views

Stretching a rod? [closed]

The stress applied on a rod is linearly proportional to its strain. But shouldn't the opposite be true? I mean if you pull particles further apart doesn't the force they apply on each other decrease ...
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2answers
5k views

Why don't FCC metals have a brittle-to-ductile temperature transition?

I initially thought that it had something to do with the number of slip systems in FCC vs. BCC, but they're both the same.
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3answers
371 views

Is an atom-thick sheet of a material visible and tangible?

If one could make a sheet of a material (thickness of an atom), Aluminum for example, would it be visible to naked eyes? What about tangibility? would it be tactile by human finger skin?
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0answers
75 views

What's the typical material used as a low-k ILD in semiconductors?

Semiconductor companies (namely IBM, Intel, TSMC and etc.) may use different low-k materials as inter-layer dielectric (ILD) in their fabrication process. I'm wondering what is the most typical one. ...
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2answers
468 views

What causes liquids to have different densities?

We know that different liquids have different densities and it is mass over volume. When the mass is more, then its gravitational attraction will be higher (Compared to other lighter atomic mass ...
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3answers
422 views

Is there a simple approximation to calculate the index of refraction of water?

A very rough approximation from first principles, from the elementary charge and hbar, would suffice. But is there such an approximation at all? (Alternatively, if water is too difficult: is there ...
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1answer
82 views

Transparency of gypsum and concrete for RF waves

Is there a database (or any other source) of graphs of average transparency of various materials (cardboard, concrete, gypsum etc.) as a function of wavelength?
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1answer
216 views

In a game of tug of war, what concepts are involved in determining where the rope breaks?

Assume that in a game of tug-of-war the rope ends up breaking. What concepts/factors would contribute to the position of where the rope breaks?
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4answers
735 views

Hooke's law limitation question

Let's consider a spring. I am a strong man(well, lets assume) and I am pulling the spring. the work I do is being stored in the spring in the form of its elastic potential energy. Then suddenly, ...
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1answer
3k views

Calculating force absorbed by compression of a material (i.e. rubber)

Say I was trying to design padding to absorb impacts using polymers or similar materials, such as rubber. I have a good understanding of any relevant physics, most likely, but I wouldn't know where to ...
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1answer
550 views

Where I can find a torsional stiffness table for different types of stainless steels?

I am trying to comparing the torsional stiffness of different types of stainless steels. I googled the keywords but I could not find any useful information. Would anyone please give me some links ...
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2answers
4k views

Wyckoff positions and lattice coordinations

Many papers use Wyckoff positions and Space Groups to report atom coordinates, making use of the structure's symmetries to save space in the notation (e.g. diamond = Fd-3m, only). How can I ...
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2answers
702 views

Is there a Tungsten alloy more dense than gold?

This thought came from researching a previous question. In the spirit of our get-rich-quick scheming I looked up element densities and prices near gold. Element (g/cm^3) (dollars/kg) Uranium ...
6
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1answer
217 views

Why can we skate on ice? [duplicate]

I have known the reason why skate can slide over ice is that water's melting curve in terms of pressure and temperature has a negative slope. If the pressure due to our mass increases sufficiently ...
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0answers
94 views

Is there a derivation of all possible Bravais lattices in 2D and 3D?

Do any of you know a (possibly elegant) derivation of all possible Bravais Lattice and the Crystallographic Group of Lattices in 2 and 3 dimensions? Group theory /abstract nonsense approaches are ...
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1answer
312 views

Regarding Bravais lattices

There is 'End-Centered' Orthorhombic lattice . Why this type is not in 'Cubic' lattice ? On which basis did Bravais propose his theory ?
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3answers
873 views

Can the speed of light become complex inside a metamaterial?

The speed of light in a material is defined as $c = \frac{1}{\sqrt{\epsilon \mu}}$. There are metamaterials with negative permittivity $\epsilon < 0$ and permeability $\mu < 0$ at the same time. ...
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0answers
90 views

Where does one find pair-correlation functions for various materials?

What is the canonical source for finding pair-correlation functions for atoms in various materials? I am interested in both numeric computations and experimental measurements (like might be obtained ...
4
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2answers
273 views

Why are there direct bandgaps?

This Question has been bugging me for sometime. Some semiconductors have direct bandgaps and indirect bandgaps. So what causes a direct bandgap to occur? The physics behind ,why there are direct ...
2
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1answer
109 views

Is this 2D structure triclinic?

The only rotation axis obvious to me is rotation by 360 degrees, the identity. Vertical mirror planes I've been dicing and cutting it through several planes and I still see none. Yet, the structure ...
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0answers
142 views

Why Does Germanium Spontaneously Extrude Long Screw Dislocations?

Pure germanium is known to spontaneously extrude very long screw dislocations. They are one of the primary reasons for the failure of older diodes and transistors made from germanium; depending ...
3
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1answer
365 views

How much does a steel spring wire bend due to it's own weight?

I'm working on an art project and I need to know how much a steel spring wire bends dependent on it's diameter. It's point of support is in the middle and it's lengths is ...
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0answers
85 views

Best material for heat transfer between ice and water

What is the best container material for heat transfer between ice and water? this is a difficult question to ask without displaying a picture of what I'm meaning.
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1answer
230 views

Do bifacial solar panels operate at lower temperature than normal solar panels?

Bifacial solar panels have a glass backplane instead of the usual aluminum and are designed to absorb and convert to electricity light incident on either face. Many manufacturers claim that their ...
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1answer
137 views

Order of magnetic phase transitions

Is there any phase transition occur in paramagnetism to diamagnetism transitions state. What should be the order and how will I calculate the order?
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3answers
6k views

If aerographite is lighter than air, why doesn't it float?

Air is 6 times denser than aerographite but looking at pictures or videos presenting the material, I see it resting on tables rather than raising to the ceiling. Also, since the material is made of ...
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0answers
51 views

Can we make any substance that will produce ions at low temprature

I am talking about thermal ionization, Is to possible to make any material or is there any element that can be ionized at let say 20 degree centigrade Temperature? I am a computer engineer and into ...
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0answers
238 views

X-Ray transparent material [duplicate]

I am looking for a material which is fully transparent to X-rays. In addition, it should be solid enough to serve as a substrate on which I will deposit some biomolecules.
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0answers
41 views

Twisted Nematic liquid crystal: extent of degradation due to DC drive?

It is commonly accepted wisdom that a Twisted Nematic LCD must always be driven using AC instead of DC, because DC will supposedly denature the LC. I have two questions: Does this effect only happen ...
2
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2answers
135 views

Can a liquid shrink as something is dissolved into it?

Not much more to add. By shrink, I mean become more dense at the same pressure and temperature. And I don't mean vol(A+B) < vol(A) + vol(B). I'm sure this is possible. Is it possible to ...
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1answer
148 views

'Push' in a rigid rod travel at speed of sound or speed of light [duplicate]

Two person, $A$ and $B$, each holding one end of a long solid rod. Now person $A$ pushes the rod on one end. Question: Is it correct that the information that the rod has been pushed will travel ...