All Questions
Tagged with material-science crystals
84
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Electron microscopy and Interatomic distances of miller planes [duplicate]
I am studying Transmission Electron Microscopy (TEM), and have been seeing in articles TEM images of different materials typically come accompanied by these diffraction patterns, caused by the ...
- 548
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Structure factor correct calculation
I have a set of 2D points and wish to test it for hyperuniformity.
As I've learned from papers, the good idea is to calculate structure factor $S(\mathbf {q})$ and test it for
$$\lim _{\mathbf {q} \to ...
- 163
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What is the unit cell and the bravais lattice of a perovskite?
First year PhD. student here. I keep trying to wrap my head around what kind of bravais lattice and how does the unit cell of a perovskite look? I am specifically interested in bismuth ferrite (BiFeO3)...
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Are there any materials known to be harder than diamond under high pressure as of April 2024?
This is a variation of this question where I asked if materials under high pressure can break standard pressure density records.
I am curious about materials that become superhard under very high ...
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1
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Why are there triclinic and monoclinic lattices, but biclinic is never mentioned?
When classifying the Bravais lattices we have the
triclinic (point group ${\rm C_i}$) and the monoclinic $({\rm C_{2h}})$ cases, but we do not see the "biclinic" case listed. Why not?
It ...
- 4,912
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What happens when slip direction is the same as applied force?
Using the equation
$$ \tau R = \sigma y \cos \left( \phi \right) \cos \left( λ \right) \tag{1} $$
means that when the angle $\phi$ between the tensile axis and slip plane normal is $90$, $\cos \left( ...
- 1
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2
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65
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Why don't all metals have closed pack structures?
A lot of times, in my materials classes, metal atoms' behavior during deformation is described like a bunch of stacked balls. In my introduction to material class, our professors explained that metals ...
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Structural notation for multi-element FCC crystal structures
I was wondering if different compound FCC structures share any kind of indicator or structural notation which I could use to find and categorise them.
To clarify my problem: the FCC L12 structure, ...
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Question about the elasticity matrix in metals
The most general anisotropic linear elastic material has 21 elastic constants. I am working with an HCP material and I found that it has 5 independent elastic constants. I am programming a subroutine ...
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1
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How to calculate Lennard-Jones potential for a crystalline material?
Suppose that we have the unit cell of a crystalline material. We want to calculate the Lennard-Jones (LJ) interaction energy between an hydrogen atom at a point $\mathbf{r}$ (inside the unit cell) ...
- 1,648
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Are solid materials ergodic systems?
It is stated that a system is considered ergodic if it can access all available states with the same energy in the phase space over long periods of time and that time average and ensemble average of ...
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Why delocalized states cannot exist in 2D systems
In "Topological Insulators and Topological Superconductors" by Bernevig and Taylor, it is written on page 60:
In a seminal paper, Laughlin argued that the presence of
edge modes is an ...
- 592
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1
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96
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What are the visible differences of single-crystal and polycrystals?
I saw a question where it supposes a particle of quartz sand with 1 mm in diameter is opaque white. I am then asked on whether this particle is single-crystal, or polycrystal. Admittedly, I am quite ...
2
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2
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Why does the the dielectric constant of a ferroelectric increases with temperature, below $T_C$?
The above figure is taken from C. Kittel.
When a ferroelectric substance (say, BaTi${\rm O}_3$) at room temperature is gradually heated, the dielectric constant $\varepsilon_r$ first increases and ...
- 11.8k
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Can oxides of uranium be used to color aluminium oxide based gemstones, or diamonds?
Rubies and sapphires are chemically equivalent to the mineral corundum, with the exception of transition metal impurities that impart different colors to the aluminium oxide. Uranium is not a ...
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