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Questions tagged [crystal-structure]

In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms or molecules in a crystalline liquid or solid.

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What is burst nucleation? [closed]

Can you tell me what is a burst nucleation process, and how can it be used for synthesising uniform nanoparticles? Can you also provide (if possible) any links to papers or materials regarding ...
Eka's user avatar
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7 votes
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What salts are/are not birefringent?

Is there a quick way to determine if a salt (or ionic compound in general) crystal should be birefringent from its formula without having to know/look up the crystal structure? When I'm looking for ...
Nick T's user avatar
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17 votes
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When we heat a borax crystal, why does it first expand and then contract?

In the borax bead test, we take a crystal of borax and then heat it. A small loop is made in the end of a platinum or nichrome wire (as used in the flame test) and heated in a Bunsen flame until ...
ManishEarth's user avatar
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7 votes
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How do copper sulphate and the like change crystal structure on adding water of hydration?

Copper sulphate, in its hydrated form, is crystalline, whereas the anhydrous form is amorphous. Gypsum has a similar story-- on heating the crystalline dihydrate we get an amorphous hemihydrate. (...
ManishEarth's user avatar
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19 votes
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Choice of doping elements in semiconductors

In a typical semiconducting material, we start with silicon (group IV) and introduce atoms of group V or group III depending on whether we are constructing an n- or p-type semiconductor respectively. ...
SimonS's user avatar
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7 votes
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Are these two space groups in a group–subgroup relationship?

Given two crystal space groups, how can one determine if they are in a group-subgroup relationship? The specific case at hand is P 21/m 2/m 2/a (aka P m m a, #51) and P m m 2 (#25), but knowing how to ...
F'x's user avatar
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7 votes
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What is it about the relationship between the Fe²⁺ and Fe³⁺ in magnetite that makes it diamagnetic?

Hematite is composed of $\ce{Fe2O3}$, and is paramagnetic, whereas magnetite is $\ce{Fe3O4}$ and is diamagnetic. Magnetite's nature is due to the presence of both $\ce{Fe^{2+}}$ and $\ce{Fe^{3+}}$ (...
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8 votes
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Why are there no edge dislocations in a face-centered cubic (FCC) lattice?

In crystallography, we know that the Burgers vector is parallel to the dislocation direction in a screw dislocation, and perpendicular in a edge dislocation. Furthermore, I have in my lecture notes "...
nofe's user avatar
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16 votes
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Is there a theory behind selecting elements that may be successful in potential superconductors?

Looking at something like $\ce{YBa2Cu3O7}$ which was one of the first cuprate superconductors to be discovered, I'm always curious how the selection of these substances as likely superconductors comes ...
jonsca's user avatar
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12 votes
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How is the electron "trapped in the crystal" in irradiated NaCl?

Pennsylvania State University provides irradiated $\ce{NaCl}$ (180,000 rads of gamma radiation) to teachers for a very entertaining demonstration. The salt is orange after irradiation. When it is ...
Janice DelMar's user avatar
25 votes
4 answers

How does NaCl maintain its crystalline structure?

My understanding is that $\mathrm{NaCl}$ is an ionic compound, in which $\mathrm{Cl}$ becomes (effectively) $\mathrm{Cl^-}$ and $\mathrm{Na}$ becomes $\mathrm{Na^+}$. So I understand why I would get a ...
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