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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 the power density of graphite caused by the Wigner effect?

The energy that graphite released upon a cascade of defects by neutron radiation is 2.7 MJ/kg, however there is no data on how quick this energy is released. I am interested in this as this not ...
C-Consciousness's user avatar
7 votes
0 answers
2k views

Why does the dielectric constant of a solid increase due to a Frenkel defect?

In crystalline solids, an atom may be displaced from its original position in order to create a vacancy in the original location. This is referred to as a Frenkel defect. Why does this defect result ...
Aditya Garg's user avatar
7 votes
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203 views

What factors contribute most to solubility of ionic substances in highly polar solvents, esp. ionic liquids and DES?

I am trying to determine a method to dissolve a mineral salt with a lattice energy of ≈18000 kJ/mol. I know that lattice energy is the most significant factor affecting solubility of an ionic ...
Arun Johnson's user avatar
5 votes
0 answers
166 views

How is the Born-Lande equation modified when the structure is not NaCl?

Often the Born-Lande equation is quoted (alongwith the calculation of the Madelung constant and Born exponent) with reference to rock-salt structure. But what if we take some other crystal, like ...
Awe Kumar Jha's user avatar
5 votes
0 answers
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Does a [B4O8]4- anion really exist?

I am currently collecting information for an abstract and therefore I wanted to discuss different $\ce{[BO3]^3-}$ and $\ce{[BO4]^5-}$ connectivities. I also found a book on crystallography and the ...
Justanotherchemist's user avatar
5 votes
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130 views

Fractal patterns on water

I stored water in a bucket (of aluminium probably), and some random fractal-like patterns are formed on the water: See here for some more pictures. Why this happened? I'm unable to reproduce it. ...
Excel Hand's user avatar
4 votes
0 answers
50 views

Why is reported effective pore size smaller that the one declared in the name of the molecular sieve type X?

The molecular sieve type is often coded with <number><letter> combination, where <number> specifies the pore ...
andselisk's user avatar
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Is this the first report that acetonitrile & propionitrile crystals create highly polar nano surfaces? How does one detect or quantify such surfaces?

Phys.org's Titan-in-a-glass experiments hint at mineral makeup of Saturn moon says: Titan, Saturn's largest moon, is a natural laboratory to study the origins of life. Like Earth, Titan has a dense ...
uhoh's user avatar
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4 votes
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Sense of radii quotient to determine coordination number in crystals?

Every common textbook explains the method of the radii quotient between the cation and anion of a selected salt to determine to coordination number(s) in that salt. For example deduce "Inorganic ...
Nilsfrank99's user avatar
4 votes
1 answer
1k views

Why is there a difference in crystal shapes of sodium chloride (NaCl) and potassium chloride (KCl)?

According to Sodium chloride and Potassium chloride: Sodium chloride (NaCl) crystallizes, among various other shapes, into octahedron and tetragonal pyramid shapes which are absent in potassium ...
Vishal's user avatar
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Why does gallium expand on solidification

I've heard that Ga exist as Ga2 molecules in its crystal lattice. Does that have anything to do with expansion of Ga while solidifying? Why and how does it actually expand?
Neet aspirant's user avatar
3 votes
0 answers
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Radius ratio of capped octahedral coordination (CN=7)

I was asked to work out the Radius ratio of capped octahedral coordination when CN = 7. How to define a capped octahedral? Is there any restrictions on the lengths of the edges or the distances of the ...
Edward Kerman's user avatar
3 votes
0 answers
88 views

Possibility of non-hexagonal graphene

I understand that monolayer carbon naturally forms in a regular hexagonal tiling. Is it, however, possible (if difficult) to form carbon monolayers of a different structure? A 3-12-12 tiling, for ...
Tau's user avatar
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0 answers
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Computational determination of unique adosrption sites

I'm not sure it's a chemistry question or physics question or math question. Since I'm active on this site, maybe someone here can point me in the right direction. I'm trying to enumerate all the ...
Osman Mamun's user avatar
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3 votes
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Physical reason for the ideal lattice approximation

Why can we approximate a lattice as being infinite when we describe it as an ideal crystal? Is there any physical reason or is it just because the number of ions (/atoms) is so huge that we can treat ...
Luigi Bana's user avatar
3 votes
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240 views

In powder x rd, if the crystals are randomly oriented ,why then do we get Debye rings and not random patterns?

In powder x-ray diffraction ,as I have learnt the sample is multi-crystalline.So if x-ray is diffracted through these randomly oriented crystal grains, aren't we supposed to get a random pattern?
Titto Sunil John's user avatar
3 votes
0 answers
1k views

Why are certain reflections forbidden in body centered cubic and face centered cubic structures?

I know that for body centered cubic structures the allowed reflections only happen if h+k+l is even and reflections are forbidden is h+k+l is odd, and for basic face centered cubic structures (...
Petrichorr's user avatar
3 votes
0 answers
202 views

Chemical bond at Aluminum / Aluminum oxide interface

I am trying to find out what chemical bond holds aluminum oxide to the aluminum on which it forms. The only information I was able to find on the internet was in a Google book which suggested that the ...
William Howard's user avatar
2 votes
0 answers
66 views

Would fluorides stabilize zirconia?

The reason for zirconia's cubic and tetragonal phases not being stable is that the cation-anion ratio is too small for proper contact between ions. One way is to use other oxides that have a bigger ...
user145034's user avatar
2 votes
0 answers
33 views

Small-Angle X-Ray Scattering of Bulk Polymers

Does anyone have any recommendations on how to get useful information from SAXS of polymers when the system is not dilute? This is the type of data we're working with: My understanding is that since ...
polythenesam's user avatar
2 votes
0 answers
40 views

Finding Equivalent representation of a molecule/crystal

Is there a website or online calculator to determine the reducible representation of a crystal/molecule using wyckoff positions without having to analyse the number of unmoved atoms/bonds for ...
Tachy's user avatar
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Why upon melting of PEO between crossed polars colours appear?

Crystalline PEO when under crossed polars shows distinct Maltese cross pattern. Being birefringent, when polymer crystal align with the polarizer or analyser it shows extinction regions (effect known ...
Wojtek Adamczyk's user avatar
2 votes
0 answers
395 views

Could you form quartz crystals by melting and cooling sand very slowly?

Since glass is amorphous quartz and when you slow the cooling of something enough it will crystallize, couldn’t you melt $\ce{SiO2}$ (sand) and then very slowly cool it to cause spontaneous nucleation ...
Quartz man's user avatar
2 votes
0 answers
161 views

Gallium - Practical use to remove aluminium

Would gallium pass through aluminium into steel? The situation is two joined pieces of metal. Gallium could be applied to the aluminium to degrade it, for mechanical removal, but would it pass ...
Jernau's user avatar
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Are dopant ions on a crystal lattice free or bonded?

This question seems simple but I don't seem to find many answers right away for this. When you make a crystal doped with ions (like a luminescent phosphor) and the ions then become a defect in the ...
user2934303's user avatar
2 votes
0 answers
1k views

Body centered cubic lattice vs Primitive cubic unit cell

I was reading about Bravias lattices(cubic crystal system) when got confused about an article in my book. Please refer to Counting body center as lattice point when basis consists of 2 atoms. The ...
Mayank Mittal's user avatar
2 votes
0 answers
77 views

What system of nomenclature can I use to indicate the positions of specific kinds of atoms of a surface reconstruction?

I was reading a journal based on SiC reconstructions, and they seem to mention that every dangling bond in the $(1\times 1)$ unreconstructed Si face or the $(0001)$ direction bonds up with a Si adatom ...
Ghosal_C's user avatar
  • 501
2 votes
0 answers
275 views

What is the crystal structure for a crystal where the ratio of the squares of the angle peaks is 0.825?

I followed this and it gives an example of how to identify a crystal structure using XRD data. I have an unknown alkali halide where two peaks were found at $2\theta =25.66$ and $2\theta = 28.3$. I ...
whatwhatwhat's user avatar
2 votes
0 answers
491 views

Osazone crystal structures

What is the reason behind the formation of different shapes of crystals for different osazones? Like glucose osazone- needle shaped, maltose osazone- sunflower shaped, lactose osazone - powderpuff ...
JM97's user avatar
  • 3,487
2 votes
2 answers
486 views

Understanding three-dimensional structure of common salt

I started reading through The Feynman Lectures and came across this diagram. What do the numbers next to the nodes in the diagram represent? It's not explained in the text. All that is mentioned is: "...
John's user avatar
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19F MAS NMR chemical shift tensor and the crystal structure

$\ce{^{19}F}$ MAS NMR is measured on fluorine-doped $\ce{TiO2}$. $\ce{F}$ is to substitute $\ce{O}$ and the crystal structure is anatase, which has a tetragonal crystal system with a space group $\ce{...
user40014's user avatar
  • 517
2 votes
0 answers
139 views

RCSB PDB - how to choose between multiple copies of the same protein?

I want to map the location of missense mutations on a protein, SERPINB3. I intend to do this using PyMol and download the protein structure from RCSB PDB. However, ...
Slavatron's user avatar
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2 votes
0 answers
229 views

Fermi Level of an alloy

How could one calculate the Fermi level of a copper-nickel alloy? They are both structurally face-centered cubic, however how would this structure affect the Fermi level of the individual atom or the ...
Paul Lemus's user avatar
2 votes
0 answers
69 views

Is Polymorphism accompanied with an energy change?

Differential Scanning Colorimetry (DSC) is a technique used to identify Polymorphism by revealing two melting points of a pure crystalline structure. DSC shows a peak associated with the formation ...
Snfkn's user avatar
  • 21
2 votes
0 answers
356 views

Equivalent points for 3 fold and 6 fold symmetry

In a crystal Lattice how to find the equivalent points for 3 fold and 6 fold symmetry?
user202476's user avatar
2 votes
0 answers
365 views

Why is there one octahedral and two tetrahedral positions for every anion in a close packed structure?

I'm reading about ionic crystal structures with planes of close-packed anions and the interstitial sites for cations. There are two types of interstitial sites: tetrahedral and octahedral. That makes ...
clay's user avatar
  • 253
2 votes
0 answers
1k views

Bond Lengths in FCC, BCC and HCP Structures

I was wondering what the crystal structures of FCC, BCC and HCP actually look like, and where atoms are placed in their configuration? Specifically I'm looking at elemental nickel, iron and cobalt ...
NictraSavios's user avatar
2 votes
0 answers
161 views

How do octahedral seed crystals yield polyhedral Cu₂O crystals?

In an article I am trying to understand, the following occurs: (summarized below) Synthesis of octahedral $\ce{Cu_2O}$ seeds:In a typical synthesis, 2.9946 g of $\ce{Cu(CH_3COO)_2}$ was dissolved ...
Dale's user avatar
  • 2,674
2 votes
0 answers
49 views

Would the detaching of dendrites from electrodes in a cell, result in the crystal dissolving back into the electrolyte?

Dendrites that form on the electrodes of cells shorten the cell's lifetime, and result in reduced capacity before the end of life. If the dendrites could be detached from the electrode, would they ...
410 gone's user avatar
  • 1,530
1 vote
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Converting Quartz data from one (P3221) space group to another (P3121)

For my studies, I’ve done a lot of work on coal fly ash QXRD QPA on TOPAS which has been a fun and interesting challenge. Apart from theory reviewing, a lot of my learning so far has come from a prior ...
Hendrix13's user avatar
  • 500
1 vote
0 answers
92 views

Why are crystals of carboxylic acid fluffy

I'm an undergrad student and we recently performed saponification of esters which resulted in the formation of carboxylic acid which we had isolated out of the reaction mixture. After ...
Stu's user avatar
  • 29
1 vote
0 answers
31 views

What does “Average Width” mean in crystallography?

Mathematician G. Polya noted (the solution for Problem 8, Axes of a Cube) in his book How to Solve it: ... there are three kinds of axes: (1) 4 axes, each through two opposite vertices ... (2) 6 axes,...
auntyellow's user avatar
1 vote
0 answers
41 views

How to Visualize the crystal planes of calcite?

I've been struggling to visualize the structure of calcite. Most papers say it grows in a rhombohedron capped by (104) faces. However, I don't see why it would do this when looking at it using ...
Lauratoyos's user avatar
1 vote
0 answers
6k views

Calculating distance between adjacent planes (hkl) in a simple cubic crystal

My textbook says the following in a section on Miller indices: Adjacent planes $(hkl)$ in a simple cubic crystal are spaced a distance $d_{hkl}$ from each other, with $d_{hkl}$ given by: $$d_{hkl} = \...
The Pointer's user avatar
  • 1,083
1 vote
0 answers
101 views

Difference in properties of water as ligand vs 'in lattice'

I'm trying to understand the difference in properties between water in crystals in different positions in the lattice. In this wikipedia article It quotes: Both notations can be combined as for ...
tomhepz's user avatar
  • 111
1 vote
0 answers
28 views

charge transfer between layers of graphite with stacking fault

As a general rule, we only expect two parts of a system to have the exact same amount of charge if they are symmetry-related to each other. How much charge transfer would occur in graphite with a ...
user1704042's user avatar
1 vote
0 answers
86 views

Rietveld refinement "fronting" of peak signal

I was trying to refine a crystal structure using Rietveld refinement yesterday. The crystal structure is already known for a related compound and the powder pattern seems to show a phase pure compound....
Justanotherchemist's user avatar
1 vote
0 answers
809 views

Can you heat Bismuth crystals to reset the oxide layer for new colors?

I'd like to get a bismuth crystal with small structures and deep blue colors for a ring I want to make. I can find these properties in different crystals online but never together. Can I just take a ...
CoolGuy47's user avatar
1 vote
0 answers
113 views

What can be concluded from two different values for the interplanar distance between planes of atoms in an X-Ray diffraction experiment?

I analyzed an unknown Alkali Halide crystal using x-rays from a copper source. I need to find the d-spacing for this crystal, i.e. the interplanar distance between planes of atoms. I found my $K_\...
whatwhatwhat's user avatar
1 vote
0 answers
29 views

Post-synthetic Anisotropic Wet-Chemical Etching of Colloidal Sodalite ZIF Crystals

It's well known that Metal-organic Frameworks can be made by attaching inorganic metal ions to organic linkers via strong chemical bonds, ZIF-67 is one of this big family which could be prepared by ...
JaafarMehrez's user avatar