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 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 ...
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Why are so many ionic compounds brittle?

Even when ionic compounds are strong (e.g. rubies and sapphires), they are neither malleable nor ductile in the slightest, and if sufficient stress is put on them, they will shatter, not bend. Why is ...
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What is the difference between an amorphous solid and glass?

They are both formed when a liquid is supercooled rapidly, no free energy, and they both have irregular structures. What defines a glass other than how it is amorphous, transparent, and has a glass ...
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R32 Space Group (Crystallography)

Why R32 Space Group is so named? I mean, if R stands for Rhombohedral and 3 for Threefold Axis, what 2 stands for? I don't see any Twofold Axis in the cell: ...
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Do Crystals have stronger intermolecular bonds than amorphous solids?

Do Crystals have stronger intermolecular bonds than amorphous solids and are the properties of amorphous solids vs. crystals explained by their structures?
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Finding Ice CIF files in crystal database

Could anyone please tell me where I could find the the structure of cubic ice (ice Ic) as a .cif file? I have been searching the cambridge structural database using "H2O", "water", "dihyrogen oxide" ...
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How to compute the NMR shift in Gaussian09 for only one specific atom in a bigger unit cell?

I am trying to compute the NMR shift for a specific atom in the middle of the surrounding crystal unit cell (1 surrounding anion sphere and 1 cation sphere) in Gaussian09. I only need the chemical ...
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32 views

How are piezoelectric crystals made?

I want to know how the powdered formed of piezoelectric material is converted to crystal like used in quartz watches. I know that some more chemicals are mixed with the material and then it is pressed ...
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141 views

How to add hydrogens to a crystal structure

PDB protein crystal structures most of the time lack hydrogen atoms. Usualy I use PyMOL (h_add) but it does not always seem to be giving the correct result. What ...
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What is omega and nu in this expression?

In the picture below a proportionality equation is shown: $$\omega \propto \nu \exp\left(\frac{-\Delta G_m}{RT}\right)\propto \dots$$ While $\Delta G_m$ is the Gibbs free energy, $R$ is the gas ...
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Why do some crystal structure files not include bonds?

Why do some crystal structure files not include bonds (the atoms are just placed in the respective position in the cell without bonds between any atoms)? Shouldn't the bonds always be there? Also, ...
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Deformation of the nematic phase of liquid crystals surviving in the solid state

Does anyone know if I were to cool a liquid crystal with a deformed nematic phase quickly, if it will preserve the deformation in the crystal lattice? I didn't find any information in classical ...
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How would one construct a 3D model of a molecule based on the crystal structure of its salts?

Often crystal structures found online from past published crystallography experiments are of the salt of a molecule of biologic interest, as opposed to the freebase form of the molecule itself. For ...
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What things form crystals? [closed]

Just getting interested in this stuff. People are saying I should crystallize salt, for example. What things could I do instead of salt with and still get a crystal from? Thanks a ton!!
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Crystal field theory for calculating lattice parameters

If I have an 8-coordinated metal cation (e.g., $\ce{Te}$, $\ce{Nb}$, $\ce{Ta}$, $\ce{Sb}$, $\ce{Bi}$, $\ce{Zr}$, $\ce{Hf}$) by oxygen anions, is there a way to theoretically calculate the structure of ...
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40 views

Can bone mineral be obtained in pure, crystalline form?

Can bone mineral be obtained in pure, crystalline form outside a living organism? Had this been done ever?
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Structure of Ca2B6O11

What is its structure? I found an image of $\ce{B6O11}$ unit but it looks incorrect: The top left corner one. The oxygen can make max 2 bonds but $\ce{O8}$ has three! There are six ...
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How to determine the Bravais lattice and atom basis vectors from a CIF file?

Say I have a CIF file describing some material in terms of its symmetry space group, lattice parameters and in-cell atom positions. A simple example might be, ...
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Modified DNA bases in Pymol and Coot

When using Pymol or Coot molecular visualization software to solve x-ray crystallography structures, how can I mutate a cytosine to a 5-methylcytosine?
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Theoretical Calculation of Lattice Parameter from Space Group

If I am given a compound which belongs to, say the cubic $\text{Ia}\bar 3\text{d}$ space group, is there a known way to calculate the lattice parameter of the compound? In general, can lattice ...
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How to predict if hydrogen atoms could be placed in the interstials of a lattice

Palladium hydride is an example of a hydride which contains H atoms in palladium's crystal lattice (which is fcc). I would like to know if it's possible to predict if another hydride, $\ce{NbH_{x}}$ ...
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Determining structure factors for crystals from lattice and motif

I understand that the structure factor for a crystal is given by: $$F_{hkl} = \sum_r f_{r} e^{2{\pi}i(hx_{r}+ky_{r}+lz_{r})} $$ My textbook (''Structures of crystals'', Glazier) suggests that you ...
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Why is sand/glass polar? How does lattice structure change polarity?

The molecular geometry of sand is linear. Dipole moment is thus cancelled. But we all know from the meniscus water makes with glass that the dipole-dipole/H-O attraction between sand and water is ...
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Can chemicals change crystal structure by only touching?

Are there any known, or suspected compounds that take the crystal structure of what ever object they are touching, i.e. if it touches $\ce{NaCl}$ it would turn into a face centered cubic crystal ...
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Is there any required data missing from my CIF file?

I previously asked a question about a CIF file here (namely CIF fields that are available for some atoms, but not others) I think I have the answer (namely to place dots [.] at places where the two ...
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CIF fields that are available for some atoms, but not others

I've been working on another CIF file, this time for (-)-threo-methylphenidate based on Pharma Res, 1995 (sadly the relevant crystallography data isn't supplied in the free preview at Springer). I ...
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Azathioprine CIF data file rendering problem in Accelrys

I have been working on a CIF data file (URL: http://goo.gl/2cprI6) based on data from this experiment: Acharya, 1984 (free full text isn't available, but the page [page 2] with the experiment details ...
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How does the atomic structure of crystals determines its shapes? [duplicate]

for example, table salt has an a cubic structure in the atomic level, and they are often cube like in the visible level. I don't see any reason that the atomic crystal structure should reflect the ...
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Why does pyrite form cubic crystals?

Pyrite ($\ce{FeS2}$) forms cubic crystals, like these ones: I know that the crystal structure is primitive cubic, but I don’t see how cubic structure on the molecular level translates to cubic ...
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When does hydrogen bonding happen?

What kinds of molecules will experience hydrogen bonding (inter and intra)? Why does it occur for some H atoms but not others?
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169 views

What is a catemer?

What is a catemer and how does it differ from a dimer? What type of compounds could form catemers and how does their formation influence its crystal structure?
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Coloration of substances because of F-Centers

In case of metal deficient defects in the crystal lattice of a metal, the positive voids are filled by electrons. How does this result in the coloration of a substance? Does this condition arise ...
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Unit cell of CdCl2

I understand that $\ce{CdCl2}$ has a rhombohedral unit cell as shown in this book. However I often find it being referred to as a "CCP analogue" of $\ce{CdI2}$. Presumably it is the chlorides which ...
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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 ...
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Allotropy and polymorphism

Polymorphism is defined as the ability of a solid material to exist in more than one form or crystal structure, whereas allotropy is defined as the property of some chemical elements to exist in two ...
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Amorphous to crystalline: Opposite trend?

Well my book says that on heating- amorphous solids crystalline at some temperature. As far as I know , amorphous solids have a very disordered structure compared to crystalline solids and on further ...
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How to measure band gap of powder sample with using diffuse reflectance method

We have UV SHİMADZU 2550 and its diffuse reflectance attachment. I want to measure band gap of single crystal samples. What should I do? Which formulas should I use to calculate band gap? I don't have ...
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Having trouble understanding the iron-carbon phase diagram

At room temperature, alpha and alpha+$\ce{Fe3C}$ are present (depending on carbon content), which is ferrite and pearlite. In the lab we polished and etched samples of carbon steel to observe the ...
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Correlation between crystal structure and underlying atomic properties

Can the crystal structure of an element/metal be explained by any underlying atomic or quantum mechanical properties of the element or is it an intrinsic property by itself (like atomic number)?
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Is there an experiment that visibly shows the effects of metastability?

I am attempting to create an experiment to show the effects of metastability to a public audience and get people excited about science. More specifically, I am wondering if there is any sort of liquid ...
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63 views

How to run crystal simulation on GAMESS?

I know GAMESS is not best suited for crystal simulation but I am not ready to start learning another package as VASP. As I heard GAMESS is able to do some calculations in a "terminated" crystal (I ...
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Replacement for optical calcite (Glan Thompson prism)?

I notice that Glan Thompson prisms seem to be the preferred optics for doing polarimetry and have been for at least 75 years. One instrument maker says that polaroid films can be used but they tend to ...
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281 views

Possible to grow optical calcite?

I notice that most optical calcite for sale seems to be from natural (mined) sources. Also, I know in World War 2, mining optical calcite was a strategic objective. Is there some reason why ...
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How do you calculate a unit cell's dimensions from an XRD spectra?

My Inorganic lab had us do an XRD measurement, but I've never been explained how to interpret the data. Question Calculate the unit cell dimensions a,b, and c, for $\ce{YBa2Cu3O7}$ from the ...
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Why does the sodium acetate solution crystallize by touching? [closed]

As the title stated above, why and how does the sodium acetate solution crystallize by touching?
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Why do people assume 28 oxygens in chlorite mineral formula?

I have been trying to calculate chlorite mineral formulas from microprobe data. However, all of the mineral formula spreadsheets on the internet, including those from the Open University assume 28 ...
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Crystal Lattice Defects

Why do defects in crystal lattices of various molecules and compound occur ? Is it due to the continuous contact or it arises due to impurities and human error during the formation?
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What does delta letter mean in some ceramics chemical material formula?

Here is a given chemical formula for ceramic material: La0.6Sr0.4Fe0.8Ni0.2O3-δ There is a letter δ. What does it stand for? I guess it is something about oxygen vacancies in crystal lattice.
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Interpreting X-ray diffraction data

So I've got my data for some x-ray crystals of small molecules of Ag, Cu,... I was curios to know what the best way to determine what type of lattice each of these atoms may have?
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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?