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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Calculating vacancies in crystal structure

I have this question on a practice exam. I'm not quite sure how to find the number of vacancies when replacing atoms. Question: The stable oxide for lithium is Li2O. How many oxygen vacancies in ...
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Chemical structure of SiO2 vs CO2 [duplicate]

why does SiO2 form a crystal structure while CO2 forms a linear one? Would it be possible to make a CO2 crystal or SiO2 gas in a lab or is there something preventing that from happening. Thanks
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Which elements exhibit allotropy?

I was just reading this article about allotropes which relates allotropy with some specific elements and also this wiki article. Also some other articles some of which relate allotropy with catenation ...
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Calculating Transient Nucleation Rate

Let say, at each discrete time step, $t_i$, we can forecast of a transient nucleation rate, $I_{trans}$ by following formulation: $$I_{trans}(t) = I_{ss}. \sqrt{(\frac{A\tau}{t})} .e^{-\frac{B\tau}{t}...
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Crystallography - physical reason for ideal lattice approx

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 ...
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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?
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Is the plane close packed?

Is the (200) plane of fcc crystal structure(the plane parallel to the face of unit cell and passing through the body centre of it) a close packed plane? A close packed palne is a plane where the ...
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28 views

Is (high) pressure required to form (quartz) crystals?

I've been reading a lot of sources about the hydrothermal synthesis of quartz using autoclaves. I want to try doing this myself, but before I can I need to know the minimum pressure required. If you ...
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What hinders Monoclinic crystal system from having face centered variation and body centred variation?

Base centered monoclinic cubic cells exists.I think that we can just place some lattice points at the center of other faces to get a Face-Centered structure. But, Two monoclinic Bravais lattices ...
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41 views

Alternative to Hanging Drop Crystallization

Forgive my ignorance if I am way off, but I was having a look at the crystallization of a number of different substances (e.g. proteins) through the hanging drop vapour diffusion method. The examples ...
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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: "...
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Copper density modification

Can you increase the density of a material surface (metal) by surface treatment? For example commercial copper. If we take the ordinary OF copper (99.95%), I would expect not to have the tabulated 8....
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How does the colouration of alum crystals work?

I see the experiment of making potassium alum crystals in most places showing basic science experiments and some of them will include adding in food colouring to the solution in order to colour the ...
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Edge length unit cells ionic crystals

In ionic crystals there are mainly 3 types of structures: Face-centered cubic and octahedral interstices; face-centered cubic with tetrahedral interstices; and body-centered cubic. My question is how ...
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21 views

Is it feasible to make dendritic crystals at home?

I've become interested in the forms of dendritic metal crystals from an aesthetic perspective, and I'm interested in whether it is feasible (from a cost, safety, resources) perspective to create metal ...
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64 views

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{...
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Does deep cryogenic treatment on metal has effect on electrolysis?

Referring to this websites, http://www.frozensolid.co.uk/audio/ , what implication does it has on metal that has gone through the process? It sure seem to me, that it toughen the metal at molecular ...
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How to make sense of the crystal systems names

I cannot fix the names and structures of the seven crystal systems in my head. There's a thousand books explaining their geometry and it's totally fine and understandable, no problem. But what do the ...
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26 views

Semilocal (GGA) vs hybrid functionals: structural parameters

I searched for a while, without success, an article containing an extensive comparison of structural properties (of molecules and solids) computed using GGA and hybrid functionals. Does anybody know ...
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Slips System of BCC

We have been taught that there are 48 slip Systems in BCC. I need the miller indices of each slip plane and direction. Out of 48 I got miller indices of 12 systems of {110}<111> and 12 systems of {...
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How is knowing about the symmetry of a crystal useful

I am studying the space groups and know that we use them to talk about crystal symmetry, I would like to know what material properties may be produced or predicted from knowing the symmetry or lack ...
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Basis of structural change of tin | Tin pest

What is underlying molecular intuition for the phenomenom of tin pest where tin under 13°C undergoes change in its crystal structure? Is the idea same as freezing of water, where atoms lose their ...
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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 (...
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If I have an alloy of two materials, will I have a chemical reaction between the two materials

I have always been told that an alloy is a mixture without chemical interference between the materials, but if I look at highly doped silicon (doped with Aluminum via ion implantation and then lattice ...
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46 views

Does crystalline glass exist?

As far as I know, glass is a non-crystalline amorphous solid. Does glass exist in crystalline forms? Or is it the definition of glass that it's non-crystalline, in which case my question is based off ...
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Do crystallite size and particle size need to be same?

In my experiments I have to find the particle size of nanoparticles. I use mainly XRD for finding crystallite size of nanomaterial using Scherrer formula and TEM for particle size analysis. In most of ...
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Why are there no hydrogen atoms in the crystal structure of a biomolecule?

I am taking a physics and chemistry at the nanoscale class at my university and for a project I must learn how to use Visual Molecular Dynamics (VMD). One of the models involved in this project is apo-...
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136 views

Bravais lattice problem

A base-centered cubic lattice can be redrawn as a primitive tetragonal lattice, therefore we do not include it in the list of Bravais lattices. Why is it then that a face-centered cubic lattice cannot ...
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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, ...
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38 views

Structure of crystals vs melting point

Calcium oxide has a melting point of 2700C and sodium chloride has a melting point of 801C, if they have the same crystal structure and ions are about the same distance in each crystal why is there ...
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341 views

Why are X-rays used in crystallography?

Can any other wavelength of electromagnetic radiation be used? Why can't gamma radiation be used?
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Why can't two Silicon tetraoxide tetrahedrons share an edge or a face?

Our teacher told us about structural types of silicate minerals (neosilicate, sorosilicate, cyclosilicates ...) saying that those tetrahedrons can only share one corner (oxygen), but he didn't give us ...
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37 views

What are unit cells, and how do you determine the number of atoms in one of them?

I've read several websites to try to figure out what exactly a unit cell is, but I can't seem to understand it. Could someone explain what a unit cell is, and the different types? Thanks!
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Protein Data Bank: Asymmetric Anit/Biological Assembly

For a schoolproject I have to interpret the 3D structure of an imatinib-BCR ABLC kinase complex. When I visited the PDB website I downloaded the PDB file corresponding to this complex. Once I opened ...
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If glass is made from silica, then why is glass on the top of triboelectric series and silicon at the bottom?

I have frankly asked this question out of curiosity. I just want to know what make one positively charged and other negative on rubbing.
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How can the bulky octadecyltriethoxysilane molecule promote single-crystal growth?

Octadecyltriethoxysilane is very bulky (source), yet it was used to promote single crystal growth (source). How can such a bulky molecule induce crystal growth? (For example epitaxial growth ...
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What are the bubbles and crystals found in sodium acetate hot packs after use and storage in the solid form?

When sodium acetate trihydrate hot packs are regenerated soon after activation, they regenerate to a clear liquid upon boiling (typically with an air bubble that was not present in the new pack) On ...
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Drying the solution of two salts

What will be the arrangement of crystals if a solution of two salts, say, Sodium Chloride and Potassium Chromate, is dried? Will one salt crystallize before the other and become the crystallization ...
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Would a melted crystal recrystallize back into the same lattice structure when frozen?

Two things that I'm not sure about melted crystals: For a material that has only one possible crystal structure, would freezing cause it to recrystallize, or could it become amorphous upon freezing? ...
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Crystal defects involving electroneutrality violation

Is there any example of a non-stoichiometric defect in crystal lattices which involves electroneutrality violations (i.e., the system itself ends up having unbalanced charge which may be neutralized ...
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143 views

Growing crystals that are in a magnetic field or subjected to an electric field

I know different crystals resonant at different frequencies but is it possible to grow crystal at a certain frequency. An example would be growing crystals using Epsom salt or Alum in a magnetic ...
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Hexagonal unit cell vs crystal system

Is hexagonal unit cell (resulting from hexagonal closed packing) same as the unit cell of hexagonal crystal system? The unit cell of hexagonal crystal system is described by the following sides ...
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What is the difference between crystal structures of proteins, organic and inorganic materials?

From the definition of crystal and the main differences between crystalline and amorphous material, it is known that crystal formation requires ordered bonding between atoms or molecules. How can ...
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51 views

Aren't unit cell and the relevant crystal similar?

"A crystal is formed by a large number of repetitions of basic pattern of particles in space. The basic structural unit which when repeated in three spatial directions generates the crystal ...
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311 views

Is NaCl crystal always going to have even number of atoms?

I just read: In $\ce{NaCl}$, atoms don't aggregate so as to form discrete molecules but they are held together in a network structure. The ratio of the $\ce{Na}$ to $\ce{Cl}$ atoms in a sodium ...
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Lattice structures, Metallic Bonding

How and under what circumstances can cations form a lattice structure? Would they not repel each other?
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Why is a face-centred cubic unit cell not regarded as equivalent to a body-centred tetragonal unit cell?

When studying crystal lattices, I decided to learn which combinations of unit cells and lattice systems lead to the 14 Bravais lattices. I learnt that, for example, no centred triclinic unit cell ...
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83 views

General notation for one of the d-orbitals

What is the general notation to represent the d-orbital with $l=2$, $m_l=0$, i.e. the orbital normally referred to as $\mathrm{d}_{z^2}$. To elaborate more, this orbital can be ordered in various ways ...
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modeling structure of crystals

I came accross this image of crystal strucure in an article The Structure of Ferrihydrite, a Nanocrystalline Material by Michel et al. Does someone know the software in which it was produced. I have ...
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Are adamantane crystals covalently bonded?

I'm writing a report and need one thing clarified after reading the Wikipedia article on adamantane: 'All the above methods yield adamantane in the form of polycrystalline powder. Using this powder, ...