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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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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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?
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Structure of Metallic Hydrogen

I am simply curious what the theoretical arrangement of metallic hydrogen would be. I found this article which gives a picture, but I don't understand what the labels mean (e.g. is H5 an isotope, ...
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42 views

Can alloys or ceramics have higher density than elemental solids?

Are there any examples of alloys or ceramics that have higher density than their densest elemental constituent? If so, do they have unusual or difficult synthesis processes? If not, is it provable ...
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Does mercury fulminate really look like crystal methamphetamine?

In the AMC series Breaking Bad , Walter (aka Heisenberg) smuggles in a bag of mercury fulminate under the guise of crystal methamphetamine and threatens to blow the room up if he doesn't get his ...
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Is there anything akin to molecular chirality for crystalline?

For example, in hexagonal closed-packed (HCP) structure, the atoms may be arranged in ABAB stacks or ACAC stacks. Can these two be considered enantiomers? Do they possess different solid state ...
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How is “F2/sig(F2)” the data quality in SXRD?

When I recieve a dataset from single crystal X-ray diffraction, I can determine the quality from a graph in which F2/sig(F2) is displayed in dependence of the frame. But I forgot the basics... I have ...
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Can a network covalent solid be amorphous?

All the definitions I'm seeing give examples of crystalline solids like diamond or boron nitride. But I'm wondering if it also includes amorphous macromolecules like vulcanized rubber. I'm thinking ...
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52 views

Rock Salt structure

Source BY looking at this structure of rock salt (NaCl) we can say that the chloride ions and the sodium ions have the same environment that is the nearby atoms position relative to that ion except ...
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542 views

Why is sand, sand; and why is glass, glass; While both mainly contain Silicon Dioxide?

I know that there is the famous process of heating material and converting them to glass; but what I don't know is, what is the chemical process of the creation of glass? Is it crystallization? How ...
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Etching around corners

In etching of mono silicon, why does the etching process around the corners differ from the etching process around the flat edges? What brings about this difference and is there some way that MEMS ...
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How do I make PDB 1HIG's data usable for producing ball-and-stick models?

PDB: 1HIG, when opened using Accelrys DS Visualizer, Avogadro and Jmol produces a series of dots in space and cannot be displayed as 3D ball and stick models. Is there any way to overcome this ...
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Is it possible to construct a 3D molecular model using x-ray powder diffraction data?

I've got x-ray powder diffraction (XRPD) data on bendamustine HCl from a patent and I want to know how to construct a 3D model using this data with software.
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Are the native starch's structure and properties different from retrograded starch?

Starch gelatinization occurs when native starch is being expose to heat and water. Gelatinized starch then can be retrograded under cool temperature. But the structure and properties of retrograded ...
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crystalline structure of Si wafers used for MEMS

When they say that we have a {1 0 0} single crystal wafer, I know that the surface normal to the wafer is oriented in the <1 0 0> family direction, but if I draw a line on the wafer, parallel to my ...
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Is it possible to infer the structure of hydroxychloroquine based on the crystal structure of chloroquine?

I've been trying to construct an experimentally-based structure of hydroxychloroquine based on the crystal structure of chloroquine, as depicted by PDB: 1CET (R-enantiomer) and PDB: 4FGK ...
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How is the crystal direction important for etching silicon surfaces?

I am a student of masters study with a background only in electrical engineering, but I have studied Miller indices and crystallographic planes and directions, personally, to help myself understand ...
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Where is the center of symmetry in the PbO crystal?

I'm very confused as to where the center of symmetry is for the PbO (litharge form). I know that it is in the P4/nmm space group, and that it's centrosymmetric, but beyond that I'm clueless. Thank ...
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Binding forces in crystalline solids

I am referring to rocks in this instance. Individual crystals grow together in an igneous rock as it solidifies. I know that the $\ce{SiO4}$ tetrahedron is the basic building unit of silicate ...
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Cubic lattice: How corner atom of a cube is shared by 8 atoms

Since ,"Each atom is at the corner of a cube and 8 cubes meet at each corner. Therefore each atom is shared by 8 cubes." But i don't visualize it ,so please tell how i Visualize it .
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How to predict the type of intrinsic defect?

How do we predict the type of intrinsic defects in materials. For example what are the intrinsic defects in $\ce{HgSe}$ and $\ce{Ba3N2}$ ?
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XRD-Shorter distance between planes than actual radius of atoms/or cell parameter

I'm solving problems related to X-ray diffraction, and I get these results which apparently are correct. My question may be dumb, but I just can't see how the interplanar distance might be shorter ...
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110 views

How do I write a valid CIF, PDB or XYZ file from the coordinates listed below?

I want to create a 3D molecular file using coordinates taken from: Hrynchuk, RJ; Barton, RJ; Robertson, BE (1983). "The crystal structure of free base cocaine, C17H21NO4" (PDF). Canadian Journal of ...
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Empirical formula of Berthollides

Can the empirical formula be defined for berthollides? Is it equal to the molecular formula, or it can't be defined?
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Miller indices. What determines the appropriate axis?

So, first of all, what's up with this "plane" I see two planes! The basis of my question is that to determine miller indices the plane cannot lie on your origin, so you have to make a translation. ...
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Central Atom in EXAFS

I read somewhere that EXAFS (Extended X-ray absorption fine structure) gives us the distances between central atom and its neighboring atoms. Is that true? Why can't we get the distance between two ...
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Two-dimensional Networks of Coordination Polyhedra

Does anyone know of any references that use {V/P, P/V} notation? This involves polyhedra joining to form polygons, or vice versa (this is where my confusion lies) V/P may refer to the number of ...
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Determining perovskite crystal structure

I've been reading that perovskite presents a sort of pseudocubic crystalline system, however it can be stretched and suffer modifications to become orthorhombic etc. The thing is, if I consider it ...
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What's the most efficient way to find crystal structures of drugs?

I'd like to be able to find the crystal structures of drugs, for example at the moment I want to find the crystal structure of (R)-fluoxetine so that I can use Jmol to create an accurate 3D model of ...
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Determining the Packing Geometry of Compounds

I'm a little confused on the method to determine packing geometry. The question I'm given is Determine the packing geometry of the following compounds by using the radius ratio rules. For your ...
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Carbon atoms at the edge of a diamond

It is well known (the simplest textbook example) that a diamond has a well-defined arrangement of sp3 carbon atoms, as each atom is connected to four others in a ...
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Approach to model solvent in a lattice: e.g. H2O in NaCl

If a lattice contains a solvent, lets say NaCl and water of crystallisation, what is the condition for a solvent molecule to change it's location? From my current point of view I assume that such a ...
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Grocery store crystalline citric acid

Which type of citric acid crystalline powder do they sell in grocery stores? Is the concentration of citric acid in the crystals 100%?Is it anhydrous or a monohydrate?
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Represent bonds spanning a unit cell boundary plane

Is there a chemical input format that is- Supported by Open Babel (and hence supports visualization in avogadro??) Can represent a bond connecting an atom to its partner in a neighbouring unit cell, ...
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What happens when ice melts?

What happens when ice melts? I have this question, with two possible answers: regularly arranged molecules change into irregularly arranged molecules water molecules become less densely packed ...
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how to determine timescale with characterization methods?

There are as classified in the Atkins textbook 4 different timescales on material characterization: a)Time during which a quantum of radiation or a particle can interact with a molecule. b)Lifetime of ...
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Dihedral angle of gaseous and crystalline HOOH

Why does hydrogen peroxide exhibit a dihedral angle of 111.5 degrees in the gaseous state? And a dihedral angle of 90.2 degrees in the crystalline phase? I know that in general, there is likely to ...
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Is there a systematic way to determine the expected cubic structure of metals?

I've noticed that some groups of metals with similar properties tend to belong to the same cubic structure group, such as $\text{FCC, BCC, or HCP}$. What is a good explanation as to why these metals ...
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How do people check the type of defect in a crystal?

There are many types of defects like Vacancy Interstitial Schottky Frenkel Non-Stoichiometric Alien Impurities But given a sample, how do scientists know which kind of defect is present in it ...
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What is the length of a unit cell of CuCl assuming that it is fcc?

The density of CuCl is given - x gm/cmm The crystal structure is assumed to be fcc. My teacher is claiming the we can apply the formula $$\rho=\frac{Z * M}{a^3 * N_0}$$ And he took M = 35.5+63.5gm = ...
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Structure of diamond

"diamond structure. Every carbon atom is bonded to four other carbon atoms forming a three-dimensional lattice of chair conformations." SENTENCE FROM A BOOK What does this mean? Where I am struck ...
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What are Lattice Points

What are lattice points exactly? And Also How many Lattice Points are there in each of the Unit Cells?
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What are these crystals on my champagne cork?

I opened up a bottle of champagne that was left in a wine cooler for approx. 8 years. To my astonishment there were small crystals at the underside of the cork. The crystals are colorless, odorless ...