Questions tagged [lattices]
For questions about systems with a repetitive arrangement of constituents, such as a crystal lattice or Bravais lattice.
61 questions
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If AlCl3 has such a high lattice energy, why is it so soluble in organic solvents?
AlCl3 is well known to be relatively covalent, but doesn't solubility generally go down as lattice energy increases, (I.e born-haber cycle?)? However it's soluble in many organic solvents
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2
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0
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41
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What is the precise definition of crystal systems and unit cell?
I was just wondering why there wasn't a rhombic 2D Bravais unit cell (wasn't there in the material provided to us) and realised upon drawing that it is the same as a centered rectangular unit cell. ...
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1
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402
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Can alkaline earth chalcogenides be doped with halogens for conductivity?
Which salts, of all the binary alkaline earth chalcogenides with a 'rock-salt' structure, can be doped with halogen anions replacing some of the chalcogen, without destroying the lattice? (That is not ...
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4
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1
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432
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How to Derive the Born-Mayer Equation?
Born-Mayer Equation: $E_{P,min}=-A\frac{N_A|z_1z_2|e^2}{4\pi\varepsilon_0d}(1-\frac{d^*}{d})$
Here is where I have gotten:
$$
E_P=-A\frac{N_A|z_1z_2|e^2}{4\pi\varepsilon_0d}, E_P^*=N_AC'e^{-d/d^*}\\
$$...
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2
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144
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Why does Cs2SO4 have more lattice energy that Na2SO4?
My chemistry teacher told us that $\ce{NaF}$ has a higher lattice energy than $\ce{CsF}$. He explained it by telling lattice energy is inversely proportional to size of ions added. He then mentioned ...
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1
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125
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If gold does not oxidise in air, why doesn't it reform it's lattice?
It is a common fact that without oxidation, a metal can reform it's lattice with a tad bit of pressure.
Gold is often said to be non-oxidising(doesn't oxidise in ambient temperature and pressure) and ...
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2
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58
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In cubic system how many atoms arrangement exist in nature? [closed]
All websites say the answer should be 3 , however shouldn't it be four ?
Primitive
BCC
CCP
End Centered
2
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0
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84
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Brittle Properties of Ionic Compounds? [closed]
From my understanding, ionic compounds are brittle due to the alternating cations and anions within their lattice. Hence when stress is applied, similarly charged ions will repel causing the structure ...
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4
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1
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777
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Why does KCl have FCC structure instead of BCC?
I have this table here.
\begin{array} {|r|r|}\hline \text{Radius Ratio} & \text{Coordination number} & \text{Type of Void} \\ \hline <0.155 & 2 & \text{Linear} \\ \hline 0.155-0....
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1
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80
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Explanation for the low melting point of zinc nitrate in terms of its lattice energy and electrostatic interactions?
I understand that ionic compounds tend to have higher melting points, but I was surprised to see zinc nitrate having an unusually low melting point. I tried understanding it in terms of lattice energy ...
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2
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1
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134
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Why metal hydrides have low lattice enthalpy
Lattice enthalpy is inversely proportional to the distance between the ions. And the trend of lattice enthalpies is: $\ce{MF>MCl>MBr>MI}$. But why do metal hydrides have lesser lattice ...
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2
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540
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What is the difference between alloying and doping? [closed]
When compared to doping, how is alloying different? What modifications to the structure are brought about by both of these?
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1
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235
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Lattice energy as a factor that helps determine which charge the atoms take on?
I do not quite understand the following line of reasoning:
Why does Na not form $\ce{Na^{2+}}$ ions? To obtain $\ce{Na^{2+}}$ ions, the first and second ionization energy must be applied: 496 + 4563 ...
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1
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884
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MgSO4 is soluble while BaSO4 isn't, what's the role of Lattice energy here? [closed]
I came across a question asking the reason behind
MgSO4 is soluble while BaSO4 is insoluble in H2O
Now, I know
Solubility has inverse relation with Lattice energy. While Lattice energy is more when ...
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0
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0
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61
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Data for Madelung Constants
Where can I find data for the Madelung constants for various ionic compounds? Specifically, I am looking at silicon tetrachloride, yttrium (III) chloride, zirconium (IV) oxynitrate hydrate, niobium (V)...
3
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1
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How do other elements fit into a diamond's carbon lattice (e.g. nitrogen in yellow diamonds)
Traditional pure-carbon diamonds have a simple structure (tetrahedral, if I'm not mistaken). But common types of diamonds have other elements within them. For example, yellow diamond has nitrogen in ...
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1
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In calculating the radius ratio in a tetrahedral site in an FCC lattice, why do we take tetrahedral void in the middle of the body diagonal line? [closed]
When calculating the ratio of cation / the ratio of anion in a Tetrahedral system in an FCC lattice, why do we take the void to be in the center instead of it being √3a/4 from the corner.
-1
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2
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151
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Why does density decrease when pressure is increased on an NaCl type lattice?
I was told that the effect of pressure on an NaCl type structure would make the atoms come closer and therefore change the type to CsCl type making Z (no of atoms per unit cell) go down, hence density ...
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8
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2
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Why are there only 14 types of Bravais lattices and not 28 when there are 7 types of unit cells and each can have four variations?
As the title suggests, I can't understand why certain kinds of variations (like Face-centred or Body-centred) are restricted to certain types of unit cells. An orthorhombic unit cell has Primitive, ...
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2
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Hydrogen Bond Length and Lattice Density [closed]
The subject of the density of solid water is discussed on Physics Stack Exchange in this post.
In the post, it is said that..
the way the molecule is angled ensures that a specific (energetically
...
3
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2
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934
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Why sulfonate of detergent is less likely to bind to ions present in hard water than carboxylate?
I was reading about why detergents do not form scum with hard water but soaps do, and according to wikepedia it has to do something with electrostatic interaction of sulfonates( most commonly) with ...
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Radius ratio of octahedral interstitial site in BCC lithium
Problem
Determine the minimum radius of an atom that will just fit into (a) the tetrahedral interstitial site in FCC nickel and (b) the octahedral interstitial site in BCC lithium.
Solution
(a) For ...
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4
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1
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141
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Do superoxide salts of heavier alkali metals contradict the principle that lattice energy depends inversely on cation-anion distance?
I have a very basic understanding of quantitative lattice energy calculations: I only know that the lattice energy is directly proportional to the product of charges on the ions and inversely ...
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1
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0
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37
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HCP and hexagonal primitive cell [duplicate]
There are 14 types of Bravais lattices one of them is hexagonal which is just present as primitive cell ie the basis are at its corners , now when I read about hexagonal closed packing I came to know ...
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1
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0
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29
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X-ray Diffraction Lattice Spacing
I have crystal structure data which I have indexed. I am able to index the (010) (100) (011) (110) and (111) planes. Is there a straightforward method to calculate the a,b,c lattice constants based ...
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Whats the difference between unit cell and motif?
The definition in my material is that motif and unit cells are both a repeating unit, but whereas motif is with respect to 2D lattice the unit cell is with respect to 3D lattice. But I can't find ...
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2
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Why are there exactly 5 types of two-dimensional lattices, and what distinguishes them?
In the book Chemistry: The Central Science, they introduced the following 5 types of two-dimensional lattices:
The book said that the blue square represents the unit cell, the black dots are lattice ...
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0
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Why does malleability and ductility of interstitial carbides decrease?
Why does the malleability and ductility of interstitial carbides decrease? I read the following in my book, but I am not able to find what is the reason for the same. Why does this happen? Is it to do ...
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0
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885
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Unit cell of hcp structure
It is given in my book that the structure in figure-1 is the unit cell of hcp structure.
So why then is the structure in figure-2 not the unit cell as we can repeat the structure in figure-2 to get ...
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1
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319
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Height of CCP Lattice
Are the height of the Cubic Close packing Lattice and the cubic Hexagonal Close Packing the same?
My understanding says that these unit cells are formed by different arrangement of atoms, ABC for CCP ...
4
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1
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Finding the atomic packing factor (APF) of Sodium Chloride and other FCC ionic compounds
For a piece of coursework I am doing, I need to calculate the atomic packing factor of some ionic compounds. I have had no formal teaching in this area, so what I know comes from information I have ...
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331
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If a good choice of a unit cell should be the one of most symmetry ,then why keep body centered tetragonal if face centered cubic exists?
For any lattice a good choice of a unit cell is the one that is the most symmetric.
Now if every lattice made by a body centered tetragonal unit cell can be made by a face centered cubic unit cell ,...
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Conventional unit cell for a hexagonal crystal system
The figure shows a unit cell of a hexagonal crystal system. Drawn in bold, is the unit cell. The lightly shaded one is a unit cell as well and has a six fold symmetry along an axis, hence is more ...
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Interplanar distance given Miller indice of the planes
Say we've a cubic crystal of unity edge length.
A set of planes in such a crystal is specified by their miller indice as $(3 2 0)$. One of these planes then has intercepts on the axes as $(2 ,3 ,\...
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How do I find miller indices for a plane whose intercepts are fractions of the lattice constant?
[I'm talking with respect to cubic lattices alone.]
For instance, if a plane has $x,y,z$ intercepts $a/2,a/2,a/2$ (where $a$ is the lattice constant) the miller index would be $[2\space2\space2]$. The ...
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2
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Is there a standard scholarly reference for lattice constants of crystals of the elements?
I need to discuss the lattice constants of bulk crystals of several metal and semiconductor elements. I can find plenty of tables and numbers that are probably "close enough" but for a paper ...
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Converting fractional coordinates into cartesian coordinates for crystallography
So let's say for a given molecule I have the volume of a unit cell, the shape of the unit cell (monoclinic, cubic, etc), the cell angles alpha, beta, and gamma, the cell lengths a,b, and c, and a list ...
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125
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What is meant by "rotation about an axis that passes through a lattice point"?
I am currently studying Introduction to Solid State Physics, 8th edition, by Charles Kittel. In the section Fundamental Types of Lattices of chapter 1, the author says the following:
Crystal lattices ...
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2
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Sketching lattice points, primitive axes, primitive cell, and basis of atoms
I am currently studying Introduction to Solid State Physics, 8th edition, by Kittel. Chapter 1 provides the following figure and accompanying explanations:
It also says the following:
An ideal ...
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5
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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 ...
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How many nearest neighbours does a corner atom have? [closed]
Figure shows a unit cell of a cubic lattice. The atom in the middle has 8 nearest neighbours (the atoms in the corner). How many nearest neighbours does a corner atom has ?
I identified the given ...
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What are the limitations of the Born-Lande' equation?
The Born-Lande' equation is used to theoretically calculate the lattice energy, $\Delta U$, of ionic compounds. It is often cited as such in literature,
$$\Delta U = -\frac{k_Az_1z_2Me^2}{4 \pi \...
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1
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600
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Unit cell structure of ionic crystal
I have a question about the structure of an LiH unit cell, and while this is related to a homework problem, it isn't the problem itself, I'm just looking for conceptual understanding. I've already ...
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2
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Stacking two square (2D) layers to make a 3D close packed structure
My textbook states these ways of stacking 2D layers to make 3D close packed structures:
Square close packing layer over Square close packing layer (though not written explicitly, the illustration ...
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1
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0
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32
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Unit cell in a hexagonal closed pack structure
My textbook says that there are only 14 possible 3D lattices(Bravais Lattices).
One of these 14 lattices is a hexagonal lattice in which only a primitive variation is given to be possible.
But then I ...
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2
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200
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Calculate the lattice energy of ammonium carbonate
The lattice energy is a measure of the stability of a compound and I need this data for the ammonium carbonate ($\ce{(NH4)2CO3}$) but I don't know how to calculate and I can't find it anywhere. I know ...
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1
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Does a unit cell have to contain a whole number of atoms?
I was given this problem recently to compute the number of ions in a unit cell of ferrous oxide $\ce{FeO}$. The data given was:
Side length $a = \pu{5 Å}$
Density $d = \pu{4 g/cc}$
Using the formula ...
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1
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1
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Why for compounds of elements in a group with larger anions have nearly constant lattice enthalpy?
Why do compounds of elements in a group with larger anions have nearly constant lattice enthalpy?
In the reasons for the decrease of the solubility of sulphates of alkaline earth metals, it is given ...
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1
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How do the three Miller indices (hkl) denote planes orthogonal to the reciprocal lattice vector?
The Wikipedia page for Miller indices defines Miller indices as follows:
There are two equivalent ways to define the meaning of the Miller indices: via a point in the reciprocal lattice, or as the ...
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2
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1
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430
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Do we really have technology with the resolution to distinguish between layers of single atoms of materials?
My textbook, Solid-State Physics, Fluidics, and Analytical Techniques in Micro- and Nanotechnology, by Madou, says the following:
X-ray analysis reveals the symmetries of crystals (lattice type), ...
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