Questions tagged [solid-state-chemistry]
Study of chemical species that are in solid phase, either in cases of their properties, or about ways of synthesizing them.
226 questions
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21 views
How do hard drives store information using magnetic layering? (Antiferromagnetic/ferromagnetic films)
I am doing some work with solid state materials in some chemistry courses and I've been doing some research into exactly how a hard drive stores information as 1's and 0's. It seems like a bunch of ...
0
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0answers
33 views
Equilibrium concentration of point defects in solids at sufficiently elevated temperature
Equilibrium concentration of point defects in solids is defined as $\chi=\exp(\frac{\Delta s}{k_B})\exp(\frac{-\Delta h}{k_BT})$. At high temperatures, may be even higher than melting temperature of ...
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1answer
187 views
Contribution of Tetrahedral and Octahedral voids in HCP
I cannot find anywhere what the contribution of atoms situated at octahedral or tetrahedral voids in a HCP unit cell would be. I need to know this to be able to calculate the formula of a compound ...
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0answers
26 views
Oxidation states of Cu in YBa2Cu3O6 based on crystal structure [duplicate]
How does on go about this? I understand There is a +5 charge distributed on 3 copper ions. So either we have 2+, 2+ and 1+ or 3+, 1+, and 1+. Judging from the structure there are to unequivalent types ...
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0answers
43 views
Conversion of graphite into diamond [duplicate]
The standard state Gibbs free energies of formation of C(graphite) and C(diamond) at $T = \pu{298 K}$ are $\pu{0 kJ mol-1}$ and $\pu{2.9 kJ mol-1}$, respectively.
The conversion of graphite [C(...
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1answer
24 views
Is there any book or text where ionic radius of elements are given?
So my research has me looking for ionic radius characterization. If anyone could post any link or give the name of any book where ionic radius of all elements are given that would be really great?
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30 views
Packing fractions of HCP and FCC
The packing fractions of hexagonal close packed unit cell and face centred cubic unit cell come out to be same when calculated geometrically.
Is it just a coincidence? Differently put, could it be ...
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0answers
15 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 ...
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16 views
Why does alpha alumina have less surface area than gamma alumina?
Its been documented extensively that when gamma alumina (cubic) changes into alpha alumina (hexagonal) at temperatures around 1200 °C the specific surface area reduces considerably.
What are exact ...
2
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1answer
36 views
Why does dielectric constant of crystal fluctuates in case of Frenkel defect in a crystal?
So I was studying Frenkel defect in crystal and came across this line that said
The closeness of like charges tends to increase the dielectric constant of the crystal.
I'm not able to understand ...
8
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2answers
224 views
Calculating the strength of an ionic bond that contains poly-atomic ions
So the bond association enthalpy for ionic compounds like $\ce{NaCl}$ and $\ce{NaBr}$ can be easily calculated from a Born-Haber cycle. But the way a Born-Haber cycle is constructed it uses info that ...
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2answers
62 views
Chemical formula of fluoroapatite
My textbook says the formula for fluoroapatite is $\ce{CaF2 * 3Ca3(PO4)2}$, whereas according to Wikipedia it's $\ce{Ca5(PO4)3F}$.
What is the correct chemical formula of fluoroapatite and why there ...
3
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1answer
189 views
What does x mean in (1-x)A – xB composite materials, molar ratio, weight ratio or volume fraction?
I've been collecting data about ceramic materials and often I get to see composite materials are described as $(1-x)\ce{A} - x\ce{B}$. I am confused what this $x$ means. And I haven't seen any of the ...
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1answer
59 views
Is there an element with no liquid state? [closed]
I know this question might be dumb but, is there an element that will go directly from solid to gas, with almost no visible or no liquid state? Just a random curious question.
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1answer
177 views
How does lime prevent soda lime glass from dissolving in water?
How does lime addition as an ingredient prevent soda lime glass from dissolving in water? Does it form calcium silicate in the process of melting?
3
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1answer
113 views
Influence of the neighbouring molecules in a crystal at the example of XeF4
For reasons of symmetry I (without deeper chemical knowledge) supposed, that $\ce{XeF4}$ has a shape like $\ce{CH4}$. But according to Wikipedia its
crystalline structure was determined by both NMR ...
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1answer
88 views
Solid state and Bragg's Equation
A frst order reflection from (111) plane is observed for LiX with 2theta =24.6 degree (X-ray of wavelength 1.54 angstrom). Assuming LiX to be a cubic crystal system, calculate the length of the side ...
3
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3answers
225 views
How do I know crystal structures from formula?
Give an explanation why $\ce{MgF2}$ and $\ce{CaF2}$ adopt different structure types.
For example, the structure of calcium fluoride is 'fluorite' and the structure of magnesium fluoride is 'rutile'. ...
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1answer
39 views
vapor pressure of one part of binary compound
Let's say we have a binary compound AB in an enclosed container, and let's say there's a tendency to form B-vacancies so that B atoms/molecules escape and form a vapor. Let's assume there's enough of ...
7
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1answer
122 views
Why do we need to add hydrogen to amorphous silicon?
I was recently studying about Staebler-Wronski effect observed in amorphous silicon (a-Si). I realised it was due to imperfections in the lattice structure and breaking of Si-Si bond to Si-H bonds.
...
2
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0answers
61 views
Putting high symmetry points labels to a band structure plot
So far I've got this plot using Quantum Espresso. I want to put gamma, X, L, etc labels to the k-path.
Quantum Espresso's ouput states the following:
...
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1answer
205 views
Comparing the Lattice energy of different compounds
I am confused about some concepts related to Lattice energy.
First of all,how to compare lattice energy between $2$ compounds belonging to different groups and periods?
1.Between $\ce{AlF3}$ and $\...
1
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1answer
32 views
Effective diffusion coefficient of a species in a heterogeneous mixture
I want to calculate the effective diffusion coefficient of hydrogen radical in a mixed-phase consisting of metal oxide, metal hydride and metal. I consider the interfaces to be diffuse.
How can I ...
1
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1answer
28 views
Silver in defect chemistry
When talking about conductivity in combination with lattice defects you can often see that AgX is taken as an example for a Frenkel defect where the $\ce{Ag^+}$ moves to intersticial voids. I remember ...
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0answers
28 views
Diffusion equation I can't seem to find anywhere
So I was looking through some old lecture notes from a few years back when I stumbled upon a useful and simple equation that should, according to my former professor describe the diffusion in solid ...
3
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0answers
2k views
Number of octahedral and tetrahedral voids present in a HCP structure
The given image depicts the tetrahedral and octahedral voids in HCP structure.
For the tetrahedral part
I figured out that there would be 6 tetrahedral voids in total.
My visualisation: In the ...
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1answer
40 views
How does a molecule find the lowest energy state? [closed]
I understand that in a crystal lattice the molecule will tend towards the structure that is the lowest in energy (fcc, hcp, ccp, etc.). How does the molecule find these lowest energy states? Is it ...
3
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1answer
72 views
Does a molecule need to be placed symmetrically in the unit cell?
I was watching an OCW by MIT (3.091X) on solid state. My previous notion of lattice point and unit cell got shattered after this example.
Where are the unit cell and lattice points in this picture?
...
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1answer
49 views
Solid structures related question [closed]
In which of the following compounds are all tetrahedral voids vacant?
$\ce{NaCl(s)}$
$\ce{CaF2(s)}$
$\ce{ZnS(s)}$
$\ce{Na2O(s)}$
Kindly explain what this question asks from me and provide a ...
3
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2answers
919 views
Understanding Equivalent Wyckoff positions
I'm somewhat confused by the concept of Wyckoff positions in crystal structures. From Quantum Chemistry of Solids by Robert Evarestov, the definition of a Wyckoff position is "all the crystallographic ...
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1answer
262 views
Coordination number of spheres (all identical) in hexagonal close packing (HCP)
I was revising solid state chapter when I came across this question
What is the maximum coordination number of an atom in a hcp crystal
structure of an element?
The word 'maximum' drew my ...
3
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1answer
848 views
ABC arrangement of FCC/CCP
I know that FCC shows ABC type but I am confused about it. For simple cubic and body centered, it is pretty easy to work out the packing arrangement but FCC is giving me a headache.
What is this ...
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2answers
2k views
Calculate the third and fourth nearest neighbours in bcc
My textbook has given data for third and fourth nearest neighbours to be 12 and 8 with distances $\sqrt{2}a$ and $\frac{\sqrt{11}a}{2}$.
I have been able to calculate for the first and second ...
3
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2answers
218 views
In a copper wire, how many electrons does each atom give away?
As an ion, copper can give off 1, 2, 3 or 4 electrons. But it has 1 s electron in the last shell and 10 d electrons. So as a metal, how many of those are delocalised and free to move around, and how ...
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1answer
454 views
How can a vacancy defect be a stoichiometry defect?
NCERT (India) explain stoichiometric defects as those defects which do not disturb the stoichiometry of the solid. Vacancy defects are stated to be under the category of stoichiometric defects. When ...
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2answers
156 views
Formation of strontium peroxide
Wikipedia states:
Strontium peroxide is produced by passing oxygen over heated strontium oxide. Upon heating in the absence of $\ce{O2}$, it degrades to $\ce{SrO}$ and $\ce{O2}$.
I found some ...
0
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2answers
62 views
Is there an equivalent unit cell that can describe a bcc unit cell where all points are the same element?
Similar to how an NaCl-structure can be described as just a primitive cubic structure if all the lattice points were the same element or ion. I'm asking if there any such alternative for the CsCl-...
0
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1answer
159 views
Will ice be cold or not when formed using pressure? [closed]
We know that ice can be formed either by lowering the temperature of water or by applying more pressure. If we lower the temperature of water the ice so formed will be cool which is obvious.
If ice ...
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0answers
388 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 ...
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2answers
169 views
Counting body centre as lattice point when the basis consists of 2 atoms
An article in my book gives the following informatiom :-
I understood part a) and b) but faced problems with c).
It says that here the basis consists of 2 atoms which doesnt seem to be very ...
1
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1answer
66 views
How do phase transitions occur in the solid phase? [closed]
For example, how does graphite transform into diamond as pressure increases at a certain (adequate) temperature? I'm not sure if this is a great example to look at the bigger picture, so another ...
3
votes
1answer
34 views
Polyhedron with four capping ions
Let's say I have a trigonal prism in my crystal structure and this is further capped by two ions it's called a bicapped trigonal prism. If I have three ions it's called a tricapped trigonal prism. But ...
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0answers
36 views
What does this chemical formula mean?
Wikipedia says the formula of aluminum oxynitride is this $\ce{(AlN)_x·(Al2O3)_{1−x}}$,
$0.30 \leq x \leq 0.37$ . What does this formula mean?
3
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0answers
673 views
Comparison between Boron Nitride and Graphite: Interlayer distance
Boron-nitrogen chemistry has attracted significant attention, partly because a B–N unit is isoelectronic with C–C. Furthermore, the radius of carbon and its electronegativity are roughly the
average ...
2
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0answers
32 views
Defects in crystalline structure
Starting from a perfect $\ce{MgO}$ crystal a solid solution of $\ce{Al2O3}$ and $\ce{MgO}$ is prepared with an atomic proportion of $15:85$ of $\ce{Al}:\ce{Mg}$. Knowing the number of vacancies per $\...
2
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1answer
2k views
How to determine the edge length of the aluminium unit cell?
I'm having trouble understanding why I can't get the correct answer from this homework problem:
Solid aluminum forms a face-centered cubic unit cell. Aluminum has a density of $\pu{2.70 g/cm^3}$. ...
-1
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2answers
322 views
Does titanium(II) oxide conduct electricity? [duplicate]
In my book, it is given that $\ce{TiO(s)}$ is an electrical conductor. But I'd think that since $\ce{TiO(s)}$ is ionic and in solid state, it shouldn't conduct electricity. So, why does it conduct ...
3
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0answers
48 views
Compound metal oxide stoichiometries
When certain oxides are combined in a pre-determined stoichiometry and synthesized with a ceramic-like synthesis process(power-in-tube), multiple phases may be obtained which not necessarily is same ...
2
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0answers
37 views
Synthesis of compound metal oxides [closed]
When certain oxides are combined in a pre-determined stoichiometry and synthesized with a ceramic-like synthesis process(power-in-tube), multiple phases may be obtained which not necessarily is same ...
-1
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1answer
36 views
Concentration of electrons in silicon sample with a phosphorus dopant
I'm studying electrical and computer engineering and all I remember from chemistry is from high school. We have a $\ce{Si}$ sample and we want to replace one in every million atoms with a phosphorus ...
