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.
3
votes
3answers
188 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'. ...
1
vote
1answer
21 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
votes
1answer
107 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
votes
0answers
25 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:
...
1
vote
1answer
96 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
vote
1answer
29 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 ...
0
votes
0answers
12 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 ...
1
vote
0answers
26 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 ...
0
votes
0answers
202 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 ...
0
votes
1answer
38 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
votes
1answer
66 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?
...
-1
votes
1answer
38 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 ...
1
vote
2answers
264 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 ...
-1
votes
1answer
113 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 ...
4
votes
1answer
262 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 ...
6
votes
2answers
954 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
votes
2answers
113 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 ...
0
votes
0answers
482 views
Solid State — Locating and counting the number of voids in hcp structure
First off, a small doubt: Is the hcp structure same as the hexagonal crystal lattice (one of the 14 Bravais lattices)?
Secondly, what is the unit cell of a hexagonal crystal structure based on the ...
0
votes
1answer
203 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 ...
0
votes
2answers
98 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
votes
2answers
53 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
votes
1answer
107 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 ...
1
vote
0answers
261 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 ...
-1
votes
2answers
109 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
vote
1answer
60 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
31 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 ...
1
vote
0answers
35 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?
1
vote
0answers
413 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
votes
0answers
30 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
votes
1answer
951 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 $\pu{2.70 g/cm^3}$. ...
0
votes
0answers
30 views
Why different shapes of crystals are formed despite having cubic unit cell? [duplicate]
For instance, diamond has a cubic unit cell inspite of that it forms octahedron crystal.
-1
votes
2answers
225 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
votes
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
votes
0answers
36 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
votes
1answer
34 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 ...
0
votes
1answer
645 views
Let us say that height of HCP is h then what is the distance of tetrahedral voids [closed]
In a hexaoal cose-packedstructue et $h$ be the spacing between equivalent basal planes. Then what are the "heights" of the tetrahedral voids lying between any two adjacent, equivalent basal planes, ...
1
vote
0answers
25 views
why lattice energy have to be greater than IE and EA? [closed]
Why is lowering effect of the lattice energy not able to be greater than the combined net energy raising effects of the IE &EA?
3
votes
1answer
1k views
Calculating nearest neighbor distances
For cubic materials, there are equations in which to calculate nearest neighbor (NN), second nearest neighbor, etc. Can this be done with tetragonal crystal structures? I want to calculate NN, 2NN, ...
3
votes
1answer
39 views
Which is the suitable process for ball milling?
Why do we mainly choose the wet ball milling process in spite of dry ball milling process? Both processes are used to make a homogeneous mixture of different compounds.
10
votes
1answer
117 views
Thermochromism in PbI2
I noticed while heating some PbI2 powder that it reversibly changes from a yellow to a dark red. However, I was unable to find anything on this thermochromism.
There are related cases in TlI and AgI ...
13
votes
2answers
799 views
What is “chemical pressure”?
While reading some publications on solid superconductors, I encountered a term "chemical pressure" a few times, which is usually attributed to the changes of superconducting transition temperature $T_\...
1
vote
0answers
318 views
To what extent are the radius ratio rules valid for predicting the crystal structure of an ionic compound?
The ionic radii of $\ce{Ba^2+}$ and $\ce{O^2-}$ in barium oxide are $\pu{135pm}$ and $\pu{140pm}$, respectively. The ratio of the radius of $\ce{Ba^2+}$ to $\ce{O^2-}$ is approximately $0.964$.
...
2
votes
1answer
346 views
Why we don't talk about unit cells in hcp/fcc structures?
I'm studying basics of Solid State Chemistry from this source.
So there are 14 types of Bravais crystal lattices (Primitive + Centered) in 3D. Every solid in this universe is made by the unit cells ...
0
votes
1answer
31 views
Phases in iron carbon diagram
The definition of phase :
Uniform chemical and physical composition.
So Alpha iron (0.001% carbon) and alpha iron (0.002% carbon) are two different phases??
1
vote
0answers
288 views
Distance between two parallel planes in a cubic unit cell
The distance between two parallel planes in a cubic unit cell is
$$
\frac{a}{\sqrt{h^2 + k^2 + l^2}}
$$
where
$a$ is the unit cell parameter and
$h$, $k$, and $l$ are Miller indices
I have two ...
1
vote
1answer
4k views
How many tetrahedral and octahedral holes are there in a bcc unit cell?
When I tried to count, I found 24 tetrahedral holes (each formed by 2 body centers of 2 unit cells sharing a face and 2 vertices of the same edge of that face). As each hole is being shared by 2 unit ...
9
votes
0answers
73 views
Physical meaning of thermal parameters dimension (Ų)
In single-crystal x-ray crystallography both isotropic and anisotropic displacement parameters $U_{ij}$ of thermal ellipsoids have dimension of square angstrom ($Å^2$) as follows from the definition ...
1
vote
1answer
433 views
How is solid titanium(II) oxide an electrical conductor?
Most salts in the solid state are electrical insulators, since the ions are not mobile (e.g. sodium chloride). However, solid titanium(II) oxide, $\ce{TiO (s)}$, is a conductor. How is this so?
4
votes
0answers
620 views
Can a solid be both crystalline and amorphous? [closed]
The first line in the Wikipedia article for "Glass" reads:
Glass is a non-crystalline amorphous solid that is often transparent and has widespread practical, technological, and decorative usage in, ...
4
votes
0answers
74 views
Brillouin zones of a compound after structural relaxation
My background in solid-state chemistry isn't much, so I apologize in advance if there arises the need to raise a basic fact while answering my question. I've been learning mostly from the web, with my ...
