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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.

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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'. ...
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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
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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
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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: ...
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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 $\...
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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 ...
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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 ...
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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 ...
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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 ...
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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
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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? ...
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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 ...
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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 ...
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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
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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
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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
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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 ...
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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 ...
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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 ...
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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 ...
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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
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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 ...
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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 ...
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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 ...
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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
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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 ...
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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?
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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
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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
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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 $\pu{2.70 g/cm^3}$. ...
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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.
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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
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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 ...
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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 ...
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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 ...
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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, ...
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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?
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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, ...
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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
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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
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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_\...
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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
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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 ...
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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??
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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 ...
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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
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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 ...
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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?
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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, ...
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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 ...