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.
297
questions
2
votes
0answers
27 views
What makes up the conduction band?
Prologue/Rant about online classes
We have been taught the electron sea model to explain metallic bonding and conduction of electricity by metals. Then out of the blue, the band theory was introduced, ...
0
votes
0answers
25 views
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 ...
-1
votes
0answers
26 views
Why might X- Ray Powder Diffraction be Difficult for Analysing Zeolites? [closed]
Would it be to do with defects in their structures?
1
vote
1answer
51 views
Why is the disordered CuAu structure more stable at high temperatures?
I know that the disordered CuAu structure is based around FCC whereas the ordered CuAu structure is tetragonal. Why would the FCC structure be more stable at high temperatures?
For context, I was ...
2
votes
1answer
47 views
Getting an “index” of 7 for a Set of Powder Diffraction Data
I know a value of $h^2 + k^2 + \ell^2 = 7$ is not allowed but I cannot understand where I am going wrong with the indexing here. Any insight would be greatly appreciated as I am wondering if this is ...
-3
votes
2answers
26 views
Coordination number of 3D close packing [closed]
Can anyone explain me that how the coordination number of corner sphere of this 3-D packing is 6 ? it should be 3
-1
votes
0answers
46 views
Why does a covalent solid have a high melting point and boiling point as compared to an ionic solid? [duplicate]
Why does a covalent solid have a high melting point and boiling point as compared to an ionic solid? Shouldn't it be less than that of ionic solids since the coulombic forces in ionic solid is ...
0
votes
0answers
26 views
How many types of 3D packing are possible?
In my book it's said that there are 3 types of unit cubic cell - primitive , face and body centered . But for 3d packing types they have only mentioned FCC and HCP . I know that these 2 concepts- ...
2
votes
1answer
52 views
On the exact definitions of Frenkel and Schottky defects
The wiki page on vacancy defects says;
It is also known as a Schottky defect, although in ionic crystals the concepts are not identical.
As far as I'm aware, they're the same. Furthermore, the wiki ...
1
vote
0answers
42 views
Pressure vs electric conductivity in solids
If we apply pressure to a solid, does it change its electric conductivity? I am asking this because in 2020 they announced a superconductor at room temperature but under a pressure of 3/4 of the ...
0
votes
1answer
43 views
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
votes
0answers
62 views
Why is ruthenium dioxide a conductor while titanium dioxide is an insulator?
Ruthenium dioxide has the same crystal structure as rutile (titanium dioxide), and the metal atoms are in the same oxidation state. Yet ruthenium dioxide is a metal-like conductor (its resistivity is ...
0
votes
0answers
19 views
Degenerate semiconductors /N type dopants/Low fermi level
In extrinsic semiconductors the donor level of some N type dopants is lower in energy than some other dopants . For example as we move from the V to the VIII group if we draw the band diagram the ...
1
vote
1answer
108 views
How is Gibbs free energy related to stability? [closed]
I have been learning thermodynamics for quite some time and I fail to relate Gibbs free energy and stability.
For example, how do I compare stability of metal oxides using the following data?
Also, do ...
0
votes
0answers
35 views
Interatomic spacing vs electric conductivity
I have a theory which may be wrong but I will write it down.If 2 elements at the same group (in solids)have the same crystal structure then the one with the biggest interatomic spacing has better ...
1
vote
0answers
23 views
Clarification of term symbol explanation of laser crystal doping from textbook
I am currently studying Diode Lasers and Photonic Integrated Circuits, second edition, by Coldren, Corzine, and Mashanovitch. In chapter 1.2 ENERGY LEVELS AND BANDS IN SOLIDS, the authors say the ...
2
votes
2answers
206 views
Silicon–Boron Covalent Bond
This is a semiconductor-related question, but in order to understand the acceptor level energy state of boron in bilicon, I figured I'd ask here for hints.
Boron is a p-type material when introduced ...
0
votes
1answer
76 views
Is the lattice point in ZnO crystal structure occupied by the molecule ZnO or the ion O^2-/Zn^2+?
I learnt that ZnO has a hexagonal crystal system. I was expecting that cations or anions would occupy the lattice points in hcp while voids would be occupied by anions or cations respectively. But ...
0
votes
1answer
72 views
What is the form of the Hamiltonian for solids?
For atoms, and even molecules, I can understand how the Hamiltonian would be constructed, but what of solids (as in, for electronic structure calculations)? Thank you for any help.
1
vote
1answer
54 views
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 ,\...
1
vote
0answers
29 views
How to calculate planar density of a face /plane of crystal with cation and anions?
Planar density is given by numer of atoms in plane /plane area .
Suppose I want to calculate
planar density of 100, 101 and 111 planes of Nacl. Radius of Na+ and Cl- ions is 0.086 nm and 0.126 nm.Na+ ...
0
votes
0answers
24 views
Where are the tetrahedral voids and octahedral voids located in an FCC? [duplicate]
A crystal is made up of atoms X, Y, and Z. Atoms X are in FCC packing, Y occupy all octahedral voids and Z occupies all the tetrahedral voids. If all the atoms along two body diagonal are removed, ...
-3
votes
1answer
82 views
Ice geometrical shapes [duplicate]
https://en.wikipedia.org/wiki/Ice
https://www.google.com/search?q=ice&prmd=inmv&sxsrf=ALeKk028fJvrUcWLWu8EV-KsRGuiw0iWWw:1596098668929&source=lnms&tbm=isch&sa=X&ved=...
1
vote
3answers
141 views
Why water cools from outside to inside?
It is a well-known fact that
Water kept in a container, on cooling, results in freezing with initially at the circumference of surface
(1D), then on the surface (2D) and then throughout the volume (...
0
votes
0answers
31 views
“e and a” as combinations of pi bonds
I am trying to get a better intuition on solid-state physics but I am a chemist by degree. I came across this article that attempts to bridge the gap between solid-state physics and molecular ...
5
votes
0answers
68 views
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 ...
0
votes
1answer
24 views
Doping of a solid with impurities [closed]
This question is a continuation of the previous question of mine:press me if you wish
And my question is how can I dope a solid with impurities and if the process can be understood with basic ...
0
votes
2answers
144 views
How to identify if a material is perovskite or not?
This is more of a materials science question, but I believe many of you have referred NIST Inorganic Crystal Structure Database (ICSD) database.
I am collecting a database of perovskite materials and ...
-1
votes
1answer
161 views
Are HCP and Primitive Hexagonal Unit Cell the same thing? [closed]
In HCP, the [2D] Hexagonal packed layers are arranged in ABAB form. The same happens in Primitive Hexagonal Unit Cell. So does that mean they are the same? If not what differentiates one from the ...
1
vote
2answers
246 views
Why rutile structure have primitive unit cell instead of body centered?
In the literature (Wikipedia), I read that $\ce{MgH2}$ have a structure of rutile. Then, I looked at its space group which is $P4_2/mnm$. From this notation, I understood that it possesses a (...
0
votes
0answers
41 views
Do all metals expand on heating? [duplicate]
This question came up when I was reading about substances with negative thermal expansion. The article by Takenaka [1] gives a good list of materials displaying negative thermal expansion. I noticed ...
0
votes
0answers
50 views
How can fluorite structure exist?
From the information from Google the radius of $\ce{Ca^2+}$ cation is $100 \,\pu{pm}$ and of $\ce{F-}$ anion is $132\, \pu{pm}$, so essentially $\ce{F-}$ ion should form the Bravais lattice (FCC/CCP) ...
0
votes
0answers
49 views
Reason behind more prioritising of normal spinels
According to my textbook:
In normal spinels $\ce{A^{II}}$ should have occupied octahedral voids, but this factor is outweighed by greater lattice energy or smaller cation $\ce{B^{III}}$.
Later,
...
-3
votes
2answers
175 views
Change in the number of ions due to exchanging ions [closed]
If the position of Na+ and Cl- are interchanged in NaCl having FCC arrangement of Cl- ions then what change we can observe in the unit cell of NaCl.
I am confused as how the contribution will change ...
-1
votes
1answer
2k views
Calculate third and fourth nearest neighbours in fcc packing [closed]
My textbook has given data for third and fourth nearest neighbours to be 6 and 8 with distances a and √(3/2)a.
I have been able to calculate for the first and second nearest neighbour but it has ...
1
vote
2answers
58 views
Effect of pressure on transition temperature
I was wondering if someone can explain why the answer to the following question is volume instead of the others.
If pressure has no effect on the transition temperature between two
crystalline forms ...
2
votes
1answer
650 views
Is the number of tetrahedral voids always equal to double the number of octahedral voids in any crystal?
I came accross the question whether the number of tetrahedal voids is always equal to twice the number of octahedral voids (in the case where both the voids are present). The key was given as the ...
0
votes
0answers
24 views
Is the alloy of Fe, Si substitution alloy or interstitial alloy?
When atoms of the solute in a solid solution occupy positions
normally occupied by a solvent atom, we have a substitutional alloy. When the sol-
ute atoms occupy interstitial positions in the “holes” ...
0
votes
1answer
247 views
Melting point of crystalline solids
Why crystalline solids have sharp melting points but melting point of amorphous solids vary within a range?
Is it because the interaction energy is equal between atoms of crystalline solids so they ...
0
votes
1answer
89 views
Why are crystalline solids anisotropic? [closed]
Why crystalline solids are anisotropic whereas amorphous solids are isotropic?
Is it because in crystalline solids, X, Y and Z dimensions vary, but so does in amorphous.
Please write as simple as ...
0
votes
1answer
213 views
Are clathrates and interstitial compounds the same thing?
In the book$\ce{^{[1]}}$, it's given that clathrates are compounds in which gases are entrapped within cavities of crystal lattices of certain organic or inorganic compounds. Interstitial compounds ...
1
vote
0answers
20 views
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 ...
0
votes
1answer
87 views
Cation-anion radius ratio of manganese difluoride
How to determine the cation-anion radius ratio for $\ce{MnF2}?$
I tried to calculate the $r_\mathrm{c}/r_\mathrm{a}$ ratio using the relationships:
$$2r_\mathrm{c} = c$$
and
$$(2r_\mathrm{c} + 4r_\...
1
vote
0answers
28 views
Sphalerite type structure
There are binary diamond type structures for example S and Zn form sphalerite. I thought the reason this formed was because of the big difference in the radii of the atoms that allows the smaller atom ...
1
vote
1answer
66 views
Is there a crystal structure of ammonia in ionic form?
Like solid $\ce{PCl5}$, does solid $\ce{NH3}$ exist as $\ce{[NH4+][NH2-]}$ (i.e. ammonium amide)?
1
vote
0answers
92 views
Why is liquid germanium denser than solid germanium?
Why are some elements like Ge and Si have liquids denser than their solids? In water it is explainable by H bonding, but no H bonds or such are there in Ge and Si.
Well, I want an explanation about ...
1
vote
1answer
169 views
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 ...
-4
votes
1answer
203 views
Why does Xenon Hexafluoride exist as [XeF5+][F-] and not [XeF5+][XeF2-] in the solid state [closed]
I already referred to this similar question but it yielded no explanation for the reason. Cations and anions of similar sizes stabilize each other through lattice energy effects in the solid state. ...
4
votes
1answer
107 views
Fractional index in a chemical formula of metal oxide
I have just read an article in which they used $\ce{WO3}$ and $\ce{WO_{2.9}}$ as precursors, whose objective was to form $\ce{WS2}$, in an atmosphere of argon by CVD. In one boat there is the powder ...
2
votes
0answers
93 views
Data-processing pipeline for protein x-ray crystallography: uncertain of terminology and order of procedures [closed]
Background: I am trying to get an overview of the data-processing pipeline for solving protein structures by x-ray crystallography, and in a very simple way understand what mathematical procedures are ...
