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Pseudocubic unit cells: how to construct one?

I keep coming across the term pseudocubic unit cell while reading about orthorhombic perovskite structures. No clear explanation ...
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Number of reflections for BCC crystal [closed]

I need to calculate the number of reflections expected for the (110) and (200) plane of a BCC crystal. How would you do it?
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1answer
29 views

Electrons scatter light; x-ray diffraction

why accelerated electrons "scatter" light? From Yale's chemistry open class, the professor said when a light passes by an electron, it "pulls" the electron up and down, and emit radiation in all ...
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1answer
53 views

Compute distance between planes in a crystal

I want to compute the distance between two (111) planes in a cubic crystalline structure, in order to do some computations involving Bragg reflection. I have a sketch of which the (111) planes are, ...
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10 views

Impurities involved in nucleation centres

When magmas begin to crystallise, a first step is the formation of a crystal nucleus around an impurity (nucleation centre), whereby a few of the right atoms get together to form a speck of a crystal. ...
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Bragg's law - intensity “sensitivity” to lattice spacing or scattering angle

I don't understand this sentence (emphasis added): A consideration of Bragg's law (nλ = 2dsinθ), i.e. the relationship between scattering angle (θ) and the interplanar spacing (d) shows that if ...
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1answer
368 views

Why do quasicrystals have well-defined Fourier transforms?

I was recently reading about quasicrystals, and I was really surprised to learn that even though they do not have a periodic structure, and only have long range order in a very different sense to the ...
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50 views

Electron scattering

I'm trying to figure out the missing step here, in a problem about X-ray crystallography. I am referring to the attached image: In the image, $A =$ electron density, $Z =$ distance traveled, ...
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30 views

When does a crystal take the shape of its Primitive Cell?

I know thought that a crystal, if annealed for long enough at high enough temperatures, will "shed" its higher index (higher energy) planes, leaving only its most stable form. This, I wrongfully ...
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148 views

Is the thickness of a sample related to the intensity of x-ray diffraction?

I understand that in general if we're adding more planes of atoms (increasing thickness of sample) then the intensity would increase because we have more constructive interference. But isn't there a ...
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1answer
188 views

X-ray and neutron powder diffraction: peak broadening due to crystal size

When analysing powder diffraction patterns, the broadening of peaks can be used to estimate crystal sizes. Smaller crystal size gives larger broadening according to the Scherrer equation: $$ \beta = ...
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1answer
62 views

If I take an XRD image of a single cubic unit cell, would the diffraction pattern simply be its reciprocal lattice?

I've seen the rings from powder diffraction images, and I read that each line is made up of a lot of dots, I was wondering if these dots are reciprocal lattice points of the structure. And if we ...
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1answer
50 views

Methods for determination of crystal lattice's homogeneity

I know of X-Ray diffraction, which produces a pattern corresponding to the inverse Fourier Transform of the lattice (reciprocal lattice). While this method is widely employed, it provides more ...
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1answer
1k views

How to calculate lattice parameter of wurtzite struture

I am trying to calculate lattice parameter of ZnO (wurtzite). I have found out the formula for calculating lattice parameter of this system from a research article. $\frac{1}{^{d^{2}}}=\frac{H ^{2}+ ...
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1answer
196 views

gaussian fitting of xrd peaks

I am reading a paper regarding the nano crystalline material with hexagonal crystal structure. In that paper in order to find out lattice parameter of hexagonal crystal structure they have fitted a ...
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1answer
227 views

Planes of graphite crystal on diffraction experiments

When doing electron diffraction on graphite (a popular experiment for students at universities) always diffraction at these two planes with distances $d_1$ and $d_2$ are observed: But a plane ...
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1answer
179 views

Algorithm for identifying planes in a Bravais Lattice

I have a lattice with Lattice Vectors $(\vec{t}_1,\vec{t}_2,\vec{t}_3)$ which are NOT orthogonal in general. How can I identify the atoms/unit cells that belong to a plane - that is normal to a given ...
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2answers
236 views

X-ray diffraction from Metals

Is X-ray crystallography is possible for metals? Or not due to absorption?
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1answer
185 views

X-ray diffraction (is it possible?)

Is it possible to extract full lattice structure of a crystal from any of X-ray diffraction methods? (especially that the diffraction pattern is 2-Dimensional most of times)
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112 views

How are X-rays focused? Specifically in XRD. Well do they even focus X-rays in XRD?

I read in a government website that reflecting an x-ray from a parabolic mirror followed by a reflection from a hyperbolic mirror results in focusing the x-ray, but this was for astronomical purposes. ...
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2answers
1k views

Is the index of refraction dependent on the wavelength of light?

I just read in some class notes for a crystallography class that there are no refractive lenses for X-rays because the index of refraction of most materials is close to 1. Is the index of refraction ...
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1answer
79 views

How can I cheat an XRD sample (~10 mg) from a total 1g required? How can I use for the background.

How much can affect (in terms of hump) my X-ray diffraction pattern the "amorphous" glass or maybe someone can suggest me other material to compensate for the small amount of the sample. Note: my ...
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1answer
195 views

Why can I add the Atomic form factors in the calculation of the Diamond Structure factor

When trying to calculate the structur factor for diamond I came across the calculation on the wikipedia. In the calculation they just add up the atomic form factors of alle the atoms in the unit cell ...
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1answer
547 views

Calculating diffraction patterns using FFT

I'm trying to write a piece of code that calculates a diffraction pattern similar to an X-ray experiment using a FFT. From my knowledge, the diffraction pattern for point particles can be calculated ...
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2answers
137 views

X-ray diffraction from crystals and time-averaging

To calculate the elastically scattered intensity of x-rays from crystals, one classically considers scattering from a free electron first and then one sums up the scattered em-fields of all electrons ...
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1answer
112 views

How to estimate number of Laue Spot

Why are "Laue Spots" spots instead of rings? Or is there an effective way to estimate the number of Laue spots? I can't find any formulas or theory concerning this issue. Thanks for your attention!
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2answers
526 views

X-Ray crystallography using Bragg's Law

I was looking up X-Ray crystallography using Bragg's Law: $2d\sin\theta = n\lambda$ and I can understand the values of everything except this integer value $n$. As far as my research got $n$ is ...