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Questions tagged [x-ray-crystallography]

X-ray crystallography encompasses the structural characterization of crystalline materials by means of X-rays. This is done most commonly by X-ray diffraction, which can be applied to monocrystalline materials or heterostructures, as well as to polycrystalline materials, where the later is referred to as powder X-ray diffraction.

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Why is intensity decreasing for higher orders of Bragg (x-ray)diffraction?

Bragg diffraction for x-rays by a crystal structure is governed by $$ n\lambda=2dsin\theta ,$$ where $n$ is an integer and the diffraction order, $\lambda$ is the x-ray wavelength, $d$ the lattice ...
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X-ray frequency or crystal structure: which was known first?

In the classical Bragg setup, one can determine the distance between crystal layers if the wavelength of a characteristic line is known or the other way round, calculate the distance if the wavelength ...
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Structure Factor for diffraction patterns

im trying to figure out myself the use of Structure Factor for Diffraction patterns. I have the Structure Factor for a monoatomic lattice $S(\overline G)=\sum_{i=1}^n f e^{\overline G \cdot \...
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Comparison between X-ray diffraction and slit experiment

Most diagrams regarding X-ray diffraction suggest that after hitting an atom, X-ray would get reflected. But then the method results in an interference pattern which means X-ray get diffracted. I am ...
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What is the difference between the structure factor of a crystal and of that liquid phase?

What is the difference between the structure factor of a crystal and of that liquid phase? Why the graph has smooth behaviours for liquid?
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Using Miller indices to determine interference from a particular plane in a crystal lattice

In terms of x-ray diffraction from crystals. I was wondering how you can use the miller indices to determine whether there will be constructive or destructive interference from a particular plane in ...
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How can I tell the cubic structure of different crystals?

So I have a couple of crystals I am analysing (LiF RbCl NaCl...) and I have the x ray diffraction patterns for them. How do I determine the different structures of these crystals as I need to ...
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Why the first peak in the X-ray diffraction of an amorphous solid has significantly high, in terms of intensity than the second peak?

In the XRD pattern of an amorphous solid we do not observe sharp peaks. Instead we see only diffused peaks. Why these peaks are diffused and more importantly why the first peak is significantly high ...
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Why is base centered lattice not possible in cubic system?

It still has symmetry,then why is the existence of base centered lattice not possible? Is it that it is impossible or is it that we have seen none like that in real?
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Issues with Miller indices

I have read that to find the intercepts of a plane represented by Miller indices is to take the reciprocal of each index. However, I noticed that does not give the original plane if we had to reduce ...
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Phase Retrieval and Oversampling

In signal and image processing theory, it is known that taking the Fourier transform of a zero-padded image gives the oversampled Fourier transform of the image. And that oversampling is a necessary ...
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What causes Lorentzian broadening of X-ray diffraction peaks?

In X-ray diffraction, the pseudo-Voigt model is a combination of Gaussian and Lorentzian distributions, and is often used to model peaks. The form of the peak is often described as $V(x)$ = (1-$\...
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Why/when can the chemical structure of crystals be assumed to be diffraction gratings?

Why/when can the chemical structure of crystals be assumed to be diffraction gratings? Like how does one know a priori, whether the structure is like a diffraction grating, if one doesn't yet know ...
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How to determine the degree of how high a symmetry of high-symmetry points in the first Brillouin zone?

For exmple, we have a hexagonal lattice with hexagonal Brillouin zone, shown in the picture The points $\Gamma$, K, M and $\Lambda$ are high symmetry points. Now, $\Gamma$ point is the highest-...
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calculating lattice parameter for rhombohedral mineral

I would like to know how to calculate the lattice parameter values for rhombohedral mineral (tourmaline) from the d-spacing values produced by the diffraction pattern. Thanks, tarek
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Meaning of crystal orientation

If I have a crystal, say (001)-oriented ABO3, what does the 001 imply, from an experimental perspective? I understand that the 001 is referring to a plane as described by Miller indices, but what is ...
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Miller indices and FCC structure - non-existent planes

Below is a copy from Kittel's Introduction to Solid State Physics, 8th edition, page 42. It is a picture to illustrate that in FCC structures (loosely said and exactly cited) "no reflections can ...
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SAXS: Why would a second order peak behave differently than first order?

What is the significance of a second order peak in SAXS and during an assembly of nanoparticles, why would it have a different shape over time: What are factors that are unique to first or second ...
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How to calculate the lattice constant of NaCl using chemical information? [closed]

More specifically, how would I show that: $a_0=\sqrt[3]{\frac{4M}{N_A\rho}}$ where $a_0$ is the lattice constant, M is the molecular mass of NaCl, $\rho$ is the density of NaCl, and $N_A$ is ...
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Miller indices of planes and axes and some crystallography definitions

I am reading Kittel's book on Solid State Physics. And while it is a good book, the basics of crystallography are not well explained. One of the issues is various names that are not properly defined. ...
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Why is $K_{\alpha,3/2}$ always more intense than $K_{\alpha,1/2}$ in copper?

Consider characteristic X-ray emission from copper. The $K_{\alpha}$ line is a doublet because of the spin-orbit interaction. But why is the $K_{\alpha,3/2}$ line always more intense than the $K_{\...
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Finding the atomic scattering factor of iron using X-ray powder diffraction

I need to find the atomic scattering factor of iron at room temperature using X-ray powder diffraction. I'm exposing the iron powder sample to $\text{Mo}K_{\alpha}$ radiation and using a Zr filter. ...
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Debye-Waller factor from X-ray diffraction data

I'm conducting a X-ray diffraction experiment for lab, but am new to solid-state physics and crystallography. I have to find the Debye-Waller factor (DWF) of Al at room temperature using X-ray powder ...
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Structure factor calculation for non-cubic lattices

I have an equilibrated trajectory from a molecular dynamics simulation and I would like to calculate the structure factor using the atomic positions. I think I am able to do it right for cubic ...
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Why do we do a linear regression to find the minimum wavelength in a X-Ray diffraction spectrum?

As part of a an experiment, I was to determine the minimum wavelength emitted by an x-ray source through analysing the detected count rate (detected by a GM counter) of a diffracted x-ray source, via ...
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How to find which crystal planes are symmetric

Is there a strict mathematical procedure to find all equivalent planes given a unit cell and a particular plane of interest? For example, consider a conventional FCC unit cell and the (100) plane. I ...
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Crystal space groups with -1 at origin instead of an axis perpendicular to projection plane

I'm trying to figure out how to tell from the symbol of the space group, whether I should place the center of symmetry (one that has no axis perpendicular to the projection plane going through it) at ...
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Relative intensity in powder method

I cracked KCl and made two samples. One is a fine powder, another is a coarse powder. Using these samples, diffraction intensity was measured. The results were as followed. ...
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Analyzing composition of a mineral using SEM

If I have a mineral in which I did a SEM analysis on and got the data (elements and their wt% with Std. Dev., MDL, atomic % oxide % and k ratio) how would I go about quantifying the sample's ...
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285 views

How to find the Miller indices for a family of planes

So I'm a bit confused about this question This question asks for the miller indices for the "families of planes". Is there a single set of Miller indices for each cubic unit cell which I can use to ...
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How do we find the angle of incidence $\theta$ in a Bragg diffraction experiment?

Suppose I have a crystal of which I like to determine the distance $d$ between the lattice planes. We can use a Bragg diffraction experiment to do so by making a plane wave of X-ray radiation with ...
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Width of X-ray diffraction peaks

I have this problem: Prove that width of X-ray diffraction peaks is a value of order $N_{cell}^{-1/3}$ where $N_{cell}$ is number of number of cells in a crystal. Amplitude of the secondary wave is ...
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Medical X-Ray - why no diffraction?

When I go to a doctor and he wants to see my bones he uses X-Ray. My bones contain crystalline material called hydroxyapatite. Why the result of imaging is the shape of my skeleton and not just XRD ...
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Is there a known physical crystal for each space group? [duplicate]

Group theory tells us that there are 230 crystallographic spaces possible in 3D space. Is there physically at least one crystal known to form every in each space group, or are certain space groups ...
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Does X-Ray Diffractometry actually involve diffraction?

To my understanding, diffraction is the bending of waves as they pass by edges or go through slits. However, I cannot find a description of x-ray diffractometry that actually involves diffraction. All ...
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Why use simple cubic reciprocal lattice vector to determine Miller indices?

Bragg diffraction: $$ d_{hkl}= \frac{\lambda}{2sin(\theta)}.$$ This equation would allow us to determine the lattice spacing ($d_{hkl}$) of parallel crystal planes given that we observe an intensity ...
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XRD with random orientation

How can XRD examine a randomly oriented crystal lattice. Doesn't it needs a tidy structure? Why does the diffractogram always show the same image even when we change the sample(the sample shoulder ...
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How can a monochromatic X-Ray tube produce a spectrum in XPS?

I thought that if we use monochromatic source, we can only get one peak, if it exists. Because Photoelectric Effect allows only the electron that have the corresponding frequency(energy level) that ...
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How do I determine the $n$ integer in the Bragg's law?

I'm studying X-rays crystallography. The basic assumption is that if I let some X-rays scatter on a crystal the atoms act as sources of new waves. Considering two waves that hit two "neighbouring" ...
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X-Ray Diffraction: Why does FCC have MORE peaks than SC?

Reading Kittel, I understand that the structure factor of an fcc lattice is such that there is only scattering from those planes with all even or all odd indices. He then shows XRD for KCl and KBr ...
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Crystallite size in thin films

First thing is, what is the difference between grain size and crystallite size? Well, I have basic knowledge between the two. As far as I know the grain size is single crystal within the bulk/thin ...
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Why is amplitude of x-rays scattered by crystal is less than the amplitude of rays incident on crystal? [closed]

Why is amplitude of scattered rays less than the amplitude of rays incident on crystal? Also what will be the situation in case of free electrons?
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Determine geometry structure factor for plane within the crystal

I got the problem that isn't solved yet from my lecturer. He asked me to determine geometry structure crystal from plane : (2 1 1), (2 2 1), and (2 2 2) in the cubical crystal system for SC, FCC, and ...
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How to go from space group to crystal structure?

I'd like to easily be able to define a group of lattice points for any crystal structure, with or without a basis. It seems the space group is the most commonly given quantity describing the ...
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Why aren't there Bragg peaks from sublattices of the unit cell?

I've been struggling with what is probably a basic question about Bragg peaks, diffraction, and I guess geometric structure factors. Basically, as I understand it, Bragg peaks depend on the symmetry ...
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711 views

Miller indices vs Laue indices?

I am looking at the difference between the Miller indices and Laue indices in crystal structures. I will denote the former by $hkl$ and the latter by $HKL$. I understand that $hkl$ must be coprime ...
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174 views

X-ray experiment: Bremsstrahlung radiation and Bragg's law

I've done an experiment in which X-rays were diffracted through a NaCl crystal and also a LiF crystal to investigate the position of the K alpha peaks and also its Brehmstrallung radiation. I have ...
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Noncentrosymmetric crystal symmetries; list of polar and chiral space groups

In the following webpages, I can find a list of polar or chiral point/space groups. http://symmetry.otterbein.edu/tutorial/applications.html https://en.wikipedia.org/wiki/Polar_point_group However, ...
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Why peaks (of same order) in X-ray diffraction have different intensity?

The image shows the intensity vs 2-theta plot of X-Ray diffraction pattern obtained from an aluminium target. Why is it so that as the 2-theta increases the peak intensity decreases?
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How to determine this c-lattice parameter using x-ray diffraction?

I have an x-ray diffraction data of a single xtal with clear (002),(004),(006) and (008) intensity peaks. I can calculate the c-lattice parameter for each peak. But then do I average them or is there ...