X-Ray Diffraction: Single Crystal Peak?

In summary, the number of peaks obtained in the theta-2theta technique in XRD depends on the radiation used and the setup of the XRD system. With monochromatic radiation and a single crystal, only one diffraction peak may be obtained in most positions, while with white radiation, multiple peaks may be obtained at once. The crystal must also be rotated in 3D for more than one rotation axis to get peaks.
  • #1
dg88
10
0
Hello all,

I have a basic question with the theta-2theta technique in XRD. Here it is:

If I have a single crystal material and I perform the above mentioned characterization. Should I get one diffraction peak associated to the orientation of the bulk crystal or should I get many peaks. This doubt arises because of two reasons:
1)as we scan theta in a given range, the direction of the wave vector changes. This wave vector coincides with different lattice directions as we change theta.
2) The bulk crystal has all the crystal directions [hkl] within it. So if we do the Ewald construction, I feel that the wave vector sphere should intersect with more than one reciprocal lattice point rather than just one.

Thanks in advance
 
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  • #2
I am not familiar with XRD but TEM.
Based on the formula 2dsinθ=λ， I thought that many peaks will be obtained when we scan in a not small range.
 
  • #3
dg88 said:
Hello all,

I have a basic question with the theta-2theta technique in XRD. Here it is:

If I have a single crystal material and I perform the above mentioned characterization. Should I get one diffraction peak associated to the orientation of the bulk crystal or should I get many peaks. This doubt arises because of two reasons:
1)as we scan theta in a given range, the direction of the wave vector changes. This wave vector coincides with different lattice directions as we change theta.
2) The bulk crystal has all the crystal directions [hkl] within it. So if we do the Ewald construction, I feel that the wave vector sphere should intersect with more than one reciprocal lattice point rather than just one.

Thanks in advance
It depends on the radiation you use (and also the XRD system)
If it's monochromatic and you have a single crystal, it's very likely that in most positions you'll get no peaks. The crystal need to be rotated in 3D so more than one rotation axis is required. If yo have a powder diffraction setup, with only one axis, you'll need quite some experimenting to find the positions for the peaks.

If you use white radiation then you could get many peaks at once (Laue setup).
 

1. What is X-ray diffraction and how does it work?

X-ray diffraction is a technique used to study the structure of materials by analyzing the diffraction pattern produced when an X-ray beam passes through a crystal. The X-rays interact with the electrons in the crystal, causing them to diffract in a predictable pattern. By measuring the angle and intensity of the diffracted X-rays, we can determine the arrangement of atoms within the crystal.

2. What is a single crystal and why is it important for X-ray diffraction?

A single crystal is a solid material with a regular and repeating atomic structure in all three dimensions. It is important for X-ray diffraction because it produces a distinct and sharp diffraction pattern, making it easier to analyze and interpret the data. Single crystals also have a higher degree of order compared to polycrystalline materials, allowing for more accurate structural analysis.

3. How is a single crystal peak determined from an X-ray diffraction pattern?

A single crystal peak is determined by measuring the angle and intensity of a specific set of diffracted X-rays. These angles and intensities correspond to the spacing and orientation of atoms within the crystal lattice. By comparing these values to known crystal structures, we can identify the peak and determine the crystal structure of the material.

4. What information can be obtained from a single crystal peak in X-ray diffraction?

A single crystal peak in X-ray diffraction can provide valuable information about the crystal structure, including the unit cell dimensions, atomic positions, and symmetry of the crystal lattice. It can also reveal the presence of impurities or defects within the crystal.

5. What are the applications of X-ray diffraction with single crystal peaks?

X-ray diffraction with single crystal peaks has a wide range of applications in materials science, geology, chemistry, and other fields. It is commonly used to determine the structure of unknown materials, identify new compounds, and study changes in crystal structure under different conditions. It is also an important tool in the development of new materials and pharmaceuticals.

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