XRD graph has a shifted peak when vary contents materials or vary temperature. The peaks on plane changed such as transfer to another degree, higher intensity, lower intensity. What do these indicate?
actually, residual stress can shift some peaks in one direction, and other peaks in the opposite direction. This is due to the need to balance stress at grain boundaries, and satisfy constraints on the strain tensor (for example a tensile stress along one direction must be balanced by a compressive stress in the normal direction, so the direction of peak shift is often hkl dependent.
increasing the intensity and shifted peak to high angle with increasing temperature meaning the increasing crystal quality and relax strain between thin film and substrate the low intensity meaning power crystalline of your sample
If I compared tree peak, first pane shifted peak move on right hand, second peak is a middle, and last peak shifted to left hand, How will explain these affect?
If you change the temperature or the composition of a material, the until cell dimensions (lattice parameters) will change which will result in a shift of peaks (and not all my the same amount even in the same direction). Changes in intensity of peaks can be a result of a number of things, most likely either a composition change in the unit cell or a change in ordering. Also higher angle peaks will decrease in intensity with temperature faster than lower angle peaks. If you have anisotropic thermal parameters the change will be hkl dependent as well as angle dependent. If you want to truly "explain" these effects you will have to refine the structure at each temperature or composition and look for correlations between crystallographic properties and temperature(by fitting the thermal expansion coefficient) or composition. I have no idea was Sha is talking about, but it obviously applies only to a very specific type of material, and most likely has nothing to do with your case.
It s all about changing the lattice size. By heating we have dilatation hence a peak shift. If you replace one atom from the lattice with a foreign atom again the distance changes and again a peak shift
The shift of the peaks show the lattice structure of materials and their deviation shows the lattice is changing may be due to stresses or due to formation of other phases. phases which are forming at different temperatures.
The shift of diffraction peaks towards higher diffraction angle means crystal lattice is compressed and if the peaks are shifted towards lower diffraction angle that means lattice is expanded. If you cool the sample or pressurize the sample your peaks will be shifted to the higher angle.
What does the other that we know from XRD peaks?
"What does useful about crystallite size and lattice strain, what are they tell about characterization? "
For crystallite size, how it different from grain size? and also either high lattice strain or low lattice strain value, how these have effected to the structure?
Grain or crystallite size will not influence the peak positions. The type
(Unixial, triaxial, rolling etc) of strain will determine the type and amount of elastic strain in the lattice, which can manifest itself in a variety of ways. In some cases all peaks will shift in the same direction, in others the direction of peak shify is hkl dependent , for example uniaxial compression or tensile strain.
Contrastly, paper publish show XRD peaks, not only dope atoms or varies temperature that XRD peaks not shift but they have different intensity, what will these tell us?
How will I separate between cubic phase and rhombohedral, if main peak rather cubic phase than rrhombohedral, I found at 2theta = 55 has a few split. How will I find a lattice and beta angle?
you need to learn how to index peaks. Until you do, no one can answer your question unless you send the data and they do it for you.
actually, residual stress can shift some peaks in one direction, and other peaks in the opposite direction. This is due to the need to balance stress at grain boundaries, and satisfy constraints on the strain tensor (for example a tensile stress along one direction must be balanced by a compressive stress in the normal direction, so the direction of peak shift is often hkl dependent.
When XRD peak moves either right or left ca mean there are constraints or machining, either residual stresses, therefore, they are positive or negative, depending on the displacement peaks
"residual stress can shift some peaks in one direction, and other peaks in the opposite direction. This is due to the need to balance stress at grain boundaries, and satisfy constraints on the strain tensor (for example a tensile stress along one direction must be balanced by a compressive stress in the normal direction, so the direction of peak shift is often hkl dependent."
Can you give a reference please? ... Lawrence Margulies
Doping another atom into any structure lead to peak shift because atomic radius substitution into atom vacancy is difference.
The crystal structure is not pure. It includes another phase or structure (atom) etc. that cause to shıft in the peak positions.
If you are interested in the answer then I suggest the following to help stop intellectual meandering:
This will help us help you better :-)
https://www.flickr.com/photos/85210325@N04/10221065324/in/album-72157645018820696/
if you have noticed a peak displacement, this means that you're lattice parameters got changed.
"But if we are talking of a bulk material, or other particular cases, yes, they will shift accordingly to the orientation! Thanks Lawerence Margulies, never thought on that before"
Most likely because you've never seen or visualized the 2D diffraction pattern from a polycrystalline sample either with photographic film or with a 2D XRD detector. As Lawrence pointed out, individual grains may shift based on local stress/strain conditions as well as orientation of individual "grains" when bulk is deformed.
In thin films the stress/strain imbalance between substrate and film (epi and polycrystalline), I would have to think there to be some sort of an interface layer with additional dislocations to transition from compressive to tensile and vice versa.
https://www.flickr.com/photos/85210325@N04/14348488010/in/album-72157645018820696/
https://www.youtube.com/watch?v=QRcj_t1WgVs&index=21&list=PL7032E2DAF1F3941F
"When XRD analyzed, what does it mean when a shifted peak is either left hand or right hand"
Let us assume left is lower angle and right higher :-)
As enumerated earlier, there are many causes to peak shift including:
In order to reduce equivocation most astute experimentalists would include in the analysis a "known standard" to calibrate the instrument and truly compare multiple conventional linear diffractograms from that instrument, properly normalized.
Attached are some alternative methods of acquiring and analyzing powder diffraction data more effectively and much FASTER:
https://www.researchgate.net/post/How_do_I_calibrate_the_diffractometer_2Theta_angles_with_this_powder_diffractogram_of_corundum_standard_from_a_Bruker_D8_XRD_instrument
https://www.researchgate.net/post/Bloody_Murder_Why_is_there_nearly_such_a_visceral_response_to_any_disruption_to_alignment_of_existing_diffractometers_by_XRD_users_technicians
https://www.researchgate.net/post/Is_this_a_reasonable_way_to_eliminate_effects_of_sample_surface_misalignment_with_the_diffractometer_axis_Theta-2Theta_Diffractograms
iRavi Ananth indicates that oritention of crystal may have an effect on the shifting of peaks in his statement,who can heip me to explain it theoretically?
- Badges
- Science topic
- Similar topics
- Chemistry
- Theoretical Chemistry