this is happening because your dopant ions have been incorporeted into the lattice and changed the lattice constant of your host. that is the evidence that your dopant incorporeted sucessfully 

The main reason in your case is the increase/decrease in the lattice parameters that is reflected by the shift of diffraction peaks. This effect is mainly due to the difference in ionic radii between the main element and the dopant ion 

As all have mentioned. the inclusion of other ions (such as dopants) will cause a shifty due to changes in lattice parameters.  I have seen that in TiC when small amount so of oxygen was present in the lattice

 Due to the change in lattice parameters.

If we modify the original system by using a dopant, it affect the lattice/unit cell of the material. Change in lattice parameters result in shift in XRD peaks. You can also calculate the lattice strain by using the broadning of the XRD peaks.

is the effect of dopant. 

One possible effect of dopant atoms incorporated into the lattice is decreasing (or increasing) of residual stress. When nanocomposites are in tension stress all peaks are shifted to higher angles (in compression to lower angles). 

change in the parametre cristallin

Dear Amin,

The shift in the peak during the XRD analysis is due to (i) due to linkage between host and doped particle (ii) due to change in the size of the host particle (iii) change in the binding energy and due to change in mechanical properties.

Dear Amin,

The dopant atoms are being taken into the host structure substituting for some of the host atoms and thus causing the structure to either contract or expand. If the peak shift is to higher angles the host structure is contracting and vice-versa. Clearly if the particles are of n.m. size the diffraction peak will be very diffuse and broad as the structure of particles will be strongly reflected in their surface structure which is highly disordered.

I confirm all above beside

peak shift maybe attributed to

1-     changes in stoichometric composition by doping.

2-     Instrumentations (Doppler effect during counts)

3-     Microstructure parameters (crystallize size and lattice strain"

4- Thermal annealing

How can we differentiate or how can we identify the reasons? because if this could be the reason in peak shift what would be the main factor than, what are the circumstances in which we could identify the shift factor? Essam R. Shaaban

Some of the motives for the shif of the diffractions peaks are:

1. When the surface of the sample doesn´t coincide with the surface of the holder. This effect produce a systematic shift of the peaks.

2. Uniform strain or compression produce systematic shift of the peaks.

3. Doping the sample with an element of different atomic or ionic size than that which is sustituted. This sustitution can be systematic in all directions or along one direction or plane.

Dear Naveed,

Actually, research means to identify the all possible causes either physical or chemical. Yes, you point out very important criteria that the cause is due to one factor or several factors indulge in it. Nano-physics based on Quantum mechanics and that part always tells possibilities.

Ok, come in to your question. The main cause is change in the lattice structure. The all other causes arises due to change in the lattice structure in XRD measurements. If the lattice size increases the peak shift arises before the peaks of host particle and if lattice size decrease the peak shift after the peak of the host particle. 

With best regards.

1. Random Stress due to intercalation of foreign atoms.

2. Stoichiometric inhomogeneity

3. Polytypic structure changes  

  are the key factors for the peak shifts. For X-M-X type structures these reasons are prominent.

Firstly, due to dopant, secondly instrument,  and may be due to change in lattice structure

It may change due to annealing at higher temperature, at high temperature the crystal may start to grow

Among  the parameters mentioned for shifting the XRD peaks, I think doping changes the lattice parameters and the XRD peak shifts in the opposite direction. That is, if the dopant leads to an increase in the lattice constant then the diffraction angle 2θ decreases and vice verse. Annealing can shift the XRD peaks but not too much it will have higher effect on the FWHM.

The shift may be due to the difference in the ionic radii of the main element and the dopant.

The shift of the peak position in x-ray diffraction can be attributed to the change of the lattice constants of the unit cell of the investigated crystal system.  This may result in expansion or shrinking of the unit cell depending on the ionic radius of the dopant. 

Please post your XRD data along with reference scan and describe the composition of your material better.

due to different ionic radii

You can find a good summary of possible reasons for peak shift in the attached pdf.

Best regards

because due to different atomic radii

how can we account for a broader peak?? means large fwhm???

Broadining of the diffraction peak can be due to the small nano size of the crystalline sample, strain and instrumental factors. Fitting of the peak can provide you with the FWHM from wich the particle size and strain can be deduced after elimination broading due to instrumental factors by considering diffraction standard material such as silicon.

If it is a bulk sample, the primary reason could be attributed to the change in the orientation of the crystal lattice with respect to an inertial frame of reference. That means the miller indices would be different, and that can be caused due to either different ways of sample preparation, or due to different sample thickness where the orientation of the crystal planes vary with the thickness.

0.2 Theta variation is allowed as per the instrument manufacturer's. More than this difference was observed means, there might be sample mounting or disturbed surfaces on the slide / sample holder. The difference may be justified based on the scientific discussion of physio-chemical property of the compound.

The reason for the shifting of XRD peaks, in general, can be any of the following:

1. Change in the chemical composition (most likely in your case). The peak shifting due to the chemical pressure is caused by the change in lattice parameters as per Vegard's law and Shannon-Prewitt radii.

2. Instrumental error during the measurements (in the form of zero or displacements). But this effect should be common for all of your samples if the XRD measurements are performed on the same diffractometer, without any change in calibration.

3. The expansion or compression of the lattice caused by stress or temperature.

In any case, I would suggest you to perform Rietveld refinements of your XRD patterns for detailed analysis. You can get most of your queries resolved from the refinements. Microstructures parameters (crystallite size and local random lattice strain) generally result in the broadening of the XRD peak and do not contribute to shifting.

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.

As you change the composition, Lattice parameter 'a' gets changed and comparing with the bragg equation: nlamda =2dsintheta, d is related to 'a' directly, hence as 'a' increases, theta decreases and as 'a' decreases theta increases. This theta change is reflected as peak shift in the XRD graph.

There are several reasons ......

Indirectly speaking......any factor that can affect the d-spacing can be the cause of the peak shifting........Furthermore.....if peaks shifting observes for all peaks...then it is better to relate it with the instrumental error.

changes in stoichometric composition by doping.

Instrumentations (Doppler effect during counts)

Microstructure parameters (crystallize size and lattice strain"

Thermal annealing

The peak shift in XRD is related to the structural changes on the synthesized product. As the dopant concentration increases, there may be an increase or decrease in crystallite size, depending on the nature of the peak shifting which is closely related to broadening or shrinking of the XRD peaks. I hope the information will of immense benefit to you.

As many has pointed out the 3 main reasons for peakshifts. It is possible, though to determine which one is responsible:

If the shift gets larger towards low 2theta, it is sample displacement

If the shift is constant trough out 2 theta, it is a misalignment in the system

In all other cases, it is sample related, but generally there will be an increased shift towards high 2 theta ( very notable for cubic materials )

Mechanical strains of tension and compression in bulk materials, their doping heating, and radiation treatment can be followed by broadening and shifts of XRD peaks in different ways. Simply according to Cosine low or in dependence on possible distortions of crystal lattice. The latter is the most interesting and difficult situation to understand

worth noting the impact of sample loading on the peaks shift of XRPD or PXRD. It can be identified if the whole diffraction peak pattern shifted.

The structural changes on the synthesized product are related to the peak shift in XRD. one of the reason is it is the dopping effect.

Could anyone kindly confirm if a shift to the right (i.e. higher diffraction angle) necessarily implies stress or compression of the lattice?

@idris a shift to right means expansion of the lattice. It can be be due to stress, substitutional elements, or a nonstoechiometric phase

Flemming B. Grumsen , thank you for your answer. After the perusal of classical literature and further reading, I found out that the shifting of the peak to the right (i.e. higher diffraction angle) implies lattice contraction while a shift to the left implies an expansion in the lattice. In my area of expertise, the popular and widespread belief is that lattice expansion engenders improved performance which is not necessarily true. Recent articles in nature and science have shown that contraction in the lattice could be used to achieve improved performance of materials. Lattice engineering is an indeed interesting area that could give us more insights into the behaviour and property of materials. I hope this helps someone out there and save them the time I spent to gather this information.

Idris Temitope Bello sorry for the incomplete answer

If the peak shift is due to compressive stress you will measure a larger d spacing (shirt to the left), due to that you measure the d spacing normal to the stress direction. This is related to the poission ratio

You may extract the answer of your question from the below achieved data from our research analysis.

The seventy two Sb-based detached single crystals have been grown by the indigenous system (self-designed and developed in our lab) Vertical Directional solidification Process (VDS-Process). Research investigation of these crystals are reported here.

First of all, care had been taken for the calibration, standardisation and alignment to avoid - i) for the larger shift towards 2Theta, which is due to sample displacement, and ii) for the throughout constant 2Theta is a misalignment in the system.

The as grown entire detached ingots different samples were characterized. Specifically, XRD diffraction measurements informations had been obtained from the FWHM, diffraction peak height and shifting either left or right site of the 2Theta.

For illustration, In(1-x)GaxSb (x

Taking Debye’s law into account 2dhkl(Sinθ) = nλ, let's say the peaks shift toward the small angle sides, the interplanar distance (d) increases and the host lattice expands. The peak shifting towards small angle side at high concentration of dopant ions could be accredited to ions inhabiting the interstitial sites in host lattice and vice versa.

Hi all,

in a phase identification for iron oxide mixture ( at least 4 compounds), what is the acceptable 2 theta shifting to either direction between experimental and database such as (PDF+4)?

For example from the experiments. 2theta =21.25. and database 2theta = 21.42

I am mainly interested in the phase-only.

Thannks

It is because od lattice strain or lattice parameter change. This is also due to the different ionic raddii of dopant and the host atoms.

There are two types of peak shifts, to the right and to the left.The two confirm the presence of a distortion in the crystal lattice.

✓This is due to the rearrangement of the deposited crystals, which creates compressive stress (to the right).

✓The left shift is attributed to the expansion of the crystal lattice by incorporating larger atoms into the main lattice (alternate or interstitial).

The shift in the peak during the XRD analysis is due to :

1- due to linkage between host and doped crystal particle

2- due to change in the size of the host particle .

3- change in the binding energy and due to change in mechanical properties of the particles.

A straightforward answer is: lattice expansion or contraction can cause a peak shift in XRD. A shift to the left means expansion and to the right means contraction.

To get a sustainable solution to your problem, please refer to the preprint article given at link DOI: 10.13140/RG.2.2.27720.65287/3 or at link https://www.researchgate.net/publication/352830671.

The peak shift in XRD (X-ray diffraction) can be caused by several factors, including changes in lattice parameters, microstrain, and crystal size. When the lattice parameters of a crystal change, the diffraction angles will also change, resulting in peak shifts. Microstrain can also cause peak shifts by distorting the crystal structure and altering the diffraction patterns. Finally, changes in crystal size can affect the diffraction angles and cause peak shifts. Other factors that can contribute to peak shifts include sample preparation, instrument calibration, and data analysis methods. Therefore, it is important to carefully consider all of these factors when interpreting XRD data and identifying peak shifts.

You can also check:

Analyzetest.com/category/analyzing/xrd