Dear Ahmad,

you should know that different isotopes of the same atom species only differ in the number of neutrons in the atomic nucleus. The number of protons and thus the charge of the atom is not altered, neither its electron orbital configuration. Therefore there is no reason why different isotopes will cause different bonding strengths and/or bonding type to its neighbor atoms resulting in a change of atomic distances or even a change in  the type of lattice they set up  together. 

The XRD pattern remain the very same.

@ Ravit: what could be the reason for a change in peak width/shape from your point of view?

@ Mohd: what could be a reason for change in intensity from your point of view?

If the crystal structure keeps uchanged, the XRD pattern will be the same. Normally, there will be no change in XRD pattern.

 The factors affecting XRD patterns are: peak positions, intensity and shape (including width) of peaks. The first parameter is related to phase identification and lattice parameter, the second one among others to texture or phase content and the last parameter is affected by lattice distortion, grain size et cetera. The first two parameters usually will not change when comparing between isotope of a material, since the difference in isotopes are due to change in neutrons(i.e. crystal structure will not change). The third parameter, however, might changed, which can affect the peaks broadening or shape.     

Dear Ahmad,

you should know that different isotopes of the same atom species only differ in the number of neutrons in the atomic nucleus. The number of protons and thus the charge of the atom is not altered, neither its electron orbital configuration. Therefore there is no reason why different isotopes will cause different bonding strengths and/or bonding type to its neighbor atoms resulting in a change of atomic distances or even a change in  the type of lattice they set up  together. 

The XRD pattern remain the very same.

@ Ravit: what could be the reason for a change in peak width/shape from your point of view?

@ Mohd: what could be a reason for change in intensity from your point of view?

The answer from Mr. Gerhard Martens is perfectly alright. Thank you Gerhard.

To follow up on Dr Martens answer which should be sufficient on its own, but oddly, according to the ratings it's not. X-rays do not interact with the nucleus of atoms, X-rays scatter because of its interactions with electrons and the amount of electrons does not change when the isotope changes. So XRD patterns do not change at all if the only difference is the isotope ratio. The isotopes might have an influence, but only indirectly and if the isotope is radioactive. When the isotope is radioactive, two changes in the crystallinity of the sample might occur affecting the XRD pattern: amorphisation of the structure, causing a broadening of the XRD peaks, and the daughter product of radioactive decay will have a different chemistry also affecting the broadening of the peaks. 

On the other hand, neutrons scatter because of interactions with the nucleus, so neutron diffraction patterns do change with a different isotope of the same atom. But the only direct change that will be observed from the change in isotopes is the aspect ratio between peaks in the diffraction pattern. So for example by analysing two samples of a hydrated crystal with one where all the water is H2O, and one where all the water is D2O, you can determine the coordination and configuration of water in the structure perfectly.

Dear Pieter Bots

Thanks

Does it apply to FTIR as well?

FTIR does appear to change with different isotopes, but I don't know why....

Peter Kapusta

Thank you very much for your sincere efforts. Actually  I need a straight forward answer to my question like given by Pieter Bots. Thanks Bots

Let be more specific, I have synthesized hexagonal boron nitride nanostructures by using B-10 and  B-11 separately with other precursors. For  both B-10 and B-11, I got almost no change in the peaks position reported by XRD and FTIR, however, I got a change in raman shift when I replaced B-11 with B-10 in the precursors. Actually, I was expecting a change in the FTIR peak, however, it remained the same. 

Please comments, why I did not get a change in the position of FTIR peaks. 

@ Peter Bots and  Pervaiz Ahmad

IR spectra are among other effects affected by the vibrational modes. Thus when changing the masses involved in the vibration, such as in the case of substituting one isotope by another,  you will have different resonant frequency/ies showing up.

So I will expect changes in the IR / FTIR with different isotopes.

@ Peter Kapusta 

 Thanks for your clear statement with respect to down votings.  Down voting in this series of answers is dishonorable, especially in the case of Ravit's and Mohd's answers collecting 3 down votes each at the moment. Their answers are right.

I do agree with the ravit's straight forward answer. Because, X-ray diffraction ray is unaffected by the neutorn Thnx Ravit for your nice answer.

It varies

Dear colleague Dr. Mahadeva,

 you may comment on why XRD diffractograms vary when atoms are substituted by  their isotopes?

I think many of  us are eager to know this.

Many thanks in advance.

It is inappropriate to use this forum to pass judgement on assumed "down-voting" championing on the part of those asking questions and seeking knowledge and understanding, particularly since down-voting is supposed to be anonymous. There are other social media at your disposal for such negative comments. Let's keep this forum just for discussing technical and scientific questions and not for finger pointing.

I would to know what happens to the crystalline planes when increasing the deposition thickness on a substrate

Dear Radhika,

you should post this question as a new one here in RG. The origin of the starting question of this series is 2 years old. So only the followers (19 persons at this time) of this series will see your query without scanning the very old questions.