Dear all,
I have found that among reasons for the shifting of XRD peaks to higher two theta positions with increased annealing temperature in the nano regime are many including cation re-distribution, defect reduction, enhanced crystallization, etc.
Could you provide me some reference papers for these interpretations?
Best regards
Hi Brahim
Great question. XRD gives information about the interlayer spacings in crystalline materials. When you anneal or calcine nanocrystalline materials, interparticle sintering will occur resulting in an increase in the mean crystallite size in your sample. As the mean crystallite size increases, the interlayer spacings between particular planes in your material will decrease slightly and for very large crystallites resemble closely those of the bulk material.
Accordingly to Bragg equation, 1/d is proportional to sintheta. Thus, as d gets smaller with increasing annealing temperature (i.e. as your material becomes more crystalline), sintheta and therefore 2theta will increase, consistent with you experimental observations.
Dear Geoffrey
Thank you for you answer and this huge enlightenment.
I will be very thankful if you provide me some references
Best regards
Hi Brahim
this paper on the annealing of nanocrystalline CeO2 provides a good example.
Temperature Effects on the Crystallization and Coarsening of Nano-CeO2 Powders
http://dx.doi.org/10.1155/2013/208614
Best regards
Geoff
Dear Aswin,
Thank for you answer, but I think the shift in these papers does not concern XRD patterns?
Best regards
In the case of partial substitution material, peak shift can be caused by strain. However, the effect of temperature doesn't bring significant change on shifting of the XRD peak. It seems logical that the influence of temperature on crystallization.
Dear Mohamed
Thank you for your important answer
could you please provide me with some related paper references
Best regards
Hello Brahim,
Due to various defects present in material may cause the shift in XRD peak position depending on type of strain in the crystal i.e. tensile or compressive strain, the peak position shift respectively towards higher or lower angle
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