To be more clear. Three samples was characterize by XRD spectroscope (the sample is Graphite powder, Graphene oxide powder and Graphene oxide paper). The results indicate that the peak intensity was decreased from 180000 for graphite to 20000 for Graphene oxide powder, and more than 5000 for Graphene oxide paper. The peak of GO and GO Paper showed a dramatic shift form 2θ angles = 26.5 for Graphite to lower 2θ angles (9.89° for GO and10.27° for GO paper) and was wider than that of the Graphite. How I can explain difference in the peaks intensity, position and peaks broaden of these samples? The attached present these results.
For a polycrystalline solid consisting of strain-free crystallites, the XRD peak broadening for a particular (hkl) diffraction line is a function of the mean crystallite size in the direction normal to the corresponding (hkl) lattice planes, while peak position is a function of d-spacing. Hence for crystallites having a plate-like habit (as in the case of graphite) one would expect the XRD peaks correspondind to the direction normal to the plane of the plates to show considerable peak broadening (when the thickness of the plates is small). In fact, the thickness of the crystal (D) in the direction normal to the diffracting planes is related to the corresponding peak broadening (L) by Scherrer's equation: L = K(lambda)/Dcos(theta), were K is a constant, lambda is the X-ray wavelength and theta is the Bragg angle.
For a polycrystalline solid consisting of strain-free crystallites, the XRD peak broadening for a particular (hkl) diffraction line is a function of the mean crystallite size in the direction normal to the corresponding (hkl) lattice planes, while peak position is a function of d-spacing. Hence for crystallites having a plate-like habit (as in the case of graphite) one would expect the XRD peaks correspondind to the direction normal to the plane of the plates to show considerable peak broadening (when the thickness of the plates is small). In fact, the thickness of the crystal (D) in the direction normal to the diffracting planes is related to the corresponding peak broadening (L) by Scherrer's equation: L = K(lambda)/Dcos(theta), were K is a constant, lambda is the X-ray wavelength and theta is the Bragg angle.
1) Different peak positions tell you that Graphene oxide and Graphite powder have different crystal structure.
2) Narrow peak for Graphite tells that it has much bigger crystalline size than other samples.
3) You can forget about intensity in this case. If you had a mixture of different samples the integral intensity (not peak intensity!) would give you relative concentration of different phases.
Different peak positions tell you that Graphene oxide and Graphite powder have different crystal structures. In addition, Narrow peak for Graphite tells that it has much bigger crystalline size than other samples.
Dear prof Carlos, Aram, Mohammad
I really appreciate your help in resolving this problem, but how to explain the changing position from 9.89 for GO peak to 10.27 for GO paper.
The shift of peak from 9.89 to 10.27 is not too much and this could be due to sample height/position in XRD. GO paper is much flatter than you GO powder sample and this could shift peak position in XRD.
The peak position tells you about distance of individual layers. Because oxidized graphite (GO) is very well exfoliated system it increases distances (decreasing 2theta). Difference between GO and GO paper are results of stacking GO layers into paper
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