XRD of synthesized material is showing a slightly decreased d-spacing as compared to standard data, and it can be indexed, but HRTEM fringe pattern shows increased d-spacing. The value of d-spacing according to HRTEM image is higher than the maximum value of d-spacing in standard data. So it does not matches at all. Kindly suggest the reasons and solution.
Dear Nipin Kohli ,
Conventional X-ray powder diffraction will probe the surface of your sample with a minimum depth. Otherwise, the TEM will probe the core of your particles as well.
In some conditions, you may have a core particle that not underwent to some physical-chemical treatment, such as oxidation, and end up with an oxidized surface and intact core. At the X-ray experiment, the beam only probes the oxidized surface. In TEM, both are going to be explored.
Considering that the oxidized phase is only a minor component if compared with the relative amount of the unoxidized core phase, as an example, the TEM will show a significantly different result.
I suggest decrease as much as possible the particles of the sample and repeat the X-ray diffraction aiming to expose the core of the particle as much as possible.
Best regards,
WNM
Nipin Kohli as point out by Flavio F. Contreras-Torres
you have to consider the crystallite size statistic of your sample, this one what u see with the HRTEM (direct method), while XRD looking at domain distribution (indirect method). If you encounter a smaller crystallite size, the core size (unaltered) not the same as the corona (altered), in other words at corona size the distance between atom layers will increase compared to the core. It called the grain surface relaxation (GSR) effect. Use WPPM (Prof. Matteo Leoni) if you encounter this.TEM tends to look/use a small particle in a small area while XRD uses a whole sample.
Anyway, what is your sample? nanoparticles?
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