What was the nature of the sample ? In which conditions did you observe a change of morphology ? Without a few explanations of the context, it is impossible to answer this very general question.
Alain
Few years ago I meet situation when ZrO2 splitted along of plane with high concentration of electric charge (layer of Zr4+ then layer of O2- then again Zr4+....) has reconstruct surface for change facet of surface to electrical neitral planes. Probably you meet similar effect...
It is a general question and there is no specific answer for this kind of question.
Depending on the material you can potentially melt your particle under the beam
to Alain Celzard sir,
sir I have doped my base material with two dopants simultaneoulsy.
In pure( UNDOPED ) state I got the morphology as polyhedral ok
with doping other ( two elements) the morphology has become spherical in nature.
please inform me further sir
waiting for your answer
Well, it seems that the pure material crystallised normally, leading to faceted crystals, whereas doping it prevented the crystallization, thereby leading to the spherical shape. I don't know what was the base materials nor what were the doping elements, but depending on the concentration, the atomic size, the valence, the electronegativity, ..., of the latter, their presence certainly may have distroyed the crystalline order. This is well known for alloys through the rule of Hume-Rothery. All materials tend to present morphologies minimizing their surface energy, leading to spheres for non-crystallized materials (just like a drop of water), but leading to facets thus to polyhedral shapes in the case of crystals. You may check the change of crystallinity by XRD if you have enough material, or with SAED in a TEM if the amount is low.
Alain
refer to the very little my knowledge on crystal and nano- structures and i dead this point searching but it can be summarizes as under the preparation conditions such as temperature,nature of dopant,...etc the surface charges on the crystal surface change the growth mechanism as the crystal may grow in some directions instead the others form certain shape to minimize its surface energy, if the conditions changed the growth direction and growth rate also changes produce another shape. you can well understand what i mean from the attached photo. my opinion conformed from the change of piezoelectric properties with the shape of the material.
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