I made one composite material of metal oxide and graphene. In SEM, particle size of metal oxide ranges between 1-10 um even in the composite, but in TEM, the composites showing 100-200 nm particles in graphene matrix (Please note that morphology of metal oxide also changed significantly in composite).
Before doing TEM, sonication was done in ethanol for 10-15 mins.
What can be the possible reasons of decreased and distorted particle size of metal oxide in composite?
Important Thing: I also did TEM of metal oxide only with and without sonication. With sonication, I obtained random shaped particles and without sonication or dispersion under mild conditions, I obtained Perfectly shaped particles.
Can it be concluded that sonication leads to distortion/breakage of particle shape which results in less sized particle?
Or any other possible reasons?