I have coated rGO on quartz and by characterizing through FEGSEM I observed that some of the sheets formed bubbles, which I did not observe on glass or Si substrate. Please help me to draw a mechanism for the evolution of such morphology. For your information I have synthesized it by using a natural source, where I coated first on substrate and heated it in inert atmosphere, and in the process the source was converted to rGO. The process is able to coat rGO on any substrate which can sustain 600 degrees. I have also studied the same as function of temperature, where I got the same morphology on Quartz. Please help me to draw the mechanism for such morphology evolution.
Assuming that your natural source has C, O, there's chance that some gases are trapped during heating .. try vacuum annealing.
Might be, liquids inside the film evporated on high temperature heating.
Yes Sridhar there is possibility of gas entrapment but I am not observing such bubbles with glass and silicon substrate,that is my worry...I have gone upto 900 degree where bubbles are stable upto that temperature. I have also annealed it at high temperature in vaccum and observed similar results.
No K.P. there is no liquid as in my process I am making the thin film first and it is a polymer which was disssolved in Iso propanol to make a solution and after dip coating on the substrates it forms a very thin layer and solvent evaporates very first leaving the polymer coating then I am heating it to get graphene. So please suggest the mechanism of evolution of morphology only with quartz substrate not with others
Are you sure that these are really "bubbles" at all? Since you are using an electron microscope I assume the image would be sensitive to the local reduction state of the
sample and this could be affected by the choice of substrate. Have you got AFM images of the bubbles showing a true height difference? What do you see in AFM/SEM of the bare quartz?
High Mark in SEM image of the bare quartz we got the plain surface anyway we could not go to higher magnification because of charging effect of bare quartz substrate as it is nonconducting. We have not done AFM as these are micron size bubbles. I am quite sure that these are bubbles and not due to local reduction state as I have done Raman on the bubbles and out side also which confirms the rGO signature.Yes the evolution of morphology is substrate dependent but I could not draw a conclusion that it arises due to local reduction state. Another information is that when I am changing the concentration of polymer in the solution and annealing temperature the morphology is changing. So how to approach the science behind bubble frmation
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