I am sonicating graphene (725W, 20KHz) in ethanol to re-exfoliate. After sonication, Raman spectroscopy showed a symmetric 2D band but when thermal annealing was performed, the shape of peak changed from symmetric to several overlapping mode. It is known that the shape of 2D-band can tell us the number of layers. The I2D/IG after sonication was 0.51 and after annealing was 0.46. Also, ID/IG changed from 0.09 to 0.01, indicating fewer defects after thermal annealing. Why annealing change the shape of 2D peak?
Dear colleague Hamid,
Have a nice time and good day.
Peace be up on you.
The structural, optical and electrical properties of the final obtained alloy depend on the thermal literature, heating rate, cooling rate, coating rate or deposition rate, thermal aging, physical aging, homogeneity, container type.......etc.
There are two types of annealing; fast and slow annealing. The annealing is a function of temperature of annealing, substrate type, ambient of vacuum, properties of material (physical and chemical). Structural form of the materials (amorphous, poly crystalline and crystalline). etc. the annealing may develop the properties of material or vice versa depending on the mentioned parameters.
The annealing may reduces the presence of imperfections, defects or localized states. So more order and arrangement are available consequently the small particle size my be joined or agglomerate to produce larger one with different sizes and different shapes. The growing process of particle size due to annealing may has different orientations. So the peak broadening of XRD will decreases and the intensity will increases.
I wish this is useful and help you.
Yours
A. El-Denglawey
Annealing in what atmosphere and temperature?
However, the spectra that you attached after annealing (blue) corresponds to graphite.
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