I have coated a ferrite nanoparticle with an organic acid. But I want to know whether the coatings have been formed around the particles or not. What are the techniques generally used and which technique will be the best for confirmation of coated nanoparticles?
Depending on the method you coated the nanoparticles, is it chemical functionalization or just physical adsorption? If there are chemical bonds formed, you could use FTIR? If it is only physical adsorption, FTIR wouldn't do you any good. You could use surface charge to indirectly tell you whether the coating's there or use TEM to see if you could see a extra layer outside the nanoparticles.
thanks Prosper...but I know XPS gives the different oxidation states of an element in a compound.
In my case, during mechanical ball milling, I just added oleic acid to alloy nanoparticles. So, it is physical adsorption case mostly.
I guess AFM might be a good option then.
you can go for any probe microscope for analysing the coating.
For an average information standard is to measure coating molecules concentration before and after adsorption in continuous phase.
Since I was interested in the matter due to for compacting powder with a binder and trying to form as thinner adsorbed layer as possible on the MnZnFe2O4 particles with PVA and PEG I will tell you my opinion. Coating depends on the type of bonding between powders particle surface and, let s say, polymer. You can hardly expect to have a monolayer that is formed with strong bonds of functional groups at the end of chain as, for example, oleic acid and metal particles that can form such interaction. In that case it is convenient to use zeta seizer to determine the type of interaction and coating specifics. With polymer, it is important to declare the thickness of the layer on the surface and to know what it is consisted of. Namely, the quantity of the area occupied by the one polymer molecule is declared as gyration size. With polymer chains you can use the apparent viscosities of the powder suspensions determined at various shear rates with concentric cylinder rheometer. T.-H. Ho et al. /Materials Chemistry and Physics 172 (2016) 1-5, Effect of surface hydroxyl groups on the dispersion of ceramic powders, take a look at the reference 21 – A. Doroskowski, Journal of colloid and interface science, 26, 214-221 (1968). That is important since thickness of the layer can make problems with binder burnout during sintering see - R. Mauczok, V.T. Zaspalis, Journal of the European Ceramic Society 20 (2000) 2121-2127, Binder burnout-material-process interaction during sintering of MnZn-ferrites.
Hope you’ll find it correct and useful
Regards
Nebojsa Labus
ITS SASA
Belgrade, Serbia
P.S. I will also attach a work before the ferrites approach on the compaction issue
Thank you all for your nice and valuable answers. These will definitely help me.
STM will be able to find out the coating separately. Even TEM may give you the idea depending of the contrast.
I agreed with prof. Samui.
From the TEM two distinct phases you are clearly seen in the TEM images. From AFM you get results but its sometimes not good. Because AFM is used d for surface ruffnes easily found and its necessary to give the more time for scanning of samples and takes more time. But in TEM easily found.
If you want to just predict the whether coating is done or not than, Just match the XRD pattern of the neat nanoparticle and coated nanoparticles. You found that coat nanoparticle's XRD peaks slightly or more broad. Checked it.
Thanks for your answers. I guess as we are using organic solvent to quote the NPs, FTIR microscopy can give the details regarding new bonds
If you are interested in the quantitative aspects, TGA in air will tell you exactly how much organic coating agents on particles you have, as well as what is the temperature dependence of coating.
If you have DSC/TGA, it will also show the energy of evaporation/burning/decomposition depending in which media (air, nitrogen) you perform the measurement.
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