Are there any effect on coercivity of nano particles (e.g. ferromagnetic spherical Fe NPs or Fe-oxides) ?
The Oe value of our NPs shows diverse values, for instance, 40 Oe or 60 Oe.
As I believe the magnetic properties of nano crystals are size- , shape-, oxidation- dependence, I am trying to find any possiblie reasons why the value can be shifted.
Your kind advise or references would be very appreciated !
Best Regards,
I support Stanislav's view that there is not enough information to (even try giving an) answer (to) your question. There are quite a few things to consider when pondering HC values and it may amount to quite a lot of experimental work when you seriously try to not only make speculations about your observations.
Below, I have enclosed the link to a paper from which you can see how far we got in a case with (imho) relatively well defined Fe particles. You will readily see that there are quite a few open issues. [RG have put the figures on the publication page. In case you cannot access the paper online, please request a reprint which I can make available to you.]
Article Magnetic properties of Fe nanoclusters on Cu(111) studied wi...
To comment on your suggestion of the role of oxidation: I do believe that oxidation is able to change HC and that M(H,T) of a given specimen may vary as oxidation progresses. But things may be complex and subtle! HC alone is hardly a good indicator of what's going on in your specimen(s).
But for the general role of surface oxides, you might want to check the Mössbauer effect literature on Fe nanoparticles. There is early work involving Morup (author), for example, and this work has been well cited. Following these leads, you should be able to find material of relevance to you.
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