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Here, taking the example of NiO nanoparticles [1], we present the usefulness of the XAFS technique in studyingthe nanomaterials. The local defect structure of NiO nanoparticles was determined by EXAFS method. By using thebulk and surface sensitive EXAFS, we show that the vacancies mostly reside on the surface of the particles and thedistribution of vacancies can be considered within a core-shell model. We argue that these observations can give asuitable explanation for the venerable problem of observed magnetic behaviors of antiferromagnetic nanoparticlesand other functional properties of the material. The observed magnetic moment has been attributed to the interactingvacancies inside the antiferromagnetic host and the distribution of vacancies over the particle volume determinesbehaviors such as size-dependent different nature of spin-glass freezing and exchange bias.
References:
[1] S. Mandal, S. Banerjee, and K. S. R. Menon, Phys. Rev. B 80, 214420 (2009).
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