**8. Conclusion**

In recent years, a remarkable progress has been made in understanding the magnetic phenomenon in nanomanganites with perovskite structure. This advance is mainly made possible through experimental measurements and theoretical approaches. In this work, ESR spectroscopic measurements were adopted to study crystallite size-dependent magnetic properties of La0.8Sr0.2MnO3 nanomanganite. Samples with different crystallite sizes ranging from 9 to 57 nm were prepared by autocombustion method with a two-step synthesis process. Significant differences in the ESR spectrum parameters, namely, resonant field (Hres), line shape, low-field microwave absorption, and linewidth (ΔHpp), are used to determine the critical sizes of magnetic state changes. The findings from the ESR measurements

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**Author details**

Mondher Yahya1

\*, Faouzi Hosni<sup>2</sup>

Materials Sciences, Soliman, Tunisia

provided the original work is properly cited.

and Ahmed Hichem Hamzaoui1

1 Laboratory of Useful Materials Valuation, National Center for Research in

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

2 Faculty of Sciences, University of Bisha, Bisha, Saudi Arabia

\*Address all correspondence to: mondher.yahya@cnrsm.rnrt.tn

*Synthesis and ESR Study of Transition from Ferromagnetism to Superparamagnetism…*

are confirmed by VSM measurements. Anomaly observed in the superparamagnetic state has been explained by the formation of multicore magnetic crystallites. These results show the potential use of nanoparticles with crystallite size less than 24.5 nm for biomedical applications. Multicore superparamagnetic state has interesting magnetic properties and can have a large heating capacity equivalent to the mag-

*DOI: http://dx.doi.org/10.5772/intechopen.89951*

netic nanoflowers.

*Synthesis and ESR Study of Transition from Ferromagnetism to Superparamagnetism… DOI: http://dx.doi.org/10.5772/intechopen.89951*

are confirmed by VSM measurements. Anomaly observed in the superparamagnetic state has been explained by the formation of multicore magnetic crystallites. These results show the potential use of nanoparticles with crystallite size less than 24.5 nm for biomedical applications. Multicore superparamagnetic state has interesting magnetic properties and can have a large heating capacity equivalent to the magnetic nanoflowers.
