Nanocomposites and nanomaterials

Structural and magnetic properties of lanthanum-strontium manganite nanopowder
Liedienov N.A.1,2, Polynchuk P.Yu.3, Pashchenko A.V.1,2,3, Dzhezherya Yu.I.3, Levchenko G.G.1,2
1 State Key Laboratory of Superhard Materials, International Centre of Future Science, Jilin University. Qianjin Street, 2699, Changchun-130012, China.
2 Donetsk Institute for Physics and Engineering named after O. O. Galkin, NAS of Ukraine. Prospect Nauki,46, Kyiv-03028, Ukraine.
3 Institute of Magnetism, NAS of Ukraine and MES of Ukraine. Vernadsky Blvd., 36, Kyiv-03142, Ukraine. E-mail: phenix77310@gmail.com

Manganites with a perovskite structure belong to the multifunctional materials owing to their rich variety of phase diagrams and multiplicity of magnetic ground states [1]. All of this makes them a promising material for a wide application and deep investigation in different areas of science and technology [2].
Here, we have synthesized the La0.6Sr0.4MnO3 (LSMO) nanopowder using the sol-gel method with a post-annealing at tann = 700–900 °C (each cycle 10 h). As the tann increases the impurity of SrCO3 reduces and vanishes at 850 and 900 °С, whereas the specific surface area decreases and the average crystallite size grows from 16 to 30 nm. According to the magnetic data, the LSMO-800 nanopowder shows two critical temperatures TC1 = 328 K and TC2 = 362 K which are related to the particle size effect. As turned out the main part of the LSMO-800 nanoparticles is in the single-domain state, whereas others are in the superparamagnetic and multi-domain states. Such size dispersion leads to broadening the magnetocaloric effect with the maximum value −ΔSmax = 1.818 J/(kg·K) at 5 T near TC1. The obtained results exhibit perspectives on the practical use of manganite nanomaterials in physics, chemistry, materials science, and nanotechnology.

1.	Markovich V., Wisniewski A., Szymczak H., Magnetic Properties of Perovskite Manganites and Their Modifications // Handbook of Magnetic Materials.-2014.-22.-P. 1-201.
2.	Wei Z., Pashchenko A.V., Liedienov N.A., Zatovsky I.V., Butenko D.S., Li Q., Fesych I.V., Turchenko V.A., Zubov E.E., Polynchuk P.Yu., Pogrebnyak V.G., Poroshin V.M., Levchenko G.G. Multifunctionality of Lanthanum-Strontium Manganite Nanopowder // Phys. Chem. Chem. Phys.‑2020.-22.‑P. 11817.