Size effect in nanocrystalline manganites La1−xAxMnO3 with A=Ag, Sr

• Published in: Physica. B, Condensed matter Condensed matter, 2004-07, Vol.350 (1-3), p.55-58
• Main Authors: Teplykh, A.E, Bogdanov, S.G, Valiev, E.Z, Pirogov, A.N, Dorofeev, Yu.A, Ostroushko, A.A, Udilov, A.E, Kazantzev, V.A
• Format: Article
• Language: English
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2004.03.252

Nanocrystalline manganites La0.9Ag0.1MnO3, La0.7Ag0.3MnO3, and La0.7Sr0.3MnO3 have been synthesized by pyrolysis and subjected to isothermal annealing. The atomic, magnetic, and mesoscopic structures of these manganites were investigated using magnetic measurements as well as X-ray and neutron diffraction. Particles of sizes ranging from 30-40 to 600-700nm coalesced with an increase in the annealing temperature from 600 deg C to 1300 deg C. All investigated samples had a rhombohedral structure and were ferromagnetic. The Curie temperature of the samples containing silver decreased while that of the samples containing strontium increased with the annealing temperature (i.e. with the growth in particle size). The magnetization of the Mn ions increased with annealing in all three systems. It is reasonable to assume that the growing size of the nanoparticles lead to an increased magnetization owing to the reduction of the angle between the nearest magnetic moments of the Mn ions.