In:
Journal of Materials Chemistry C, Royal Society of Chemistry (RSC), Vol. 9, No. 32 ( 2021), p. 10361-10371
Abstract:
LaMnO 3+ δ is one of the classical-formal nonstoichiometric systems in materials science that, for δ = 0, shows antiferromagnetic ordering by super-exchange interactions between Mn 3+ ions. Nevertheless, the chemical reactivity of solids goes through different pathways when the particle size is reduced to the nanometric range, leading to the modification of the physico-chemical properties of materials. It is demonstrated here that octagonal LaMnO 3+ δ nanoparticles of average size 20 nm significantly modify their non-stoichiometry, microstructure and magnetotransport properties and are thus able to tune their behavior, as a function of the cationic vacancy concentration. For δ = 0, LaMnO 3 nanoparticles, even with only Mn 3+ , become ferromagnetic, whereas for δ = 0.23, i.e. La 0.93 Mn 0.93 O 3 , due to a cationic diffusion mechanism, weaker ferromagnetic interactions appear promoting the emergence of magnetoresistance. This accommodation of compositional variations triggers Mn 3+ → Mn 4+ oxidation and facilitates, as observed by atomically resolved scanning transmission electron microscopy and electron energy loss spectroscopy, the displacement of some La atoms around their normal site that can introduce restrictions in double exchange Mn 3+ –O 2− –Mn 4+ interactions.
Type of Medium:
Online Resource
ISSN:
2050-7526
,
2050-7534
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2021
detail.hit.zdb_id:
2702245-6
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