Structure, Surface Composition and Magnetic Properties of Mechanosynthesized Lafeo3 Nanoparticles and Their Eu3+-Doped and Eu3+/Cr3+-Co-Doped Modifications
24 Pages Posted: 14 Dec 2023
Abstract
The structure, surface composition and magnetism of mechanosynthesized LaFeO3 nanoparticles (30-40 nm), and their Eu3+-doped (La0.70Eu0.30FeO3) and Eu3+/Cr3+ co-doped (La0.70Eu0.30Fe0.95Cr0.05O3) modifications are reported. Doping results in a transition from the O՝-type to the O-type distorted structure. Traces of reactants, intermediate phases and a tiny amount of Eu2+-ions are detected on the nanoparticles' surfaces. The nanoparticles consist of antiferromagnetic cores flanked by ferromagnetic-like shells. The Eu3+ dopant ions enhance the magnetization values relative to those of the pristine nanoparticles and result in magnetic susceptibilities compatible with the presence of Eu3+ van-Vleck paramagnetism of spin–orbit coupling constant (λ = 363 cm-1) and a low temperature Curie-Weiss like behaviour associated with the minority Eu2+ ions. An anomalous temperature-dependent magnetic hardening due to competing magnetic anisotropy and magnetoelectric coupling effects together with a temperature-dependent dopant-sensitive exchange bias, caused by thermally activated spin reversals at the nanoparticles’ cores, are observed.
Keywords: Orthoferrites, XRD: Mössbauer spectroscopy, XPS, van-Vleck paramagnetism
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