Abstract

In order to understand the interaction mechanisms in RE2O3 (RE=Gd, Er) nanoparticles (NPs), Perturbed Angular Correlation (PAC) spectroscopy, a local technique, plus external magnetic field, was used to elucidate local interactions and possible mapping of the different contribution in these compounds. NPs were synthesized by thermal decomposition and characterized by transmission electron microscopy and X-ray diffraction. PAC measurements were performed using 111In(111Cd) as probe nuclei, with and without the application of an external magnetic field (EMF) of 0.5 T in different temperatures (50 K, 100 K, 200 K, 300 K). Results show that the hyperfine magnetic field is almost zero when the probe is located at the symmetric site, and ∼4 T and ∼5 T for Gd2O3 and Er2O3, respectively, when the probe occupies the asymmetric field.

Highlights

  • The rare-earth (RE) oxides present three different structures depending on the RE ionic radii: hexagonal (A-type), monoclinic (B-type) or cubic (C-type).1 In the latter, RE ions occupy two nonequivalent cation sites: asymmetric 24d sites and symmetric 8b sites

  • After the almost complete 111In decay samples were structurally characterized by X-ray diffraction (XRD) using a Philips X’Pert diffractometer and analyzed by Rietveld method, and NPs shape, size and size distribution were determined by transmission electron microscopy (TEM), using a Joel JEM-2100 microscope

  • Perturbed Angular Correlation (PAC) measurements were performed in Gd2O3 and Er2O3 NPs with and without the application of an external magnetic field of around 0.5 T

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Summary

Introduction

The rare-earth (RE) oxides present three different structures depending on the RE ionic radii: hexagonal (A-type), monoclinic (B-type) or cubic (C-type). In the latter, RE ions occupy two nonequivalent cation sites: asymmetric 24d sites and symmetric 8b sites. The rare-earth (RE) oxides present three different structures depending on the RE ionic radii: hexagonal (A-type), monoclinic (B-type) or cubic (C-type).. The rare-earth (RE) oxides present three different structures depending on the RE ionic radii: hexagonal (A-type), monoclinic (B-type) or cubic (C-type).1 In the latter, RE ions occupy two nonequivalent cation sites: asymmetric 24d sites and symmetric 8b sites. Gd2O3 and Er2O3 crystallize in this structure and have a paramagnetic behavior, Er2O3 orders antiferromagnetically below 4 K.2,3. Several works have been done in order to determine magnetic properties in NPs.. It is well known that NPs, due small size, present magnetic characteristics that can be attributed to: (a) core magnetic contribution, due to crystalline structure (point symmetry of magnetic atom) and exchange interactions and (b) surface contributions, due to canted spins or spin-glass-like behavior of the surface spins Several works have been done in order to determine magnetic properties in NPs. It is well known that NPs, due small size, present magnetic characteristics that can be attributed to: (a) core magnetic contribution, due to crystalline structure (point symmetry of magnetic atom) and exchange interactions and (b) surface contributions, due to canted spins or spin-glass-like behavior of the surface spins

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