Delocalization of 4f Electrons in Gadolinium Oxide on the Nanometer Scale

Abstract

Some metals such as silver are known to become strong reducers on the nanometer scale. Electron energyloss spectroscopy (EELS) shows that modifications of the electronic structure of metal ions also arise in nanoparticles of gadolinium oxide. Indeed, the oxygen K and gadolinium N 4,5 edges present modifications for particles size below 1.5 nm which are the signature of an hybridization of the initially atomiclike Gd 4f states with the valence band and especially the O p states. These modifications evidence that, like in metals, electron delocalization from metal sites also occurs in oxides on the nanometer scale.

A strategy for simulating Electron Energy-Loss Near-Edge Structures of nanoparticles: application to size effects in Gd2O3

“…We are in an experimental situation where the collection aperture For instance, let us now consider a cluster with 86 atoms which contains the probed oxygen at its centre. This cluster is very similar to the NP experimentally studied in a previous paper [8]. Figure 4 shows the six intrinsic components used in the case of c trichroism (see section 2.3).…”

“…In the present paper, we have used Gd 2 O 3 NPs, wellcalibrated in size, which were recently studied by EELS [8].…”

“…drug delivery and/or cancer therapy, see, for instance among recent overviews, [10][11][12][13][14]). Among these objects mixing organic and inor- It was shown that the O-K edge varies with the size of the particles [8], and this feature will be examined using Electron energy-Loss Near-Edge Structure (ELNES) simulations accounting for steps 1) to 3) previously enumerated. These calculations were performed using the feff code based on a multiplescattering approach [15,16].…”

Evidence for 5d-σ and 5d-π covalency in lanthanide sesquioxides from oxygen K-edge X-ray absorption spectroscopy

“…Because the radial extension of the 4f orbitals is small, increases in 4f orbital covalency have primarily been achieved by minimizing the energy separation (degeneracy driven covalency). 127,138,139 Within the limits of this model, changes in the intensity of the O K-edge can be rationalized using eqn (1) in the following manner: Fig. 9 shows how the spectra can be partitioned into several groups with distinct behavior, and correlates well with expectations from the physical and theoretical studies described above.…”

The key energy scales of Gd-based metallofullerene determined by resonant inelastic x-ray scattering spectroscopy

“…Such a charge-transfer scenario, implying certain covalency for Gd 3+ 4 f states, would be in line with our RIXS findings. The more delocalized Gd 3+ 4 f states may also play a role in the enhanced relaxitivities in the EMFs, as recent studies on Gd 2 O 3 nanoparticles showed enhanced relaxitivities when particle size approaches to 3 nm that Gd 4 f wave functions become comparable to the particle size 32 , 33 .…”