The incorporation site of Er in nanosized CaF 2

TL;DR

This study investigates the specific site of erbium dopants in nanosized calcium fluoride using X-ray absorption spectroscopy and computational modeling, revealing substitutional behavior and clustering at higher concentrations.

Contribution

It combines experimental XAS data with DFT-based modeling to identify the erbium incorporation site and behavior in CaF 2 nanoparticles at different concentrations.

Findings

Er substitutes for Ca in CaF 2.

At low concentration, Er ions are isolated.

At high concentration, Er ions cluster and bind vacancies.

Abstract

The incorporation site of Er dopants inserted at high and low concentration (respectively 5 and 0.5 mol %) in nanoparticles of CaF 2 is studied by X-ray Absorption Spectroscopy (XAS) at the Er L III edge. The experimental data are compared with the results of structural modeling based on Density Functional Theory (DFT). DFT-based molecular dynamics is also used to simulate complete theoretical EXAFS spectra of the model structures. The results is that Er substitutes for Ca in the structure and in the low concentration case the dopant ions are isolated. At high concentration the rare earth ions cluster together binding Ca vacancies.