# Can Europium Atoms form Luminescent Centres in Diamond: A combined Theoretical-Experimental Study

## TL;DR

This study combines theoretical calculations and experimental methods to explore the potential of europium atoms to create luminescent centers in diamond, identifying specific defect structures that could enable Eu3+ luminescence.

## Contribution

It provides new insights into the defect configurations of Eu in diamond and demonstrates preliminary experimental evidence of Eu incorporation through plasma treatment.

## Key findings

- Eu-vacancy complex induces minimal lattice strain
- Eu3+ luminescence likely from 4-coordinated Eu substitutional sites
- Experimental PL spectra suggest Eu incorporation after plasma exposure

## Abstract

The incorporation of Eu into the diamond lattice is investigated in a combined theoretical-experimental study. The large size of the Eu ion induces a strain on the host lattice, which is minimal for the Eu-vacancy complex. The oxidation state of Eu is calculated to be 3+ for all defect models considered. In contrast, the total charge of the defect-complexes is shown to be negative -1.5 to -2.3 electron. Hybrid-functional electronic-band-structures show the luminescence of the Eu defect to be strongly dependent on the local defect geometry. The 4-coordinated Eu substitutional dopant is the most promising candidate to present the typical Eu3+ luminescence, while the 6-coordinated Eu-vacancy complex is expected not to present any luminescent behaviour. Preliminary experimental results on the treatment of diamond films with Eu-containing precursor indicate the possible incorporation of Eu into diamond films treated by drop-casting. Changes in the PL spectrum, with the main luminescent peak shifting from approximately 614 nm to 611 nm after the growth plasma exposure, and the appearance of a shoulder peak at 625 nm indicate the potential incorporation. Drop-casting treatment with an electronegative polymer material was shown not to be necessary to observe the Eu signature following the plasma exposure, and increased the background luminescence.