# Photoluminescence and Crystal-Field Analysis of Reddish CaYAl3O7: Eu3+ Phosphors for White LEDs

## TL;DR

This paper studies red CaYAl3O7: Eu3+ phosphors for white LEDs, focusing on their photoluminescence and crystal-field properties.

## Contribution

The study introduces a complete diagonalization method (CDM) to accurately analyze and predict the fluorescent behavior of Eu3+ in CaYAl3O7.

## Key findings

- Phosphors show efficient excitation at 398 nm and emission at 622 nm.
- Optimal Eu doping concentration is found to be x = 0.16.
- CDM successfully models 18 fluorescent spectra with high accuracy.

## Abstract

Red melilite structure CaY1−xAl3O7: Eux (x = 0.04–0.24) phosphors for white LEDs were synthesized through a straightforward solid-state reaction process. These phosphors exhibit efficient excitation under near-ultraviolet light at 398 nm (7F0 → 5L6), producing the desired emission peak at 622 nm from the transitions of 5D0 → 7F2. The Eu doping concentration was also optimized as x = 0.16. The complete 3003 × 3003 energy matrix was constructed based on an effective Hamiltonian including both free-ion and crystal-field interactions within a complete diagonalization method (CDM). Eighteen experimental fluorescent spectra for Eu3+ ions at the Y3+ site of CaYAl3O7 crystal were quantitatively identified with high accuracy through fitting calculations. The fitting values are in reasonable agreement with the experimental results, thereby showcasing the efficacy of the CDM in probing luminescent phosphors for white LEDs.