# Unraveling Thermal Interactions in Lanthanide-Doped Phosphors: A Frequency-Domain Analysis Approach

## TL;DR

This paper introduces a new method to study how heat affects the light-emitting properties of special materials used in lighting and sensors.

## Contribution

A novel frequency-domain analysis is introduced to separate thermal ionization and crossover effects in lanthanide-doped phosphors.

## Key findings

- SAO:Eu,Dy shows dominant trapping behavior with high ionization efficiency.
- GYAGG:Ce,Cr exhibits significant competition between ionization and crossover.

## Abstract

Ensuring
the thermal
reliability of luminescent materials is a
key requirement for next-generation lighting, display, and sensing
technologies. The intricate interplay of thermal crossover and thermal
ionization in lanthanide-doped phosphors often obscures their individual
contributions. We present a frequency-domain photoluminescence analysis
that disentangles these competing mechanisms. Using single crystals
of SrAl2O4:Eu2+,Dy3+ (SAO:Eu,Dy)
and (Gd0.33Y0.67)3Al2.4Ga2.6O12:Ce3+,Cr3+ (GYAGG:Ce,Cr)
as model systems, we extract temperature-dependent trapping efficiencies
and decay rates by analyzing the phase and amplitude response of luminescence
under modulated excitation. Our approach reveals distinct signatures
of thermal ionization and enables the direct quantification of ionization
barriers and crossover rates. We demonstrate that SAO:Eu,Dy exhibits
dominant trapping behavior with high ionization efficiency, while
GYAGG:Ce,Cr shows significant competition between ionization and crossover.
This method provides a powerful framework for resolving overlapping
quenching pathways and offers new insights for the design of thermally
robust luminescent materials.