Ratiometric Boltzmann thermometry with Cr<sup>3+</sup> in strong ligand fields: Efficient nonradiative coupling for record dynamic working ranges

Gülsüm Kinik; Ingo Widmann; Benedikt Bendel; Hubert Huppertz; Andries Meijerink; Markus Suta

doi:10.1038/s41377-025-02082-8

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Ratiometric Boltzmann thermometry with Cr³⁺ in strong ligand fields: Efficient nonradiative coupling for record dynamic working ranges

Original Articles

- Ratiometric Boltzmann thermometry with Cr³⁺ in strong ligand fields: Efficient nonradiative coupling for record dynamic working ranges
- Light: Science & Applications Vol. 14, Issue 12, Pages: 4133-4144(2025)
- Affiliations：
  
  1.Inorganic Photoactive Materials, Institute of Inorganic Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
  2.Department of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innsbruck, Austria
  3.Condensed Matter & Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, The Netherlands
- Author bio：
  
  Hubert Huppertz (Hubert.Huppertz@uibk.ac.at)
  Andries Meijerink (a.meijerink@uu.nl)
  Markus Suta (markus.suta@hhu.de)
- Funds：
- DOI：10.1038/s41377-025-02082-8
  CLC：
- Received：20 May 2025，
  
  Revised：2025-09-17，
  
  Accepted：05 October 2025，
  
  Published Online：25 November 2025，
  
  Published：31 December 2025
- Accepted：
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Kinik, G. et al. Ratiometric Boltzmann thermometry with Cr³⁺ in strong ligand fields: Efficient nonradiative coupling for record dynamic working ranges. Light: Science & Applications, 14, 4133-4144 (2025).
DOI：

Kinik, G. et al. Ratiometric Boltzmann thermometry with Cr³⁺ in strong ligand fields: Efficient nonradiative coupling for record dynamic working ranges. Light: Science & Applications, 14, 4133-4144 (2025). DOI： 10.1038/s41377-025-02082-8.

摘要

Abstract

A new ratiometric Boltzmann thermometry approach is presented for the narrow-line red-emitting bright phosphor Al

0.993

0.007

N. It relies on thermalization between the two excited states

(

G) and

(

G) of Cr

with an energy gap of 620 cm

−1

for optimized thermometry at room temperature. It is shown that nonradiative coupling between these excited states is v

ery fast

with rates in the order of several µs

−1

. Due to the comparably slow radiative decay (

= 0.033 ms

−

) of the lowest excited

(

G) state

the dynamic working range of this Boltzmann thermometer for the deep red spectral range is exceptionally wide

between

77 K and

873 K

even outperforming the classic workhorse example of Er

. At temperatures above 340 K

also spectrally well-resolved broad-band emission due to the spin-allowed

(

F) →

(

F) transition is detectable

which simultaneously offers a possibility of very sensitive (

(500 K)

2% K

−1

) ratiometric Boltzmann-type crossover thermometry for higher temperatures. These findings imply that Al

0.993

0.007

N is a particularly robust and bright red luminescent thermometer with a record-breaking dynamic working range for a luminescent transition metal ion.

关键词

Keywords

references

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Ratiometric Boltzmann thermometry with Cr3+ in strong ligand fields: Efficient nonradiative coupling for record dynamic working ranges

DOI：10.1038/s41377-025-02082-8

摘要

Abstract

关键词

Keywords

references

Ratiometric Boltzmann thermometry with Cr³⁺ in strong ligand fields: Efficient nonradiative coupling for record dynamic working ranges