Influence of Chemical and Mechanical Pressure on the Luminescence Properties of Near-Infrared Phosphors

Abstract

In this study, we aim to compare the changes in the luminescence properties of Ga2O3:Cr3+ modified by Al or Sc ion substitution (chemical pressure) and hydrostatic pressure. We find the same behavior for Ga2–x Al x O3:Cr3+ and different behavior for Ga2–x Sc x O3:Cr3+ in terms of the optical properties under chemical and mechanical pressure. We consider Al substitution, which does not affect the chemical bond angles in the Cr3+ local environment and changes the crystal volume, like mechanical pressure does. As confirmed by Raman spectroscopy, the Sc ions cause lattice distortion and influence the chemical bond lengths and angles in the Cr3+ local environment. The energy structure diagrams of all levels of the d3 configuration of the Cr3+ ion as a function of pressure are calculated by considering the pressure dependence of the Racah parameters. The energy structure diagrams presented in the paper show a decrease in the energy of the 2E, 2T1, and 2T2 excited levels with an increase in Dq. This does not align with the behavior predicted for these excited levels by the standard Tanabe–Sugano diagram. It seems correct that a high-pressure experiment involving Cr3+ and other transition metals should be interpreted using the method and diagrams presented herein.

Advancing Near-Infrared Light Sources: Enhancing Chromium Emission through Cation Substitution in Ultra-Broadband Near-Infrared Phosphors

“…At atmospheric pressure, only broadband emissions are simultaneously observed for Cr 3+ and Cr 4+ luminescence. The strong dependence of the 4 T 2 state of Cr 3+ ions on crystal field strength leads to a substantial increase in the energy of the 4 T 2 → 4 A 2 transition with pressure and a slight decrease in the energy of 2E → 4A2 transition, 24 as shown in the schematic energy structure diagram present in Figure 5 e (left panel). For Cr 3+ luminescence, the maximum broadband ( 4 T 2 → 4 A 2 ) emission spectra shift toward a shorter wavelength (higher energy).…”

“…In recent years, Cr 3+ -activated broadband NIR phosphors have garnered significant research interest owing to their exceptional characteristics, including high efficiency, high thermal stability, and tunable spectra. − These phosphors offer a broad range of emission wavelengths in the near-infrared region. Additionally, Cr 4+ has emerged as a promising luminescent center with broadband emission spanning from 1100 to 1700 nm.…”

Highly‐Sensitive, Tri‐Modal Luminescent Manometer Utilizing Band‐Shift, Ratiometric and Lifetime‐Based Sensing Parameters

“…As evident from the Tanabe-Sugano diagram, the energy of the 4 T 2 level is markedly affected by the strength of the crystal field 10Dq, in contrast to the weekly dependent energy of the 2 E level. [33] Therefore, to develop a highly sensitive luminescent pressure sensor, it is crucial to exploit the emission band associated with the 4 T 2 → 4 A 2 transition of Cr 3+ ions. [10,14,17] The Li 3 Sc 2 (PO 4 ) 3 :Cr 3+ is an example of a phosphor, showcasing a broad emission band asso-ciated with the 4 T 2 → 4 A 2 .…”

High-Pressure Synthesis of Corundum-Type Ga2O3:Cr3+ and Application of Its Fluorescence to the Pressure Scale

“…This is probably because of the difference in CN. Recently, there have been studies on the fluorescence properties of Cr-doped corundum-type Ga 2 O 3 synthesized from hydroxide GaO­(OH) as a precursor and, very recently, on the structural phase transition of Cr-doped β-Ga 2 O 3 under metastable room temperature by applying excessive pressure . However, there has been no study of the pressure effects on the R 1 and R 2 lines of single-crystal Cr-doped corundum-type Ga 2 O 3 synthesized under high-pressure and high-temperature conditions.…”