Bifunctional Luminescent Thermometer-Manometer Based on Cr³⁺-Cr³⁺ Pair Emission

Area of Science:

• Materials Science
• Spectroscopy
• Luminescence Thermometry

Background:

• Luminescence manometry often relies on pressure-dependent spectral shifts of Cr³⁺ ions, linked to covalency and crystal field variations.
• Cr³⁺-Cr³⁺ pair luminescence has been largely overlooked for sensing applications.

Purpose of the Study:

• To investigate the pressure dependence of Cr³⁺-Cr³⁺ pair luminescence in CaAl₁₂O₁₉:Cr³⁺.
• To explore the potential of Cr³⁺-Cr³⁺ pairs as a luminescence reference in sensing.
• To develop a dual-function luminescence thermometer utilizing distinct Cr³⁺ crystallographic sites.

Main Methods:

• Investigated the pressure dependence of luminescence from Cr³⁺ ions and Cr³⁺-Cr³⁺ pairs in CaAl₁₂O₁₉:Cr³⁺.
• Analyzed thermal and pressure dependences of luminescence from Cr³⁺ in different crystallographic positions.
• Demonstrated dual-function operation (ratiometric and lifetime-based) for a luminescence thermometer.

Main Results:

• Cr³⁺-Cr³⁺ pair luminescence exhibited insensitivity to pressure, validating its use as a luminescence reference.
• Distinct thermal and pressure dependences were observed for Cr³⁺ ions at different crystallographic sites.
• A dual-function luminescence thermometer was successfully demonstrated using these properties.

Conclusions:

• Cr³⁺-Cr³⁺ pair luminescence offers a stable reference signal for optical sensing under pressure variations.
• The differential responses of Cr³⁺ in CaAl₁₂O₁₉:Cr³⁺ enable advanced luminescence thermometry.
• This work highlights the potential of Cr³⁺-Cr³⁺ pairs for developing novel optical sensors for physical quantities.