Thermometer or freezer: dual functionality in a 2D mixed-anion terbium(III) oxide carbodiimide

Area of Science:

• Materials Chemistry
• Solid State Physics
• Luminescence and Magnetism

Background:

• The NCN^2- anion is a key component in novel material discovery.
• Two-dimensional (2D) materials offer unique structural and electronic properties.
• Terbium (Tb)-based compounds are known for their luminescent and magnetic characteristics.

Purpose of the Study:

• To comprehensively investigate the optical and magnetic properties of the 2D phosphor Tb₂O₂NCN.
• To explore its potential for luminescent thermometry and magnetic refrigeration.
• To understand the underlying mechanisms of its observed phenomena.

Main Methods:

• Temperature-dependent luminescence spectroscopy.
• Optical ratiometric thermometry and principal component analysis for temperature sensing.
• Magnetic property measurements, including magnetic ordering and field-induced transitions.

Main Results:

• Tb₂O₂NCN exhibits an anti-thermal quenching luminescence effect, enhancing its utility in temperature sensing.
• Principal component analysis provides higher sensitivity for optical thermometry compared to traditional methods.
• The material displays antiferromagnetic ordering below 6.5 K and field-induced metamagnetic transitions.
• A significant magnetocaloric effect (-ΔS_M = 11.7 J kg^-1 K^-1 at 5 T) was observed, indicating potential for magnetic cooling.

Conclusions:

• Tb₂O₂NCN is a promising 2D material combining advanced optical thermometry with efficient magnetic refrigeration capabilities.
• Its unique structure and properties make it a strong candidate for next-generation cooling technologies.
• The anti-thermal quenching luminescence and large magnetocaloric effect warrant further investigation for practical applications.