Reversible structural and colorimetric transitions in LuMnGaO₄ upon oxygen uptake and release

Area of Science:

• Materials Science
• Solid-state Chemistry
• Crystallography

Background:

• AB2O4-type compounds are of interest for various applications.
• Understanding oxygen uptake and release mechanisms is crucial for developing advanced materials.

Purpose of the Study:

• To synthesize and characterize LuMnGaO4, focusing on its oxygen uptake and associated color change.
• To elucidate the structural transitions during oxygenation and deoxygenation processes.
• To explore the potential applications of LuMnGaO4 as an oxygen carrier and colorimetric sensor.

Main Methods:

• Solid-state synthesis of LuMnGaO4.
• Neutron diffraction and in situ synchrotron X-ray powder diffraction for structural analysis.
• UV-visible spectroscopy to quantify electronic transitions and color change.
• Electron diffraction to investigate structural modulations.

Main Results:

• LuMnGaO4 was synthesized and characterized, existing in reduced (R-3m) and oxidized (P-3m) phases.
• A reversible phase transition upon oxygen uptake/release was observed around 250 °C.
• Oxidation induced a distinct color change from greenish-grey to black.
• Structural modulations and oxygen disorder were identified in the oxidized phase.

Conclusions:

• LuMnGaO4 exhibits reversible bulk oxygen uptake and release at low temperatures.
• The material's color change upon oxygenation suggests bifunctional potential for oxygen carriers and colorimetric sensors.
• This research lays the groundwork for further studies on AB2O4-type compounds for oxygen-related technologies.