Tailoring the absorption peaks for enhanced in-line transmittance of Y2O3–MgO composites

Y 2 O 3 MgO composites have emerged as promising mid-infrared (MIR) materials owing to their exceptional broadband transmittance and remarkable thermal stability at elevated temperatures. Nevertheless, the presence of uncontrollable absorption bands within the 4–7 μm spectral range, compromises their optical performance in advanced MIR systems. To address this limitation, we systematically investigated annealing as a strategic approach for modulating defect chemistry in oxide composites. In this paper, the absorption peaks of Y 2 O 3 MgO composites were controlled by varying the annealing conditions. As the annealing temperature increases from 600 °C to 1100 °C, the absorption peaks of Y 2 O 3 MgO composites gradually shift from ∼4.9 μm to ∼6.8 μm, with a transition temperature ∼900°C. This behavior is attributed to the oxidation of metal-organic coordination (MOC) to CO 3 2- in high-temperature air. Ultimately, Y 2 O 3 MgO composites featuring controllable absorption peaks were obtained, demonstrating a transmittance of ∼81 % at 7 μm - the highest value ever reported for this composite system, which broadens the potential application space, particularly in fields requiring mid-infrared transparency such as gas detection, materials characterization, and biomedical imaging. This study not only elucidates specific strategies for enhancing the performance and microstructure of Y 2 O 3 MgO composites but also furnishes reliable methodologies and datasets to support the annealing processes of other material systems.