A self-esterification galactose-assisted system for Y2O3–MgO composite with high mechanical properties and transmittance

This study presents a simplified self-esterification galactose-assisted sol–gel combustion synthesis for Y 2 O 3 –MgO composite nanopowders, eliminating the need for additional chelating agents. Galactose serves as both fuel and structure-directing agent, producing highly uniform, fine powders (17 nm). Subsequent hot-pressing yielded fully dense ceramics with exceptional performance: high in-line transmittance (>80% [2.3–6.3 µm]; maximum transmittance >84%, approaching the theoretical value ∼86%), excellent phase homogeneity (phase distribution coefficient α f of Y 2 O 3 = 96.64%, α f of MgO = 95.62%; a value of α f closer to 1 corresponds to improved phase homogeneity, a stronger pinning effect, and a finer grain size, resulting in enhanced properties of the Y 2 O 3 –MgO), superior Vickers hardness (12.1 ± 0.3 GPa), and fracture toughness (2.5 ± 0.4 MPa·m 1/2 ). This work establishes galactose sol–gel combustion as a facile, effective route for tailoring powder morphology, enabling the fabrication of transparent Y 2 O 3 –MgO composites with outstanding integrated properties for demanding optical applications.