Distinctive features of fluorescence and waveguides in magnesium aluminate spinel crystals driven by structural discrepancy

• Predicting internal tracks through ion velocity and electronic energy losses . • The relationship between surface nanoscale hillocks and internal track formation. • Introducing defects to create new energy band and reduce the bandgap. • Modifying the internal refractive index to fabricate a waveguide structure. Transparent polycrystalline ceramics are of significant importance for a wide range of scientific and industrial applications. Developing a deeper understanding of their thermodynamic behavior is essential for achieving their maximum output performance in technological applications. This study provides a systematic investigation into the thermal excitation-induced fluorescence kinetics and waveguide characteristics of Magnesium Aluminate Spinel (MgAl 2 O 4 ) single crystals, with a focus on the intricate relationship between structure and properties. High-temperature extreme environments through irradiation with swift heavy ions 645.0 MeV Xe and 352.8 MeV Fe ions were created; the atomic deposition energy threshold ( E th ) associated with disorder morphologies was assessed between 0.91 and 0.99 eV atom −1 . The track prediction model was developed to support the theoretical prediction of track formation. Electronic energy loss ( E ele ) disrupts the balance of the initial structure through the thermal spike effect, leading to the formation of absorption-related F and F + color centers. These defects enhance photoluminescence in the visible spectrum and result in an effective modulation of the intrinsic bandgap. Moreover, as ion beams penetrate into the material, the uneven damage distribution induces the formation of waveguide structures. These findings provide valuable insights into the fabrication of functional devices through irradiation technologies and the structural changes of MgAl 2 O 4 at high temperatures within extreme environments.