Defects engineering of α-Al ₂ O ₃ via high-temperature annealing and Ti ion implantation for enhanced luminescence and thermometric applications

Aluminum oxide (<i>A</i><i>l</i>₂<i>O</i>₃) has garnered considerable interest owing to its defect characteristics, superior optoelectronic, and mechanical properties, enabling broad application prospects in chemical, sensing, and related technologies. Oxygen vacancies (F and <i>F</i>⁺ center), as prevalent defects in <i>A</i><i>l</i>₂<i>O</i>₃, have attracted considerable research attention due to their promising application prospects. In this study, oxygen vacancies and their aggregates (<i>F</i>₂ and <i>F</i>22+) were efficiently and conveniently fabricated in <i>A</i><i>l</i>₂<i>O</i>₃ via high-temperature (1450^∘<i>C</i>) annealing under <i>N</i>₂ atmosphere. Subsequent low-energy and low-dose Ti ion implantation effectively sensitized the <i>F</i>22+ luminescence, enhancing the fluorescence intensity by an order of magnitude. Temperature-dependent studies revealed that elevated temperatures attenuated the sensitization effect, resulting in progressive fluorescence quenching. Concurrently, spectral broadening (increased FWHM) accompanied a blueshift of the emission peaks. This synergistic thermal response suggests promising potential for thermometry applications.