1：Experimental Design and Method Selection:

The study used the Czochralski method for crystal growth in a reducing atmosphere to facilitate oxygen vacancy formation. Optical absorption, excitation-emission spectroscopy, single-crystal diffraction, and first-principles simulation were employed to investigate structure and properties.

2：Sample Selection and Data Sources:

The α-Al2O3:C,Mg crystal was grown from

3：999% pure Al2O3, 99% MgO, and C powder with specific stoichiometry (α-Al2O

C (5000 ppm), Mg (27 ppm)). Samples were cut and polished for measurements.

4：List of Experimental Equipment and Materials:

Equipment includes a DJL-500 furnace for crystal growth, UV-3600 PC Shimadzu spectrophotometer for optical absorption, Hitachi F-7000 fluorescence spectrometer for excitation-emission spectra, Xcalibur EOS with CrysAlis PRO for single-crystal diffraction, Autoconcept GD90RF GDMS for impurity measurement, and VESTA software for first-principles simulation. Materials include Al2O3, MgO, graphite powder, molybdenum crucible, and diamond/silica suspensions for polishing.

5：Experimental Procedures and Operational Workflow:

Raw materials were mixed, pressed, sintered, and grown in the furnace with specific pulling and rotation rates. After growth, crystals were cooled, cut, polished, and subjected to optical, structural, and impurity analyses. Annealing was performed in H2, air, or vacuum at specified temperatures and durations.

6：Data Analysis Methods:

Gaussian fitting was used for absorption spectra, Smakula's equation for color center concentration calculation, and first-principles simulation for theoretical absorption spectra analysis.