Abstract
First‐principles calculations with the most accurate hybrid functional are used to investigate the effect of native point defects and Ti/Fe impurities on electrical and optical properties of α‐Al2O3. For dominant native point defects, the Al vacancy (VAl), O vacancy (VO), and Al interstitial (Ali) defects are considered, and it is found that only VAl defect provides the absorption line in the visible light region. Regarding Ti‐doped or Fe‐doped sapphire, it is found that their colors should be related to intra‐atomic d–d transitions. For the Ti–Fe pair, it is found that the ground‐state configuration is TiIII–FeIII, and its binding energy is very high, indicating that this pair can exist in high concentration. The calculated optical absorption energy associated with Ti–Fe pair is ≈1.92 and 1.84, which is appropriate for sapphire to be blue. It is, therefore, suggested that the intervalence charge transfer (IVCT) mechanism is the cause of blue color in blue sapphire.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
