Chromaticity coordinates of ruby based on first-principles calculation

Abstract Understanding the local atomic configuration is crucial for studying phosphor materials. Their performance in many applications is strongly dependent upon their optical properties. Much experimental and theoretical effort has been made to meet the requirements. Specifically, ab-initio studies have extensively reported the absorption spectra and the multiplet energies of phosphors. However, the qualitative analysis on the emitted light has not yet been reported. In this work, we characterized the emitted light of ruby, which is a widely studied phosphor material. The absorption spectra of ruby were calculated utilizing the non-empirical discrete variational Xα (DV-Xα) and discrete variational multi-electron (DVME) software. Then, the investigation on the (x,y) chromaticity coordinates of was performed under the standard illuminant D65 utilizing ColorAC software, a chromaticity diagram maker. In this work, we used a ruby model cluster generated from an α-Al2O3 crystal. The model consists of seven atoms, where one chromium atom surrounded by six oxygen atoms. We compared the absorption spectra obtained via simple configuration interaction (CI) and those obtained which include energy corrections called configuration dependent correction (CDC) and correlation correction (CC). We successfully reproduced the color that is observed in experiment. The chromaticity coordinates approach red region for higher concentration. The results show that the calculation with CDC-CC shows better agreement with experiment. This research confirms the non-empirical calculations based on the DV-Xα and DVME methods, in the terms of emitted light.