Y3Al5O12:Ce3+isthemostfamousphosphormaterialduetoitsexcellentphotolumincentproperties.Here,throughfirst-principlescalculation,theeffectofcarboninterstitialdefectsonY3Al5O12:Ce3+phosphorwasinvestigated.Itisfoundthatthecarboninterstitialstendtooccupythenext-nearestsitesofCe3+ioninY3Al5O12:Ce3+lattice.Specially,theseinterstitialdefectscanshortentheCe3+-O2-bondlength,leadingtoalargercrystalfieldsplittingof5dorbitaloftheCe3+atomandbigger5dcentroidshift.ThesetwofactorscausetheemissionspectrumofY3Al5O12（C）:Ce3+redshiftcomparedwiththatofY3Al5O12:Ce3+.Moreover,withourcomparisonexperiment,wefindthattheY3Al5O12（C）:Ce3+hasanobviousredshiftcomparedwiththatofY3Al5O12:Ce3+system,whichisinaccordwithourfirstprinciplescalculation.OurworksystematicallyinvestigatestheimpactofthecarboninterstitialdefectonY3Al5O12:Ce3+,andprovidesanewroutetotunetheemissionspectruminY3Al5O12:Ce3+.
