A novel tunable green-to-red emitting phosphor Ca4LaO(BO3)3:Tb,Eu via energy transfer with high quantum yield

A novel green phosphor composed of Ca4LaO(BO3)3:Tb3+ (CLBO:Tb) has been synthesized by a combustion method with urea. Its crystal structure, temperature-dependent luminescence, and quantum yield (QY) have been characterized by X-ray diffraction (XRD) and photoluminescence (PL) spectra with heating device and integrate sphere. No concentration quenching has been observed when all of La3+ ions are substituted with Tb3+ ions. Green phosphor Ca4TbO(BO3)3 (CTBO) has 200% luminescence intensity of commercially available phosphor LaPO4:Ce, Tb (LPO:Ce, Tb) under 378 nm excitation. The QY of CTBO is as high as 98%. Through a Dexter energy transfer mechanism, Eu3+ ions are efficiently sensitized by Tb3+, resulting in an emission with color tunable from green to red under ultraviolet excitation. A possible mechanism of energy transfer from Tb3+ to Eu3+ has been investigated by PL spectra and decay measurements. The energy transfer efficiency from Tb3+ to Eu3+ increases linearly with concentration of Eu3+ increasing.