Synergistic effects of Tb doping in long-persistent luminescence in Ca3Ga4O9: xBi3+, yZn2+ phosphors: Implications for novel phosphorescent materials

Long afterglow phosphors constitute an emerging class of compounds with wide application in several fields, from photonic to dosimetry, solar energy storage and photocatalysis. In this study, we synthesized and thoroughly characterized a new class of persistent emitting materials, Ca3Ga4O9: xBi3+, yZn2+, zTb3+. Through the utilization of X-ray and Raman spectroscopy, as well as optical measurements including static and time-resolved luminescence, thermoluminescence, and phosphorescence, the effects of the Tb concentration on the optical and structural properties of the material has been deeply studied. A suitable mechanism was proposed to account for the long afterglow emission, wherein Tb3+ and Bi3+ ions occupying the Ca2+ sites serve as recombination centers, facilitating the generation of oxygen defects. Zn2+ in the Ga3+ sites, contribute to the charge balance and generates hole traps in the matrix. The enduring phosphorescence persists for over 3 h following the cessation of UV irradiation, discernible to the naked eye in low-light conditions.