Structure, photoluminescence and influence of temperature on energy transfer of green-emission phosphor Ca9La(GeO4)0.75(PO4)6:Ce3+,Tb3+

Abstract

To explore a new phosphor, Ca₉La(GeO₄)_0.75(PO4)₆ was investigated to obtain better understanding of its synthesis and crystal structure. Ce³⁺/Tb³⁺ co-doped Ca₉La(GeO₄)_0.75(PO₄)₆ green phosphor was successfully synthesized with the objective of application in ultraviolet-based light-emitting diodes. The characteristic photoluminescence properties were analysed by photoluminescence excitation (PLE) spectra, emission (PL) spectra and decay times. Ca₉La(GeO₄)_0.75(PO₄)₆ offers high thermal stability in the green-emission area. Instead of thermal quenching, with the increase in temperature, the intensity of Tb³⁺ increases slightly. To explain this special phenomenon reasonably, an implicit mechanism between thermal quenching and energy transfer is proposed based on the configurational coordinate diagram. This mechanism could be a helpful reference for understanding the thermal properties of multiple activator Ce³⁺ and Tb³⁺ co-doped phosphors.