Spectroscopic Analysis in GdSr3(PO4)3:Tb3+/Eu3+ Phosphor for Optical Applications

Abstract

A series of Tb³⁺/Eu³⁺ co-activated GdSr₃(PO₄)₃ commonly known as GSP phosphors with tunable luminescence properties were successfully synthesized using conventional solid-state reaction (SSR) method. The structural analysis of GdSr₃(PO₄)₃:Tb³⁺, Eu³⁺ confirms the cubic crystal system with I \(\overline{4 }\) 3d (220) space-group. Also, the scanning electron microscopy (SEM), X-ray energy dispersive spectra (EDS), and photoluminescence (PL) spectroscopy were employed to characterize the samples. The luminescent behavior of synthesized compound was examined at various excitation as well as at different doping concentration, confirming high intensity emission near white light. The emission spectra for GSP:Tb³⁺ recorded at 337 nm give the dominant peak of green color at 546 nm, with highest intensity noted for 3 mol% of doping. Whereas, emission spectra plotted for GSP:Eu³⁺ at excitation 394 nm emit intense red color emission at 615 nm for 4 mol% doping concentration. The co-activated GSP:Tb³⁺, Eu³⁺ phosphor excited at 337 nm, 377 nm, and 393 nm gives tunable properties. When excited at 337 nm, the characteristics emission of only Tb³⁺ ion is recorded in emission spectra, while for 377 nm excitation, both Tb³⁺ and Eu³⁺ ions emission are observed, and for 393 nm excitation, only Eu³⁺ ion emissions are recorded. The energy transfer from Tb³⁺  → Eu³⁺ is observed. The variation in lifetime, color rendering index (CRI), and correlated color temperature (CCT) is observed due to varied doping concentration of Eu³⁺, Tb³⁺ ions indicating vibrant and intense light. This phosphor has potential applications in the field of optoelectronics specifically as a wLED.