Synthesis and Luminescence Studies of Tb³⁺-Doped Li₂CaSiO₄ Phosphor for Optical Device Application

A series of Tb³⁺-doped Li₂CaSiO₄ phosphors were prepared by high-temperature solid-state reaction method. The structural studies were done using the X-ray diffraction (XRD) technique. The XRD patterns revealed that the sample was monophased and crystallizes in a cubic structure. Scanning electron microscopy (SEM) was used to obtain information about the morphology of the prepared samples. SEM micrographs clearly indicated that the particles crystallized in inhomogeneous morphology, with the particle size ranging from 1 μm to 100 nm. Also, photoluminescence (PL) analysis of the phosphor samples for different concentrations of doping ions with variable excitations were presented. The PL excitation spectrum of Tb³⁺ ion-doped Li₂CaSiO₄ has many sharp peaks, mainly at 418 nm (⁵D₃ → ⁷F₅), 436 nm (⁵D₃ → ⁷F₄), 456 nm (⁵D₃ → ⁷F₃), 472 nm (⁵D₃ → ⁷F_2,1,0), 487 nm (⁵D₄ → ⁷F₆), 550 nm (⁵D₄ → ⁷F₅), and 590 nm (⁵D₄ → ⁷F₄), assigned to the transitions of Tb- ion respectively (excited at 237 nm). The 1931 CIE (x, y) chromaticity coordinates showed the distribution of the spectral region calculated from PL emission spectra, and found to be (0.19, 0.22) in a bluish-green region of Tb³⁺ (0.01 wt (in grams)) Li₂CaSiO₄ phosphor. Our study shows that as-prepared phosphor may be useful for optical devices, mainly for LEDs, as a bluish-green component.