Synthesis and Optical Characterization of Novel Orange-Red Emitting La₃Ga₅SnO₁₄:Sm³⁺ Phosphors with Abnormal Thermal...

This research successfully prepared a novel series of La₃Ga₅SnO₁₄:xSm³⁺ phosphors (x = 1, 2, 5, 10, 15, 20, 25, and 30 mol%) through high-temperature solid-state synthesis. This series of phosphors exhibited excellent phase purity. The excitation spectrum of La₃Ga₅SnO₁₄:Sm³⁺ showed an optimal excitation wavelength at 403 nm. Four distinct peaks (566, 598, 644, and 708 nm) were observed in the emission spectrum, with the most prominent peak appearing at 598 nm, corresponding to the ⁴G_5/2-⁶H_7/2 radiative transition of Sm³⁺ ions. The La₃Ga₅SnO₁₄:2 mol%Sm³⁺ was the optimal sample for effective optical performance. The concentration quenching effect is caused by nearest neighbor ion interactions. Within the temperature range of 300 to 480 K, the La₃Ga₅SnO₁₄:Sm³⁺ phosphor demonstrated very stable luminescence, with little changes in luminous intensity and Commission Internationale de l´Eclairage (CIE) chromaticity coordinates. The synthesized phosphors show remarkable thermal stability with an activation energy barrier of E_a = 0.51 eV, displaying unusual thermal quenching characteristics. These properties make them a highly potential candidate for white light-emitting diode (WLED) applications.