Luminescent Properties and Luminous Thermal Stability of Adjusting Colorful 100 mol% Activator Tb2(1−x)Eu2x(MoO4)3 Phosphors

Abstract

Rare-earth-doped phosphors have garnered significant attention for their pivotal role in optoelectronic devices, yet the development of high-concentration activator systems with tunable luminescence and robust thermal stability remains a challenge. By adjusting the contents of Tb³⁺ and Eu³⁺, a series of 100 mol% activator Tb_2(1−x)Eu_2xMo₃O₁₂ phosphors (0 ≤ x ≤ 1) were prepared through a solid-state reaction method. All Tb_2(1−x)Eu_2xMo₃O₁₂ phosphors crystallized in the orthorhombic phase, and the energy band gap (E_g) decreased from 3.77 eV (x = 0) to 3.39 eV (x = 1) due to lattice expansion induced by Eu³⁺ substitution. Tunable emission from green to red was achieved through efficient energy transfer (ET) from Tb³⁺ to Eu³⁺, with even 0.5 mol% Eu³⁺ doping significantly altering photoluminescence (PL) properties. Notably, Tb₂Mo₃O₁₂ and Eu₂Mo₃O₁₂ exhibited contrasting thermal behaviors despite identical crystal structures, attributed to differences in electronic configurations. The Tb_2(1−x)Eu_2xMo₃O₁₂ phosphor demonstrated stable thermal activation energy (E_a) across temperatures, highlighting its potential for high-temperature applications. Fabricated LEDs with 380- or 397-nm chips emitted adjustable green, yellow, and red light, confirming the viability of prepared materials for lighting technologies. This study provides insights into designing high-concentration activator phosphors with tunable emissions and enhanced thermal stability, advancing their applicability in next-generation optoelectronic devices.