On the luminescent properties of Eu3+ doped La2Hf3(WO4)9

Abstract

This work concerns the host material La₂Hf₃(WO₄)₉ doped with Eu³⁺ as a widely applied red emitting activator, focusing on its luminescent properties under various excitation conditions. La_2-xEu_xHf₃(WO₄)₉ solid solutions were synthesized and confirmed to crystallize in a single-phase structure. The reflectivity decreases with increasing Eu³⁺ doping level, while characteristic Eu³⁺ electronic transitions emerge, enhancing absorption strength and emission intensity. Emission spectra under various excitation conditions (395 nm; 160 nm; X-rays) reveal concentration-dependent characteristic Eu³⁺ luminescence behavior with stable peak positions and red emission profiles. Under X-ray excitation, luminescence peaks at 10 % Eu³⁺ doping, followed by intensity quenching at higher concentrations due to non-radiative mechanisms. The depth of X-ray penetration, calculated using the Feldman equation, correlates with the observed luminescence efficiency. The materials exhibit a rather low thermal quenching temperature, with T_1/2 determined as 228 K. Lifetime measurements highlight concentration quenching effects and distinct Eu³⁺ environments. Chromaticity coordinates confirm a consistent red emission with minor variations across doping levels. The study provides insights into the structural, optical, and thermal properties of Eu³⁺-doped La₂Hf₃(WO₄)₉, emphasizing its potential and limitations for luminescent applications.