Recovery rate and homogeneity of doping europium into luminescent metal hydrides by chemical analysis

Abstract

During the investigation of concentration dependent properties of phosphors, such as emission intensities, the knowledge of the activator ion concentration is of great importance. Herein we present a study on recovery rate and homogeneity of the activator ion concentration by chemical analysis in luminescent europium doped metal hydrides. The analysis method was established on the model system Eu_xSr_1−xH₂ and applied to brightly emitting hydridic perovskites LiMH₃:Eu²⁺ and LiMD₃:Eu²⁺ (M = Sr, Ba). The nominal activator ion concentrations calculated from initial weights are in good agreement with those determined via ICP-MS for 10⁻³% ≤ x both for the hydrides (deuterides) and the parent alloys. The synthesis protocol thus allows a reliable method for reproducibly doping europium into metal hydrides. Luminescence spectra of LiEu_xSr_1−xH₃ with x = 0.0037% show a broad band emission at room temperature typical for Eu²⁺ 4f⁶5d¹–4f⁷ transitions. Below 80 K, a vibronic fine structure is observed with vibrational coupling frequencies of approximately 100, 370 and 970 cm⁻¹.