Synthesis and luminescence properties of Mn4+-dopant Ca14Zn6Ga10−xAlxO35 solid solution

Abstract Mn 4+ -activated oxide phosphors, owing to their desirable spectral features, eco-friendly and low cost, are emerging as a new class of non-rare-earth red phosphors for warm white LEDs. However, these phosphors possess low photoluminescence quantum efficiency excited by blue chip currently. Herein we report an isostructural solid solution of Ca 14 Zn 6 Ga 10−x Al x O 35 : 0.15Mn 4+ (0 ≤ x ≤ 10) synthesized by a traditional solid-state reaction route. The microstructure and luminescent performance of this red-emitting phosphor are investigated in detail with the aids of X-ray diffraction, diffuse reflection spectra, photoluminescence spectra/decay/QE, and temperature-dependent PL/QE measurements. Blue shift of energy peaks of 4 A 2 → 4 T 1 and 4 A 2 → 4 T 2 transition is illustrated by the Tanabe–Sugano diagram and the configurational coordinate diagram. The crystal field strength (Dq) and the Racah parameters (B and C) are carefully calculated to estimate the nephelauxetic effect β respectively. Particularly we achieve external and internal quantum efficiencies as high as 26.1% and 40.3% for Ca 14 Zn 6 Ga 6 Al 4 O 35 : 0.15Mn 4+ excited by 466 nm, the highest one ever reported in Mn 4+ activated oxide phosphors under the similar condition.