Akademik Veri Yönetim Sistemi
MATERIALS SCIENCE AND ENGINEERING B-ADVANCED FUNCTIONAL SOLID-STATE MATERIALS, cilt.323, 2026 (SCI-Expanded, Scopus)
In this study, Eu3+-activated Ca2Gd1-xVO6 and Sr2Gd1-xVO6 (x = 0-30 mol%) red-emitting phosphors were synthesized via a conventional solid-state reaction route and systematically characterized to assess the effect of A-site variation on their structural and photoluminescence properties. X-ray diffraction results confirmed the single phase formation of monoclinic-Ca2GdVO6 (P2(1)/n) and monoclinic-Sr2GdVO6 (P2/m) structures, as further corroborated by full Rietveld refinements that yielded low-residual fits and reliable lattice parameters. SEM micrographs revealed similar grain morphologies with marginal differences in average grain sizes. Photoluminescence excitation spectra exhibited a broad charge transfer band (CTB) centered near 256 nm, attributed to O2- -> Eu3+ transitions, along with sharp f-f transitions and characteristic Gd3+ absorptions. Emission spectra under blue excitation (lambda(ex) = 467 nm) demonstrated dominant D-5(0) -> F-7(2) electric dipole transitions, with higher asymmetry ratios observed in the Ca-based system, indicating a more distorted local environment. Judd-Ofelt (JO) analysis further confirmed this distinction through elevated Omega(2) parameters, particularly at low doping levels. The quantum efficiencies (eta(QE)) calculated using the Judd-Ofelt formalism were 99.56 % and 78.05 % for the most luminescent Ca-based and Sr-based samples, respectively, while the experimentally measured IQE/EQE values were 79.82 %/41.69 % (Ca-based) and 65.58 %/36.66 % (Sr-based). Additionally, colorimetric evaluation revealed that both phosphor systems emitted warm reddish light with high color purity (up to similar to 85 % for Ca-based and similar to 96 % for Sr-based) and low correlated color temperature (CCT similar to 1600-2500 K), suitable for warm-white LED and display applications. These findings highlight the tunable nature of Eu3+-activated vanadate perovskites via A-site engineering, enabling their use in solid-state lighting, displays, and optical security.