Host-dependent microstructural evolution and radiative dynamics in Eu3+-activated Sr2(Gd1-xLax)0.9TaO6 and Ba2(Gd1-xLax)0.9TaO6 double perovskites
Ceramics International, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.ceramint.2026.09.106
- Dergi Adı: Ceramics International
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Compendex, INSPEC, Academic Search Ultimate (EBSCO), Engineering Source (EBSCO)
- Anahtar Kelimeler: Double perovskite oxides, Eu3+phosphors, Radiative dynamics, Symmetry distortion, Thermal stability
- Kocaeli Üniversitesi Adresli: Evet
Özet
Eu3+-activated Sr2(Gd1-xLax)0.9Eu0.1TaO6 and Ba2(Gd1-xLax)0.9Eu0.1TaO6 (x = 0–90 mol%) double-perovskite phosphors were synthesized by a conventional solid-state reaction and systematically investigated to elucidate host-dependent structure–luminescence relationships. X-ray diffraction and Rietveld refinement confirmed the formation of single-phase monoclinic P21/n structures throughout the investigated composition range. La3+ substitution induced distinct host-dependent microstructural evolution, promoting crystallite growth and improved densification in the Sr-based lattice, whereas the Ba-based host exhibited a gradual reduction in crystallite size. Optical band-gap analysis revealed a gradual band-gap narrowing in the Sr-based series, whereas only negligible variation was observed for the Ba-based phosphors. Photoluminescence measurements revealed markedly different spectroscopic behaviors. The Sr-based phosphors exhibited enhanced electric-dipole emission, increased asymmetry, and significantly improved luminescence intensity, whereas the Ba-based phosphors remained magnetic-dipole dominated with a gradual decrease in emission intensity. Decay, Judd–Ofelt, and quantum-efficiency analyses demonstrated that radiative relaxation becomes progressively enhanced in the Sr-based phosphors, while non-radiative relaxation plays an increasingly important role in the Ba-based series. Thermal quenching measurements revealed good thermal stability for both hosts, with superior emission retention in the Sr-based compositions. Internal quantum efficiency (IQE) measurements further supported these trends, showing a pronounced increase for the Sr-based phosphors but a gradual decrease for the Ba-based counterparts. Colorimetric analysis indicated a systematic evolution toward deeper red emission with improved color purity in the Sr-based series, whereas the Ba-based phosphors exhibited nearly unchanged chromatic characteristics. Finally, the optimized Sr2La0.9Eu0.1TaO6 phosphor was successfully demonstrated as a red-emitting phosphor-converted LED under 395 nm excitation. These results demonstrate that La3+ substitution produces strongly host-dependent structural and optical responses, providing an effective strategy for tailoring the luminescence performance of Eu3+-activated Ta-based double-perovskite phosphors.