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1.
RSC Adv ; 13(48): 33675-33687, 2023 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-38020000

RESUMO

This paper investigates the synthesis and luminescence characteristics of Tm3+/Tb3+/Eu3+ co-doped Sr4Nb2O9 (SNB) phosphors as potential candidates for white light-emitting diodes (WLEDs). The study explores the energy transfer mechanisms and color-tunable characteristics of these phosphors. The SNB phosphors were prepared using a solid-state reaction method, and their structural and morphological properties were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Fourier-transform infrared (FT-IR) spectroscopy. The diffuse reflectance, photoluminescence (PL) and time resolved photoluminescence (TRPL) properties were investigated, revealing efficient energy transfer processes from Tm3+ to Tb3+ and Eu3+ ions. The energy transfer mechanisms were determined through critical distance calculations and analysis of multipolar interactions. The co-doped phosphors exhibited tunable emission colors ranging from blue to white light, with controllable correlated color temperatures (CCTs) and high color rendering indices (CRIs). The CIE chromaticity coordinates were optimized to approach neutral white light. The PL intensity is maintained at 81.19% at 150 °C of that of room temperature which showcases the remarkable thermal stability of the as-prepared phosphors. The results highlight the potential of Tm3+/Tb3+/Eu3+ co-doped SNB phosphors for generating high-quality, color-tunable white light for advanced lighting applications.

2.
Luminescence ; 36(6): 1444-1451, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34000084

RESUMO

A series of samarium ions (Sm3+ ) activated barium sodium niobate (Ba2 NaNb5 O15 ) samples have been successfully synthesized via employing a solid-state reaction technique. Single phase, crystalline tetragonal Ba2 NaNb5 O15 were formed and the crystallite size of the prepared sample varied with doping of Sm3+ ions. The scanning electron microscopy (SEM) images of Ba2 NaNb5 O15 :Sm3+ illustrate that the particles possess a non-uniform spherical structure with some agglomeration. The prepared Ba2 NaNb5 O15 :Sm3+ phosphors were efficiently excited with near-ultraviolet (n-UV) (406 nm) and emit strong visible emission peaks in the range 550-725 nm. The phenomenon of concentration quenching was detected after x = 0.10 mol of Sm3+ ions concentration for Ba2 NaNb5 O15 , which arises due to non-radiative energy transfer through dipole-dipole interaction among activator ions. Colour coordinates (0.586, 0.412) for the optimized phosphor lies in the visible reddish orange region. A bi-exponential decay behaviour was observed for the photoluminescence decay curve of the optimized phosphor sample with an average decay time in milliseconds. The temperature dependent emission intensity confirms that the Ba2-x NaNb5 O15 :xSm3+ (x = 0.10 mol) phosphor exhibits adequate thermal stability having high value of activation energy (ΔE = 0.201 eV). The comprehensive study and analysis of the as-prepared samples suggest that the intense reddish orange emitting thermally stable Ba2 NaNb5 O15 :Sm3+ phosphor can act as a potential luminescent material in phosphor coated lighting, solar cells and other photonic devices.


Assuntos
Citrus sinensis , Substâncias Luminescentes , Bário , Luminescência , Samário
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