Colour tunability of Dy3+ & Sm3+ activated yttrium aluminium gallium nanocrystals for display applications

• Published in: Optical materials Vol. 157; p. 116105
• Main Authors: Rama Devi, N., Praveena, R., Upendra Kumar, K., Jyothi, L., Joshi, B.D.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-11-2024
• Subjects: Dy3; Garnets; Nanocrystals; Sm3; White light; YAGG; Sm3; YAGG; Nanocrystals; White light; Garnets; Dy3
• ISSN: 0925-3467
• DOI: 10.1016/j.optmat.2024.116105

A set of powder samples of Y3AlGa4O12 doped with Dy3+ and Sm3+ with different concentration of Sm3+ ion were prepared via sol-gel synthesis. X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive (EDS), Fourier transform infrared (FTIR) and photoluminescence spectral studies were carried out. All the diffraction peaks matched the cubic lattice Y3AlGa4O12, as given by the XRD. The SEM images revealed aggregated spherical particles ranging from 50 to 130 nm. The EDS analysis confirmed the presence of the initial chemicals in the synthesized samples. FTIR spectrum was used to examine the vibrational modes in the sample. Under a 366 nm excitation wavelength, the emission spectrum showed the peaks at 492 nm (blue), 580 nm (yellow), 673 nm (red), and 760 nm (near-infrared) corresponding to the characteristic transitions 4F9/2 → 6H15/2,13/2,11/2,9/2 of the Dy3+ ion, respectively. In comparison, the peaks at 568 nm, 614 nm, 664 nm, and 711 nm corresponded to the characteristic transitions 4G5/2 → 6H5/2,7/2,9/2,11/2 of the Sm3+ ion. Under near ultraviolet light excitation, the superposition of these blue, yellow and red colours produced excellent white light emission. The intensities of these transitions varied with the concentration of Sm3+ ion and the excitation wavelength. The emission spectrum of Dy3+ overlapped with the excitation spectrum of Sm3+, indicated possible energy transfer from Dy3+ to Sm3+. According to Inokuti-Hirayama's theory of energy transfer, the mechanism of energy transfer was understood to be quadrupole-quadrupole interaction. The CIE chromaticity co-ordinates and correlated colour temperature values showed that these samples were suitable for light-emitting diode applications.
The emission spectra of YAGG:Dy3+,Sm3+ nanocrystals at 366 nm. [Display omitted]
•Synthesized Dy3+ and Dy3+/Sm3+-co-doped Y3AlGa4O12 (YAGG) garnet nanocrystals by Pechini Sol-Gel method.•The variations in intensity ratios of Y/B, R/B and R/Y were investigated with respect to the Sm3+ ion concentration.•The colour co-ordinates, colour purity, CRI and CCT values indicated that the synthesized phosphors were suitable for white LED applications.