Eu3+ ion concentration induced 3D luminescence properties of novel red-emitting Ba4La6(SiO4)O:Eu3+ oxyapatite phosphors for versatile applications. Issue 5 (11th January 2016)

• Record Type: Journal Article
• Authors: Raju, G. Seeta Rama; Pavitra, E.; Hussain, Sk. Khaja; Balaji, D.; Yu, Jae Su
• Is Part Of: Journal of materials chemistry. Volume 4:Issue 5(2016)
• Page Start: 1039
• Page End: 1050
• Publication Date: 2016-01-11
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c5tc03919c
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : Novel red-emitting BLSO:Eu 3+ phosphors with the quantum efficiency of 65% have been developed for NUV excitation based solid-state lighting and display applications. Abstract : A series of Eu 3+ ions activated Ba4 La6 (SiO4 )6 O (BLSO:Eu 3+ ) phosphors were synthesized by a modified citrate sol–gel process. The structural properties of these phosphors were explored by means of X-ray diffraction (XRD) and Fourier transform infrared spectroscopy. The XRD patterns confirmed their oxyapatite structure with the space group of P 63 / m after annealing at 1400 °C. The scanning electron microscope image exhibited the irregular morphology of BLSO:Eu 3+ particles and the elemental mapping confirmed that the Eu 3+ ions were distributed homogeneously on the La 3+ ion sites. Photoluminescence (PL) excitation spectra of BLSO:Eu 3+ exhibited the charge transfer band (CTB) and intense f–f transitions of Eu 3+ ions in the violet and blue wavelength regions. The CTB intensity decreased and the f–f transition of Eu 3+ ions increased with increasing the Eu 3+ ion concentration due to the presence of defects in the 4f and 6h sites of the BLSO host lattice. This feature facilitates the strong absorption in the near-ultraviolet (NUV) region, which is useful for high color rendering index NUV based white light-emitting diodes for display and lighting applications. The PL spectra displayed intense red emission ( 5 D0 → 7 F2 ) along with considerable orange emission ( 5 D0 → 7 F1 ) with good asymmetry ratios and chromaticity coordinates, and exhibited better emission performance than that of commercial Y2 O3 :Eu 3+ phosphors. The three-dimensional PL spectra revealed their strong emission characteristics under UV, NUV and visible excitation wavelengths. The cathodoluminescence properties were also similar to the PL results, confirming that the BLSO:Eu 3+ phosphors emit stable red emission under different excitation sources as compared to the commercial Y2 O3 :Eu 3+ phosphors.