A blue to green tunable Ba 3 GdP 3 O 12 :Tb 3+ nanophosphor: structural and opto-electronic analysis
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A blue to green tunable Ba3GdP3O12:Tb3+ nanophosphor: structural and opto‑electronic analysis Heena Dahiya1 · Mandeep Dalal2 · Anju Siwach1 · Manju Dahiya1 · V. B. Taxak2 · S. P. Khatkar2 · Dinesh Kumar1 Received: 29 March 2019 / Accepted: 6 August 2019 © Springer Science+Business Media, LLC, part of Springer Nature 2019
Abstract A series of blue–green Ba3Gd(1−x)P3O12: xTb3+ nanocrystals has been successfully prepared via the urea-assisted solutioncombustion method. Its structure, morphology, energy-transfer mechanism, photoluminescent (PL) excitation-emission and decay time behavior were investigated in detail employing powder X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Diffuse Reflectance (DR) and PL spectroscopy. The Rietveld analysis exposed the cubic phase of all the nanophosphors with I-43d (220) space group and infers that Gd3+ ions can be well substituted by Tb3+ ions without any major alteration in the crystal prototype of the host lattice. The optical band-gap of the host was calculated to be 4.9 eV, unveiling the high potential as a host for lanthanide activators. Under the excitation at λex = 224 nm, the photoluminescent emission spectra exhibited the two main characteristic peaks at 545 nm and 487 nm as a result of 5D4 → 7F5 (green and magnetic-dipole) and 5 D4 → 7F6 (blue and electric-dipole) transitions, respectively. The decay analysis showed that the activator occupies a single crystallographic site, a fact that is also supported by the Rietveld refinement. The critical distance of the energy transfer (19.87 Å) integrated with Dexter’s modeling inferred about the energy migration (dipole–dipole). The PL result showed that the blue-to-green tunable emission can be achieved simply via varying the dopant concentration, with 7 mol% as the optimum concentration for standard CIE coordinates of green emission. All the results suggest that Ba3Gd(1−x)P3O12: xTb3+ crystals may find their use as a green phosphor component in display devices and solid-state lighting.
1 Introduction In the recent years, scientists all around the world have been making efforts in producing nanophosphor materials as these are considered as very valuable asset in the field of optical applications such as solid-state laser devices, optical amplifiers, light emitting diodes (LED’s), solar cells, X-ray medical radiography, cathode ray-tubes, sensor technology, optical markers, and plasma display panels [1–4]. The motive is to design and develop a near-ultraviolet (NUV) excited but ecofriendly phosphor material with better luminescence, long emission lifetime, high thermal stability, narrow emissions bands and with reasonable product reliability [5–9]. In this context, rare-earth trivalent ions play an important role when * Dinesh Kumar [email protected] 1
Department of Chemistry, Deenbandhu Chhotu Ram University of Science & Technology, Murthal, Sonepat 131039, India
Department of Chemistry, Maharshi Dayanand University, Rohtak 124001, India
2
incorporated in a suitable host matrix; which i
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