Fabrication of single-phase BaLaAlO<sub>4</sub>:Dy<sup>3+</sup> nanophosphors by combustion synthesis
Priyanka Sehrawat, Avni Khatkar, Priti Boora, Mukesh Kumar, Sonika Singh, R.K. Malik, S.P. Khatkar, V.B. Taxak
Abstract
To solve the problem of multiphased commercial light emitting diodes, a series of new single-phased BaLaAlO4:Dy3+ nanophosphors emitting cool white light were successfully fabricated via an energy-efficient approach, namely, solution combustion. X-ray diffractometry and Rietveld refinement revealed orthorhombic phase purity with P 212121(19) space group. Agglomerated orthorhombic nanoparticles (30–50 nm) were reported via scanning and transmission electron microscopy, whereas elemental distribution was confirmed by energy dispersive X-ray analysis. On excitation by 349 nm light, the nanophosphors showed peaks at 481 nm (blue color) on account of magnetic dipole transition and 573 nm (yellow color) by reason of electric dipole transition. Maximum intensity was observed for 3.0 mol% concentration of Dy3+ ions above which concentration quenching occurred due to electric multipolar interactions. Decay lifetime and energy band gap for optimized nanophosphor (BaLa1−xDyxAlO4 (x = 3.0 mol%)) were obtained as 0.651 ms and 5.41 eV, respectively. CIE coordinates (0.297, 0.283), color purity (25.44 × 10−2), and correlated color temperature (CCT) value (8480 K) of optimal nanophosphor were found approximate to white coordinates of commercial LEDs and National Television System Committee, which proved their emission of cool white light and suggested their use in the outdoor lighting devices, i.e., white light emitting diodes.