Enhanced near-infrared luminescence in zinc aluminate bestowed by fuel-blended combustion approach

Fuel-blend combustion method using urea and monoethanolamine (MEA) fuels, is employed to tune the defect states and hence luminescence properties of nanocrystalline ZnAl2O4. Prepared nanocrystals flaunt a ravishing blue and intensified near-infrared (NIR) emission with varying intensities. Sample pr...

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Bibliographic Details
Published in:Journal of alloys and compounds 2019-08, Vol.797, p.148-158
Main Authors: Jain, Megha, Manju, Gundimeda, Abhiram, Kumar, Akshay, Kumar, Sanjay, Gupta, Govind, Won, Sung Ok, Chae, Keun Hwa, Vij, Ankush, Thakur, Anup
Format: Article
Language:English
Subjects:
Aluminum
Combustion
Defects
Energy gap
Fuels
Luminescence
Medical imaging
Monoethanolamine (MEA)
Nanocrystals
Near infrared radiation
O K-edge
Optical properties
Photoluminescence
Rietveld refinement
Spectroscopy
Spectrum analysis
Urbach energy
Ureas
X ray absorption
X-ray absorption spectroscopy
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Summary:Fuel-blend combustion method using urea and monoethanolamine (MEA) fuels, is employed to tune the defect states and hence luminescence properties of nanocrystalline ZnAl2O4. Prepared nanocrystals flaunt a ravishing blue and intensified near-infrared (NIR) emission with varying intensities. Sample prepared using 80% MEA blended with 20% urea exhibits highest NIR emission, seven-fold intense than that prepared by 100% MEA, attributed to larger amount of deep band gap defects. Presence of multiple defects viz. vacancies of zinc, aluminium and oxygen is probed by means of Rietveld refinement, X-ray absorption near edge spectroscopy and photoluminescence spectroscopy. Band tailing and presence of shallow defect states are indicated by optical band gap and Urbach energy values. Broad range visible to NIR emission envisages application of ZnAl2O4 nanocrystals for bioimaging purposes. Radiative transitions among various defect levels contributing toward the emission have been depicted through a band model diagram. [Display omitted] •Synthesis of single phase ZnAl2O4 nanocrystals through fuel-blended combustion route.•Blue emission and highly intense near infrared emission exhibited by all samples.•Various types of lattice defects are indicated by Rietveld refinement, XANES and PL spectroscopy.•Colorimetric parameters revealed potential application in LEDs and bioimaging.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2019.04.257