Analysis of Nd3+ concentration on the structure, morphology and photoluminescence of sol-gel Sr3ZnAl2O7 nanophosphor

M.R. Mhlongo; L.F. Koao; T.E Motaung; R.E. Kroon; S.V. Motloung

Results in Physics (Mar 2019)

Analysis of Nd3+ concentration on the structure, morphology and photoluminescence of sol-gel Sr3ZnAl2O7 nanophosphor

M.R. Mhlongo,
L.F. Koao,
T.E Motaung,
R.E. Kroon,
S.V. Motloung

Affiliations

M.R. Mhlongo: Department of Physics, Sefako Makgatho Health Sciences University, P.O. Box 94, Medunsa 0204, South Africa; Corresponding authors at: Department of Physics, Sefako Makgatho Health Sciences University, P.O. Box 94, Medunsa 0204, South Africa.
L.F. Koao: Department of Physics, University of the Free State (Qwaqwa Campus), Private Bag X 13, Phuthaditjhaba 9866, South Africa
T.E Motaung: Department of Chemistry, University of Zululand, KwaDlangezwa, 3886, South Africa
R.E. Kroon: Department of Physics, University of the Free State, P. O. Box 339, Bloemfontein 9300, South Africa
S.V. Motloung: Department of Physics, Sefako Makgatho Health Sciences University, P.O. Box 94, Medunsa 0204, South Africa; Department of Physics, Nelson Mandela University (NMU), P. O. Box 77000, Port Elizabeth 6031, South Africa; Corresponding authors at: Department of Physics, Sefako Makgatho Health Sciences University, P.O. Box 94, Medunsa 0204, South Africa.

Journal volume & issue: Vol. 12
pp. 1786 – 1796

Abstract

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Neodymium activated strontium zinc aluminate (Sr3ZnAl2O7:x%Nd3+) nanophosphor was synthesized using the sol-gel technique whereby the Nd3+ concentration was varied in the range 0 ≤ x ≤ 2. The effect of Nd3+ concentration on the structure, particle morphology and photoluminescence properties of Sr3ZnAl2O7 were investigated. The X-ray diffraction (XRD) results revealed that all samples resembled the mixture of both ZnAl2O4 and Sr3Al2O6 cubic structures. Nd3+ doping influenced the crystallite sizes of the prepared phosphor materials. The energy dispersive X-ray spectroscopy (EDS) results confirmed the presence of all expected elements in the composition. Scanning electron microscopy (SEM) revealed that as the Nd3+ concentration increased the surface morphology changed to smooth mountain-like structures. The ultraviolet–visible (UV–Vis) diffuse reflection spectroscopy showed that the band gap of Sr3ZnAl2O7 can be tuned from 2.74 to 2.95 eV by increasing the Nd3+ concentration. When the host is excited above the bandgap (374 nm), broad emission attributed to defects occurs with the maximum near 585 nm. Doped samples excited in this manner do not exhibit additional luminescence due to the Nd3+ ions, but in contrast there is a small dip in the defect emission band near 585 nm due to absorption attributed to Nd3+ ions. Characteristic infrared emissions of Nd3+ ions at 885, 1064 and 1340 nm were observed by directly exciting the Nd3+ ions at 585 nm (4I9/2 → 5G5/2 + 2G7/2) and were attributed to 4F3/2 → 4I9/2, 4I11/2 and 4I13/2 transitions, respectively. The Commission Internationale de l’Eclairage (CIE) coordinates results showed that the orange emission colour is from the host. Keywords: Sol-gel, Nd3+ activated, Sr3ZnAl2O7, Photoluminescence, CIE

Published in Results in Physics

ISSN: 2211-3797 (Online)
Publisher: Elsevier
Country of publisher: Netherlands
LCC subjects: Science: Physics
Website: http://www.journals.elsevier.com/results-in-physics/

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