Microwave solution route to ceramic ZnAl2O4 nanoparticles in 10 minutes: inversion and photophysical changes with thermal history

Menon, Samvit G and Choudhari, Khoobaram S and Shivashankar, Srinivasrao A and Chidangil, Santhosh and Kulkarni, Suresh D (2017) Microwave solution route to ceramic ZnAl2O4 nanoparticles in 10 minutes: inversion and photophysical changes with thermal history. In: NEW JOURNAL OF CHEMISTRY, 41 (13). pp. 5420-5428.

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Abstract

Microwave-assisted synthesis of ZnAl2O4 nanoparticles in minutes using metalorganic precursors is reported. Phase-pure ZnAl2O4 with an average crystallite size of similar to 5 nm is formed in the solution medium at 185 degrees C. Annealing in air at temperatures between 500 and 1200 degrees C increases the crystallite size to similar to 32 nm. The as-prepared particles are largely shapeless, whereas polyhedral crystallites with well-defined grain boundaries can be seen in the HR-TEM image of the annealed samples. Diffuse reflectance spectroscopy provides insight into the structural development of the oxide spinel. Rapid synthesis leads to significant crystallographic inversion (similar to 33%), as observed by X-ray photoelectron spectroscopy. Photoluminescence spectroscopy shows that the different emission bands are due both to anti-site defects in the form of zinc interstitials caused by cationic inversion and to oxygen and zinc vacancies. Optical measurements suggest that inhomogeneity in cationic distribution, probably caused by the rapidity of synthesis, is prevalent even after annealing at temperatures up to 1200 degrees C, and plays a significant role in controlling the emission properties of the spinel. The microwave-assisted technique using metalorganic precursors is an easy path to the rapid synthesis of doped ZnAl2O4 phosphors.

Item Type:	Journal Article
Publication:	NEW JOURNAL OF CHEMISTRY
Additional Information:	Copy right for this article belongs to the ROYAL SOC CHEMISTRY, THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND
Department/Centre:	Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited:	21 Jul 2017 09:12
Last Modified:	21 Jul 2017 09:12
URI:	http://eprints.iisc.ac.in/id/eprint/57443

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