Nano Archive

Incipient crystallization of transition-metal tungstates under microwaves probed by Raman scattering and transmission electron microscopy

Siqueira, Kisla P. F. and Dias, Anderson (2011) Incipient crystallization of transition-metal tungstates under microwaves probed by Raman scattering and transmission electron microscopy. Journal of Nanoparticle Research, 13 (11). pp. 5927-5933.

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Abstract

Microwave synthesis was used to produce nanosized transition-metal tungstates in environmentally friendly conditions not yet reported by the literature: 110 and 150 °C, for times of 10 and 20 min. X-ray diffraction evidenced incipient crystallized materials, while transmission electron microscopy indicates nanostructured regions of about 2–5 nm inside an amorphous matrix. Raman spectroscopy was used to probe short-range ordering in the achieved samples and also to obtain a reliable set of spectra containing all the Raman-active bands predicted by group-theory calculations. The vibrational spectra showed no extra feature, indicating that the microwave processing was able to produce short-range ordered materials without tetrahedral distortions. These distortions are frequently reported when commercially modified kitchen microwave units are employed. In this work, the syntheses were conducted in a commercial apparatus especially designed for fully controlled temperature–time–pressure conditions.

Item Type:Article
ID Code:11555
Deposited By:Prof. Alexey Ivanov
Deposited On:05 Jan 2012 09:30
Last Modified:05 Jan 2012 09:42

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