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Structural Study of Nano-Sized Gahnite (ZnAl(2)O(4)): From the Average to the Local Scale

Spinel gahnite (ZnAl(2)O(4)) has been obtained through a hydrothermal synthesis method with a grain size of about 2 nm. The sample was calcined for a few hours at two different temperatures (800 and 900 °C) in order to obtain larger grain sizes to be analyzed by means of powder diffraction with the...

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Autores principales: Confalonieri, Giorgia, Rotiroti, Nicola, Bernasconi, Andrea, Dapiaggi, Monica
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7712502/
https://www.ncbi.nlm.nih.gov/pubmed/32357413
http://dx.doi.org/10.3390/nano10050824
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author Confalonieri, Giorgia
Rotiroti, Nicola
Bernasconi, Andrea
Dapiaggi, Monica
author_facet Confalonieri, Giorgia
Rotiroti, Nicola
Bernasconi, Andrea
Dapiaggi, Monica
author_sort Confalonieri, Giorgia
collection PubMed
description Spinel gahnite (ZnAl(2)O(4)) has been obtained through a hydrothermal synthesis method with a grain size of about 2 nm. The sample was calcined for a few hours at two different temperatures (800 and 900 °C) in order to obtain larger grain sizes to be analyzed by means of powder diffraction with the Rietveld method, and by means of total scattering with the Pair Distribution Function (PDF) method. The idea is to compare the average to the local structure, as a function of increasing grain size. The total scattering data were collected at the European Synchrotron Radiation Facility (ESRF), Grenoble. The samples have been also characterised by means of high resolution Transmission Electron Microscopy (TEM), showing an increasing grain size up to about 9 nm. The average structure presented variations in the inversion degree and an increase in grain size. TEM observations demonstrated that the small crystals are well crystallised: the high resolution images neatly showed the atomic planes, even in the smallest particles. However, the average structure did not properly fit the PDF data in the local region, owing to a slightly different coordination among the octahedra. A new structural model is proposed for the local region of the PDF, that helped our understanding of the differences between a real nanostructured sample and that of a microcrystalline one. The oxygen disorder, due to the inversion grade of the spinel, is demonstrates to be at the basis of the local deviation. No signals of interstitial Zn atoms were detected.
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spelling pubmed-77125022020-12-04 Structural Study of Nano-Sized Gahnite (ZnAl(2)O(4)): From the Average to the Local Scale Confalonieri, Giorgia Rotiroti, Nicola Bernasconi, Andrea Dapiaggi, Monica Nanomaterials (Basel) Article Spinel gahnite (ZnAl(2)O(4)) has been obtained through a hydrothermal synthesis method with a grain size of about 2 nm. The sample was calcined for a few hours at two different temperatures (800 and 900 °C) in order to obtain larger grain sizes to be analyzed by means of powder diffraction with the Rietveld method, and by means of total scattering with the Pair Distribution Function (PDF) method. The idea is to compare the average to the local structure, as a function of increasing grain size. The total scattering data were collected at the European Synchrotron Radiation Facility (ESRF), Grenoble. The samples have been also characterised by means of high resolution Transmission Electron Microscopy (TEM), showing an increasing grain size up to about 9 nm. The average structure presented variations in the inversion degree and an increase in grain size. TEM observations demonstrated that the small crystals are well crystallised: the high resolution images neatly showed the atomic planes, even in the smallest particles. However, the average structure did not properly fit the PDF data in the local region, owing to a slightly different coordination among the octahedra. A new structural model is proposed for the local region of the PDF, that helped our understanding of the differences between a real nanostructured sample and that of a microcrystalline one. The oxygen disorder, due to the inversion grade of the spinel, is demonstrates to be at the basis of the local deviation. No signals of interstitial Zn atoms were detected. MDPI 2020-04-26 /pmc/articles/PMC7712502/ /pubmed/32357413 http://dx.doi.org/10.3390/nano10050824 Text en © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Confalonieri, Giorgia
Rotiroti, Nicola
Bernasconi, Andrea
Dapiaggi, Monica
Structural Study of Nano-Sized Gahnite (ZnAl(2)O(4)): From the Average to the Local Scale
title Structural Study of Nano-Sized Gahnite (ZnAl(2)O(4)): From the Average to the Local Scale
title_full Structural Study of Nano-Sized Gahnite (ZnAl(2)O(4)): From the Average to the Local Scale
title_fullStr Structural Study of Nano-Sized Gahnite (ZnAl(2)O(4)): From the Average to the Local Scale
title_full_unstemmed Structural Study of Nano-Sized Gahnite (ZnAl(2)O(4)): From the Average to the Local Scale
title_short Structural Study of Nano-Sized Gahnite (ZnAl(2)O(4)): From the Average to the Local Scale
title_sort structural study of nano-sized gahnite (znal(2)o(4)): from the average to the local scale
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7712502/
https://www.ncbi.nlm.nih.gov/pubmed/32357413
http://dx.doi.org/10.3390/nano10050824
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