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High-Field One-Dimensional and Two-Dimensional (27)Al Magic-Angle Spinning Nuclear Magnetic Resonance Study of θ-, δ-, and γ-Al(2)O(3) Dominated Aluminum Oxides: Toward Understanding the Al Sites in γ-Al(2)O(3)

[Image: see text] Herein, a detailed analysis was carried out using high-field (19.9 T) (27)Al magic-angle spinning (MAS) nuclear magnetic resonance (NMR) on three specially prepared aluminum oxide samples where the γ-, δ-, and θ-Al(2)O(3) phases are dominantly expressed through careful control of t...

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Autores principales: Xu, Suochang, Jaegers, Nicholas R., Hu, Wenda, Kwak, Ja Hun, Bao, Xinhe, Sun, Junming, Wang, Yong, Hu, Jian Zhi
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2021
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7876829/
https://www.ncbi.nlm.nih.gov/pubmed/33585784
http://dx.doi.org/10.1021/acsomega.0c06163
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author Xu, Suochang
Jaegers, Nicholas R.
Hu, Wenda
Kwak, Ja Hun
Bao, Xinhe
Sun, Junming
Wang, Yong
Hu, Jian Zhi
author_facet Xu, Suochang
Jaegers, Nicholas R.
Hu, Wenda
Kwak, Ja Hun
Bao, Xinhe
Sun, Junming
Wang, Yong
Hu, Jian Zhi
author_sort Xu, Suochang
collection PubMed
description [Image: see text] Herein, a detailed analysis was carried out using high-field (19.9 T) (27)Al magic-angle spinning (MAS) nuclear magnetic resonance (NMR) on three specially prepared aluminum oxide samples where the γ-, δ-, and θ-Al(2)O(3) phases are dominantly expressed through careful control of the synthesis conditions. Specifically, two-dimensional (2D) multiquantum (MQ) MAS (27)Al was used to obtain high spectral resolution, which provided a guide for analyzing quantitative 1D (27)Al NMR spectra. Six aluminum sites were resolved in the 2D MQ MAS NMR spectra, and seven aluminum sites were required to fit the 1D spectra. A set of octahedral and tetrahedral peaks with well-defined quadrupolar line shapes was observed in the θ-phase dominant sample and was unambiguously assigned to the θ-Al(2)O(3) phase. The distinct line shapes related to the θ-Al(2)O(3) phase provided an opportunity for effectively deconvoluting the more complex spectrum obtained from the δ-Al(2)O(3) dominant sample, allowing the peaks/quadrupolar parameters related to the δ-Al(2)O(3) phase to be extracted. The results show that the δ-Al(2)O(3) phase contains three distinct Al(O) sites and three distinct Al(T) sites. This detailed Al site structural information offers a powerful way of analyzing the most complex γ-Al(2)O(3) spectrum. It is found that the γ-Al(2)O(3) phase consists of Al sites with local structures similar to those found in the δ-Al(2)O(3) and θ-Al(2)O(3) phases albeit with less ordering. Spin–lattice relaxation time measurement further confirms the disordering of the lattice. Collectively, this study uniquely assigns (27)Al features in transition aluminas, offering a simplified method to quantify complex mixtures of aluminum sites in transition alumina samples.
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spelling pubmed-78768292021-02-12 High-Field One-Dimensional and Two-Dimensional (27)Al Magic-Angle Spinning Nuclear Magnetic Resonance Study of θ-, δ-, and γ-Al(2)O(3) Dominated Aluminum Oxides: Toward Understanding the Al Sites in γ-Al(2)O(3) Xu, Suochang Jaegers, Nicholas R. Hu, Wenda Kwak, Ja Hun Bao, Xinhe Sun, Junming Wang, Yong Hu, Jian Zhi ACS Omega [Image: see text] Herein, a detailed analysis was carried out using high-field (19.9 T) (27)Al magic-angle spinning (MAS) nuclear magnetic resonance (NMR) on three specially prepared aluminum oxide samples where the γ-, δ-, and θ-Al(2)O(3) phases are dominantly expressed through careful control of the synthesis conditions. Specifically, two-dimensional (2D) multiquantum (MQ) MAS (27)Al was used to obtain high spectral resolution, which provided a guide for analyzing quantitative 1D (27)Al NMR spectra. Six aluminum sites were resolved in the 2D MQ MAS NMR spectra, and seven aluminum sites were required to fit the 1D spectra. A set of octahedral and tetrahedral peaks with well-defined quadrupolar line shapes was observed in the θ-phase dominant sample and was unambiguously assigned to the θ-Al(2)O(3) phase. The distinct line shapes related to the θ-Al(2)O(3) phase provided an opportunity for effectively deconvoluting the more complex spectrum obtained from the δ-Al(2)O(3) dominant sample, allowing the peaks/quadrupolar parameters related to the δ-Al(2)O(3) phase to be extracted. The results show that the δ-Al(2)O(3) phase contains three distinct Al(O) sites and three distinct Al(T) sites. This detailed Al site structural information offers a powerful way of analyzing the most complex γ-Al(2)O(3) spectrum. It is found that the γ-Al(2)O(3) phase consists of Al sites with local structures similar to those found in the δ-Al(2)O(3) and θ-Al(2)O(3) phases albeit with less ordering. Spin–lattice relaxation time measurement further confirms the disordering of the lattice. Collectively, this study uniquely assigns (27)Al features in transition aluminas, offering a simplified method to quantify complex mixtures of aluminum sites in transition alumina samples. American Chemical Society 2021-01-25 /pmc/articles/PMC7876829/ /pubmed/33585784 http://dx.doi.org/10.1021/acsomega.0c06163 Text en © 2021 The Authors. Published by American Chemical Society This is an open access article published under a Creative Commons Non-Commercial No Derivative Works (CC-BY-NC-ND) Attribution License (http://pubs.acs.org/page/policy/authorchoice_ccbyncnd_termsofuse.html) , which permits copying and redistribution of the article, and creation of adaptations, all for non-commercial purposes.
spellingShingle Xu, Suochang
Jaegers, Nicholas R.
Hu, Wenda
Kwak, Ja Hun
Bao, Xinhe
Sun, Junming
Wang, Yong
Hu, Jian Zhi
High-Field One-Dimensional and Two-Dimensional (27)Al Magic-Angle Spinning Nuclear Magnetic Resonance Study of θ-, δ-, and γ-Al(2)O(3) Dominated Aluminum Oxides: Toward Understanding the Al Sites in γ-Al(2)O(3)
title High-Field One-Dimensional and Two-Dimensional (27)Al Magic-Angle Spinning Nuclear Magnetic Resonance Study of θ-, δ-, and γ-Al(2)O(3) Dominated Aluminum Oxides: Toward Understanding the Al Sites in γ-Al(2)O(3)
title_full High-Field One-Dimensional and Two-Dimensional (27)Al Magic-Angle Spinning Nuclear Magnetic Resonance Study of θ-, δ-, and γ-Al(2)O(3) Dominated Aluminum Oxides: Toward Understanding the Al Sites in γ-Al(2)O(3)
title_fullStr High-Field One-Dimensional and Two-Dimensional (27)Al Magic-Angle Spinning Nuclear Magnetic Resonance Study of θ-, δ-, and γ-Al(2)O(3) Dominated Aluminum Oxides: Toward Understanding the Al Sites in γ-Al(2)O(3)
title_full_unstemmed High-Field One-Dimensional and Two-Dimensional (27)Al Magic-Angle Spinning Nuclear Magnetic Resonance Study of θ-, δ-, and γ-Al(2)O(3) Dominated Aluminum Oxides: Toward Understanding the Al Sites in γ-Al(2)O(3)
title_short High-Field One-Dimensional and Two-Dimensional (27)Al Magic-Angle Spinning Nuclear Magnetic Resonance Study of θ-, δ-, and γ-Al(2)O(3) Dominated Aluminum Oxides: Toward Understanding the Al Sites in γ-Al(2)O(3)
title_sort high-field one-dimensional and two-dimensional (27)al magic-angle spinning nuclear magnetic resonance study of θ-, δ-, and γ-al(2)o(3) dominated aluminum oxides: toward understanding the al sites in γ-al(2)o(3)
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7876829/
https://www.ncbi.nlm.nih.gov/pubmed/33585784
http://dx.doi.org/10.1021/acsomega.0c06163
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