Order-Disorder in the Structures of Lithium Aluminosilicate Minerals by XRD and Multinuclear NMR
The crystal structures of the lithium aluminosilicate minerals of the Li<sub>2</sub>O–Al<sub>2</sub>O<sub>3</sub>–SiO<sub>2</sub> (LAS) system (Li<sub>1−x</sub>Al<sub>1−x</sub>Si<sub>1+x</sub>O<sub>4</sub>...
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| Format: | Article |
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MDPI AG
2022-03-01
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| Series: | Minerals |
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| Online Access: | https://www.mdpi.com/2075-163X/12/4/427 |
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| author | Luis Sánchez-Muñoz Jesús Sanz Pierre Florian Virginia Diez-Gómez Marta Furio Isabel Sobrados |
| author_facet | Luis Sánchez-Muñoz Jesús Sanz Pierre Florian Virginia Diez-Gómez Marta Furio Isabel Sobrados |
| author_sort | Luis Sánchez-Muñoz |
| collection | DOAJ |
| description | The crystal structures of the lithium aluminosilicate minerals of the Li<sub>2</sub>O–Al<sub>2</sub>O<sub>3</sub>–SiO<sub>2</sub> (LAS) system (Li<sub>1−x</sub>Al<sub>1−x</sub>Si<sub>1+x</sub>O<sub>4</sub> system for 0.0 ≤ <i>x</i> ≤ 1.0), and bikitaite were determined by X-ray diffraction (XRD) in literature, suggesting several possible lattice models for each of the crystallized phases, because of the intrinsic experimental difficulties of this technique. Here, we correlate powder XRD patterns with Rietveld refinement of cell parameters and magic angle sample spinning multinuclear magnetic resonance (NMR) spectra, including <sup>29</sup>Si, <sup>27</sup>Al, <sup>7</sup>Li, and <sup>6</sup>Li spectroscopy at 7.05 T, 9.4 T, and 20 T. The aim is to select appropriate lattice models from short-range order schemes in the lithium aluminosilicate phases, from natural minerals and synthetic crystals from the crystallization of amorphous gel precursors by a ceramic route and also by hydrothermal high-pressure experiments. Solid solutions were found in <i>α</i>-quartz and <i>α</i>-cristobalite up to <i>x</i> ≥ 0.75, and in <i>β</i>-eucryptite and <i>β</i>-spodumene for 0.0 ≤ <i>x</i> ≤ 1.0, when the ceramic synthesis is at work. The local structures of these intermediate members of the <i>β</i>-eucryptite and <i>β</i>-spodumene solid-solution series have <sup>29</sup>Si NMR spectra consistent with the Loewenstein’s rule, i.e., they have short-range order but are strictly non-periodic structures. However, <i>β</i>-eucryptite LiAlSiO<sub>4</sub> end-member has a short-range structure compatible with the long-range order of the <i>P</i>6<sub>4</sub>22 symmetry, when the crystallization is produced at hydrothermal conditions. The local structure of α-spodumene LiAlSi<sub>2</sub>O<sub>6</sub> is consistent with the <i>C</i>2/c model. α-eucryptite LiAlSiO<sub>4</sub> shows a short-range structure as that suggested by the <i>R</i>-3 lattice model. Petalite LiAlSi<sub>4</sub>O<sub>10</sub> has a local structure compatible with the <i>P</i>2/a space group. Finally, the <sup>29</sup>Si NMR spectra of bikitaite LiAlSi<sub>2</sub>O<sub>6</sub>·H<sub>2</sub>O indicate a short-range structure well-suited with the <i>P</i>1 symmetry. These results are consistent with the Ostwald‘s rule of stages, forming a order-disorder sequence of increasing long-range order from the starting fully disordered solid gels, through crystalline pseudoperiodic structures in non-stoichiometric solid solution crystals that respect the Lowenstein’s rule, up to fully ordered crystals with short-range structures from NMR close to the long-range structures by XRD, as in the stoichiometric compounds found in some natural minerals. |
| first_indexed | 2024-03-09T04:21:42Z |
| format | Article |
| id | doaj.art-2a4eeec39e1f47049855dd1016835126 |
| institution | Directory Open Access Journal |
| issn | 2075-163X |
| language | English |
| last_indexed | 2024-03-09T04:21:42Z |
| publishDate | 2022-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Minerals |
| spelling | doaj.art-2a4eeec39e1f47049855dd10168351262023-12-03T13:45:35ZengMDPI AGMinerals2075-163X2022-03-0112442710.3390/min12040427Order-Disorder in the Structures of Lithium Aluminosilicate Minerals by XRD and Multinuclear NMRLuis Sánchez-Muñoz0Jesús Sanz1Pierre Florian2Virginia Diez-Gómez3Marta Furio4Isabel Sobrados5Museo Nacional de Ciencias Naturales (MNCN-CSIC), José Gutierrez Abascal 2, 28006 Madrid, SpainInstituto de Ciencia de Materiales de Madrid (CSIC), 28049 Madrid, SpainCentre National de la Recherche Scientifique (CNRS), UPR3079 CEMHTI, Université d’Orléans, 1D Av. Recherche Scientifique, CEDEX 2, 45071 Orléans, FranceInstituto de Ciencia de Materiales de Madrid (CSIC), 28049 Madrid, SpainMuseo Nacional de Ciencias Naturales (MNCN-CSIC), José Gutierrez Abascal 2, 28006 Madrid, SpainInstituto de Ciencia de Materiales de Madrid (CSIC), 28049 Madrid, SpainThe crystal structures of the lithium aluminosilicate minerals of the Li<sub>2</sub>O–Al<sub>2</sub>O<sub>3</sub>–SiO<sub>2</sub> (LAS) system (Li<sub>1−x</sub>Al<sub>1−x</sub>Si<sub>1+x</sub>O<sub>4</sub> system for 0.0 ≤ <i>x</i> ≤ 1.0), and bikitaite were determined by X-ray diffraction (XRD) in literature, suggesting several possible lattice models for each of the crystallized phases, because of the intrinsic experimental difficulties of this technique. Here, we correlate powder XRD patterns with Rietveld refinement of cell parameters and magic angle sample spinning multinuclear magnetic resonance (NMR) spectra, including <sup>29</sup>Si, <sup>27</sup>Al, <sup>7</sup>Li, and <sup>6</sup>Li spectroscopy at 7.05 T, 9.4 T, and 20 T. The aim is to select appropriate lattice models from short-range order schemes in the lithium aluminosilicate phases, from natural minerals and synthetic crystals from the crystallization of amorphous gel precursors by a ceramic route and also by hydrothermal high-pressure experiments. Solid solutions were found in <i>α</i>-quartz and <i>α</i>-cristobalite up to <i>x</i> ≥ 0.75, and in <i>β</i>-eucryptite and <i>β</i>-spodumene for 0.0 ≤ <i>x</i> ≤ 1.0, when the ceramic synthesis is at work. The local structures of these intermediate members of the <i>β</i>-eucryptite and <i>β</i>-spodumene solid-solution series have <sup>29</sup>Si NMR spectra consistent with the Loewenstein’s rule, i.e., they have short-range order but are strictly non-periodic structures. However, <i>β</i>-eucryptite LiAlSiO<sub>4</sub> end-member has a short-range structure compatible with the long-range order of the <i>P</i>6<sub>4</sub>22 symmetry, when the crystallization is produced at hydrothermal conditions. The local structure of α-spodumene LiAlSi<sub>2</sub>O<sub>6</sub> is consistent with the <i>C</i>2/c model. α-eucryptite LiAlSiO<sub>4</sub> shows a short-range structure as that suggested by the <i>R</i>-3 lattice model. Petalite LiAlSi<sub>4</sub>O<sub>10</sub> has a local structure compatible with the <i>P</i>2/a space group. Finally, the <sup>29</sup>Si NMR spectra of bikitaite LiAlSi<sub>2</sub>O<sub>6</sub>·H<sub>2</sub>O indicate a short-range structure well-suited with the <i>P</i>1 symmetry. These results are consistent with the Ostwald‘s rule of stages, forming a order-disorder sequence of increasing long-range order from the starting fully disordered solid gels, through crystalline pseudoperiodic structures in non-stoichiometric solid solution crystals that respect the Lowenstein’s rule, up to fully ordered crystals with short-range structures from NMR close to the long-range structures by XRD, as in the stoichiometric compounds found in some natural minerals.https://www.mdpi.com/2075-163X/12/4/427quartzcristobalite<i>α</i>-spodumene<i>β</i>-spodumene<i>α</i>-eucryptite<i>β</i>-eucryptite |
| spellingShingle | Luis Sánchez-Muñoz Jesús Sanz Pierre Florian Virginia Diez-Gómez Marta Furio Isabel Sobrados Order-Disorder in the Structures of Lithium Aluminosilicate Minerals by XRD and Multinuclear NMR Minerals quartz cristobalite <i>α</i>-spodumene <i>β</i>-spodumene <i>α</i>-eucryptite <i>β</i>-eucryptite |
| title | Order-Disorder in the Structures of Lithium Aluminosilicate Minerals by XRD and Multinuclear NMR |
| title_full | Order-Disorder in the Structures of Lithium Aluminosilicate Minerals by XRD and Multinuclear NMR |
| title_fullStr | Order-Disorder in the Structures of Lithium Aluminosilicate Minerals by XRD and Multinuclear NMR |
| title_full_unstemmed | Order-Disorder in the Structures of Lithium Aluminosilicate Minerals by XRD and Multinuclear NMR |
| title_short | Order-Disorder in the Structures of Lithium Aluminosilicate Minerals by XRD and Multinuclear NMR |
| title_sort | order disorder in the structures of lithium aluminosilicate minerals by xrd and multinuclear nmr |
| topic | quartz cristobalite <i>α</i>-spodumene <i>β</i>-spodumene <i>α</i>-eucryptite <i>β</i>-eucryptite |
| url | https://www.mdpi.com/2075-163X/12/4/427 |
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