Determination of the aluminium coordination in aluminium-oxygen compounds by solid-state high-resolution 27AI NMR

Müller, D.; Geßner, W.; Behrens, Harald; Scheler, G.

doi:10.1016/0009-2614(81)85288-8

Cited by 352 publications

(111 citation statements)

References 5 publications

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“…Solid-state nuclear magnetic resonance (NMR) spectroscopy has been used successfully in studying complex cement hydration processes due to its sensitivity to disordered as well as crystalline phases [26], including in the analysis of CACs [27][28][29]. Magic angle spinning (MAS) NMR spectroscopy has in particular been widely used to probe local environments of aluminium and silicon nuclei in cements.…”

Section: Preprint Version Of Accepted Article Please Cite As: Ma Cmentioning

confidence: 99%

“…27 Al MAS NMR 27 Al MAS NMR spectra of anhydrous CAC clinker and hydrated samples are shown in Figure 5A. 27 Al MAS NMR spectra typically show three distinct aluminium coordination environments (Al IV , Al V and Al VI ) which are located at chemical shifts between 52 to 80 ppm, 30 to 40 ppm, and -10 to 20 ppm, respectively [27,29]. The spectrum of the anhydrous CAC clinker in Figure 5A is dominated by a large resonance at 78 ppm, due to the tetrahedral aluminium in the CA present in the clinker [28], in addition to a very small response at 9 ppm indicative of the partial hydration of the materials during storage, consistent with the ~1% mass loss observed in the clinker by thermogravimetry, Figure 3.…”

Section: Solid-state Nmr Spectroscopymentioning

confidence: 99%

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Identification of the hydrate gel phases present in phosphate-modified calcium aluminate binders

Chavda

Bernal

Apperley

et al. 2015

Cement and Concrete Research

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The conversion of hexagonal calcium aluminate hydrates to cubic phases in hydrated calcium aluminate cements (CAC) can involve undesirable porosity changes and loss of strength.Modification of CAC by phosphate addition avoids conversion, by altering the nature of the reaction products, yielding a stable amorphous gel instead of the usual crystalline hydrate products. Here, details of the environments of aluminium and phosphorus in this gel were elucidated using solid-state NMR and complementary techniques. Aluminium is identified in both octahedral and tetrahedral coordination states, and phosphorus is present in hydrous environments with varying, but mostly low, degrees of crosslinking. A 31 P/ 27 Al rotational echo adiabatic passage double resonance (REAPDOR) experiment showed the existence of aluminium-phosphorus interactions, confirming the formation of a hydrated calcium aluminophosphate gel as a key component of the binding phase. This resolves previous disagreements in the literature regarding the nature of the disordered products forming in this system.

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Section: Preprint Version Of Accepted Article Please Cite As: Ma Cmentioning

confidence: 99%

Section: Solid-state Nmr Spectroscopymentioning

confidence: 99%

Identification of the hydrate gel phases present in phosphate-modified calcium aluminate binders

Chavda

Bernal

Apperley

et al. 2015

Cement and Concrete Research

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“…Spectroscopic methods like XANES (e.g., Brown et al, 1988) and nuclear magnetic resonance (NMR) are direct probes of local Al-environments. 27A1 NMR is an important structural tool for determining AI coordination number in minerals (Miiller et al, 1981 ), particularly in clay minerals (Sanz and Serratoza, 1984;Kinsey et al, 1985;Woessner, 1989) and in low temperature, XRD-amorphous aluminosilicate allophanes from soils and stream deposits (Wilson et al, 1984;Goodman et at., 1985;Childs et al, 1990). XANES has provided useful information about Al-coordination in crystalline and glassy silicates (McKeown et al, 1985;McKeown, 1989).…”

Section: Introductionmentioning

confidence: 99%

²⁷Al Mas NMR and Aluminum X-Ray Absorption Near Edge Structure Study of Imogolite and Allophanes

Ildefonse

Kirkpatrick

Montez

et al. 1994

Clays and clay miner.

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Abstract--This paper compares the results of 27A1 nuclear magnetic resonance spectroscopy (NMR) and AI-K-edge X-ray Absorption Near Edge Structure (XANES) of natural imogolite and allophanes and some crystaUine reference minerals. All soil allophanes studied contain 4-coordinated A1 (AlIV). The highest relative proportion of A1TM, 21% of the total AI, was found in Si-rich allophane. This value is close to that found in spring allophanes, which were previously considered to be different from soil allophanes. For a quantitative determination of the AlXV/Alt~ ratio, NMR is more reliable than XANES, because of the sensitivity of the chemical shift to low A1TM concentrations, but XANES may be used even if paramagnetic impurities (mostly Fe) are present. Al-K XANES also yields more information than NMR on the local environment of A1 vi and especially site multiplicity. AI w XANES of imogolite and allophanes are similar regardless of the AI/Si ratio. They yield two well-resolved resonances with maxima near 1568 and 1570 eV, which indicates the presence of a unique A1 vt site by comparison with crystalline references. The presence of only one A1 w site indicates that imogolite and allophanes have an octahedral sheet with a structure similar to 2/1 dioctahedral phyllosilicates but different from gibbsite or kaolinite, previously considered as structural analogues. The 27AltV MAS NMR peak maxima of allophanes are between 58.6 and 59.8 ppm, in the range observed for crystalline and amorphous framework aluminosilicates, and less positive than those of sheet silicates, which are typically in the range 65-75 ppm. 27A1-H 1 CPMAS NMR spectra suggest that both A1TM and A1 vI have A1-O-H linkages.

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“…As expected from the crystal structure of palygorskite (Brindley and Brown, 1980), the results show that A1 in palygorskite was chiefly in octahedral coordination, along with a minor amount in tetrahedral coordination. The strong 27A1 resonance at 4.1 ppm from [Al(H20)6] 3+ indicates the presence of AI in octahedral coordination, and the minor resonance at 55.7 ppm (Figure 2) suggests the presence of a minor amount of tetrahedrally coordinated A1 (Muller et aL, 1981). The smectite product from the palygorskite showed a strong 27A1 resonance at 58.2 ppm from [Al(H20)6] 3+ (Figure 2) which represents tetrahedrally coordinated AI.…”

Section: Alteration Of Palygorskite In Naoh Solutionmentioning

confidence: 99%

“…The advent of solid-state magic-angle spinning-nuclear magnetic resonance (MAS-NMR) spectroscopy has provided a new tool to experimental petrologists for the investigation of the alteration of minerals and especially the mechanisms of the alteration. 27A1 and 29Si MAS-NMR spectroscopy have been shown to be useful in determining the A1 coordination and nearest neighbor environment of Si in aluminosilicate minerals (Lippmaa et al, 1980;Muller et al, 1981;Fyfe et al, 1982;Komarneni et al, 1986). The objective of the present study was to investigate the mechanisms of alteration of palygorskite and sepiolite to smectite under mild hydrothermal conditions using the data obtained from 27A1 and 29Si MAS-NMR and/or powder XRD and TEM analyses.…”

Section: Introductionmentioning

confidence: 97%

Mechanisms of Palygorskite and Sepiolite Alteration as Deduced from Solid-State ²⁷Al and ²⁹Si Nuclear Magnetic Resonance Spectroscopy

Komarneni

1989

Clays and clay miner.

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Abstract--The mechanisms of palygorskite and sepiolite alteration to smectite under mild hydrothermal conditions were investigated by solid-state 27A1 and 29Si magic-angle spinning-nuclear magnetic resonance (MAS-NMR) spectroscopy, X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). Palygorskite altered to smectite in the presence of NaOH at 150"C. 27A1 MAS-NMR spectroscopy showed that the Al coordination changed from chiefly octahedral in palygorskite to chiefly tetrahedral in the smectite product. 29Si MAS-NMR spectroscopy showed that the nearest neighbor environment of Si also changed when palygorskite altered to smectite. The XRD data showed that the synthetic smectite is trioctahedral in nature with tetrahedral charge. The TEM results revealed that the needle-like morphology of palygorskite was preserved in the product smectite. The MAS-NMR results in conjunction with the above XRD and TEM studies suggest that the mechanism of palygorskite alteration was a dissolution and recrystaUization process rather than a solid-state reorganization to form 2:1 layer silicate units from the preexisting chain structure. Sepiolite altered to smectite in the presence of 2 N salt solutions at 300*(2. The trioctahedral nature of the product smectite as detected by XRD and the foil-like morphology of product smectite as shown by TEM suggest that the mechanism of sepiolite transformation to smectite was also a dissolution and recrystaUization process. The tetrahedral A! coordination detected by 27Al MAS-NMR in the smectite altered from sepiolite corroborated the XRD and TEM results.

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Determination of the aluminium coordination in aluminium-oxygen compounds by solid-state high-resolution 27AI NMR

Cited by 352 publications

References 5 publications

Identification of the hydrate gel phases present in phosphate-modified calcium aluminate binders

Identification of the hydrate gel phases present in phosphate-modified calcium aluminate binders

²⁷Al Mas NMR and Aluminum X-Ray Absorption Near Edge Structure Study of Imogolite and Allophanes

Mechanisms of Palygorskite and Sepiolite Alteration as Deduced from Solid-State ²⁷Al and ²⁹Si Nuclear Magnetic Resonance Spectroscopy

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Determination of the aluminium coordination in aluminium-oxygen compounds by solid-state high-resolution 27AI NMR

Cited by 352 publications

References 5 publications

Identification of the hydrate gel phases present in phosphate-modified calcium aluminate binders

Identification of the hydrate gel phases present in phosphate-modified calcium aluminate binders

27Al Mas NMR and Aluminum X-Ray Absorption Near Edge Structure Study of Imogolite and Allophanes

Mechanisms of Palygorskite and Sepiolite Alteration as Deduced from Solid-State 27Al and 29Si Nuclear Magnetic Resonance Spectroscopy

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²⁷Al Mas NMR and Aluminum X-Ray Absorption Near Edge Structure Study of Imogolite and Allophanes

Mechanisms of Palygorskite and Sepiolite Alteration as Deduced from Solid-State ²⁷Al and ²⁹Si Nuclear Magnetic Resonance Spectroscopy