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Thomas Vogt - One of the best experts on this subject based on the ideXlab platform.
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high pressure and high temperature transformation of pb ii Natrolite to pb ii lawsonite
Dalton Transactions, 2016Co-Authors: Junhyuck Im, Douglas A Blom, Thomas VogtAbstract:We report on high-pressure and high-temperature chemical transformations of Pb2+-exchanged Natrolite (Pb-NAT, Pb8Al16Si24O80·16H2O) using a combination of in situ synchrotron X-ray powder diffraction and ex situ HAADF-STEM real space imaging. Three high-pressure polymorphs of Natrolites (Pb-NAT-I, II, III) are observed via step-wise pressure-induced hydrations (PIH) up to 4.5 GPa, during which the number of H2O molecules located inside the Natrolite channel increases from 16 to 40 H2O per unit-cell. At 4.5 GPa after heating the high-pressure Pb-NAT-III phase at 200 °C a reconstructive phase transits into a lawsonite phase (Pb-LAW, Pb4Al8Si8O28(OH)8·4H2O) with an orthorhombic space group Pbnm and a = 5.8216(9), b = 9.114(1) and c = 13.320(1) A is observed. The structure of the recovered Pb-LAW phase was characterized using Rietveld refinement of the in situ synchrotron X-ray powder diffraction data and HAADF-STEM real space imaging. In the recovered Pb-LAW phase the Pb2+ content is close to 42 wt% and as bond valence approximations reveal the Pb2+ cations are more tightly coordinated to the framework oxygen atoms than originally in the Natrolite phase.
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two step pressure induced superhydration in small pore Natrolite with divalent extra framework cations
ChemInform, 2015Co-Authors: Donghoon Seoung, Thomas VogtAbstract:K-Natrolite is prepared by combining a 4 M KNO3 solution with the natural mineral Na16Al16Si24O80 ·16H2O in a 100:1 weight ratio for 24 h.
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two step pressure induced superhydration in small pore Natrolite with divalent extra framework cations
Chemistry of Materials, 2015Co-Authors: Donghoon Seoung, Thomas VogtAbstract:In situ high pressure X-ray powder diffraction studies of Natrolite (NAT) containing the divalent extra-framework cations (EFC) Sr2+, Ca2+, Pb2+, and Cd2+ reveal that they can be superhydrated in the presence of water. In the case of Ca-NAT, Sr-NAT, and Pb-NAT pressure-induced hydration (PIH) inserts 40 H2O/unit cell into the zeolite compared to 32 in superhydrated Natrolites containing monovalent EFC. Cd-NAT is superhydrated in one step to a zeolite containing 32 H2O/unit cell. PIH of Ca-NAT and Sr-NAT occurs in two steps. During PIH of Pb-NAT three distinct steps have been observed. The excess H2O in Natrolites with divalent EFC are accommodated on sites no longer required for charge compensation. Two distinct families with ordered and disordered EFC–water topologies have been found. Our work established the importance of both size and charge of the EFC in PIH.
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potassium exchanged Natrolite under pressure computational study vs experiment
Journal of Physical Chemistry C, 2014Co-Authors: Alena Kremleva, Thomas Vogt, Notker RöschAbstract:Using density functional theory we modeled the effects of pressure on K-exchanged Natrolite, K-NAT, including superhydration and the experimentally observed structural phase transition. Natrolites are composed of T5O10 secondary building units (T = Si, Al) linking two Al- and three Si-based TO4 tetrahedra which in projection have an average chain rotation angle ψ with respect to the crystallographic a- and b-axes. Besides an isomer with pore axes orientations characterized by a negative chain rotation angle, found experimentally at moderate pressure, we also examined a superhydrated isomer with pore axes orientations resulting from positive chain rotation angles in the pressure range 1–2.5 GPa. We estimated the critical pressure for possible transformations between various isomers, but we were unable to identify any specific energetic preference for a superhydrated structure with a negative chain rotation angle. Therefore, our computational results suggest that both isomers coexist in the same pressure ra...
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Monovalent Cation-Exchanged Natrolites and Their Behavior under Pressure. A Computational Study
Journal of Physical Chemistry C, 2013Co-Authors: Alena Kremleva, Thomas Vogt, Notker RöschAbstract:Recently Natrolite was shown to be an auxetic material that is able to exchange extra-framework Na+ cations with other mono-, di-, and trivalent cations. Under pressure up to several GPa, these cation-exchanged Natrolites undergo superhydration and/or phase transformations in the cation–water arrangement. Using density functional theory we studied in silico the ion exchange in Natrolites. First we optimized the structures of Li+-, Na+-, K+-, Rb+-, and Cs+-exchanged Natrolites at ambient conditions and compared the resulting lattice energies to that of the hypothetical H-form of Natrolite. Of all Natrolites, the smallest formal exchange energy was found for Na-NAT, in agreement with the natural occurrence of this material. Then we modeled the effect of pressure on Na-, Rb-, and Cs-Natrolites, addressing (i) the incorporation of water ligands into the zeolite framework, accompanied by an increase in volume; and (ii) the changes in the cation–water arrangement within the zeolite pores. The computational mode...
Donghoon Seoung - One of the best experts on this subject based on the ideXlab platform.
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two step pressure induced superhydration in small pore Natrolite with divalent extra framework cations
ChemInform, 2015Co-Authors: Donghoon Seoung, Thomas VogtAbstract:K-Natrolite is prepared by combining a 4 M KNO3 solution with the natural mineral Na16Al16Si24O80 ·16H2O in a 100:1 weight ratio for 24 h.
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two step pressure induced superhydration in small pore Natrolite with divalent extra framework cations
Chemistry of Materials, 2015Co-Authors: Donghoon Seoung, Thomas VogtAbstract:In situ high pressure X-ray powder diffraction studies of Natrolite (NAT) containing the divalent extra-framework cations (EFC) Sr2+, Ca2+, Pb2+, and Cd2+ reveal that they can be superhydrated in the presence of water. In the case of Ca-NAT, Sr-NAT, and Pb-NAT pressure-induced hydration (PIH) inserts 40 H2O/unit cell into the zeolite compared to 32 in superhydrated Natrolites containing monovalent EFC. Cd-NAT is superhydrated in one step to a zeolite containing 32 H2O/unit cell. PIH of Ca-NAT and Sr-NAT occurs in two steps. During PIH of Pb-NAT three distinct steps have been observed. The excess H2O in Natrolites with divalent EFC are accommodated on sites no longer required for charge compensation. Two distinct families with ordered and disordered EFC–water topologies have been found. Our work established the importance of both size and charge of the EFC in PIH.
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Super‐Hydrated Zeolites: Pressure‐Induced Hydration in Natrolites
Chemistry: A European Journal, 2013Co-Authors: Donghoon Seoung, Thomas VogtAbstract:High-pressure synchrotron X-ray powder diffraction studies of a series of alkali-metal-exchanged Natrolites, A16Al16Si24O80⋅n H2O (A=Li, K, Na, Rb, and Cs and n=14, 16, 22, 24, 32), in the presence of water, reveal structural changes that far exceed what can be achieved by varying temperature and chemical composition. The degree of volume expansion caused by pressure-induced hydration (PIH) is inversely proportional to the non-framework cation radius. The expansion of the unit-cell volume through PIH is as large as 20.6 % in Li-Natrolite at 1.0 GPa and decreases to 6.7, 3.8, and 0.3 % in Na-, K-, and Rb-Natrolites, respectively. On the other hand, the onset pressure of PIH appears to increase with non-framework cation radius up to 2.0 GPa in Rb-Natrolite. In Cs-Natrolite, no PIH is observed but a new phase forms at 0.3 GPa with a 4.8 % contracted unit cell and different cation–water configuration in the pores. In K-Natrolite, the elliptical channel undergoes a unique overturn upon the formation of super-hydrated Natrolite K16Al16Si24O80⋅32 H2O at 1.0 GPa, a species that reverts back above 2.5 GPa as the potassium ions interchange their locations with those of water and migrate from the hinge to the center of the pores. Super-hydrated zeolites are new materials that offer numerous opportunities to expand and modify known chemical and physical properties by reversibly changing the composition and structure using pressure in the presence of water.
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pressure induced hydration and insertion of co2 into ag Natrolite
Chemistry: A European Journal, 2013Co-Authors: Donghoon Seoung, Young Nam Jang, Thomas VogtAbstract:: CO2 insertion under pressure: In silver-exchanged Natrolite, a low and technically achievable onset pressure-induced hydration has been established at 0.4 GPa accompanied by an approximately 5 % expansion in the unit-cell volume (see figure). This unique property has been utilized to trap CO2 under pressure in nominally non-penetrating Natrolite pores.
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immobilization of large aliovalent cations in the small pore zeolite k Natrolite by means of pressure
Angewandte Chemie, 2012Co-Authors: Donghoon Seoung, Jun Hyuk Im, Hee Jung Hwang, Thomas VogtAbstract:: High-pressure ion exchange of small-pore zeolite K-Natrolite allows immobilization of nominally non-exchangeable aliovalent cations such as trivalent europium. A sample exchanged at 3.0(1) GPa and 250 °C contains about 4.7 Eu(III) ions per unit cell, which is equivalent to over 90 % of the K(+) cations being exchanged.
Mahmoud Nasrollahzadeh - One of the best experts on this subject based on the ideXlab platform.
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In situ green synthesis of Cu nanoparticles supported on natural Natrolite zeolite for the reduction of 4-nitrophenol, congo red and methylene blue
IET Nanobiotechnology, 2017Co-Authors: Mahmoud Nasrollahzadeh, Mohammad S. Sajadi, Mehdi Maham, Hamid Reza DasmehAbstract:This study demonstrates a clean, non-toxic and environment friendly synthetic strategy for the preparation of the Natrolite zeolite/Cu nanoparticles (NPs) using Natrolite zeolite as a natural support and <i>Anthemis xylopoda</i> flowers aqueous extract as a reducing and stabilising agent for the synthesis of Cu NPs. Cu NPs with 20 nm diameter were immobilised homogeneously on the surface of Natrolite zeolite. The synthesised Natrolite zeolite/Cu NPs was used as an environmentally benign catalyst for the reduction of 4-nitrophenol, congo red and methylene blue in aqueous media at an ambient temperature. It has been found that the catalyst can be reused several times without any decrease in activity.
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green synthesis of a Natrolite zeolite palladium nanocomposite and its application as a reusable catalyst for the reduction of organic dyes in a very short time
RSC Advances, 2015Co-Authors: Arezo Hatamifard, Mahmoud Nasrollahzadeh, Janusz LipkowskiAbstract:A Natrolite zeolite/palladium (Natrolite zeolite/Pd) nanocomposite has been successfully synthesized applying a simple in situ reduction method using an aqueous extract of fruits of Piper longum as a reducing and stabilizing agent. The Natrolite zeolite/Pd nanocomposite is characterized using Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM) equipped with an energy dispersive X-ray spectroscopy (EDS), X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). The crystal structure of Natrolite zeolite is determined by single-crystal X-ray diffraction analysis. The catalytic activity of the Natrolite zeolite/Pd nanocomposite is excellent for organic dye reduction at room temperature and remains the same for several cycles. The present strategy gives a promising way to prepare heterogeneous nanocatalysts composed by metal nanoparticles for broad applications in catalysis and organic transformations.
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Green synthesis of a Natrolite zeolite/palladium nanocomposite and its application as a reusable catalyst for the reduction of organic dyes in a very short time
RSC Advances, 2015Co-Authors: Arezo Hatamifard, Mahmoud Nasrollahzadeh, Janusz LipkowskiAbstract:A Natrolite zeolite/palladium (Natrolite zeolite/Pd) nanocomposite has been successfully synthesized applying a simple in situ reduction method using an aqueous extract of fruits of Piper longum as a reducing and stabilizing agent. The Natrolite zeolite/Pd nanocomposite is characterized using Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM) equipped with an energy dispersive X-ray spectroscopy (EDS), X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). The crystal structure of Natrolite zeolite is determined by single-crystal X-ray diffraction analysis. The catalytic activity of the Natrolite zeolite/Pd nanocomposite is excellent for organic dye reduction at room temperature and remains the same for several cycles. The present strategy gives a promising way to prepare heterogeneous nanocatalysts composed by metal nanoparticles for broad applications in catalysis and organic transformations.
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synthesis of n arylureas in water and their n arylation with aryl halides using copper nanoparticles loaded on natural Natrolite zeolite under ligand free conditions
RSC Advances, 2014Co-Authors: Mahmoud Nasrollahzadeh, Mojtaba Enayati, Mehdi KhalajAbstract:A new method for the synthesis of N-arylureas and their N-arylation with aryl halides has been developed using copper nanoparticles supported on natural Natrolite zeolite as a reusable heterogeneous catalyst under ligand-free conditions.
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green synthesis of formamides using the Natrolite zeolite as a natural efficient and recyclable catalyst
Journal of Molecular Catalysis A-chemical, 2013Co-Authors: Davood Habibi, Mahmoud Nasrollahzadeh, Hesam SahebekhtiariAbstract:Abstract Chemoselective N -formylation of different amines was carried out with formic acid in the presence of the Natrolite zeolite as an efficient, stable and natural heterogeneous catalyst to give the corresponding formamides at room temperature under solvent-free conditions. This method has the advantages of high yields, mild conditions, simple methodology, easy work up and short reaction times. The catalyst was characterized by different techniques such as powder XRD, XRF, TGA–DTA, SEM and FT-IR spectroscopy. The Natrolite zeolite was recovered and reused several times without the significant loss of its catalytic performance.
A V Sapiga - One of the best experts on this subject based on the ideXlab platform.
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nmr study of microscopic mechanism of water molecules diffusion in Natrolite
Solid State Nuclear Magnetic Resonance, 2019Co-Authors: A V Sapiga, N A SergeevAbstract:Abstract The mineral Natrolite is a good object for studying the features of the molecular mobility of water molecules in spatially restricted structures by NMR techniques. The microscopic mechanisms of water molecule mobility in channels of monocrystal natural zeolite Natrolite (Na16Al16Si24O80·16H2O) have been investigated by broad-line (CW) NMR method. The CW NMR method, which accurately reproduces the shape of a Pake doublets of water molecules, has made it possible to trace diffusion of individual water molecules between specific positions in the crystal lattice as a function of temperature, which is important in understanding diffusion mechanisms in narrow channels of Natrolite, where a diameter of the channel is smaller than the diameter of the water molecule. It has been shown that at temperatures higher than 250 K the regular diffusion of water molecules along the Schottky defects located along channels parallel to the c-crystal axis is a main kind of water molecules mobility. At temperature higher than 350 K the diffusion of water molecules in transversal channels of Natrolite was observed also. Using the structural data the possible pathways of water molecules diffusion in Natrolite channels have been discussed. The relationship between diffusion of water molecules and the dynamics of the zeolite framework and sodium cations is discussed on the basis of the assumption non-Markovian characte of diffusion in Natrolite.
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proton dipolar spin lattice relaxation in nano channels of Natrolite
Applied Magnetic Resonance, 2016Co-Authors: M. Paczwa, A. A. Sapiga, N A Sergeev, M Olszewski, A V SapigaAbstract:The 1H nuclear magnetic resonance (NMR) spectra and the dipolar spin–lattice relaxation time T1D for 1H in the natural Natrolite (Na2Al2Si3O10·2H2O) have been measured in the temperature range of 190–390 K. From the temperature transformations of 1H NMR spectra, it follows that at T > 300 K, the diffusion of water molecules along the nano-channels is observed. From experimental T1D data, it follows that the 180° flip motion of the water molecules takes place in Natrolite. At low temperature (T < 250 K), the dipolar interaction with paramagnetic impurities as a relaxation mechanism of 1H nuclei becomes significant.
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spin lattice relaxations study of water mobility in natural Natrolite
Journal of Structural Chemistry, 2016Co-Authors: M. Paczwa, A. A. Sapiga, N A Sergeev, M Olszewski, A V SapigaAbstract:The mobility of water molecules in natural Natrolite (Na2Al2Si3O10∙2H2O) is investigated by the 1H NMR method. The spin-lattice relaxation times in the laboratory and rotating frames (T 1 and T 1ρ) are measured as a function of the temperature for a polycrystalline sample. From experimental T 1 data it follows that at T > 286 K the diffusion of water molecules along channels parallel to the c axis is observed. From experimental T 1ρ data it follows that at T > 250 K the diffusion of water molecules in transversal channels of Natrolite is also observed. At a low temperature (T < 250 K) the dipolar interaction with paramagnetic impurities (presumably Fe3+ ions) becomes significant as a relaxation mechanism of 1H nuclei.
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27al nmr study of the structure and dynamics of Natrolite
Applied Magnetic Resonance, 2015Co-Authors: M. Paczwa, A. A. Sapiga, Marek Olszewski, N A Sergeev, A V SapigaAbstract:The temperature dependences of nuclear magnetic resonance and magic angle spinning nuclear magnetic resonance spectra of 27Al nuclei in Natrolite (Na2Al2Si3O10· 2H2O) have been studied. The influence of water molecules and sodium ions mobility on the shape of the 27Al NMR spectrum and framework dynamics have been discussed The temperature dependences of the spin–lattice relaxation times T1 of 27Al nuclei in Natrolite have also been studied. It has been shown that the spin–lattice relaxation of the 27Al is governed by the electric quadrupole interaction with the crystal electric field gradients modulated by translational motion of H2O molecules in the Natrolite pores. The dipolar interactions with paramagnetic impurities become significant as a relaxation mechanism of the 27Al nuclei only at low temperatures (<270 K).
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nmr investigation of Natrolite structure
Crystal Research and Technology, 2001Co-Authors: A V Sapiga, N A SergeevAbstract:The temperature dependencies of NMR spectra of 1 H, 23 Na and 27 Al nuclei in Natrolite Na 2 Al 2 Si 3 O 10 2H 2 O have been studied. It has been shown that the model of the normal distribution of the activation energy may be considered as a preferable model for the diffusion of the water molecules in the Natrolite. The influence of the water molecule diffusion on the NMR spectra of 23 Na and 27 Al has been discussed. It has been established that the internal mobility of aluminium and sodium ions does not occur in Natrolite.
N A Sergeev - One of the best experts on this subject based on the ideXlab platform.
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nmr study of microscopic mechanism of water molecules diffusion in Natrolite
Solid State Nuclear Magnetic Resonance, 2019Co-Authors: A V Sapiga, N A SergeevAbstract:Abstract The mineral Natrolite is a good object for studying the features of the molecular mobility of water molecules in spatially restricted structures by NMR techniques. The microscopic mechanisms of water molecule mobility in channels of monocrystal natural zeolite Natrolite (Na16Al16Si24O80·16H2O) have been investigated by broad-line (CW) NMR method. The CW NMR method, which accurately reproduces the shape of a Pake doublets of water molecules, has made it possible to trace diffusion of individual water molecules between specific positions in the crystal lattice as a function of temperature, which is important in understanding diffusion mechanisms in narrow channels of Natrolite, where a diameter of the channel is smaller than the diameter of the water molecule. It has been shown that at temperatures higher than 250 K the regular diffusion of water molecules along the Schottky defects located along channels parallel to the c-crystal axis is a main kind of water molecules mobility. At temperature higher than 350 K the diffusion of water molecules in transversal channels of Natrolite was observed also. Using the structural data the possible pathways of water molecules diffusion in Natrolite channels have been discussed. The relationship between diffusion of water molecules and the dynamics of the zeolite framework and sodium cations is discussed on the basis of the assumption non-Markovian characte of diffusion in Natrolite.
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proton dipolar spin lattice relaxation in nano channels of Natrolite
Applied Magnetic Resonance, 2016Co-Authors: M. Paczwa, A. A. Sapiga, N A Sergeev, M Olszewski, A V SapigaAbstract:The 1H nuclear magnetic resonance (NMR) spectra and the dipolar spin–lattice relaxation time T1D for 1H in the natural Natrolite (Na2Al2Si3O10·2H2O) have been measured in the temperature range of 190–390 K. From the temperature transformations of 1H NMR spectra, it follows that at T > 300 K, the diffusion of water molecules along the nano-channels is observed. From experimental T1D data, it follows that the 180° flip motion of the water molecules takes place in Natrolite. At low temperature (T < 250 K), the dipolar interaction with paramagnetic impurities as a relaxation mechanism of 1H nuclei becomes significant.
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spin lattice relaxations study of water mobility in natural Natrolite
Journal of Structural Chemistry, 2016Co-Authors: M. Paczwa, A. A. Sapiga, N A Sergeev, M Olszewski, A V SapigaAbstract:The mobility of water molecules in natural Natrolite (Na2Al2Si3O10∙2H2O) is investigated by the 1H NMR method. The spin-lattice relaxation times in the laboratory and rotating frames (T 1 and T 1ρ) are measured as a function of the temperature for a polycrystalline sample. From experimental T 1 data it follows that at T > 286 K the diffusion of water molecules along channels parallel to the c axis is observed. From experimental T 1ρ data it follows that at T > 250 K the diffusion of water molecules in transversal channels of Natrolite is also observed. At a low temperature (T < 250 K) the dipolar interaction with paramagnetic impurities (presumably Fe3+ ions) becomes significant as a relaxation mechanism of 1H nuclei.
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23Na Nuclear Magnetic Resonance Study of the Structure and Dynamic of Natrolite
Zeitschrift für Naturforschung A, 2015Co-Authors: M. Paczwa, A. A. Sapiga, Marek Olszewski, N A SergeevAbstract:Abstract The temperature dependences of nuclear magnetic resonance (NMR) and magic angle spinning (MAS) NMR spectra of 23Na nuclei in Natrolite (Na2Al2Si3O10·2H2O) have been studied. The temperature dependences of the spin-lattice relaxation times T1 in Natrolite have also been studied. It has been shown that the spin-lattice relaxation of the 23Na is governed by the electric quadrupole interaction with the crystal electric field gradients modulated by translational motion of H2O molecules in the Natrolite pores. The dipolar interactions with paramagnetic impurities become significant as a relaxation mechanism of the 23Na nuclei only at low temperature (<270 K).
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27al nmr study of the structure and dynamics of Natrolite
Applied Magnetic Resonance, 2015Co-Authors: M. Paczwa, A. A. Sapiga, Marek Olszewski, N A Sergeev, A V SapigaAbstract:The temperature dependences of nuclear magnetic resonance and magic angle spinning nuclear magnetic resonance spectra of 27Al nuclei in Natrolite (Na2Al2Si3O10· 2H2O) have been studied. The influence of water molecules and sodium ions mobility on the shape of the 27Al NMR spectrum and framework dynamics have been discussed The temperature dependences of the spin–lattice relaxation times T1 of 27Al nuclei in Natrolite have also been studied. It has been shown that the spin–lattice relaxation of the 27Al is governed by the electric quadrupole interaction with the crystal electric field gradients modulated by translational motion of H2O molecules in the Natrolite pores. The dipolar interactions with paramagnetic impurities become significant as a relaxation mechanism of the 27Al nuclei only at low temperatures (<270 K).
