Magnetism and nuclear magnetic resonance of hectorite and montmorillonite layered silicates

E. M. Levin; S. S. Hou; S. L. Bud'ko; K. Schmidt-Rohr

doi:10.1063/1.1794364

Magnetism and nuclear magnetic resonance of hectorite and montmorillonite layered silicates

E. M. Levin, S. S. Hou, S. L. Bud'ko, K. Schmidt-Rohr

Department of Chemical Engineering

Research output: Contribution to journal › Article › peer-review

24 Citations (Scopus)

Abstract

The temperature and magnetic-field (H) dependencies of the bulk dc magnetization (M) and the M/H ratio of montmorillonite (MMT), hectorite (HCT), and synthetic mica-montmorillonite (SMMT) clays have been measured and compared with the signal intensity of ¹H and ²⁹Si nuclear magnetic resonance (NMR) spectra. MMT exhibits Langevin paramagnetism with an effective magnetic moment of 5.5±0.1 μ _B per Fe ion whereas SMMT has diamagnetic properties. At 300 K, M/H of HCT measured in a magnetic field of H≤ 1 kOe is larger than that of MMT, whereas in a field of 50 kOe, the inverse situation is observed. The difference arises because the magnetization of HCT is dominated by a contribution from ferromagneticlike impurities. The ¹H and ²⁹Si NMR signals of MMT are broadened beyond detectability due to the paramagnetic effect. Although HCT contains ferromagneticlike components that result in a large M/H in low field, it yields ¹H and ²⁹Si NMR spectra with signal intensities similar to those of diamagnetic SMMT. Our data highlight that the quality of the NMR spectra is not related to the low-field magnetic susceptibility but to the bulk magnetization in the high magnetic field used for NMR.

Original language	English
Pages (from-to)	5085-5092
Number of pages	8
Journal	Journal of Applied Physics
Volume	96
Issue number	9
DOIs	https://doi.org/10.1063/1.1794364
Publication status	Published - 2004 Nov 1

All Science Journal Classification (ASJC) codes

Physics and Astronomy(all)

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10.1063/1.1794364

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title = "Magnetism and nuclear magnetic resonance of hectorite and montmorillonite layered silicates",

abstract = "The temperature and magnetic-field (H) dependencies of the bulk dc magnetization (M) and the M/H ratio of montmorillonite (MMT), hectorite (HCT), and synthetic mica-montmorillonite (SMMT) clays have been measured and compared with the signal intensity of 1H and 29Si nuclear magnetic resonance (NMR) spectra. MMT exhibits Langevin paramagnetism with an effective magnetic moment of 5.5±0.1 μ B per Fe ion whereas SMMT has diamagnetic properties. At 300 K, M/H of HCT measured in a magnetic field of H≤ 1 kOe is larger than that of MMT, whereas in a field of 50 kOe, the inverse situation is observed. The difference arises because the magnetization of HCT is dominated by a contribution from ferromagneticlike impurities. The 1H and 29Si NMR signals of MMT are broadened beyond detectability due to the paramagnetic effect. Although HCT contains ferromagneticlike components that result in a large M/H in low field, it yields 1H and 29Si NMR spectra with signal intensities similar to those of diamagnetic SMMT. Our data highlight that the quality of the NMR spectra is not related to the low-field magnetic susceptibility but to the bulk magnetization in the high magnetic field used for NMR.",

author = "Levin, {E. M.} and Hou, {S. S.} and Bud'ko, {S. L.} and K. Schmidt-Rohr",

note = "Funding Information: Two of the authors (S.L.B. and E.M.L.) thank Professor P.C. Canfield (Iowa State University) for his support for this work. One of the authors (E.M.L.) thanks Professor J.M.D. Coey (Trinity College, Dublin, Ireland) for helpful discussions. This manuscript has been authored by Iowa State University of Science and Technology under Contract No. W-7405-ENG-82 with the U.S. Department of Energy, and supported by the Office of Basic Energy Sciences, Materials Sciences Division.",

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AU - Bud'ko, S. L.

AU - Schmidt-Rohr, K.

N1 - Funding Information: Two of the authors (S.L.B. and E.M.L.) thank Professor P.C. Canfield (Iowa State University) for his support for this work. One of the authors (E.M.L.) thanks Professor J.M.D. Coey (Trinity College, Dublin, Ireland) for helpful discussions. This manuscript has been authored by Iowa State University of Science and Technology under Contract No. W-7405-ENG-82 with the U.S. Department of Energy, and supported by the Office of Basic Energy Sciences, Materials Sciences Division.

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N2 - The temperature and magnetic-field (H) dependencies of the bulk dc magnetization (M) and the M/H ratio of montmorillonite (MMT), hectorite (HCT), and synthetic mica-montmorillonite (SMMT) clays have been measured and compared with the signal intensity of 1H and 29Si nuclear magnetic resonance (NMR) spectra. MMT exhibits Langevin paramagnetism with an effective magnetic moment of 5.5±0.1 μ B per Fe ion whereas SMMT has diamagnetic properties. At 300 K, M/H of HCT measured in a magnetic field of H≤ 1 kOe is larger than that of MMT, whereas in a field of 50 kOe, the inverse situation is observed. The difference arises because the magnetization of HCT is dominated by a contribution from ferromagneticlike impurities. The 1H and 29Si NMR signals of MMT are broadened beyond detectability due to the paramagnetic effect. Although HCT contains ferromagneticlike components that result in a large M/H in low field, it yields 1H and 29Si NMR spectra with signal intensities similar to those of diamagnetic SMMT. Our data highlight that the quality of the NMR spectra is not related to the low-field magnetic susceptibility but to the bulk magnetization in the high magnetic field used for NMR.

AB - The temperature and magnetic-field (H) dependencies of the bulk dc magnetization (M) and the M/H ratio of montmorillonite (MMT), hectorite (HCT), and synthetic mica-montmorillonite (SMMT) clays have been measured and compared with the signal intensity of 1H and 29Si nuclear magnetic resonance (NMR) spectra. MMT exhibits Langevin paramagnetism with an effective magnetic moment of 5.5±0.1 μ B per Fe ion whereas SMMT has diamagnetic properties. At 300 K, M/H of HCT measured in a magnetic field of H≤ 1 kOe is larger than that of MMT, whereas in a field of 50 kOe, the inverse situation is observed. The difference arises because the magnetization of HCT is dominated by a contribution from ferromagneticlike impurities. The 1H and 29Si NMR signals of MMT are broadened beyond detectability due to the paramagnetic effect. Although HCT contains ferromagneticlike components that result in a large M/H in low field, it yields 1H and 29Si NMR spectra with signal intensities similar to those of diamagnetic SMMT. Our data highlight that the quality of the NMR spectra is not related to the low-field magnetic susceptibility but to the bulk magnetization in the high magnetic field used for NMR.

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Magnetism and nuclear magnetic resonance of hectorite and montmorillonite layered silicates

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