NMR in single crystals of Ca(OH)<sub>2</sub>

Holuj, F.; Wieczorek, John

doi:10.1139/p77-091

Cited by 12 publications

(5 citation statements)

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“…The broad components of the pulsed FT-NMR spectra are compatible with the NMR absorption spectra measured by the continuous-wave method. [18][19][20] Not simple Gaussian but rectangular-type line shapes characterize the broad components. The intensities of the broad components relative to the narrow ones were underestimated in the original analysis 6) and were properly corrected in a previous report.…”

Section: Fid Analysismentioning

confidence: 99%

Intrinsic Proton NMR Studies of Mg(OH)₂ and Ca(OH)₂

Itoh¹,

Isobe²

2016

J. Phys. Soc. Jpn.

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We studied the short proton free induction decay signals and the broad 1 H NMR spectra of Mg(OH) 2 and Ca(OH) 2 powders at 77−355 K and 42 MHz using pulsed NMR techniques. Using a Gaussian-type back extrapolation procedure for the obscured data of the proton free induction decay signals, we obtained more precise values of the second moments of the Fourier-transformed broad NMR spectra than those in a previous report [Y. Itoh and M. Isobe, J. Phys. Soc. Jpn. 84, 113601 (2015)] and compared with the theoretical second moments. The decrease in the second moment could not account for the large decrease in the magnitude of the intrinsic proton spin-lattice relaxation rate 1/T 1 from Mg(OH) 2 to Ca(OH) 2 . The analysis of 1/T 1 ∝ exp(−E g /k B T ) with E g ∼ 0.01 eV points to a local hopping mechanism, and that of 1/T 1 ∝ T n with n ∼ 0.5 points to an anharmonic rattling mechanism.

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Section: Fid Analysismentioning

confidence: 99%

Intrinsic Proton NMR Studies of Mg(OH)₂ and Ca(OH)₂

Itoh¹,

Isobe²

2016

J. Phys. Soc. Jpn.

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“…As regards the calculation of the anharmonic frequency, as anticipated in the introduction, the following scheme has been used: (i) the OH distance, R OH , is treated as a pure normal coordinate decoupled with respect to all other modes and only the H atom is moved during the OH scan; (ii) the total energy of the system is calculated for a set of R OH values around See [41,42].…”

Section: Harmonic and Anharmonic Frequenciesmentioning

confidence: 99%

Quantum mechanical calculation of the OH vibrational frequency in crystalline solids

Tosoni

Pascale²,

Ugliengo

et al. 2005

Molecular Physics

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The OH vibrational frequency of four crystalline compounds ranging from ionic (brucite, Mg(OH) 2 , and portlandite, Ca(OH) 2 ) to semi-covalent (edingtonite, as representative of free surface OH groups in silica, and acid chabazite, as representative of acid zeolites) has been investigated at quantum mechanical level with the CRYSTAL program using the B3LYP hybrid functional. The OH vibration is calculated in two ways: (i) in the harmonic approximation, by diagonalizing the fully coupled dynamical matrix to yield the harmonic frequency ! h . (ii) at the anharmonic level, by decoupling the OH stretching mode from the bulk phonons and by numerically solving the one-dimensional Schro¨dinger equation associated with the OH potential energy to yield the fundamental ! 01 and the first overtone ! 02 frequencies. The harmonic and anharmonic frequencies differ by more than 150 cm À1 . In the cases where direct comparison is possible (brucite, portlandite and edingtonite), the experimental and calculated frequencies differ by less than 10 cm À1 ; the calculated anharmonicity constant, ! e x e ¼ (2! 01 À ! 02 )/2, is systematically smaller than the experimental value by about 10 cm À1 . The effect of the computational parameters on the computed frequencies is explored, with particular attention to the grid used for the construction of the DFT exchange and correlation contribution to the Hamiltonian and the accuracy in the geometry optimisation.

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“…Single-crystal 1 H NMR studies of Mg(OH) 2 at room temperature showed wide NMR spectra and angular dependences with respect to the crystal axes [13,14], while powder NMR studies showed narrow NMR spectra [15,16]. Both single-crystal and powder 1 H NMR studies of Ca(OH) 2 showed wide NMR spectra [17].…”

Section: Introductionmentioning

confidence: 99%

Extrinsic Proton NMR Studies of Mg(OH)₂ and Ca(OH)₂

Itoh

Isobe

2016

J. Phys. Soc. Jpn.

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We studied narrow 1 H NMR spectra of Mg(OH)2 and Ca(OH)2 powders at 100−355 K and 42−59 MHz using pulsed NMR techniques. The Fourier transformed NMR spectra of the proton freeinduction signals show the superposition of broad and narrow components, which can be assigned to immobile protons and extrinsic mobile protons, respectively. We found that a narrow spectrum develops on heating above about Tc = 260 K and widens above a Larmor frequency of about νc = 50 MHz for Mg(OH)2. The temperature-induced NMR spectrum and the characteristic frequency νc of 50 MHz are the noteworthy features of the nuclear spin fluctuation spectra of the extrinsic protons.

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NMR in single crystals of Ca(OH)₂

Cited by 12 publications

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Intrinsic Proton NMR Studies of Mg(OH)₂ and Ca(OH)₂

Intrinsic Proton NMR Studies of Mg(OH)₂ and Ca(OH)₂

Quantum mechanical calculation of the OH vibrational frequency in crystalline solids

Extrinsic Proton NMR Studies of Mg(OH)₂ and Ca(OH)₂

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NMR in single crystals of Ca(OH)2

Cited by 12 publications

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Intrinsic Proton NMR Studies of Mg(OH)2 and Ca(OH)2

Intrinsic Proton NMR Studies of Mg(OH)2 and Ca(OH)2

Quantum mechanical calculation of the OH vibrational frequency in crystalline solids

Extrinsic Proton NMR Studies of Mg(OH)2 and Ca(OH)2

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Product

Resources

About

NMR in single crystals of Ca(OH)₂

Intrinsic Proton NMR Studies of Mg(OH)₂ and Ca(OH)₂

Intrinsic Proton NMR Studies of Mg(OH)₂ and Ca(OH)₂

Extrinsic Proton NMR Studies of Mg(OH)₂ and Ca(OH)₂