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Journal ArticleDOI

NMR study of hydrogen molybdenum bronzes: H1.71MoO3 and H0.36MoO3

01 Sep 1980-Journal of Solid State Chemistry (Academic Press)-Vol. 34, Iss: 2, pp 183-192
TL;DR: In this paper, the authors reported the NMR relaxation times (T2 T1, and T1ϱ) and absorption spectra for the compounds H1.71MoO3 (red monoclinic) and H0.36MoO 3 (blue orthorhombic) in the temperature range 77 K < T < 450 K.
About: This article is published in Journal of Solid State Chemistry.The article was published on 1980-09-01. It has received 63 citations till now. The article focuses on the topics: Proton NMR & Molybdenum bronze.
Citations
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Journal ArticleDOI
TL;DR: In this article, the molybdenum oxide monomers, clusters and chains linked by======bpy-bpy groups and represented by the============formulae [M(bpy)-bpy)================== x======

149 citations

Journal ArticleDOI
TL;DR: In this article, a quasi-one-dimensional zig-zag line connecting the vertex-sharing oxygen atoms of the MoO6 octahedra is used to detect interlayer positions coordinated with terminal oxygen atoms at van der Waals gap.
Abstract: 1H NMR solid state techniques have been used to study bonding properties, location, and mobility of hydrogen in various phases of the hydrogen bronze HxMoO3. Temperature‐dependent spectra characteristic of different degrees of intercalation have been observed, and furthermore, from measurements of the relaxation rate, dynamic properties have been derived. There is strong evidence of intralayer hydrogen positions on a quasi‐one‐dimensional zig–zag line connecting the vertex‐sharing oxygen atoms of the MoO6 octahedra and these are first occupied if the degree of intercalation x is low. For x>0.85 the hydrogen in excess starts to fill up interlayer positions coordinated with terminal oxygen atoms at the van der Waals gap. Both isolated and paired protons have been detected in the interlayers, whereas clusters or pairs appear along the zig–zag lines. Hydrogen separations within the clusters, bonding with oxygen and charge transfer to the conduction band of the host lattice, are discussed. Hydrogen diffusion c...

100 citations

Journal ArticleDOI
TL;DR: The hydrothermal reaction of MoO and 4,4′-bipyridine yields a step-layered molybdenum oxide material, a material structurally related to layered materials as mentioned in this paper.

79 citations

Journal ArticleDOI
TL;DR: In this paper, the Glemser method was used to extract molybdenum bronzes from Type I (HxMoO3), Type II (H2) and Type III (H3) by standing in air for 120 days.
Abstract: Hydrogen molybdenum bronzes, HxMoO3, of Type-I (x=0.21), Type-III (x=1.55), and Type-IV (x=1.90) were prepared by the Glemser’s method. Type-II (x=0.91) was obtained from Type-III by standing in air for 120 days. The bronzes with low hydrogen contents were stable, but those with high contents were not so stable. All these bronzes have been studied by X-ray diffraction, IR spectroscopy, and TG-DTA. Bronzes with high hydrogen contents were changed upon heating in air, successively, to those with low hydrogen contents by the evolution of H2.

65 citations

Journal ArticleDOI
TL;DR: In this article, the structure, bonding and proton mobility in transition metal oxides (and oxide hydrates) with dissociated hydrogen insertion compounds are examined. And the structure and bonding properties of these compounds are analyzed.

53 citations

References
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Book
01 Jan 1961

8,649 citations

Journal ArticleDOI
TL;DR: In this article, a spin echo method adapted to the measurement of long nuclear relaxation times (T2) in liquids is described, and the pulse sequence is identical to the one proposed by Carr and Purcell, but the rf of the successive pulses is coherent, and a phase shift of 90° is introduced in the first pulse.
Abstract: A spin echo method adapted to the measurement of long nuclear relaxation times (T2) in liquids is described. The pulse sequence is identical to the one proposed by Carr and Purcell, but the rf of the successive pulses is coherent, and a phase shift of 90° is introduced in the first pulse. Very long T2 values can be measured without appreciable effect of diffusion.

5,389 citations

Journal ArticleDOI
TL;DR: In this paper, a double nuclear resonance spectroscopy method is introduced which depends upon effects of magnetic dipole-dipole coupling between two different nuclear species, and a minimum detectability of the order of {10}^{14}$ to ${10}−16}$ nuclear Bohr magnetons/cc of a rare $b$ nuclear species is predicted, to be measured in terms of the change in a strong signal displayed by an abundant $a$ nuclear mass.
Abstract: A double nuclear resonance spectroscopy method is introduced which depends upon effects of magnetic dipole-dipole coupling between two different nuclear species. In solids a minimum detectability of the order of ${10}^{14}$ to ${10}^{16}$ nuclear Bohr magnetons/cc of a rare $b$ nuclear species is predicted, to be measured in terms of the change in a strong signal displayed by an abundant $a$ nuclear species. The $a$ magnetization is first oriented by a strong radio-frequency field in the frame of reference rotating at its Larmor frequency. The $b$ nuclear resonance is obtained simultaneously with a second radio-frequency field; and with the condition that the $a$ and $b$ spins have the same Larmor frequencies in their respective rotating frames, a cross relaxation will occur between the two spin systems. The cross-relaxation interaction, which lasts for the order of a long spin-lattice relaxation time of the $a$ magnetization, is arranged to produce a cumulative demagnetization of the $a$ system when maximum sensitivity is desired. Final observation of the reduced $a$ magnetization indicates the nuclear resonance of the $b$ system. The concepts of uniform spin temperature, when it is valid, and of nonuniform spin temperature where spin diffusion is important, are applied. The density matrix method formulates the double resonance interaction rate in second order. Preliminary tests of the double resonance effect are carried out with a nuclear quadrupole system.

1,804 citations

Journal ArticleDOI
TL;DR: By producing a train of absorption or dispersion signals (continuous wave magnetic resonance) or free induction decays (pulsed magnetic resonance), it is possible to save time in spin-lattice relaxation measurements as mentioned in this paper.
Abstract: By producing a train of absorption or dispersion signals (continuous‐wave magnetic resonance) or free induction decays (pulsed magnetic resonance) it is possible to save time in spin‐lattice relaxation measurements due to the fact that it is not necessary to wait for equilibrium magnetization before initiating the train. The relaxation time may be calculated from the train according to a simple rapidly converging iteration.

795 citations

Journal ArticleDOI
H. C. Torrey1
TL;DR: The general theory of Bloembergen, Purcell, and Pound of nuclear spin relaxation has been extended to a more quantitative study of relaxation by translational diffusion as mentioned in this paper, and it has been found necessary to treat the problem by the theory of random walk.
Abstract: The general theory of Bloembergen, Purcell, and Pound of nuclear spin relaxation has been extended to a more quantitative study of relaxation by translational diffusion. It has been found necessary to treat the problem by the theory of random walk. In the case of isotropic diffusion two cases have been studied: one in which the flight distance has a probability distribution, and the other in which it is constant. The problem of random walk to nearest neighbor sites in a lattice is also treated and quantitative results are obtained for a face-centered cubic lattice.

591 citations