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Journal ArticleDOI

N.M.R. study of hydrogen motion in hydrogen uranyl phosphate (HUP) and hydrogen uranyl arsenate (HUAs)

01 Jun 1978-Materials Research Bulletin (Pergamon)-Vol. 13, Iss: 6, pp 609-619
TL;DR: In this article, the authors measured the relaxation times in hydrogen uranyl phosphate and arsenate, which are fast proton conductors, and found that the two compounds undergo a phase transition resulting in discontinuities in T/sub 1/ and t/sub 2/ and a DTA peak.
About: This article is published in Materials Research Bulletin.The article was published on 1978-06-01. It has received 58 citations till now. The article focuses on the topics: Proton transport & Uranyl.
Citations
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Journal ArticleDOI
TL;DR: In this paper, a Grotthus-type mechanism of conduction is proposed which involves intermolecular transfer steps (hopping) and inter-parallel transfer steps in comparable numbers, the former facilitated by the high concentration of H 3 O + ions in the structure, and the latter most likely facilitated by high H-bond vacancies.

132 citations

Journal ArticleDOI
TL;DR: In this paper, single-crystal measurements on hydrogen uranyl phosphate tetrahydrate, HUO 2 PO 4 ·4H 2 O (HUP), have confirmed that the high proton conductivity is a bulk characteristic.

76 citations

Journal ArticleDOI
TL;DR: In this article, the structural roles of the interlayer cations in determining the symmetries and hydration states observed are discussed, and the smallest monovalent cation, Li, occurs in tetra- hedral coordination between fourfold squares of hydrogen-bonded H2O groups.
Abstract: Compounds of the meta-autunite group containing monovalent cations (Li, Na, K, Rb, Cs, Ag, Tl) have been synthesized by diffusion in gels or by hydrothermal methods, and their crystal structures determined. Single-crystal X-ray-diffraction intensity data were collected at room temperature using MoKradiation and a CCD-based area detector. These compounds contain the autunite-type sheet with composition ((UO2)(XO4)) - , X = P or As, which involves the sharing of equatorial vertices of uranyl square bipyramids with tetrahedra. The interlayer region contains cations and H2O groups, and the sheets are linked by hydrogen bonding and through bonds from the interlayer cations to oxygen atoms of the sheets. The structural roles of the interlayer cations in determining the symmetries and hydration states observed are discussed. The smallest monovalent cation, Li, occurs in tetra- hedral coordination between fourfold squares of hydrogen-bonded H2O groups. Despite a wide range in ionic radius, Na, K, Rb, Ag and Tl randomly substitute for H2O groups in the interlayer, in the same fashion as their ammonium and oxonium analogues. The large Cs cation adopts independent crystallographic sites in the interlayer. The size difference between Cs and the other monovalent cations probably prevents their direct substitution, and may limit the extent of solid solution. With the exception of

66 citations


Cites background from "N.M.R. study of hydrogen motion in ..."

  • ...Chernikovite and trögerite are fast proton conductors at room temperature (Childs et al. 1978), with alternating current conductivities of 0.3–0.6 ohm–1 m–1 (Childs et al. 1980, Johnson et al. 1981)....

    [...]

Journal ArticleDOI
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.

63 citations

Journal ArticleDOI
TL;DR: In this article, the authors measured the ionic conductivities of pressed pellets of the layered compounds MUO2PO4 · nH2O, and correlated the results with TGA data.

46 citations

References
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01 Jan 1961

8,649 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

240 citations

Journal ArticleDOI
TL;DR: In this article, it was shown that the layered hydrate HUO2PO4 is a rapid proton conductor with a room temperature conductivity of 4 × 10−3ohm−1cm−1.

136 citations

Journal ArticleDOI
TL;DR: In this article, the NMR theory for a two-dimensional (2D) system coupled by dipolar interaction and undergoing diffusive motion is presented and the correlation functions (c.f.) of the dipolar coefficients are split in two parts: a slow part and a fast one.
Abstract: The NMR theory for a two‐dimensional (2D) system of spins coupled by dipolar interaction and undergoing diffusive motion is presented. The correlation functions (c.f.) of the dipolar coefficients are split in two parts: a ’’slow’’ one and a ’’fast’’ one. The c.f. are also written in a form which allows easy prediction of the angular dependence of the relaxation rates. It is demonstrated that, owing to the diffusion process, the slow part decays at long times as t−1 and the fast one as t−2. Measurements of T2, T1, T1ρ on the protons of nitric acid intercalated in graphite have been performed in the temperature range −153 °C,+18 °C. The prediction of the model was checked both in the solid phases (where ω0τD≫1 with τD= diffusional correlation time) and in the ’’liquid’’ phase (above −20 °C). The measurements at room temperature prove, over several decades of frequency, the logarithmic divergence of the slow part‐spectral density for ω→0. Also in the solid phases, the 2D‐diffusive model interprets the measurements. Using the experimental results, we can illustrate the angular dependence of the relaxation rates that are predicted by the theory for planar systems in different dynamical situations. The information given by NMR on graphite nitrate are also discussed.

104 citations