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Peter G. Dickens

Bio: Peter G. Dickens is an academic researcher from University of Oxford. The author has contributed to research in topics: Neutron diffraction & Thermochemistry. The author has an hindex of 18, co-authored 65 publications receiving 1141 citations.


Papers
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Journal ArticleDOI
TL;DR: In this article, the inelastic neutron scattering spectra of HxMoO3 phases confirm that deuterium is incorporated as -OD without any major structural change to the MoO3 layer lattice.

127 citations

Journal ArticleDOI
TL;DR: The structure of D 0.53 WO 3 has been determined by a room temperature powder neutron diffraction study as discussed by the authors, and the unit cell is body centered cubic ( Im 3) and contains 8 formula weights ( a = 7.562 ± 0.002 A).

102 citations

Journal ArticleDOI
TL;DR: Powder neutron diffraction studies of Li0.36WO3, Na0.73 WO3 and La0.14WO 3 showed them to be isostructural with cubic D0.53 WO 3.

88 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the behavior of water sorbed by charcoals and in zeolites and found that the motion of protons is more liquid-like in the higher water content material, and that the mean activation energies for H + translation increase markedly relative to those around ambient temperature.

66 citations

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


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the preparation of a colloidal colloidal by un procede sol gel is described, and a procedure for determination des proprietes electriques et electrochimiques is described.

2,040 citations

Journal ArticleDOI
TL;DR: In this article, the progress that has taken place since 1993 with regard to film deposition, characterization by physical and chemical techniques, optical properties, as well as electrochromic device assembly and performance is reviewed.

1,304 citations

Journal ArticleDOI
TL;DR: In this comprehensive review, recent progress and developments on perfluorinated sulfonic-acid (PFSA) membranes have been summarized on many key topics, including structure/transport correlations and modeling, composite PFSA membranes, degradation phenomena, and PFSA thin films.
Abstract: In this comprehensive review, recent progress and developments on perfluorinated sulfonic-acid (PFSA) membranes have been summarized on many key topics. Although quite well investigated for decades, PFSA ionomers’ complex behavior, along with their key role in many emerging technologies, have presented significant scientific challenges but also helped create a unique cross-disciplinary research field to overcome such challenges. Research and progress on PFSAs, especially when considered with their applications, are at the forefront of bridging electrochemistry and polymer (physics), which have also opened up development of state-of-the-art in situ characterization techniques as well as multiphysics computation models. Topics reviewed stem from correlating the various physical (e.g., mechanical) and transport properties with morphology and structure across time and length scales. In addition, topics of recent interest such as structure/transport correlations and modeling, composite PFSA membranes, degradat...

1,217 citations

Journal Article
TL;DR: The geomeffy, bond valences, and polymerization of hexavalent uranium polyhedra from 105 well-refined structures are analyzed in this article, where a series of coordiaation polyhedr4 from square bipyramidal polyhedras with uranyl ions to holosymmehic octahedral geometry are discussed.
Abstract: The geomeffy, bond valences, and polymerization ofhexavalent uranium polyhedra from 105 well-refined structures are analyzed. The Utu cation is almost always present in crystal stnrctures as part of a nearly linear (UOr)z* uranyl ion that is coordinated by four, five or six equatorial anions in an approximately planar arangement perpendicular to the uranyl ion, giving square, pentagonal and hexagonal bipyramids, respectively. The Utu-O7\" bond length (Oy,: uranyl-ion O atom) is independent of the equatorial anions of the polyhedra;-averages of all polyhedra tlat contain uranyl ions ffs; I6lIJ6f-Or. = 1.79(3), mg0.-.9 a,= 1.79(4), and t8lu6+-Our = 1.78(3) A. Not a[ r6lu6+ polyhedra contain uranyl ions; there is a continuous series of coordiaation polyhedr4 from square bipyramidal polyhedra with uranyl ions to holosymmehic octahedral geometry. The mUo* and t8lu6+ polyhedra invariably contaitl a uranyl ion. The equatorial U6.-0 (0: O,-, OH-) bond-lengths of uranyl polyhedra depend upon coordhation number; averages for all polyhedra are t6lu6+-dq = 2,28(5), rlUot-$* = 2.37(9), afi t8tlJ6+-$q2.47 (12) A. Cunently available bond-valence parameters for U& are unsatisfactory for determining bond-valence sums. Coordination-specific bond-valence paxameters have been derived for U6|, together with parameters applicable to all coordination geometries. The parameters give bond-valence sums for Ue of -6 vlr and reasonable bond-valences for Uc,-Ou, bonds. The bond-valence paraneters facilitate the recognition of Ua, U5+ and U6| catiotrs in refined crystal structures. The crystal-chemical consfraints ofpolyhedral polymerization in uranyl phases are discussed.

762 citations

Journal ArticleDOI
TL;DR: In this article, the authors proposed a mechanism of conductivity for the proton migration in polybenzimidazole (PB1) film, a candidate polymer electrolyte membrane (PEM) for high-temperature (120-200°C) fuel cells, was cast from PBI/trifluoacetyl/H 3 PO 4 solution with constant molecular weight PBI powder and various acid doping levels.
Abstract: Polybenzimidazole (PB1) film, a candidate polymer electrolyte membrane (PEM) for high-temperature (120-200°C) fuel cells, was cast from PBI/trifluoacetyl/H 3 PO 4 solution with constant molecular weight PBI powder and various acid doping levels. Conductivity measurements on these membranes were performed using an ac method under controlled temperature and relative humidity (RH). A complete set of conductivity data for H 3 PO 4 acid-doped PBI is presented as a function of temperature (60-200°C), RH (5-30%), and acid doping level (300-600 mol %). A mechanism of conductivity is proposed for the proton migration in this PBI/acid system based on this and previous work. Proton transfer in this system appears to occur along different paths for different doping levels, RHs, and temperatures. Hydrogen bonds immobilize the anions and form a network for proton transfer by a Grotthuss mechanism. The rate of proton transfer involving H 2 O is faster, leading to higher conductivity at higher RH. The order of the rate of proton transfer between various species is H 3 PO 4 (H 2 PO 4 -)...H-O-H> H 3 PO 4 ...H 2 PO - 4 > N-H + ...H 2 PO 4 - + N-H + ...H-O-H > N-H + ...N-H. The upper limit of proton conductivity is given by the conductivity of the liquid state H 3 PO 4 .

642 citations