Fast proton conducting hydrogen sulphates and selenates: Impedance spectroscopy, Raman scattering and optical microscope study

Pawłowski, A.; Połomska, M.

doi:10.1016/j.ssi.2004.06.025

Cited by 21 publications

(14 citation statements)

References 21 publications

(21 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The frequency difference ν 1 (SO 4 ) -ν(HSO 4 ) can often be used as a spectroscopic indication of the strength of the hydrogen bond. The decrease of ν 1 (SO 4 ) -ν(HSO 4 ) indicates a weakening of hydrogen bonding in Rb 3 H (SO 4 ) 2 as previously described [8,18]. The ν 1 (SO 4 ) -ν(HSO 4 ) increased by a rate of +4.7 cm − 1 /GPa (r = 0.91) in phase II and +1.9 cm − 1 /GPa (r = 0.87) in phase III with pressure at 430 K. Thus, the ν 1 (SO 4 ) -ν(HSO 4 ) increased with pressure in both phases, and decreased 2.3 cm − 1 at the II-III transition.…”

Section: Resultssupporting

confidence: 72%

Changes in structure and proton conductivity at II–III phase transition of Rb3H(SO4)2

et al. 2010

View full text Add to dashboard Cite

Section: Resultssupporting

confidence: 72%

Changes in structure and proton conductivity at II–III phase transition of Rb3H(SO4)2

et al. 2010

View full text Add to dashboard Cite

“…The crystals achieve their superionic state through a structural phase transition at T S , except for Rb 3 H(SO 4 ) 2 , which undergoes a phase separation at the temperature of transformation to the high conducting state [5]. The salts also, except Rb 3 H(SO 4 ) 2 [6], are ferroelastic below T S , so T S ¼ T C and they undergo structural phase transition from the low temperature space group C2/c to the high temperature one R3m. Below T S , the structure consists of isolated dimers formed by XO 4 tetrahedra linked with short H-bonds connecting apical O(2) atoms of the neighbouring tetrahedra.…”

Section: Hydrogen Sulphates and Selenates -Solid Acidsmentioning

confidence: 99%

Anhydrous proton conductors for use as solid electrolytes

et al. 2010

View full text Add to dashboard Cite

Anhydrous proton conductors in which proton transport proceeds via structure diffusion are interesting alternatives for membrane materials in hydrogen/air fuel cells. Understanding the mechanism of proton diffusion in candidate materials is necessary to improve their performance. We present the results of our studies of two classes of proton conductors in which conductivity does not rely on the presence of water molecules in their structure: crystalline hydrogen sulphates and selenates and new salts of nitrogen-containing heterocyclic molecules combined with a series of dicarboxylic acids. In the former group, superprotonic conductivity results from a high molecular dynamics of S/SeO 4 groups, which creates an excess of structurally equivalent positions for protons. Ferroelastic properties of the crystals determine their physical behaviour at high temperatures. In particular, ferroelasticity makes a smooth and reversible character of superionic phase transition possible. In the second group of materials, the heterocycles exhibit extensive specific interactions that result in a fluctuating network of H-bonds. Thus, the proton conduction in these materials depends on the number of protons, which can be involved in the diffusion and on the fluctuation rate of the hydrogen bond network.

show abstract

“…As a result, each proton forms H-bonds with three O(2) oxygen atoms of the nearest SeO 4 groups with the same probability p = 1/3. In this way protons (and consequently H-bonds) are de-localized in the superionic phase and form a dynamically disordered network of H-bonds in the (0 0 1) plane [5,6]. The arrangement of H-bonds in layers results in a distinct anisotropy of proton conductivity, which is ∼20 times higher in the plane than along the direction perpendicular to it [7].…”

Section: Introductionmentioning

confidence: 99%