Fast Proton Conductors Research Articles

Dynamic aspects of a fast protonic conductor: oxonium perchlorate: Part I. Raman and inelastic neutron scattering spectra

Raman spectra and inelastic neutron scattering (INS) of polycrystalline H 3O +ClO − 4 have been investigated at different temperatures between 80 and 310 K. Raman and INS spectra of the low-temperature phase exhibit well-defined bands while, in the superconductor phase, continuous frequency distribution between 500 cm −1 and the Rayleigh line is characteristic of a highly disordered state. This disorder is provided by the quasi-isotropic rotation motions of the H 3O + ions in their sites.

HSbO 3.nH 2O, A fast protonic conductor with application for gas sensors

The antimonic acid HSbO 3.nH 2 is prepared by a sol-gel type method which allows us to obtain a well defined structural and morphological material. This compound shows high conductivity values ( σ 300K = 2.19 × 10 −4Ω −1 cm −1 for HSbO 3. nH 2 O ( n = 1.62)) which are very sensitive to water content. Deposits are realized by a printing process and an a.c. conductivity study has been carried on thick films. Potentiometric study of HSbO 2.nH 2O in H 2 concentration cells has been made and it allows us to foresee an interesting use for it as a H 2 sensor.

Electron-beam damage observed in the fast proton conductor ammonium/hydronium β''-alumina: a high-resolution electron microscope (HREM) study

Mise en evidence de 2 types de defauts nouveaux: defauts dus a des protons secondaires et formation de petites bulles de gaz a l'interieur du materiau

Raman spectroscopic studies of the fast proton conductor lithium hydrazinium sulfate

The temperature dependence of several low frequency external modes of lithium hydrazinium sulfate have been examined. The temperature dependent bandwidth and frequency of the 53 cm −1 mode have been studied over the temperature range 11–300 K. The significance of breaks observed in plots of spectral parameters vs. temperature for this mode are discussed.

Approche de la caractérisation des mouvements des protons dans des pastilles de phosphate acide d'uranyle par résonance magnétique nucléaire

The purpose of this work is to use nuclear magnetic resonance (NMR) to characterize properties of HUO 2PO 4·4H 2O (HUP) pellets; these are currently used instead of powder in most applications involving solid electrolytes. The physical characteristics of HUP greatly depend on powder precipitation, washing and drying and pellet ageing conditions. NMR measurements were performed at various temperatures using two samples prepared with two different amounts of water. Identical results were obtained from both types of sample. These results are in agreement with those already reported and correspond to those of HUP powder. This result shows that NMR measurements characterize proton motion in HUP bulk rather than in the grain boundaries. An estimated value of D H + is found to be 10 −7 cm 2 s −1 at room temperature. This high value shows that HUP is a fast protonic conductor. Accordingly the proton diffusion in HUP is not expected to be the limiting step when this solid electrolyde is associated with a solid cathodically reduced by photon insertion.

Structure and Properties of Vanadium Pentoxide Gels

ABSTRACTTransition metal oxide gels can be obtained, through a polycondensation process, by acidification of aqueous solutions. Thin layers can be easily deposited onto a substrate. Their electronic and ionic properties could lead to new developments of the sol-gel process. The semiconducting properties of V2O gels can be used for antistatic coatings or electrical switching devices. These gels exhibit a lamellar structure and can be described as particle hydrates. They are fast proton conductors and could behave as a host lattice for intercalation.

Study of protonic diffusion in hydrogen uranyl phosphate using a pulsed field gradient NMR method

The diffusion of 1H in the fast protonic conductor H(UO 2PO 4) · 4H 2O has been investigated as a function of temperature by employing pulsed field gradient NMR measurements. In the light of the present diffusion results and published conductivity observations on the same compound, it is likely that protonic diffusion and conductivity in this material occur by the same mechanism. Possible mechanistic processes for the proton motion in this material which are consistent with the activation energy for protonic diffusion found in this study are briefly discussed.

Vibrational study of hydrogenated uranyl phosphates hydrates (HUP)

HUO2PO4, 4H2O(HUP) is among the best fast proton conductors and is used as a solid electrolyte in sensors or in electrochromic displays. In the present work, HUP, ammonium and potassium isomorphs were prepared in the form of powders, oriented polycristalline transparent disks or crystals, and were studied by X Ray analysis, IR and Raman spectroscopies.Raman and IR spectra have been recorded in the 77 K to 350 K temperature range. Skeleton (PO4, UO2) vibrations as well as external modes or vibrations involving hydrogen atoms have been tentatively assigned using isotopic shifts (H/D or 16O/18O). Different degrees of disorder are present in the structure : the UO2 ν1 stretching mode is a particularly intense and narrow Raman band ; on the other hand a very broad band is observed at 115 cm−1 (δν12=25 cm−1) at room temperature in HUP. This band narrow and gives rise to three modes (90, 100 and 114 cm−1 respectively) below the ferroelectric phase transition. Vibrational modes of protonic species are assigned using isotopic shift and H3O+/K+ substitution : i.e. the ν4 mode of H3O+ is observed at about 1750 cm−1 (IR) and the ν2 mode of water is observed at 1640 cm−1. A broad diffusion observed on IR spectra of NHUP could be associated to the presence of a strong hydrogen bond.

Study of proton diffusion in NH+4 - H3O+ beta” -alumina using a pulsed, field-gradient NMR method

Diffusion of protons in single crystals of the fast protonic conductor NH+4-H3O+ beta” alumina (nominal composition: (NH+4)1.00(H3O+)0.85Al10.15O17) has been investigated over the temperature range 336–451 K with the aid of a pulsed, field-gradient NMR technique. The temperature-dependence of the proton diffusion coefficient, D1H, is given by: D1H(cm2s−1)=(6.756+ 2.077− 1.588)x 10−5exp -(0.202 ± 0.009 eV/kT) Comparison is made between these diffusion results and protonic conductivities measured within the same temperature range on the identical crystals used in the diffusion experiments. Implications of these results are briefly discussed in terms of possible mechanistic processes for proton motion in this and related compounds.

Comportement électrochimique du système hydrogèneplatine-phosphate acide d'uranyle (HUP) cristallisé

The electrochemical behaviour of the electrode H 2|Pt|HUO 2PO 4·4H 2O (HUP) was studied at room temperature, at which HUP is a fast proton conductor. The cathodic reaction was found to be rapid and stable. The anodic reaction is also rapid, provided that it follows a cathodic treatment. In the opposite case a limiting anodic current is observed. Storage for a long time in the presence of water vapour slightly increases this limit and this is attributed to a desiccation of the anodic interface producing a large superfacial ohmic drop. It was concluded that in the H 2|Pt|HUP|Pt|H 2 cell water is produced at the cathodic interface and is consumed at the anodic interface, the kinetics of this second reaction being slow.

Rigid lattice NMR spectra of fast proton conductors H 2Sb 4O 11- nH 2O

Hydrated antimonic acids H 2Sb 4O 11 · 2H 2O and H 2Sb 4O 11 · 3H 2O are fast proton conductors with the same (Sb 4O 11) 2-covalent framework delimiting intercrossing channels. Using proton magnetic resonance in the very low temperature rigid-lattice regime we show that the channels of the structure are occupied by three species: oxonium ions (H 3O +), water molecules (H 2O) and hydroxylic protons (OH) attached to the framework. Quantitative analysis of the experimental spectra lead to a rewriting of the chemical formula, as (H 3O) x Sb 4O 11- y (OH) y · zH 2O with x,y and z depending on the hydration state. Coexistence of oxonium ions and water molecules is compatible with the assumption of a Grotthuss-type mechanism for proton diffusion. Nuclear magnetic resonance of the completely dehydrated compound H 2Sb 4O 11 is also reported. The value of the second moment of the proton resonance line indicates that in this compound all the protons are attached to the (Sb 4O 11) 2- framework.

ChemInform Abstract: VEHICLE MECHANISM, A NEW MODEL FOR INTERPRETATION OF THE CONDUCTIVITY OF FAST PROTON CONDUCTORS

Chemischer InformationsdienstVolume 13, Issue 22 Physical Inorganic Chemistry ChemInform Abstract: VEHICLE MECHANISM, A NEW MODEL FOR INTERPRETATION OF THE CONDUCTIVITY OF FAST PROTON CONDUCTORS K.-D. KREUER, K.-D. KREUERSearch for more papers by this authorA. RABENAU, A. RABENAUSearch for more papers by this authorW. WEPPNER, W. WEPPNERSearch for more papers by this author K.-D. KREUER, K.-D. KREUERSearch for more papers by this authorA. RABENAU, A. RABENAUSearch for more papers by this authorW. WEPPNER, W. WEPPNERSearch for more papers by this author First published: June 1, 1982 https://doi.org/10.1002/chin.198222005Citations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume13, Issue22June 1, 1982 RelatedInformation

Vehicle Mechanism, A New Model for the Interpretation of the Conductivity of Fast Proton Conductors

Vehicle Mechanism, A New Model for the Interpretation of the Conductivity of Fast Proton Conductors

Trends in new materials for solid electrolytes and electrodes

An overview of recent developments in the field of fast solid lithium ion and proton conductors is presented. The important role of water in both types of conductors is described. Fast solid electrode materials are presented. Several general aspects such as thermodynamic stability ranges, transport mechanisms, enhancement of ionic conductivity in 2-phase mixtures, influence of electronic properties on ionic transport in electrolytes and electrodes and effects of stoichiometric variations of the compounds are discussed.

Fast hydrogen ion diffusion in solid hydrogen uranyl phosphate (HUP)

NMR relaxation time measurements and pulsed field gradient diffusion measurements have been made for 1 H in hydrogen uranyl phosphate (HUP). The results confirm that for T > 274 K HUP is a fast proton conductor exhibiting self-diffusion coefficients greater than 10 -11 m 2 s -1 .

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

Pulsed 1H n.m.r. measurements have been made of relaxation times in hydrogen uranyl phosphate and arsenate, which are fast proton conductors. Both compounds were found to undergo a phase transition resulting in discontinuities in T 1 and T 2 and a DTA peak. This transition occurs around 274 K in HUP and around 302 K in HUAs. Above the transition the n.m.r. behaviour of the two compounds is very similar, with an activation energy for T 1 and T 2 of 20 ± 1 kJ mol −1. The T 1 values are almost equal to T 2 values, and this can best be explained by the rapid diffusion of hydrogen. Possible mechanisms for hydrogen self-diffusion and charge transport are discussed that can account for the higher activation energies reported for the conductivities compared to those for n.m.r. relaxation.