Electrochemical substitution of sodium ions with protons in phosphate glass to fabricate pure proton conducting glass at intermediate temperatures

Ishiyama, Tomohiro; Nishii, Junji; Yamashita, Toshiharu; Kawazoe, Hiroshi; Omata, Takahisa

doi:10.1039/c3ta14561a

Cited by 38 publications

(45 citation statements)

References 34 publications

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“…The detailed configuration is described in our previous papers [4][5][6]. Disk-shaped glass plates with a diameter of 18 mm and a thickness of 1 mm were sliced from the cylindrical glass block and both surfaces were polished.…”

Section: Alkali-proton Substitution (Aps)mentioning

confidence: 99%

“…We refer to this as the alkaliproton substitution (APS) technique [4,5]. By applying this technique to 35NaO 1/2 -1WO 3 -8NbO 5/2 -5LaO 3/2 -51PO 5/2 glass (1 W glass), we successfully injected proton carriers with a concentration higher than 5 × 10 21 cm −3 and obtained a pure proton conductor [6]. However, the proton-conducting glass obtained (1 W glass after APS) was not stable and underwent deformation at temperatures higher than 250°C.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, the maximum proton conductivity was limited to 4.0 × 10 −4 Scm −1 at 250°C. Extrapolation of the Arrhenius plot of its electrical conductivity suggests that the proton conductivity will reach 1 × 10 − 2 Scm −1 at 370°C when the glass after APS becomes stable at N370°C [6].…”

Section: Introductionmentioning

confidence: 99%

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Improving thermal stability and its effects on proton mobility in proton-conducting phosphate glasses prepared by the electrochemical substitution of sodium ions with protons

et al. 2015

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a b s t r a c tWe investigated electrochemical substitution involving the electrochemical oxidation of hydrogen with proton injection into an oxide glass. This was accompanied by the electrochemical reduction of sodium ions and the discharge of metallic sodium out of the glass. This is referred to as the alkali-proton substitution technique and we applied it to a sodium-containing phosphate glass. The thermal stability of the 1WO 3 -35NaO 1/2 -8NbO 5/2 -5LaO 3/2 -51PO 5/2 glass that previously deformed at N 250°C improved to 350°C after alkali-proton substitution technique by the introduction of AlO 3/2 and/or YO 3/2 . However, the mobility of the proton carriers decreased by 1/20-1/50 by the introduction of AlO 3/2 and/or YO 3/2 while the thermal stability improved. Based on infrared absorption spectra the reduced mobility can be attributed to the increase in protons that are tightly bound to oxygen by weak hydrogen bondings.

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Section: Alkali-proton Substitution (Aps)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Improving thermal stability and its effects on proton mobility in proton-conducting phosphate glasses prepared by the electrochemical substitution of sodium ions with protons

et al. 2015

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“…The spectra were obtained in a back-scattering geometry, between 100 and 1100 cm -1 . M A N U S C R I P T ACCEPTED MANUSCRIPT 4 The morphology of the glasses was observed by scanning electron microscopy (SEM), performed in a Hitachi S4100-1 system, on the free surface of the glasses. All samples were covered with carbon before microscopic observation.…”

Section: Structural and Morphological Characterizationmentioning

confidence: 99%

“…Currently, proton-conducting polymer electrolyte membrane fuel cells are used for temperatures below 100 °C, and solid oxide fuel cells for temperatures between 800 and 1000 °C [4]. Intermediate temperature fuel cells, remains a subject under improvement, since new materials able to be efficiently used as electrolytes between temperatures of 200-500 °C are still needed.…”

Section: Introductionmentioning

confidence: 99%

Electrical and dielectric analysis of phosphate based glasses doped with alkali oxides

et al. 2015

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A Novel Technique for Controlling Anisotropic Ion Diffusion: Bulk Single‐Crystalline Metallic Silicon Clathrate

et al. 2022

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Na‐free Si clathrates consisting only of Si cages are an allotrope of diamond‐structured Si. This material is promising for various device applications, such as next‐generation photovoltaics. The probable technique for synthesizing Na‐free Si clathrates is to extract Na+ from the Si cages of Na24Si136. Vacuum annealing is presently a well‐known conventional and effective approach for extracting Na. However, this study demonstrates that Na+ cannot be extracted from the surface of a single‐crystalline type‐II metallic Si clathrate (Na24Si136) in areas deeper than 150 µm. Therefore, a novel method is developed to control anisotropic ion diffusion: this is effective for various compounds with a large difference in the bonding strength between their constituent elements, such as Na24Si136 composed of covalent Si cages and weakly trapped Na+. By skillfully exploiting the difference in the chemical potentials as a driving force, Na+ is homogeneously extracted regardless of the size of the single crystal while maintaining high crystallinity. Additionally, the proposed point defect model is evaluated via density functional theory, and the migration of Na+ between the Si cages is explained. It is expected that the developed experimental and computational techniques would significantly advance material design for synthesizing thermodynamically metastable materials.

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Electrochemical substitution of sodium ions with protons in phosphate glass to fabricate pure proton conducting glass at intermediate temperatures

Cited by 38 publications

References 34 publications

Improving thermal stability and its effects on proton mobility in proton-conducting phosphate glasses prepared by the electrochemical substitution of sodium ions with protons

Improving thermal stability and its effects on proton mobility in proton-conducting phosphate glasses prepared by the electrochemical substitution of sodium ions with protons

Electrical and dielectric analysis of phosphate based glasses doped with alkali oxides

A Novel Technique for Controlling Anisotropic Ion Diffusion: Bulk Single‐Crystalline Metallic Silicon Clathrate

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