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Nogami, Masayuki; Nagao, Ritsuko; Wang, Wenwen; Abe, Yoshihiro

doi:10.1023/a:1008635626256

Cited by 31 publications

(18 citation statements)

References 8 publications

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“…These two resonances can be assigned to the methyl, d ~1.06 ppm (CH 3 CH 2 O-), and methylene, d ~3.83 ppm (CH 3 CH 2 O-), groups on the basis of their chemical shifts and relative integrals. This is also confirmed by the presence of 13 C resonances in the 13 C MAS NMR experiments consistent with ethoxy groups. The resonances at d ~7.4 ppm (10P-100) and d ~8.9 ppm (30P-100) are assigned to POH groups involved in weak hydrogen bonding.…”

Section: Solid State 1 H Nmr Measurementssupporting

confidence: 62%

“…8 Phosphate glasses have found applications as fast proton conductors owing to their affinity towards water when either synthesised from oxides 9 or by using sol-gel methods. [10][11][12][13] Abe and co-workers proposed that an ionic type humidity sensing mechanism occurs in these gel derived glasses, [11][12][13] on the basis of conductivity measurements as a function of the temperature as well as of infrared (IR) absorption spectra. At low water content, chemical bonds form between the water molecules and the OH groups lying on the glass surface and the protons, dissociated from SiOH and/or POH bonds, move by hopping from the initial site to a neighbouring site.…”

Section: Introductionmentioning

confidence: 99%

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Solid state 1H NMR study, humidity sensitivity and protonic conduction of gel derived phosphosilicate glasses

Clayden¹,

Esposito²,

Pernice³

et al. 2002

J. Mater. Chem.

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H Magic Angle Spinning (MAS) NMR and 1 H T 1 and T 1r relaxation times measurements were used to investigate structural aspects of gel derived glasses of composition 10P 2 O 5 ?90SiO 2 (10P) and 30P 2 O 5 ?70SiO 2 (30P), with the aim of understanding the different humidity sensitive behaviour observed for films of the same composition. The experimental evidence suggests that 10P and 30P gel samples heat treated at 100 uC have a similar POH environment while further heating causes a different structural evolution of POH units. In particular, the 30P sample heat treated at 400 uC shows a single 1 H resonance while a number of resonances are seen in the 1 H spectrum of the 10P sample heat treated at 400 uC. Further evidence of the different structure of 10P and 30P samples was given by the NMR relaxation times measurements, the gels were found to be heterogeneous on a nanometric scale. Domains, about 60 nm in size, related to 1 H resonance in POH were evenly distributed in the matrix of both gels, only in the 10P gel also larger domains (about 700 nm) were found that can be related to 1 H resonance in SiOH groups. Finally, MAS in combination with variable temperature static NMR spectra provided detailed information on the network structural features present in the 30P sample heat treated at 300 uC as well as in the 10P sample heat treated at 400 uC and allowed investigation of the dynamic processes taking place in these samples.

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Section: Solid State 1 H Nmr Measurementssupporting

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Solid state 1H NMR study, humidity sensitivity and protonic conduction of gel derived phosphosilicate glasses

Clayden¹,

Esposito²,

Pernice³

et al. 2002

J. Mater. Chem.

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“…However, it is also known that these membranes have some disadvantages such as narrow operating temperature range and humidity range and high price. For these problems, recent interests are extending to inorganic materials 1), 2) or inorganic/organ ic composites. 3) 7) Alminotriphosphate hydrate AlH 2 P 3 O 10 EnH 2 O (n23) is acid aluminum salt of condensed phosphoric acid (H 5 P 3 O 10 ) and is mainly applied as a rustresisting paint and an adsorbent for basic gas.…”

Section: Introductionmentioning

confidence: 99%

Stability and Proton Conductivity of AlH2P3O10 nH2O under Various Water Vapor Pressures

優実

早苗

勝

2003

J. Ceram. Soc. Japan

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íXmOöC³ºjIP AlH 2 P 3 O 10 E nH 2 O mÀè«gÓéÄï`±Á« cDÀEìcE{R åw ¶YZp¤C1538505 sÚaeîê 461Stability and proton conductivity of AlH 2 P 3 O 10 EnH 2 O (n23) were investigated in the temperature range from 75 C to 150 C under various water vapor pressures. The hydrolysis from AlH 2 P 3 O 10 EnH 2 O to Al(H 2 PO 4 ) 3 started at 100 C under a relative humidity (RH) of 60÷, and further hydrolysis to AlPO 4 took place with increasing temperature and humidity. At 75 C, the original phase was maintained under saturated water vapor pressure. Conductivity measurements at 75 C (0÷RH98÷) and 100 C (0÷RH60÷) in dicated an abrupt increase in conductivity with increasing water content n in the range of n1.0 to 2.0 at both temperatures. The proton conductivity achieved a value s5.0~10 |3 SEcm |1 at 75 C and 98÷ RH. It is assumed that the proton conductivity in the crystal became larger by formation of continuous hydrogen bonding in AlH 2 P 3 O 10 EnH 2 O.

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“…The hydroxyl groups such as Si-OH, P-OH and Zr-OH on the pore surfaces of inorganic oxides are bonded with water molecules, and the proton conduction is associated with proton hopping between hydroxyl bonds and water molecules [9][10][11]. Uma et al have reported that proton conductivity of SiO 2 -P 2 O 5 -ZrO 2 glasses was shown around 10 −4 -10 −3 S/cm at temperature range of 30-90 o C [12].…”

Section: Introductionmentioning

confidence: 99%

Preparation of silica-based proton conductors for intermediate temperature fuel cells

Seo

Park

Shul

2009

Korean J. Chem. Eng.

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The ternary system SiO 2 -P 2 O 5 -ZrO 2 electrolyte and phosphotungstic acid (PWA) doped SiO 2 -P 2 O 5 -ZrO 2 electrolyte were prepared for intermediate temperature fuel cell by using sol-gel technique. These silica-based proton conductors were confirmed to be non-crystalline structure without phase separation and good thermal stability by XRD and TG/DTA analysis. The doped PWA was found to be stabilized within the silica matrix and to enhance the proton conductivity. The proton conductivities of SiO 2 -P 2 O 5 -ZrO 2 and SiO 2 -P 2 O 5 -ZrO 2 -PWA electrolytes showed 3.3×10 −5 and 1.8×10 −3 S/cm at 90 o C, respectively, and the cell performance of SiO 2 -P 2 O 5 -ZrO 2 -PWA electrolyte was obtained as 0.02-0.25 mA/cm 2 at 300 o C under humid condition.

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Cited by 31 publications

References 8 publications

Solid state 1H NMR study, humidity sensitivity and protonic conduction of gel derived phosphosilicate glasses

Solid state 1H NMR study, humidity sensitivity and protonic conduction of gel derived phosphosilicate glasses

Stability and Proton Conductivity of AlH2P3O10 nH2O under Various Water Vapor Pressures

Preparation of silica-based proton conductors for intermediate temperature fuel cells

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