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The c-axis oriented apatite-type silicates were fabricated in simple ways: fabrication of melt-quenched glass and its crystallization. It was found that a degree of c-axis orientation was affected by many factors such as crystallization temperature and kind of powder materials, in which the precursor glass embedded during crystallization. The performance of a solid oxide fuel cell (SOFC) using the crystallization glass as an electrolyte was also investigated at temperatures of 600 to 800°C.

Anode supported solid oxide fuel cells (SOFCs) utilizing apatite-type Mg-doped lanthanum silicate (MDLS) electrolytes obtained from nano-sized printable paste coated on NiO-MDLS substrates were fabricated. With optimizing fabrication conditions of MDLS films, anode and cathode materials, the performance was largely improved, and the high performance SOFC based on apatite-type electrolyte was successfully developed for the first time.

Binary x MO·(100 − x )P 2 O 5 (mol%; M = Ca, Mg) glasses were prepared using a conventional melting method, and the proton conduction mechanism in the glasses was investigated. The proton conductivities of the glasses were measured under various hydrogen (H 2 ) gas concentrations from 0 to 100 vol.% using Pt electrodes. The CaO·P 2 O 5 glasses show higher proton conductivities than MgO·P 2 O 5 ones. Fourier-transform infrared (FTIR) measurements showed that protons dissociated from H 2 gas at the Pt electrodes are incorporated into the glasses, and the proton conductivity increases as a result of an increase in the carrier (proton) concentration. There is a good linear relationship between the peak wavenumber of P O nb (O nb indicates non-bridging oxygen) and the proton conductivity measured in a 100 vol.% H 2 atmosphere. Furthermore synchrotron radiation X-ray diffraction (SRXRD) and FTIR results suggest that the π-electron of P O double bond is localized significantly in MgO·P 2 O 5 compared with CaO·P 2 O 5 glasses, which is the origin of higher proton conductivity in CaO·P 2 O 5 glasses.

Ultrathin layers of positively charged poly(diallyl dimethylammonium) choloride (PDDA) and negatively charged poly(sodium 4-styrenesulfonate) (PSS) were deposited on SiO2/ polyethylene glycol hybrid membranes via layer-by-layer assembly technique, and carbon dioxide absorption/separation properties were investigated. Quartz crystal microbalance (QCM) measurements revealed that both PDDA and PSS nanocoatings have a good affinity for CO2 absorption. PDDA-deposited film shows about two times higher CO2 ideal gas selectivity compared with unmodified silica film.

Polysilazanes functionalized with alkoxy groups were designed and synthesized as single source precursors for fabrication of micro and mesoporous amorphous silica-based materials. The pyrolytic behaviors during the polymer to ceramic conversion were studied by the simultaneous thermogravimetry-mass spectrometry (TG-MS) analysis. The porosity of the resulting ceramics was characterized by the N2 adsorption/desorption isotherm measurements. The Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopic analyses as well as elemental composition analysis were performed on the polymer-derived amorphous silica-based materials, and the role of the alkoxy group as a sacrificial template for the micro and mesopore formations was discussed from a viewpoint to establish novel micro and mesoporous structure controlling technologies through the polymer-derived ceramics (PDCs) route.

International audience; Ionic conductivities measured under GPa-order high pressure provide various information about ion hopping mechanisms such as the activation volume (ΔV). Traditionally, anvil cells have been used for high-pressure measurements. We previously reported a new method for high-pressure impedance measurements, up to a few GPa, employing an indentation-induced local stress field. In this method, both mechanical and electrical (Young's modulus and high pressure impedance) properties can be obtained simultaneously. However, in this method, high pressures are induced only around the tip of the indenter, and such stress distribution should be considered for the estimation of ΔV accurately. In the present study, employing a finite element method (FEM) calculation, the stress distribution around the tip of the indenter, and effects of such GPa-order high pressures on the O2− ion conduction of Y2O3-doped zirconia (YSZ) are shown.

Electrochemical oxygen reduction behavior for a half cell composed of a mixed ionic and electronic conducting (MIEC) oxide and an oxygen excess-type solid electrolyte was investigated. A perovskite-type MIEC oxide, (La 0.6 Sr 0.4 )(Co 1− y Fe y )O 3− δ (LSCF), was employed as a base material for an electrode catalyst of oxygen reduction reaction. As an electrolyte, Al-doped lanthanum silicate [La 10 (Si 5.8 Al 0.2 )O 26.9 (ALSO)] was used, which is a new class of oxide ion conductors with apatite-type structure. The evaluated polarization resistance, R pol , for the reaction largely depended on y , and the minimum resistance was obtained for y = 0.2. The R pol value was 0.3 Ω cm 2 at 1073 K in ambient air [ P (O 2 ) = 2.1 × 10 4 Pa] for y = 0.2. To improve the performance, introduction of silver nano-particles onto the LSCF particles was studied. With the Ag-modification, R pol at 1073 K could be minimized toward 0.08 Ω cm 2 . The cathodic overpotential of the electrode evaluated from DC polarization at 1073 K was 18 mV at 0.1 A cm −2 .

The multilayered thin film fuel cells (multilayered-TFFCs) using anatase TiO2 as an anodic catalyst were successfully prepared by layer-by-layer (LbL) assembly technique. The electrode-membrane assembly (MEA) of the multilayered-TFFC, which had a total thickness of approximately 720 nm, was constructed on a continuously porous glass substrate. The anode and the cathode were separated by the multilayered polymer electrolyte having a thickness of about 350 nm. The amounts of anodic TiO2 nanoparticles and cathodic Pt nanoparticles were calculated to be 6.2 μg cm− 2 and 18 μg cm− 2, respectively. The open circuit voltage was obtained by ultraviolet (UV) irradiation and methanol supply, because electrons were derived from photocurrent and methanol oxidation. The resultant current densities increased with increasing methanol concentration and intensity of UV irradiation. The multilayered-TFFC with 5 mol L− 1 methanol solution showed the maximum power density of 13 μW cm− 2 by UV irradiation of 20 mW cm− 2.

Gold was vacuum deposited on one side of 6-μm-diameter silica-gel particles to prepare Janus particles (JPs). Thiol-terminated pH-responsive poly(sodium 6-acrylamidohexanoate) (pAaH-SH) was immobilized onto the gold surface of JPs. pH-responsive flocculation and dispersion behavior of pAaH-grafted JPs can be observed with optical and fluorescence microscopy measurements.

Anhydrous proton conductive KHSO4–H3PW12O40 (KHS–WPA) composites were successfully synthesized using mechanochemical treatment. 95KHS·5WPA (mol%) composite, for example, showed very high anhydrous proton conductivity of 1.3 × 10−2 to 2.4 × 10−3 S cm−1 in a temperature range from 160 °C to 80 °C under ambient pressure. Chemical interactions via ion-exchange and hydrogen bond between KHS and WPA were confirmed from structural studies. Furthermore, the anhydrous proton conductivity of the KHS–WPA composites was well correlated with their estimated hydrogen bonding distance, indicating that reduction of the hydrogen bonding distance in the KHS–WPA composites is significant in the proton hopping to achieve anhydrous high proton conductivity.

An asymmetric silica membrane supported on a porous alumina tube substrate was prepared by dip-coating and then surface modification multistage assembly synthesis. The mesoporous silica membrane was repeatedly modified with hexamethyldisilazane after dip-coating in silica sol solution. The separation layer of the silica membrane had an average thickness of 2 μm, mean pore radius of 1.16 nm, and BET surface area of 225 m 2 ·g − 1 . In the presence of 1 wt.% acetic acid, the membrane effectively removed ethanol and acetone from 5 wt.% organic/water binary system, or 5.0 wt.% organic–94.0 wt.% water ternary feeds by pervaporation (PV) over a temperature range of 303–323 K. The separation factor (α) of ethanol at 303 K was about 8.7, while that of acetone was 28.4. The total permeate fluxes at 303 K were 0.92 and 1.15 kg ·m − 2 ·h − 1 for ethanol/water and acetone/water feed solution, respectively. Furthermore, the separation mechanism is discussed on the basis of the relationship between the electronegativity of the feed solution composition and electronic structure of silane coupling modifier.

Electronic as well as ionic conducting properties for oxyapatite-type solid electrolytes based on lanthanum silicate, La9.333 + xSi6O26 + 1.5x (LSO) were investigated in the oxygen-excess region (x > ca. 0.3). We have found that the oxygen excess-type LSO (OE-LSO), namely La10Si6O27 on weighted basis, exhibited high conductivity, and substitution of the Si-site of LSO with some dopants (Mn+) had a positive effect toward the conducting property. Furthermore, it was also found that addition of a very small amount of iron ions into the M-doped OE-LSO, La10(Si6-yMn+y)O27-(2–0.5n)y, improved its conductivity. On the other hand, replacement of the La-site with various ions for La10(Si6-yMn+y)O27-(2–0.5n)y did little to improve conductivity. The electronic transport numbers for Al-doped OE-LSO with Fe-addition, (1-α){La10(Si5.8Al0.2)O26.9}-α(FeOγ), evaluated with the Hebb–Wagner polarization method were very low: i.e., 1.1 × 10− 3 and 2.9 × 10− 3 under P(O2) = 1.1 × 104 Pa at 1073 K for α = 0.00 and 0.005, respectively. Conductivity for each sample was unchanged under humidified atmosphere at 1073 K sustained for over 50 h, revealing that both compositions were chemically stable. It was concluded that 0.995{La10(Si5.8Al0.2)O26.9}–0.005(FeOγ) is suitable for the fuel cell electrolytes because of its high and almost pure ionic conductivity, and its good chemical stability under humidified as well as reducing conditions.

Pervaporation of ethanol from ethanol/water mixture solution using surface-modified mesoporous silica membranes has been carried out. The mesoporous silica layers were prepared on commercially available porous alumina tubes by dip-coating in a series of silica sols. Subsequently, organosilane compounds with different alkyl chain lengths [CnH2n+1(CH3)2SiCl; n = 1, 3, 8, 12, and 18] were covalently reacted to the surface of these mesoporous layers with high coverage. Surface-modified mesoporous silica membranes showed ethanol permselectivity and the total flux increased with increasing ethanol concentration in feed composition and feed temperature. Ethanol separation factors in the range from 7.90 to 8.24 and total flux of 2.76–2.89 kg·m−2·h−1 were obtained by pervaporation at 323 K and at 5 wt % ethanol feed composition using surface modified membranes. In the presence of 1 wt % acetic acid in a ternary model fermentation (5 wt % ethanol–94 wt % water–1 wt % acetic acid), separation factor and total flux were decreased, and this tendency was minimized by increasing pH above pKa⊖ (pKa⊖ = 4.74 at 298 K) and changing HOAc to OAc− ions in the feed solution.

Proton conductive poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) ultrathin film was deposited as a multilayer on the size-controlled phenylsilsesquioxane (PhSiO3/2) particles via layer-by-layer (LbL) assembly. The composite electrolyte prepared from the PAMPS-multilayer deposited PhSiO3/2 had a grain boundary composed of the proton conductive multilayer. The interfacial conducting path having a honeycomb structure was percolated in the composite. The conductivity of the interfacial conducting path was estimated from general effective media (GEM) approximation. The interfacial conductivities of the composite under the conditions of 70 and 95%R.H. at 80°C were calculated from the fitting by GEM approximation to be 0.03 and 0.2 S cm−1, respectively.

Influences on electrical property and phase relationship of oxyapatite-type solid electrolytes based on lanthanum silicate (LSO) were investigated by addition of a small amount of transition metal elements. It was revealed that a very small amount of 3d-transition metal additives into the La-excess-type, i.e., oxygen-excess-type Al-doped LSO, La10(Si5.8Al0.2)O26.9, changed its electrical conductivity. Some metals such as iron and chromium showed a positive effect for an increase in conductivity. The specimen with a nominal composition of 0.995{La10(Si5.8Al0.2)O26.9}–0.005(FeOγ), showed the maximum electrical conductivity among the specimens measured in this study. Formed phases of oxygen-excess-type Al-doped LSO based materials were found to be altered even by addition of a small amount of transition metal oxides. La-rich impurity phases such as La(OH)3 and La2SiO5 are usually detected in the oxygen-excess-type LSO, whereas no formation of La-rich impurity phases was confirmed in the case of iron addition. These results suggest that the enhancement of electrical conductivity by iron addition is due to a disappearance of the La-rich impurity phases as insulators and/or an increase in the concentration of oxygen interstitial carriers within the LSO phase.

Phenyltriethoxysilane (PhTES) and tetraethoxysilane (TEOS) coatings [xPhTES·(100 − x)TEOS (mol%)] (x = 0 − 80) were prepared on polycarbonate (PC) substrate, and adhesion, surface hardness and distribution of phenyl groups were studied. The coatings with more than 60 mol% of PhTES showed good adhesion (≈ 100%), and the pencil hardness of PC substrate (4B) improved to 2B or B after the coatings. Bulk gels with the same compositions were also prepared, and distribution of phenyl groups were estimated using fourier transform infrared (FT-IR) spectroscopy (KBr method for bulk gels and attenuated total reflection (ATR) method for coatings). A significant difference for the distribution of phenyl groups was clearly observed between bulk gels and coatings, suggesting PC substrate affects the distribution of phenyl groups in coatings. The adhesion and FTIR results revealed that there is an interaction caused by π-electrons between benzene rings on PC substrate and phenyl groups of PhTES-TEOS coatings. It was found that the adhesion was strongly correlated with the phenylsilsesquioxane networks formed around PC substrate side.

c-axis-oriented epitaxial 1.2-μm PbMg0.047Nb0.095Zr0.416Ti0.442O3 (PMNZT) films with a comparatively large piezoelectric coefficient d 33 (=90 pC/N) fabricated on Pt(100)/MgO(100) substrates by metalorganic decomposition were treated by hot isostatic pressing (HIP). The HIP-pressure dependence on d 33 of the 1.2-μm PMNZT samples treated at 850°C for 1 h under Ar/O2 mixed gas pressures of 49–196 MPa was investigated. The d 33 value of the HIP-treated samples was almost constant (=60 pC/N), independently of the amplitude in pressure. Although the HIP treatment hardly contributes to an improvement on d 33, it can be expected to minimize the deviation of d 33 and provide highly-reliable piezoelectric elements.

The 3.0-μm (Bi3.25Nd0.75)Ti3O12 (BNT-0.75) films were fabricated on IrO2(101)/ Al2O3(012) substrates by high-temperature sputtering. The XRD pole figure demonstrated that a 3.0-μm BNT-0.75 film deposited on the IrO2 electrode is grown with a strong 10° off-(100)/(010) and a weak (101)/(011) orientations of threefold symmetry. The BNT films represented random orientation near the bottom IrO2 electrode and the intermediate part of the film. In the upper part of the BNT layer, the existence of a- and b-axis-oriented rod-shaped crystals with approximately 0.25 μm width were confirmed. In contrast, the BNT film deposited directly on the Al2O3(012) substrate represented almost completely a- and b-axis orientations in a whole BNT layer.

Proton conducting poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) ultrathin layer was deposited on sol–gel-derived phenylsilsesquioxane (PhSiO3/2) particles via layer-by-layer (LbL) assembly technique. Spherical and size-controlled particles in the range of 0.3–4.0 μm were successfully prepared by varying the condensation reaction. One PAMPS layer with 1.5 nm thickness was deposited on the particle, the volume fractions of Primer/PAMPS-multilayer varied from 0.7 to 11 vol.%. Sheet-like composite electrolytes in which PAMPS layer percolated throughout the sample can be obtained by hot-pressing the PAMPS-deposited PhSiO3/2 particles. The sample prepared using unmodified PhSiO3/2 exhibited a very low proton conductivity of 10−9 S cm−1 at 80 °C, whereas the conductivity of the composite electrolytes increased significantly with a very small amount of PAMPS-multilayer (∼1 vol.%). The composite with 11 vol.% PAMPS exhibited 2 × 10−3 S cm−1 at 80 °C and 95% of relative humidity.

SiO2·TiO2 coatings were prepared by a sol–gel route. The effect of the external fields including mechanical vibration and electric charge applied during hot-water treatment on titania precipitation at the surface of the coatings was investigated. The shape of the resulting precipitates tended to elongate by applying vibration in a parallel or perpendicular direction, or by applying an electric charge. The organization of titania nanocrystallites possibly occurs because of the concentration gradient of dissolved titania species generated by the external fields during the hot-water treatment. A maximum aspect ratio of 38.1 was achieved for the precipitate prepared by hot-water treatment performed under parallel vibration for 5 h. The shape of the resulting precipitates was also influenced by the content of TiO2 in the SiO2·TiO2 coating, with a smaller proportion of TiO2 increasing the aspect ratio of the resulting precipitate.

Polyphenylsilsesquioxane (PhSiO3/2) particles as an organic-inorganic hybrid were prepared using sol-gel method, and monolithic samples were obtained via a warm-pressing. The reaction mechanism of particles’ polymerization and transformation to the monolith under the warm-press were investigated using solid state 29Si nuclear magnetic resonance (NMR) spectrometer, thermal gravimetric-differential thermal analyzer (TG-DTA), mass spectrometer (MS) and scanning electron microscope (SEM). Transparent and void-free monoliths are successfully obtained by warm-pressing above 180 °C. Both the terminal –OH groups on particles’ surface and warm-pressing are necessary for preparation of void-free PhSiO3/2 monolith. From the load-displacement measurement at various temperatures, a viscoelastic deformation is seen for PhSiO3/2 monolith with voids. On the other hand, an elastic deformation is seen for void-free PhSiO3/2 monolith, and the void-free monolith shows much higher breakdown voltage.

The surface of H 2 Ti 4 O 9 · x H 2 O titanate nanosheets was modified using the sulfonated tetrafluoroethylene-based polymer Nafion ® , via layer-by-layer assembly. The surface modification allowed the titanate nanosheets to be highly dispersed in hydrophobic organic solvents. Thick films of surface-modified nanosheets were prepared on indium tin oxide (ITO)-coated glass substrates as a negative electrode by electrophoretic deposition. The thickness of the films increased with increasing deposition time and grew to more than 8 μm in 600 s under potentiostatic conditions at 7.5 V. The electrophoretically deposited thick films showed significant hydrophobicity with contact angle for water 95°, and enhanced adsorption and higher photocatalytic activity for hydrophobic dyes such as thionine than those of thick films prepared from unmodified titanate nanosheets.

A typical solid acid of CsHSO 4 and phosphotungstic acid (H 3 PW 12 O 40 6H 2 O: WPA6H 2 O) were mechanically milled, and non-humidified proton conductivity of the obtained composite was investigated. The 90CsHSO 4 10WPA (mol%) composite showed high proton conductivities of 10 − 2 –10 − 4 S/cm from 160 to 30 °C under dry nitrogen atmosphere, while the conductivity of pure CsHSO 4 dropped abruptly at around 145 °C due to the phase transition from superprotonic CsHSO 4 (I) phase to CsHSO 4 (II) phase. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy measurements were performed at various temperatures to study the phase transition behaviour as well as hydrogen bonding structure. The phase transition was not observed for the 90CsHSO 4 10WPA composite. FTIR measurements revealed that a peak for OH stretching shifted to a higher wavenumber with increasing temperature. The O–H•••O hydrogen bond distance was calculated from the OH band wavenumber. The proton conductivities in dry conditions were related to the bonding distance.

Ultrathin layers of positively charged poly(diallyldimethylammonium chloride) (PDDA) and negatively charged poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) were alternately deposited on the negatively charged phenylsilsesquioxane (PhSiO 3/2 ) particles via Layer-by-Layer (LbL) technique. PDDA/PAMPS multilayer-deposited PhSiO 3/2 particles once soften and glued together with plastic deformation at temperatures higher than the glass transition temperature. Sheet-like electrolytes prepared using multilayered PDDA/PAMPS-deposited PhSiO 3/2 particles showed proton conductivities 4–6 orders of magnitude higher than those of the samples without multilayers, and the proton conductivity reached about 10 − 3 S/cm at 80 °C and 80% relative humidity.

A crystalline rutile titanium oxide (TiO2)-dispersed porous glass–ceramic was successfully prepared by the phase separation of aluminosilicate-based glass. A rutile TiO2 crystal was clearly observed after the heat treatment of 20TiO2·29SiO2·13Al2O3·28CaO·5MgO·2P2O5·2B2O3·1ZrO2 (mol%) glass at 900°C for 15 h. The glass–ceramic obtained was then treated with an acid solution (3 mol/dm3 nitric acid) to leach its soluble phases. The acid-treated sample became porous, and the glass–ceramic obtained had a large surface area of 74 m2/g. The porous glass–ceramic adsorbed methylene blue (MB) rapidly, and the adsorbed MB was photodecomposed by ultraviolet irradiation.

Nafion ultrathin layers were deposited on a glass substrate by using layer-by-layer assembly technique, and proton conductivity of the multilayers was investigated. Two different types of polycations, poly(diallyldimethylammonium chloride) (PDDA) and poly(allylamine hydrochloride) (PAH) were used for the deposition of anionic Nafion layers. The incremental film growth of multilayers was monitored using a quartz crystal microbalance (QCM). QCM results revealed that the polycation and Nafion layers were deposited regularly and homogeneously. The thicknesses of one Nafion layer were estimated to be 1.5 and 10 nm for (PDDA/Nafion) n and (PAH/Nafion) n multilayers, respectively ( n means the number of layer). In the case of PDDA/Nafion multilayer, proton conductivity decreased significantly with increasing the number of layer n . On the other hand, no significant decreases in proton conductivity were observed for the PAH/Nafion multilayer. The weights of absorbed water for ultrathin multilayers were also measured and the results revealed that the formation of ionic pair of –SO 3 − ⋯N + – affects both the water uptake and proton conductivity.

New proton conductive solid acid composites were prepared by mechanical milling. First, the formation of highly proton conductive cesium-containing sulfate-phosphate double salt composites, and their phase transition are described. Second, a mechanochemical synthesis of "cesium ortho-oxosalt-heteropoly acid composites," and the relationship between proton conductivity and hydrogen bonding network in the composites are discussed. Mechanochemical treatment of mixtures of cesium hydrogen sulfate (CsHSO4) and cesium dihydrogen phosphate (CsH2PO4) using a planetary type of ball mill formed Cs3(HSO4)2(H2PO4) and Cs5(HSO4)3(H2PO4)2. Cs3(HSO4)2(H2PO4) and Cs5(HSO4)3(H2PO4)2 were transformed to the higher temperature phase of Cs2(HSO4)(H2PO4) by heating at around 100°C. Proton conductivity of the treated compound remarkably increased on heating to 2×10−3 S·cm−1 at around 180°C, whereas no steep decrease was observed on cooling. The high proton conductivity was ascribed to the presence of the high temperature phase of Cs2(HSO4)(H2PO4). Milling of Cs-containing ortho-oxosalts (Cs2SO4, Cs2CO3 or CsHSO4) and phosphotungstic acid (H3PW12O40·6H2O: WPA-6) mixtures obtained partially substituted CsxH3−xPW12O40 composites. Chemical durability and proton conductivity of the resultant composites markedly improved under both humidified and dried conditions. In addition, mechanochemically prepared 90CsHSO4·10WPA-6 (mol%) composite maintained high proton conductivity from room temperature to 180°C. Conductivity of the composite was 3.3×10−3 S·cm−1 at 100°C under dry atmosphere, much higher than those of pure CsHSO4 (4×10−7 S·cm−1) and WPA-6 (1×10−7 S·cm−1). The –O(H)···O hydrogen bonding distance in the CsHSO4–WPA-6 composites was estimated from the 1H-isotropic chemical shift of 1H MAS NMR spectra. Proton conductivities of CsHSO4–WPA-6 composites under dry atmosphere were strongly related to the bond distance.

Porous glasses (PGs) with 4 nm in diameter pores were prepared utilizing a spinodal-type phase separation of Na2O–B2O3–SiO2 glass, and their surface was modified using titanium tetraisopropoxide. Fourier transform infrared measurements revealed that the absorbance for strong hydrogen-bonding OH groups increased after the modification. Bond overlap population (BOP), which is directly related to the strength of the covalent bond, between O and H of OH groups were calculated using density functional theory and first-principles calculations. BOPs decreased by the introduction of Ti atoms on pores. The proton conductivity at 80°C and 90% relative humidity of the titania-modified PG was about five times higher than that of unmodified PG.

Highly dense pellets of an oxygen excess-type lanthanum silicate (La 9.333+x Si 6 O 26+1.5x , x > ca. 0.3, OE-LSO) were successfully fabricated, and their electrical conducting properties were studied. The replacement of Si by Al enhanced its conductivity, and the slightly Al-doped OE-LSO specimen [La 9.62 (Si 5.79 Al 0.21 )O 26.33 ] had excellent features as a solid electrolyte; that is, it had high ionic conductivity and was highly stable under reducing as well as oxidizing conditions at 873-1073 K. In addition, the ionic transference number was higher than 0.99. In the fuel cell utilizing this electrolyte (0.72 mm thick), (La 0.6 Sr 0.4 )(Co 0.2 Fe 0.8 )O 3―δ cathode, and Ni―Ce 0.9 Gd 0.1 O 1.95―δ anode, good performance with the maximum power density of ca. 0.25 W cm ―2 was obtained at 1073 K. In addition, this electrolyte also had high compatibility with these conventional mixed conducting electrodes, according to an analysis near the electrode/electrolyte interfaces after the fuel cell test.

Porous glasses with the surface area of ≈300 m2/g were prepared utilizing the spinodal-type phase separation of Al2O3-doped Na2O–B2O3–SiO2 glasses. The proton conductivity under humidified conditions and their relations to the amount of doped Al2O3 were investigated. The proton conductivity of the glass doped with 2 mol % of Al2O3 was about 6 times higher than that of the undoped glass. Fourier transform infrared (FT–IR) measurements revealed that the absorption by the strongly hydrogen-bonded OH groups increased with increasing the amount of Al2O3. Bond overlap populations (BOPs), which are directly related to the strength of the covalent bond, between the surface OH groups and an absorbed water molecule were calculated based on a first-principles theory (DVXα). The BOP values between O and H of the surface OH groups decreased by the Al2O3 doping. Substitution of Si atoms of the Si–O–Si silica networks with Al atoms, and formation of the Al–OH–Si bonds effectively improved the proton conductivity under humidified conditions.

On the basis of experimental data on the piezoelectric pinpoint composition of ceramics of the ternary system Pb(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3 (PMNZT), which we investigated in our previous report, epitaxial PbMg0.047Nb0.095Zr0.416Ti0.442O3 thick films with thicknesses ranging from 0.4 to 1.9 m were fabricated on Pt(100)/MgO(100) substrates by metalorganic decomposition. The film- thickness dependence on the structural and electrical properties (dielectric, piezoelectric and ferroelectric properties) was investigated. All PMNZT films exhibited a highly uniform (001) orientation, regardless of the film thickness. The cross-sectional transmission electron microscope micrographs and all the physical data suggest that high-density PMNZT thick films with a thickness  1.0 m can be expected to function as highly electrically insulating capacitors with high potential for piezo- and ferroelectric applications.

After depositing amorphous (Bi0.5La0.5)(Ni0.5Ti0.5)O3 (BLNT) films on BLNT seed layer/Pt(100)/ MgO(100) substrates by room-temperature sputtering, the crystallization of the perovskite-struc- tured films has been tried by hot isostatic pressing (HIP). The samples with a single-phase perovskite structure HIP-treated at 800°C for 1 h under gas pressures of 0.51.0 MPa showed good crystallinity of  = 0.960.98 without accompanying the precipitation of the secondary phase. It was confirmed that a large root mean square roughness value of 44.2 nm for the sample HIP-treated at 800°C for 1 h under gas pressure of 0.1 MPa is due to innumerable Bi4Ti3O12-like rod-shaped grains precipitated in the film surface, based on atomic force microscopy. It is shown that the BLNT sample HIP-treated at 800°C for 1 h under gas pressure of 1.0 MPa exhibits the best hysteresis loop shape with a remanent polarization of Pr = 5 C/cm2 and a coercive field of Ec = 150 kV/cm of the six.

Titanate nanosheet thick films were prepared on indium-tin oxide (ITO)-coated glass substrates by electrophoretic deposition. Three types of sols with different preparation procedures and pH values were prepared. In the case of titanate nanosheet films prepared from a sol with pH=7.0, surface of the films was flat and nanosheets which deposited on substrates were uniformly dense. Titanate nanosheet thick film deposited from the sol using dimethyl ethanol amine for the exfoliation showed a high photocatalytic activity due to the high crystallinity

Porous glasses with 4 nm diameter pores were prepared utilizing a spinodal-type phase separation of Na2O−B2O3−SiO2 glass, and the surface was modified by using mercaptoalkyltrimethoxysilane with different alkyl chain length ((CH3O)3Si(CH2)n-SH, n = 1, 3, 6, 10). The thiol groups (−SH) were oxidized with H2O2 to obtain −SO3H groups. The amount of the introduced silane coupling agents and the reactivity with H2O2 inside the nanopores drastically changed by changing the alkyl chain length (n). The molecular structures, charge distributions, bond overlap populations (BOP) between Si and alkyl chains, as well as net charges of thiol groups were calculated based on a density functional theory and a first-principle theory (DVXα). The charge distribution calculations suggest that oxygen atoms on pores affect significantly for both the net charge of S and BOP, and the BOP values were directly related with the in situ oxidation reactivity of silane coupling agents. The porous glasses modified with the silane coupli...

An inorganic–organic nanohybrid particle with a two-dimensional chain structure, diphenylsiloxane-silica (Ph2SiO–SiO2), was prepared by sol–gel process using diphenyldiethoxysilane (DPDES) and tetraethoxysilane (TEOS), and a high proton conducting polymer of poly(2-acrylamido-2-methyl-1-propane sulfonic acid) (PAMPS) was deposited on the Ph2SiO–SiO2 particles via layer-by-layer assembly. A flexible sheet-like electrolyte was successfully obtained from the resulting PAMPS-deposited particles by pressing. The proton conductivity of the sheet prepared using unmodified Ph2SiO–SiO2 particles was lower than 10−9 S/cm at 80°C. On the other hand, the PAMPS-deposited samples showed proton conductivities ∼7 orders of magnitude higher than those of the sample prepared using unmodified particles, and their conductivity reached about 1 × 10−2 S/cm at 80°C and 80% relative humidity. This is ascribed to the PAMPS layer being concentrated at the particle interfaces, which percolated throughout the monolithic sample.

A flip-flop-type hydrophobic coating film consisting of oppositely charged poly(allylamine hydrochloride) (PAH) and a perfluorosulfonate ionomer (Nation) ultrathin layers was prepared via layer-by-layer (LbL) assembly. The thickness of a Nafion layer was estimated to be 6.7 nm from the amount of deposited Nafion. The PAH/Nafion multilayers are optically transparent in UV-Vis region from 300 to 800 nm, and extremely small amount of Nafion was used for the coating (approximately 1.1 microg/cm2). The contact angle for water droplet of the PAH/Nafion multilayers was approximately 105 degrees. On the other hand, the contact angle for water droplet decreased rapidly from 105 degrees to approximately 85 degrees after being kept in closed vessel (approximately 100% of relative humidity) for 90 min. (approximatley 100% of relative humidity) for 15 h. The PAH/Nafion multilayer again showed hydrophobicity with the contact angle of 102 degrees after being dried at 125 degrees C for 30 min. PAH/Nafion multilayers obtained are hydrophobic in air and hydrophilic in water, namely flip-flop-type amphiphilic coating films.

An inorganic–organic hybrid of phenylsilsesquioxane-silica (PhSiO 3/2 –SiO 2 ) nanoparticle was prepared by sol–gel process, and a high proton-conducting electrolyte was synthesized by surface-sulfonation of phenyl groups of the particles. Chlorosulfonic acid was used as a sulfonation agent. The PhSiO 3/2 –SiO 2 particles are chemically stable as well as flexible. The proton conductivity of the pelletized sample reached about 10 − 2 S/cm at 80 °C and 80% relative humidity (RH). The open circuit voltage (OCV) of the single cell prepared using the pelletized sample as an electrolyte for a H 2 -air fuel cell increased with increasing the RH of the cell. The maximum power density of ~ 40 mW/cm 2 and OCV of 0.9 V was obtained at 80 °C and 95% RH.

Cesium salts of Cs 2 SO 4 , Cs 2 CO 3 and CsHSO 4 and phosphotungstic acid (H 3 PW 12 O 40 ·6H 2 O:WPA·6H 2 O) were mechanically milled to synthesize chemically durable WPA composites. The X-ray diffraction patterns of composites suggested the formation of partially substituted Cs x H 3 − x PW 12 O 40 composites after milling at 720 rpm for 10 min. Proton conductivities under both humidified and dry conditions of the resultant composites markedly improved. The proton conductivities strongly depended on the type of cesium salt. The hydrogen bonding distance L in the frame structures of the composites was estimated from the 1 H-isotropic chemical shift. The proton conductivities in dry conditions of WPA·6H 2 O and the composites were strongly represented to L .

Porous glass-ceramics with a skeleton of γ-Ti(HPO 4 ) 2 ·2H 2 O crystals are derived from glasses in the Li 2 O–CaO–TiO 2 –P 2 O 5 system by utilizing spinodal-type phase separation, crystallization and subsequent acid treatment of the resulting glass-ceramics. The glass-ceramics have both micro-sized (1–2 μm) and nano-sized pores (5–30 nm), and they adsorb polar molecules. In the present work, porous TiO 2 layers of 200–500 nm thickness were successfully deposited on the surfaces of the glass-ceramics by an infiltration of Ti(OCH(CH 3 ) 2 ) 4 and water vapor treatment at 100 °C under 100% relative humidity. X-ray diffractometry and laser Raman spectroscopy revealed the formation of anatase crystals. The resulting anatase-modified porous glass-ceramics show high activities for NH 3 adsorption as well as for photodecomposition of the adsorbed NH 3 molecules.

Solid-state potentiometric thin film hydrogen gas sensors were successfully fabricated using a sol-gel-derived high proton-conducting P2O5-SiO2 glass films. Manganese oxide thin film coated on an indium tin oxide (ITO)-coated glass substrate was used for reference electrode. The sensor exhibited high speed responsibility within 10 s and 120 s at 30 oC and -30oC, respectively, for 1 vol.% hydrogen gas. A linear relationship between the electromotive force (EMF) and the logarithmic hydrogen concentration of 0.1~1 vol.% was obtained in the temperature ranging from -30 to 30 oC. The sensing mechanism was also discussed to improve the sensitivity and sensing speed against low H2 concentration at low temperatures.

Thermally and chemically stable phenylsilsesquioxane (PhSiO 3/2 ) particles were prepared by sol–gel process, and ultra-thin layers of oppositely charged poly(diallyldimethylammonium chloride) (PDDA) and dodecatungstophosphoric acid (WPA) were alternately deposited on the negative-charged PhSiO 3/2 particles via layer-by-layer assembly technique. Hygroscopic property of WPA was remarkably reduced owing to the formation of PDDA/WPA complex. The amount of WPA adsorbed on PhSiO 3/2 particles was estimated to be ∼ 0.03 (g/g PhSiO 3/2 ). Transparent and monolithic pellet can be obtained from the resultant core–shell particles by pressing. Proton conductivity of WPA-deposited samples increased about 4 orders of magnitude compared with unmodified samples, and reached to about 10 − 4 S/cm at 80 °C and 80% relative humidity.

Thermally and chemically stable proton conductors were prepared via surface-sulfonation of sol–gel-derived phenylsilsesquioxane–methylsilsesquioxane (PhSiO3/2–MeSiO3/2) particles in a range from 250 to 650 nm in diameter. MeSiO3/2 component was indispensable to improve the chemical durability against sulfonation solvent. Proton conductivity of the pelletized samples prepared using the sulfonated PhSiO3/2–MeSiO3/2 particles increased linearly with increasing the ion exchange capacity (IEC) of the particles. The mobility (μ) of proton was calculated to be 0.3 × 10− 4 cm2/V s. Porous PhSiO3/2–MeSiO3/2 particles prepared using a cationic surfactant of cetyltrimethylammonium bromide (CTAB) as a template of pores showed higher both IEC and water uptake, leading to an increase in proton conductivity to ∼ 10− 2 S/cm at 80 °C and 80% relative humidity.

Cs-containing salt or solid acid (Cs2CO3 or CsHSO4) and dodecatungstophosphoric acid (H3PW12O40·nH2O:WPA·nH2O) were mechanically milled aiming at synthesis of chemically durable WPA salts and their composites. In the Cs2CO3–WPA system, XRD patterns suggested the formation of partially substituted CsxH3 − xPW12O40 after milling. After the formation of CsxH3 − xPW12O40, chemical durability of the Cs2CO3–WPA composites markedly improved. The proton conductivity of the Cs2CO3–WPA composites containing CsxH3 − xPW12O40 increased with an increase in the WPA content. CsxH3 − xPW12O40 obtained from 40Cs2CO3·60(WPA·6H2O) by milling showed 2 × 10− 2 S cm− 1 at 60 °C and 90% relative humidity (R.H.), while the conductivity drastically decreased under a dry N2 atmosphere. In the CsHSO4–WPA system, the formation of CsxH3 − xPW12O40 was not confirmed from XRD patterns after mechanical milling, whereas the water solubility of the CsHSO4–WPA composites decreased. The conductivity of 95CsHSO4·5(WPA·6H2O) with milling increased with increasing humidity and became 1 × 10− 2 S cm− 1 at 60 °C and 90% R.H. The mechanically milled 95CsHSO4·5(WPA·6H2O) composite exhibited a steep increase in conductivity at around 130 °C on heating even in a dry N2 atmosphere and the conductivity reached about 10− 3 S cm− 1 at 150 °C, which should be ascribed to the superprotonic phase transition of CsHSO4 in the composite.