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Porous alumina bodies, intended for use as heat-insulating refractory materials, were fabricated by a high-temperature evaporation method and characterized. A series of flux systems was used by adding a third component to Na2O–B2O3 glass in addition to boric acid and sodium carbonate. When SiO2 was added as the third component, the primary alumina particles grew anisotropically, forming a plate-like shape, and the house-of-cards structure was self-organized. The anisotropic growth of alumina platelets was promoted by the solid solution of Si4+ ions in the flux on the α-Al2O3 surface. Furthermore, the bonding between the alumina platelets was strengthened by the high-SiO2-concentration flux. Our typical alumina body had a porosity of 71.5%, a compressive strength of 3.7 MPa, a shrinkage rate of 2.6% when reheated at 1700 °C, and a thermal conductivity of 0.24 W m−1•K−1 at 1000 °C. Thus, the present alumina bodies are expected to find application as high-performance heat-insulating refractory materials.

Porous alumina bodies are expected to find application as refractory materials to reduce energy consumption during the manufacture of inorganic products. The porosity of such bodies can be efficiently increased by using alumina platelets to form a so-called “house-of-cards” structure. This technique was employed in the present study, together with a gelatin-sol (as binder) and freeze-drying. The porosity, compressive strength, and thermal conductivity of a porous alumina body made in this manner and heat-treated at 1600°C were 80.2%, 1.7 MPa, and 0.94 W/m−1∙K−1, respectively. These physicochemical properties would allow this alumina to be used as a thermal insulation refractory clinker material.

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A novel lightweight adiabatic refractory material combining alkaline earth silicate (AES) fiber board and SiC particles was fabricated by immersing the AES fiber board into a slurry consisting of SiC particles with a median diameter of 1.2 μm and 13% silica-sol as an inorganic binder. When the composite was heated at 1400 °C for 8 h, the fired shrinkage of the composite was almost 0%, while that of untreated AES fiber board was 3.2%. The compressive strength of the composite heated at 1300 °C for 8 h was greatly improved to 0.95 MPa, 4.6 times that of untreated AES board. The corrosion resistance of the composite to a mixture of iron (II) oxide and sodium carbonate at 1400 °C was improved by more than 40% compared to that of untreated AES fiber board.

Proton concentration of simple binary metaphosphate glasses under a pseudo fuel cell anode reaction was investigated at 350 °C by utilizing an in-situ Fourier transform infrared (FTIR) spectroscopy. Proton concentrations of both MO·P2O5 (M = Ca, Sr) glasses increase under humidified hydrogen atmosphere and applying a direct current voltage between platinum electrodes, suggesting that a proton infiltration occurs into these glasses. Compared with CaO·P2O5 glass, SrO·P2O5 glass shows higher proton concentration at the same period of time. Structure of glass network was investigated using synchrotron radiation X-ray diffraction, 31P magic-angle spinning nuclear magnetic resonance (MAS NMR) and FTIR (KBr method) spectroscopies. Strength of the cross-linking between phosphate chains via M2+ metal cations is correlated for the proton infiltration into phosphate glasses.

Porous alumina aggregates were prepared for use in adiabatic refractories via a high-temperature evaporation method. The mechanical and thermal characteristics of the porous alumina bodies and of castable refractories made using the alumina as an aggregate were investigated. Specimens were produced by adding boron hydroxide, sodium carbonate and water glass to aluminum hydroxide powder compacts in varying proportions, followed by heating at 1700 °C for 1 h in a reducing atmosphere to form porous alumina bodies. During heating, these additives formed a Na2O-B2O3-SiO2 liquid glass phase that promoted the growth of alumina platelets. These platelets subsequently formed a “house of cards” structure. The porosity and compressive strength of the resulting porous alumina were 69.8% and 1.8 MPa, while the thermal conductivity of this material was 0.23 W m−1·K−1 at 1000 °C. A castable incorporating the porous alumina aggregate exhibited improved mechanical strength, higher heat resistance and greater FeO corrosion resistance than a sample made using a CA6 (CaO∙6Al2O3) aggregate. The porous alumina castable exhibited similar thermal conductivity to that of the CA6 castable at high temperatures, with a value of 0.85 W m−1·K−1 at 1400 °C. Hence, the porous alumina aggregate fabricated in this study can be expected to have practical applications.

International audience; Superhydrophobic membranes composed of an organic-inorganic hybrid polymer, namely polycarbosilane (PCS) with Mw of 4-8.9 ×10 3 , were formed on a mesoporous γ-Al 2O3-modified α-Al2O3 porous support. Under dry condition at 50 • C, the supported PCS membranes exhibited H2 permeance of 1.1-1.6 ×10 −6 mol⋅m −2 ⋅s −1 ⋅Pa −1 and H2/N2 selectivity of 9.7-12.6 together with unique H2/He selectivity of 1.4-1.6. Even under saturated humidity at 50 • C, H2 permeance remained at 7.7 ×10 −8 mol −1 m −2 s −1 Pa −1 with improved H2/N2 selectivity of 26. Moreover, when the measurements were performed using a H2-N2 (2:1) mixed feed gas as a simulated syngas produced by novel solar hydrogen production systems, the H2 permeance almost unchanged, while the N2 permeance was below the limit of detection. These results revealed a great potential of PCSs to develop novel H 2selective membranes for purifying solar hydrogen under high-humidity conditions around 50 • C. Further study on the gas permeation behaviors of He, H2 and N2 suggested that the enhanced H2/N2 selectivity under the highhumidity conditions could be explained by the synergistic effect of preferential H 2 permeation through the dense PCS network governed by the solid state diffusion mechanism and blockage of N 2 permeation through micropore channels within the PCS network by the permeate H2O-induced plugging at around the hetero interface between the superhydrophobic PCS and highly hydrophilic γ-Al 2O3.

International audience; This work highlights the first demonstration of a low-temperature in situ formation of Co nanocrystallites embedded within an amorphous silicon nitride matrix through careful control of the chemistry behind material design using perhydropolysilazane (PHPS) as a Si3N4 precursor further coordinated with CoCl2 and ammonia as a pyrolysis atmosphere. The Co nucleation was allowed to proceed at temperatures as low as 400 8C via thermal decomposition of Co2N pre-formed in situ by the reaction of CoCl2 with the Si centers of PHPS at the early stage of pyrolysis (220-350 8C).

This paper reports the relationship between the H2 chemisorption properties and reversible structural reorientation of the possible active sites around Al formed in situ within polymer-derived ceramics (PDCs) based on an amorphous silicon–aluminum–nitrogen (Si–Al–N) system. Al-modified polysilazane, as a ceramic precursor, was first pyrolyzed at 1000 °C under flowing ammonia to generate a Si–Al–N-based ceramic. XRD and HRTEM analyses confirmed the amorphous state of the titled ceramics. N2 adsorption–desorption isotherm measurements and HAADF-STEM observation of amorphous SiAlN indicated that Al-incorporation in the early step of the process led to the generation of micro/mesoporosity in the amorphous ceramic with nanopores of 1 to 4 nm in size. XPS and pyridine sorption infra-red spectroscopy analyses revealed the in situ formation of Lewis acidic Al sites within the amorphous Si–Al–N surface network. As a result, the Si–Al–N compound was highly moisture sensitive. Then, to investigate the intrinsic properties of the highly reactive Al sites, the Si–Al–N compound was pretreated at 400–800 °C under an inert atmosphere. Temperature-programmed-desorption (TPD)-mass spectroscopy analysis of the pre-treated sample after H2 treatment above 100 °C resulted in the detection of a broad H2 desorption peak at around 100 to 350 °C. The H2 desorption peak intensity apparently increased when H2 treatment was performed at 150 °C, and the activation energy for H2 desorption was determined to be 44 kJ mol−1. 27Al MAS NMR spectroscopic analysis for the pre-treated sample showed reversible local structure reorientation around reactive Al nuclei, and formation and deformation of 5-fold coordinated Al by H2 chemisorption and desorption, respectively. In addition, the CO2 hydrogenation reaction on the pre-treated sample was successfully demonstrated by TPD measurements after exposure to a mixed gas of H2 and CO2 with a 4 : 1 ratio at 400 °C. These results suggest that highly distorted 4-fold coordinated Al serves as a Lewis acid–base Al–N pair site to promote H2 chemisorption at T > 100 °C followed by formation of a hydrogenated 5-coordinated Al unit where CO2 hydrogenation proceeds at T = 400 °C.

This work highlights the first demonstration of a low-temperature in situ formation of Co nanocrystallites embedded within an amorphous silicon nitride matrix through careful control of the chemistry behind material design using perhydropolysilazane (PHPS) as a Si3N4 precursor further coordinated with CoCl2 and ammonia as a pyrolysis atmosphere. The Co nucleation was allowed to proceed at temperatures as low as 400 °C via thermal decomposition of Co2N pre-formed in situ by the reaction of CoCl2 with the Si centers of PHPS at the early stage of pyrolysis (220-350 °C).

International audience; The effect of the local structure of Co-doped amorphous silica on the hydrogen transport property was studied with the aim to improve the high-temperature hydrogen-permselectivity of microporous amorphous silica-based membranes. Co-Doped silica materials with measured Co/Si atomic ratios ranging from 0.01 to 0.18 were successfully synthesized through the polymer-derived ceramic (PDC) route. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) analyses confirmed the amorphous state of the polymer-derived Co-doped silica, while both X-ray photoelectron and Fourier transform infrared (FT-IR) spectroscopy analyses revealed that the divalent Co cation (Co 2+) modified the matrix amorphous silica network to form hydrogen-bonded silanol. After dehydration treatment at 500°C in argon, hydrogen (H)/deuterium (D) isotope exchange behavior on the surface silanol groups (Si-OH/OD conversion) of the polymer-derived non-doped and Co-doped amorphous silica was in situ monitored by measuring diffuse reflectance infrared Fourier transform (DRIFT) spectra at 500°C. The self-diffusion coefficient for OH/OD conversion of free silanol groups of non-doped silica was 6.1 × 10 −15 m 2 s −1 , while that on the hydrogen bonded Si-OH was found to reach 15.6 × 10 −15 m 2 s −1 by Co-doping at the measured Co/Si atomic ratio of 0.05.The effect of the amount of Co 2+ doping on the hydrogen transport property was further studied by scanning transmission electron microscopy and electron energy loss spectroscopy (STEM-EELS) analyses, and it was suggested that a rather small amount of Co-doping, i.e. Co/Si atomic ratio of 0.05 was effective for enhancing high-temperature hydrogen permeance through microporous amorphous silica-based membranes.

This paper reports on a unique reversible reducing and oxidizing (redox) property of Co(III) in Co-doped amorphous SiO2/&gamma, Al2O3 composites. The Fenton reaction during the H2O2-catalyzed sol&ndash, gel synthesis utilized in this study lead to the partial formation of Co(III) in addition to Co(II) within the composites. High-resolution transmission electron microscopy (HRTEM) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) analyses for the composite powder sample with a composition of Al:Si:Co = 85:10:5 showed the amorphous state of the Co-doped SiO2 that modified &gamma, Al2O3 nanocrystalline surfaces. In situ X-ray absorption fine structure (XAFS) spectroscopic analysis suggested reversible redox reactions of Co species in the composite powder sample during heat-treatment under H2 at 500 &deg, C followed by subsequent cooling to RT under Ar. Further analyses by in situ IR spectroscopy combined with cyclic temperature programmed reduction/desorption (TPR/TPD) measurements and X-ray photoelectron spectroscopic (XPS) analysis revealed that the alternating Co(III)/(II) redox reactions were associated with OH formation (hydrogenation)-deformation (dehydrogenation) of the amorphous aluminosilicate matrix formed in situ at the SiO2/&gamma, Al2O3 hetero interface, and the redox reactions were governed by the H2 partial pressure at 250&ndash, 500 &deg, C. As a result, a supported mesoporous &gamma, Al2O3/Co-doped amorphous SiO2/mesoporous &gamma, Al2O3 three-layered composite membrane exhibited an H2-triggered chemical valve property: mesopores under H2 flow (open) and micropores under He flow (closure) at 300&ndash, C.

Solar hydrogen production via the photoelectrochemical water-splitting reaction is attractive as one of the environmental-friendly approaches for producing H2. Since the reaction simultaneously generates H2 and O2, this method requires immediate H2 recovery from the syngas including O2 under high-humidity conditions around 50 &deg, C. In this study, a supported mesoporous &gamma, Al2O3 membrane was modified with allyl-hydrido-polycarbosilane as a preceramic polymer and subsequently heat-treated in Ar to deliver a ternary SiCH organic&ndash, inorganic hybrid/&gamma, Al2O3 composite membrane. Relations between the polymer/hybrid conversion temperature, hydrophobicity, and H2 affinity of the polymer-derived SiCH hybrids were studied to functionalize the composite membranes as H2-selective under saturated water vapor partial pressure at 50 &deg, C. As a result, the composite membranes synthesized at temperatures as low as 300&ndash, 500 &deg, C showed a H2 permeance of 1.0&ndash, 4.3 &times, 10&minus, 7 mol m&minus, 2 s&minus, 1 Pa&minus, 1 with a H2/N2 selectivity of 6.0&ndash, 11.3 under a mixed H2-N2 (2:1) feed gas flow. Further modification by the 120 &deg, C-melt impregnation of low molecular weight polycarbosilane successfully improved the H2-permselectivity of the 500 &deg, C-synthesized composite membrane by maintaining the H2 permeance combined with improved H2/N2 selectivity as 3.5 &times, 1 with 36. These results revealed a great potential of the polymer-derived SiCH hybrids as novel hydrophobic membranes for purification of solar hydrogen.

Refractory ceramic fiber (RCF) boards are widely used because their insulating properties allow them to reduce energy consumption during high-temperature industrial processes. However, since conventional RCF boards undergo a linear shrinkage of more than 3% above 1300 °C, furnace lining parts, such as the ceiling, wall, and bottom made of RCF board easily become fragile. In order to suppress the shrinkage of the RCF board above 1300 °C, the RCF board surface was coated with a silica sol containing several types of alumina particles. When a RCF board coated with a silica sol slurry containing 50 mass% alumina platelets was heated at 1400 °C for 8 h, the linear shrinkage of the RCF board decreased from 4.3% to 1.5%. This, in turn, improved the heat resistance of the RCF board up to 1400 °C.

Ag+ ion conducting xAg2O·(30 − x)Al2O3·55P2O5·15SiO2 (x = 20 and 25, mol%) glasses were prepared using a conventional melting method, and structures and glass transition temperature were investigated using X-ray diffraction (XRD), differential scanning calorimetry (DSC), ultraviolet-visible (UV–Vis) and Fourier transform infrared (FTIR) spectroscopies. Impedance measurement reveals the glass with x = 25 shows a high Ag+ ion conductivity of 3 × 10−3 S cm−1 at 300 °C. Ag+ ion emission measurement was carried out using a sharpened glass fiber tip less than 1 μm, and the emission current was successfully observed above the acceleration voltage of 4 kV at 300 °C and 4 × 10−5 Pa. Silver particles were confirmed on the target substrate after the Ag+ emission measurement. A good linear correlation is obtained between log(current) and square root of the voltage, suggesting the emission of Ag+ ion from the tip of glass fiber is expressed by Schottky model. In this ion emission method, a plasma is not required for ionization and the ion emission mechanism is simple, and various ion conducting glasses can be applied for the emitter of ion gun.

For steel-making refractories, porous alumina bodies fabricated by the evaporation of chemical impurities at high temperatures was studied. Boron hydroxide and sodium carbonate were added in different proportions as impurities into the starting aluminum hydroxide powder compacts, which were heated at various temperatures for 1 h to form porous alumina bodies. During heating, the borate compounds that reacted with sodium seems to be formed in the liquid phase, so that all alumina particles were able to grow into platelets. Although the sodium inside the compacts was completely evaporated by 1400 °C, the boron melt was maintained above 1400 °C. Hence, alumina platelets grew with a card-house structure, which preserved the high porosity of the alumina body. After heating at 1600 °C for 1 h, the remaining boron oxide was completely evaporated and sintering between the alumina particles began to decrease the porosity. The compressive strength and porosity of the alumina bodies obtained by heating at 1700 °C for 1 h were 0.8 MPa and 64%, respectively. It is expected that the resulting porous alumina bodies can be used as castable porous clinkers.

Commercially available polycarbosilane has been chemically modified with primary and secondary amino silane derivatives in order to provide amine-functionalized polycarbosilane as hydrophobic solid sorbent capable of reversibly capturing CO 2 from flue gas streams. CO 2 uptake by the samples was investigated at the molecular level using thermogravimetric analysis under CO 2 atmosphere, in situ DRIFTS analysis, and CO 2 sorption isotherm. The reaction paths and sorption mechanisms were examined by comparing with the CO 2 adsorbing behaviors previously studied for amine-functionalized SiO 2 , and proven to be related to the presence of adsorbed water, as well as the nature of the grafted amino silanes. With effective CO 2 adsorption rate, regeneration capacity at 40–50 °C, and lesser sensitivity to moist due to its hydrophobic Si-C backbone, secondary amine-functionalized polycarbosilane hybrids have potential applications in membrane gas separation through facilitated transport of CO 2 .

In the final exhaust chimney of oil refinery plants, new refractory materials based on geopolymers that have high resistivity to hot sulfuric acid solution, and thus long life-times, are in high demand. In order to investigate the resistance to hot sulfuric acid, a hardened cylindrical fly-ash-based geopolymer paste product (15-mm diameter, 40-mm height) with an average compressive strength of 24 MPa was placed into a Teflon vessel filled with 1.0-M sulfuric acid solution. After heating at 60–220 °C for a fixed duration, the microstructure and compressive strength characteristics were investigated. The geopolymer paste product had no damage after treatment with hot sulfuric acid at various temperatures, although hardened ordinary Portland cement bodies swelled and surface parts broke away after exposure to the same sulfuric acid solution. After the geopolymer paste product was immersed in sulfuric acid at 180 °C for 192 h, the average compressive strength was 25 MPa. With hot sulfuric acid solution treatment, natroalunite (NaAl 3 (SO 4 ) 2 (OH) 6 ) formed inside the geopolymer product as a novel crystal phase, which led to an increase in compressive strength by the accompanying densification. The fly-ash-based geopolymer paste product is a candidate material for chimney refractories of oil refinery plants.

A high proton-conducting P2O5-SiO2 nanoporous glass rod was prepared via sol–gel technique, and its tip was sharpened by a meniscus-etching method. The glass rod shows proton conductivity of 1 × 10−3 at room temperature after absorption of water molecules. A palm-sized proton gun was prepared by utilizing the glass rod as a H+ emitter. A high voltage (~2.5 kV) was applied between the tip of glass rod and an extraction electrode, and a high ionic current was successfully observed even under non-vacuum atmosphere at room temperature. Protonation reaction for polyaniline was confirmed from the structural changes of C=N in quinone to protonated C–N+. New applications of proton implantation will be expected especially in bioscience and medical technology.

To date, there have been few reports of the fabrication of hardened, pure calcium carbonate specimens beginning from the powder state. In this study, hardened calcium carbonate bodies exhibiting high densities and compressive strengths were produced using a warm press method. The warm press conditions consisted of temperatures from 150 to 280 °C and a uniaxial pressure of 240 MPa, applied for durations of 10–180 min to powder compacts composed of pure calcium carbonate powder or powder mixed with 10% water (by mass). Heating at 150 °C and 240 MPa for 180 min with 10% water generated a relative density of 87% and an average compressive strength of 40 MPa. The added water was found to play an important role to promote a solution-precipitation process inside the calcium powder compact, allowing low temperature sintering to form dense calcium carbonate.

Silsesquioxane (SQ) derivatives possessing intramolecular H2C = CH- groups and Si-H groups were designed as precursors for ternary silicon oxycarbide (SiOC). By using R-Si(OMe)3, H-Si(OEt)3 and (H-Si(Me)2)2O as starting compounds, SQ derivatives of VH-SQ (R = vinyl) and St-H-SQ (R = stylyl) were successfully synthesized through the conventional sol-gel route. Simultaneous thermogravimetric and mass spectroscopic analyses up to 1000 &deg, C revealed that in situ cross-linking via hydrosilylation and demethanation of VH-SQ suppressed the evolution of gaseous hydrocarbon species to afford amorphous SiOC having a composition close to the desired stoichiometric SiO2(1&minus, x)Cx (x = ca. 0.3) with a high yield. The effect of carbon content on the phase separation and crystallization of the SQ-derived amorphous SiOC was studied by several spectroscopic analyses and TEM observation. The results were discussed aiming to develop a novel polymer-derived ceramics (PDCs) route for in situ formation of binary &beta, SiC-amorphous SiO2 nanocomposites with enhanced thermal and mechanical stability.

A highly porous alumina body was fabricated by heating a green clinker body consisting of platelets and yeast fungi as a pore forming agent. Four kinds of alumina platelets were used. When green clinker bodies of platelet aggregates (A11) with 10 and 30 mass% of yeast fungi were heated at 1500 °C for 2 h, their porosities reached 72% and 78%, respectively. In contrast, when the green clinker bodies composed of platelets with an average size of 10 µm and an aspect ratio of 25–30 (SERATH①), and 20 mass% of yeast fungi were heated at 1400 °C for 2 h, the porosity of the resultant porous alumina body was also approximately 72%. However, the room temperature thermal conductivities of the porous alumina bodies with 72% porosity derived from A11 and SERATH① were 0.86 and 0.50 W m −1 K −1 , respectively. The decrease in the thermal conductivity of the porous alumina body produced from SERATH① is caused by the long path route for heat transfer.

So far dense calcium hydroxide body (slaked lime plaster) with high mechanical strength has not been fabricated yet. In this study, novel method was tried in order to fabricate the dense calcium hydroxide body. As a result, a calcium hydroxide body with a dense and high mechanical strength was obtained. Pure calcium hydroxide powder was placed in a cylindrical steel mold 15 mm in diameter, and then simultaneously pressed uniaxially at 60–240 MPa and heated to 100–250 °C for various lengths of time. This compacting process is referred to as a warm press. After warm pressing, hardened compacts composed of pure calcium hydroxide were obtained. Increasing both the applied uniaxial pressure and the heating temperature increased the compressive strength of the resulting hardened compacts. Furthermore, increasing the time spent in warm press conditions also increased the compressive strength of the hardened compacts. However, these increases diminished over time, and the compressive strength reached a nearly constant value after approximately 90 min. When the uniaxial pressure, heating temperature, and duration were 240 MPa, 250 °C and 90 min, respectively, the compressive strength of the resulting hardened compact was 57 MPa. Finally, in this study, the phase stability relationship between calcium hydroxide and calcium carbonate is discussed on the basis of chemical thermodynamics. This warm press technique for the fabrication of dense hydroxide ceramics should help clarify the formation mechanism of natural hydroxide minerals.

F− ion conducting 60ZrF4·30BaF2·LaF3·2AlF3·7CsF (mol%) with outer mol% of xIn2O3 (x = 0, 5, 10) glasses were prepared using a conventional melting method, and structure and glass transition behavior were investigated using X-ray diffraction (XRD), differential scanning calorimetry (DSC) and Raman spectroscopy. Impedance measurement reveals the glass with x = 10 shows F− ion conductivity of 5 × 10−6 S/cm at 200 °C. F− ion emission measurement was carried out for the first time using a sharpened glass tip, and the emission current was observed above the acceleration voltage of 2.5 kV at 200 °C and 1 × 10−4 Pa. After the F− emission measurement, fluorine was detected on a Cu target substrate by using an energy-dispersive X-ray spectrometer. However, a small amount of glass component was also detected on the target substrate, suggesting the glass tip may also decompose. A good linear correlation is obtained between log(current) and the square root of the voltage, suggesting the emission current of F− ion from the tip of glass is expressed by Schottky model.

Excellent hydrophobicity of polycarbosilane (PCS)-derived Si–C–H organic-inorganic hybrid was characterized by measuring water vapor adsorption-desorption isotherms at room temperature. Modification with the PCS-derived Si–C–H successfully improved hydrostability in terms of stable gas permeation property of sol gel-derived hydrophilic mesoporous γ-Al2O3 membrane formed on a macroporous α-Al2O3 support: even under saturated water vapor partial pressure at 50 °C, the modified membrane exhibited high gas permeances of helium, hydrogen and nitrogen ranging from 1.2 to 3.0 × 10−6 mol m−2 s−1·Pa−1. The improved gas permeability under the humid condition achieved for the Si–C–H-modified mesoporous γ-Al2O3 membrane in this study was discussed aiming to prepare a gas permeable hydrophobic mesoporous intermediate layer essential for developing H2-permselective ceramic-based multilayered composite membranes with applications to novel solar hydrogen production system.

Polyalkoxysilsesquiazanes ([ROSi(NH)1.5]n, ROSZ, R = Et, nPr, iPr, nBu, sBu, nHex, sHex, cHex, decahydronaphthyl (DHNp)) were synthesized by ammonolysis at −78 °C of alkoxytrichlorosilane (ROSiCl3), which was isolated by distillation as a reaction product of SiCl4 and ROH. The simultaneous thermogravimetric and mass spectrometry analyses of the ROSZs under helium revealed a common decomposition reaction, the cleavage of the oxygen–carbon bond of the RO group to evolve alkene as a main gaseous species formed in-situ, leading to the formation of microporous amorphous Si–O–N at 550 °C to 800 °C. The microporosity in terms of the peak of the pore size distribution curve located within the micropore size range (

Geopolymers made from metakaolin and an alkali solution were immersed in a 0.1 mol/L copper chloride solution for 24 h. After the solution treatment, the surface color of the geopolymers changed to green to a depth of 900 μm due to ion exchange with copper ions. To evaluate the antimicrobial activity of the colored portion of the geopolymer, it was ground into 500 μm particles and mixed with a 10:1 mass ratio of oyster mushroom (a wood-rot fungus) and sawtooth oak sawdust. This mixture was placed in a glass bottle at room temperature and 100% relative humidity for one week. The results revealed that the geopolymer ion-exchanged with copper ions suppressed the growth of oyster mushrooms in sawtooth oak sawdust, indicating antimicrobial activity.

Perhydropolysilazane (PHPS) was chemically modified with various alcohols (ROH, R CH 3 , n-C 3 H 7 , n-C 5 H 11 , n-C 10 H 21, CH 3 OC 2 H 4 or C 2 H 5 OC 2 H 4 ) at a PHPS (Si basis) to ROH molar ratio of 3:1. The resulting alkoxy group-functionalized PHPS materials were successfully converted to amorphous silica-based inorganic-organic hybrids by exposure to vapour from aqueous ammonia at room temperature. Nitrogen sorption analyses demonstrated that these hybrids contained a small quantity of micropores less than 0.9 nm in size along with mesopores having a relatively wide pore size distribution (PSD). The PSD plots of the CH 3 O, CH 3 OC 2 H 4 O and C 2 H 5 OC 2 H 4 O functionalized samples had especially wide distributions extending to more than 50 nm. Water sorption tests showed that the hybrid synthesized from PHPS modified with n-C 10 H 21 OH was stable and did not exhibit significant capillary condensation even at higher levels of humidity above P/P o = 0.6. As a result, the number of water molecules adsorbed per square nanometre of the sample surface area at P/P o = 0.95 was as low as 4 mol nm −2 . The relatively low density of hydrophilic silanol groups (0.21), smaller average mesopore size (3.3 nm) and longer hydrophobic alkyl chain of the n-C 10 H 21 O moiety were all thought to contribute to improving the hydrophobicity of this hybrid. These results indicate that n-C 10 H 21 OH is a useful alcohol modifier for synthesizing amorphous silica-based inorganic-organic hybrid materials with improved hydrophobic properties through a polymer precursor route.

This paper describes a new approach to novel proton-conducting organic–inorganic nanohybrid materials by surface modification of a large amount of SiOH groups on nanoporous glass with silane coupling reagent containing double SH groups, based on pore surface analysis and first principle calculations.

H+ emission from the sharpening glass fiber was successfully observed. Here, ion current density and chemical functionalization via ion irradiation are presented.

A novel polyethoxysilsesquiazane ([EtOSi(NH)1.5]n, EtOSZ) was synthesized by ammonolysis at −78 °C of ethoxytrichlorosilane (EtOSiCl3), which was isolated by distillation as a reaction product of SiCl4 and EtOH. Attenuated total reflection-infra red (ATR-IR), 13C-, and 29Si-nuclear magnetic resonance (NMR) spectroscopic analyses of the ammonolysis product resulted in the detection of Si–NH–Si linkage and EtO group. The simultaneous thermogravimetric and mass spectrometry analyses of the EtOSZ under helium revealed cleavage of oxygen-carbon bond of the EtO group to evolve ethylene as a main gaseous species formed in-situ, which lead to the formation at 800 °C of quaternary amorphous Si–C–N with an extremely low carbon content (1.1 wt %) when compared to the theoretical EtOSZ (25.1 wt %). Subsequent heat treatment up to 1400 °C in N2 lead to the formation of X-ray amorphous ternary Si–O–N. Further heating to 1600 °C in N2 promoted crystallization and phase partitioning to afford Si2N2O nanocrystallites identified by the XRD and TEM analyses. The thermal stability up to 1400 °C of the amorphous state achieved for the ternary Si-O-N was further studied by chemical composition analysis, as well as X-ray photoelectron spectroscopy (XPS) and 29Si-NMR spectroscopic analyses, and the results were discussed aiming to develop a novel polymeric precursor for ternary amorphous Si–O–N ceramics with an enhanced thermal stability.

Surface defects of ZnO nanoparticles were induced via mechanical stressing using a Turbula shaker mixer and a planetary ball mill, and the possibilities for surface modification and functionalization of the ZnO nanoparticles were exemplified by sulfur doping of activated ZnO. Raman spectroscopy reveals that the formation of oxygen vacancies (VO) does not only occur under high stressing conditions in a planetary ball mill but even upon rather ‘mild stressing’ in the shaker mixer. The temporal evolution of the vacancy concentration in ZnO stressed under different conditions can be described by a model that accounts for stress number and vacancy diffusion with diffusion coefficients of VO of 3.7 × 10−21 m2 s−1 and 2.4 × 10−20 m2 s−1 for stressing in the shaker and the planetary ball mill, respectively. The thickness of the VO layer was estimated to be about 1 nm. Thiourea was mixed with defective ZnO particles, and then heated at various temperatures for sulfur-doping. A linear relationship between the amount of induced VO and the level of sulfur doping was found. Remarkably, mechanical activation is indispensable in order to control the level of sulfur doping quantitatively. High-angle annular dark field scanning transmission electron microscopy (HAADF STEM) observations with energy dispersive X-ray spectroscopy (EDX) analysis clearly revealed that the doped sulfur atoms are concentrated at the particle surface. Thus, ZnO (core)/ZnS (shell) structures are obtained easily via mechanochemical activation and subsequent thermal treatment.

An oxygen-excess-type lanthanum silicate (LSO) solid electrolyte with high chemical stability as well as high ion conductivity was developed by optimizing the chemical composition, La 9.333 + x (Si 6 − y Al y )O 26 + 1.5 x − 0.5 y . It was found that La 10 (Si 5.8 Al 0.2 )O 26.9 ( x = 0.667, y = 0.2) exhibited the highest conductivity among them, and addition of a small amount of iron was effective for the improvement of its chemical stability. The LSO specimen of x = 0.667 and y = 0.2 with iron addition (0.5 mol%) was chemically stable and had a conductivity of 5.6 × 10 − 2 S cm − 1 under air at 1073 K, while its electronic conductivity was less than 2.0 × 10 − 4 S cm − 1 at the same temperature. The oxygen tracer diffusion coefficient, D O * of this material was determined as 2.0 × 10 − 8 cm 2 s − 1 at 1073 K.

Nanoporous glasses and nanoporous thin films were prepared using sol–gel method, and proton conductivities in nanopores of sol–gel-derived porous glasses and thin films are overviewed in this paper. Proton motions inside nanopores were monitored by impedance and nuclear magnetic resonance (NMR) spectroscopies. The impedance data is correlated with the proton motion in bulk scale, whereas NMR data is correlated with that in nanometer scale, respectively. From the comparison of the activation energies obtained from impedance and NMR spectroscopies, percolation of proton conducting path and its relation to the amount of absorbed water molecules are shown. In the case of nanoporous thin films, directions of pores can be controlled by using cationic and non-ionic surfactants. Relationship between direction of pores and proton conductivity is discussed based on impedance test results.