It was reported in our previous work that activated alumina had been successfully applied to selective adsorption of lithium ions in molten NaNO₃ at a high temperature. In the present work, the activated alumina samples were prepared by heat treatment of commercially available alumina sol at different temperatures. Their physical properties were measured, then their adsorption uptake of lithium ions were evaluated. Amorphous alumina showed higher adsorption uptake of lithium ions than any other phases of alumina and the uptake increased in proportion to the surface area of activated alumina. The lithium ion uptake per unit surface area varied slightly with the phase of alumina, implying that the surface microstructure of each activated alumina has a different adsorptive capability for lithium ions. Since the mean pore radius of each activated alumina sample was at least forty times larger than the ionic radius of lithium, it may be concluded that there is little effect of the pore size on adsorptive capabilities for lithium ions.

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A new application of the interaction phenomenon between tip and surface to practical adhesive behavior is studied. The interactive energy between two films can be estimated from the measured data of attractive force by atomic force microscopy (AFM). The adhesive strength between inorganic materials and polymer is closely related to the estimated value of interactive energy. The adhesive strength can be estimated by using a nondestructive method.

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Precipitation and ripening of an amorphous aluminogel in an aqueous solution were subjected to irradiation of ultrasound with various intensities at different frequencies. For comparison with the ripening of aluminogels, hydration of amorphous alumina powder in ultrasonic-driven water was studied. It was found that an intensive ultrasound during ripening decreased the relative amount of bayerite, which is a product in the ripening of the amorphous gels, whereas, a moderate ultrasound during ripening increased the relative amount of bayerite. On the other hand, the relative amount of bayerite increased when the gels were precipitated ultrasonically and ripened normally. The role of ultrasound in the ripening (dissolution-precipitation) process is discussed.

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Effects of TiO₂ on the sintering and microstructure of zirconia-toughened-alumina (ZTA) composites were investigated. The starting materials were α-Al₂O₃ powder, Zr(OC₃H₇)₄ and Ti(OC₃H₇)₄. Experimental results indicated that TiO₂ additive has a significant effect on the coalescence of ZrO₂ particles as well as on the formation of a crystalline phase of ZrO₂. TiO₂ promotes the sintering of ZTA powders and the grain growth of Al₂O₃ and ZrO₂ with more pronounced effect at higher TiO₂ contents.

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Burnability of raw meal and characteristics of clinker in the system C₂S-C₄A₃S-C₄AF-CS were investigated in comparison with those of ordinary portland cement (OPC) clinker to obtain fundamental data on the clinker. The amount of CO₂ exhausted from the raw meal of the system C₂S-C₄A₃S-C₄AF-CS was expected to decrease by about 30% compared with that of the raw meal for OPC. The formation of clinker minerals occurred at about 900°C and completed at 1250°C. Since the resulting clinker is porous and clinker minerals are small in size, the grindability of this clinker was better than that of OPC. The mineralogical composition of the clinker calculated using the equation by Bogue's method was similar to the composition obtained by combining the solvent extraction method and XRD. However, the chemical composition of each mineral determined by EPMA was remarkably different from that of OPC.

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Adsorption of dissolved succinic acid on the formation of ACP and its stability were investigated in the synthetic process of ACP by the reaction of CaCl₂-(NH₄)₂ HPO₄-C₄H₆O₄-NH₄OH. The crystallization of ACP to HAp and amount of succinic acid adsorbed were affected by some conditions such as initial pH, temperature, aging time and concentration of succinic acid in the mother liquor. The largest amount of succinic acid was adsorbed to ACP when the ACP was produced at 0°C, initial pH 10 and concentration of succinic acid 6.0 mass% and aged at 25°C for 3h. From the result of infrared spectra of the ACP which adsorbed succinic acid, two peaks due to carboxylic acid were newly found at 1400cm^-1 and 1550cm^-1. These peaks were not found from the result for a mixture of ACP and succinic acid. The adsorbed succinic acid was decomposed at about 480°C and ACP was crystallized to Ca₃(PO₄)₂ at above 600°C by heating.

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In this report, controls of polymorphism and morphology of calcium carbonate compounds were studied by suspending amorphous calcium carbonate hydrate (ACC) powder in water or MgCl₂ solution. Characteristics of calcium carbonate compounds formed from ACC were determined by means of X-ray diffraction, thermal analysis (TG-DTA) and scanning electron microscopic observation. ACC was synthesized by adding 0.1mol⋅dm^-3 CaCl₂ solution into a mixed solution of 0.1mol⋅dm^-3 NaOH and 0.1mol⋅dm^-3 Na₂CO₃ at 0°C. The calcium carbonate compounds formed easily by suspending ACC in water and was affected remarkably by temperature (0-80°C) and pH (1.7-14.0). Thus ACC changed into hexagonal plate-like calcium carbonate hexahydrate at 0°C, rhombohedral calcite at 15-20°C, spherical vaterite at 30-50°C and needle-like aragonite above 80°C after aging for 1h. ACC was also changed into vaterite in the pH region of 7.0-9.5 and to basic calcium carbonate above pH 12.8 at 20-40°C. On the other hand, spherical calcium carbonate monohydrate was formed from ACC in MgCl₂ solution (0.03-0.50mol⋅dm^-3) and then changed finally to aragonite after long aging. For example, the amount of spherical monohydrate with a diameter of 30μm reached a maximum after aging for 3d, and it changed to needle-like aragonite with an average length of 50μm after 10d in 0.10mol⋅dm^-3 MgCl₂ solution. Accordingly, ACC changed easily to calcium carbonate anhydrides (calcite, aragonite, vaterite), calcium carbonate hydrates (monohydrate, hexahydrate) and basic calcium carbonate, when ACC was suspended in solutions of different conditions such as temperature, pH and concentration of MgCl₂.

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This paper describes the basic conditions for the brittle-ductile transition in the ultraprecision machining of brittle materials in order to explain the deformation and fracture mechanism of a sub-surface layer induced by the microinteraction between a tool and a material. The temperature and stress distribution were simulated by a finite element method using a indenter sliding contact model in diamond cutting of monocrystal silicon. From this analysis, the characteristics of high temperature and stress field during the microcutting of brittle materials, and also the deformation and fracture behavior were clearly understood. The stable ductile mode machining of brittle materials is achieved by controlling the depth of cut, cutting speed and lubrication.

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The pyrolysis of a low-oxygen SiC fiber, prepared by the electron-irradiation curing method, has been investigated in N₂ atmosphere at temperatures from 1673 to 1973K. Then, the pyrolytic behavior in N₂ was compared with that in Ar. The fiber absorbed a considerable amount of nitrogen, and consequently, the mass loss caused by the pyrolysis was compensated. While the nitrided layer retarded the crystallization into β-SiC below 1773K, this effect disappeared above 1873K. As a result of the reaction of SiO with carbon, coarse SiC particles grew on the surface of the fiber heat-treated at 1973K. The tensile strength of the fiber was inversely proportional to the square root of the SiC crystal size. For SiC crystals with the same size, the strength was much higher in N₂ than in Ar, because of smoothness of the surface.

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The influence of SiO₂ sources on the formation of 1.1nm-tobermorite (5CaO⋅6SiO₂⋅5H₂O) was studied by using quartz, quartz+silicic acid and silicic acid. The mixtures of lime and each SiO₂ source with the Ca/Si molar ratio of 0.8 were autoclaved at 180°C for the spcified time under saturated steam pressure, and the variation of structure and composition of the products were examined by XRD, analytical-TEM and ²⁹Si NMR. The reaction proceeds from the formation of calcium silicate gel (C-S-H) as a precursor to the tobermorite formation. The starting mixtures with quartz and quartz+silicic acid yielded tobermorite at the early stage of the reaction. However, the tobermorite formation delayed remarkably, when the silicic acid was used. This is attributable to the difference of the Ca/Si ratio among C-S-H. Tobermorite was easily formed, when the Ca/Si ratio of C-S-H was higher than 0.99. The silicate anion structure of C-S-H was influenced by the SiO₂ sources. The C-S-H had single chain structure, when quartz was used. On the other hand, the silicic acid yielded further but partly cross linked chain structure and had strongly protonated chain end structure.

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Role of precoarsening treatments in the strengthening mechanism were examined by scanning electron microscopy (SEM) observations on the fracture surface of Al₂O₃ ceramics, which were made by hot-pressing under various sintering conditions. Al₂O₃ polycrystals by general sintering procedure yielded the 4-point bending strength of 400-500MPa, while the precoarsening treatments increased the strength up to 750MPa. Since the fracture toughness kept the constant value of 3.5MPa√m regardless of the treatments, it is expected that the reduced flaw size resulted in the enhanced strength. From the observations of the fracture origin, it was found that the precoarsening treatments suppressed the stable growth of a flaw during the bending tests and gave the relatively small flaw size. The increased stability of grain boundary near the flaw is thought to be the reason for the reduced stable growth rate of the flaw. The decreasing tendency of fracture toughness with decreasing flaw size was not observed due to the small grain size, which causes the crack propagation without the development of process zone.

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Sintered bodies of (Ba, Pb)₂In₂O₅ were prepared by substituting A site of Ba₂In₂O₅ having a brownmillerite-related structure with Pb. Crystal structure and conductivity of sintered (Ba, Pb)₂In₂O₅ were investigated. The crystal structure of (Ba, Pb)₂In₂O₅ was governed by the Pb content, and changed from orthorhombic to cubic structure with an increase in Pb content. The temperature dependence of the conductivity of (Ba, Pb)₂In₂O₅ revealed that the order-disorder transition of oxygen vacancy disappears with an increase in Pb content, and that oxygen vacancies are disordered even at room temperature to have cubic structure. (Ba_0.80Pb_0.09)₂In₂O₅ showed higher conductivity than Ba₂In₂O₅ in the temperature range of 673 to 1100K. The results suggest that the changes in crystal structure and conductivity are due to the ionic polarization of Pb.

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Refractive indexes of barium borate-based glasses were measured in the wavelength range from 0.265 to 1.710μm by using the minimum deviation method. Factors affecting the refractive index dispersion are discussed by using the single-oscillator Drude-Voigt equation. Borate glasses are characterized by the larger number N of molecules in a unit volume than that for silicate glasses. The feature of borate glasses, that is, relative high refractive index and low dispersion, is dominated by the number N which is related to the fraction of four-coordinated borons estimated by Green-blatt and Bray. Borate glasses containing high valency cations, e.g., Y³⁺, La³⁺, Ti⁴⁺, Nb⁵⁺, Ta⁵⁺, posess higher refractive indexes and higher dispersion than barium borate binary glasses.

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An ultrafine BaTiO₃ powder of 80 nm diameter was consolidated to powder compacts with 58% TD and uniform structures by filtration of 2-methoxyethanol, 2-ethoxyethanol or methanol suspension and subsequent isostatic pressing under a pressure of 294MPa. These compacts were sintered into dense BaTiO₃ ceramics with average grain sizes of 1-2μm (>95% TD) within 2h at 1200-1250°C. Increasing the heating rate to the sintering temperatures of 1000-1300°C was effective in increasing the density. Grain growth from 0.5 to 2μm caused significant increase of the c-parameter of BaTiO₃, resulting in the increase of tetragonality (c/a ratio). The phase transition from tetragonal to cubic form at room temperature was estimated to occur below 0.4μm average grain size. The relative dielectric constant (ε′) at room temperature was highest (≈6000 at 1kHz) in the high-density BaTiO₃ with an average grain size of 1.4μm, sintered at 1200°C. Increase of the grain size to 2.3μm in dense BaTiO₃ caused the decrease of the ε′ value. The low-density and small-grained (0.5μm) BaTiO₃ also showed a low ε′ value (1400 at 1kHz). The ε′ values of all samples were almost independent of frequency in the range of 100Hz to 500kHz. The dielectric loss was strongly affected by the porosity and decreased at higher density. The decrease of grain size reduced the ε′ values below and above the Curie temperature, leading to the broadening of ε′ in a wide temperature range (18-220°C).

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Carbon dioxide gas in a 10% CO₂-90% N₂ mixture was fixed with Ca(OH)₂ granules under a dry condition between 100 and 800°C. The fraction of fixed CO₂ was highest between 500 and 600°C. More than 90% CO₂ was fixed under the controlled gas flow rate, weight of Ca(OH)₂, temperature and time. The porous CaO particles, which were prepared by dehydration of Ca(OH)₂, reacted with CO₂ gas and CaCO₃ was formed on the surface of CaO particles. The CO₂ recovery system using Ca(OH)₂ makes possible to CO₂ fixation by the use of simple equipment and method, and this system is effective for the minor factory.

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Double layered structure of submicron BaTiO₃ grains (0.1-0.6μm), in which the grain core is covered with a surface layer, has been analyzed using the equivalent circuit model. The observed permittivity of sintered pellets increases with increasing grain diameter. This agrees with a model in which the ferroelectric tetragonal core is covered with the paraelectric cubic surface layer. The best fit of this model to the observed permittivity has shown that the permittivity of the tetragonal phase is 5900 and that of cubic phase is 90. Also the thickness of the cubic surface layer in the sintered pellet has been estimated to be approximately 2nm, which agrees well with that estimated from the X-ray diffraction peak analysis.

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Relations between gelation and crystallization of a barium titanate precursor and experimental parameters of sol-gel processing were studied systematically. A crystalline barium titanate gel powder was obtained at room temperature through periods of hydrolysis, gelation and shrinkage from a precursor solution composed of Ba(OEt)₂ and Ti(OⁱPr)₄. The aging time enough to shrink the gel was required to obtain a crystalline powder after gelation. The obtained crystalline powder was pseudo-cubic perovskite and the primary particle was about 20nm in diameter.

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