In this work, the very weak exothermic formation reaction of MgAl₂O₄ spinel is successfully conducted in a self-sustaining manner with the advantages of energy savings, high reaction rate and highly porous product. The energy and Al₂O₃ required for this reaction are obtained from the combustion reaction of TiO₂-B₂O₃-Al while MgO is added to the reactive mixture. Ignition of the reaction mixture is carried out at room temperature despite the dilution effect of MgO (19 vol%). Reduced aluminium grain size and preheating the reactant before ignition were found to be very effective to complete the formation reaction of MgAl₂O₄ spinel. Thermodynamic calculations of adiabatic combustion temperatures and spinel molten fractions at different initial temperatures were carried out. Oxidation resistance study of this new composite shows that it can safely work up to 600°C in open atmosphere and that 700°C is considered to be its threshold oxidation temperature.

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Statistical analysis of the strength of porcelain tableware is very important; however, there are few reports on impact strength of product wares. In this research, the impact strength of commercial reinforced porcelain plates were measured using pendulum-type impact tester based on an ASTM C368. Statistical dispersion of the impact strength was analyzed for many types of reinforced porcelain tableware. The mathematical distribution of the impact strength could be estimated with a normal distribution. The statistical dispersion of the impact strength showed the same tendencies, regardless of the tableware shape or the mean impact strength value. The median coefficient of variation, (Standard deviation)/(Mean impact strength), was 0.118. Details of the destruction of reinforced porcelain tableware were studied by observations of the fractured surfaces.

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Nano-grained BaTiO₃ ceramics were prepared using a two-step sintering process. The level of shrinkage and specific surface of the BaTiO₃ green bodies were measured as a function of temperature. The two temperatures at which boundary diffusion and lattice diffusion begin to dominate were estimated by measuring the shrinkage behavior of the green bodies. These temperatures were used as the 1st- and 2nd-step temperature in this two-step sintering process. The BaTiO₃ ceramics prepared from 20 nm-sized powders using the two-step sintering process at T1 = 1230°C and T2 = 1160°C (10 h) showed a relative mass density of ∼ 91% with very little variation in grain size compared with the starting powders. The ferroelectricity was determined from the local piezoelectric response behavior of the BaTiO₃ ceramics with a grain size of 30 nm. The ∼ 30 nm-size-grained ceramics showed considerable ferroelectric behavior.

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Bipolar resistance switching was investigated on La_0.7Ca_0.3MnO₃ (LCMO) thin film with Al-Ag alloy top electrode (TE) including different Ag contents. The switching capability of Al-Ag/LCMO/Pt was greatly improved in Al-33%Ag TE structure compared to in Al-50%Ag TE structure. Switching times of faster than 100 ns and rewrite cycles of more than 400 were obtained while maintaining a ratio of resistance change larger than 1000%. The mechanism of resistance switching was explained by a model with interfacial nanostructured domains composed of Ag and insulator AlO_x matrix, as previously proposed for Al-50%Ag/LCMO/Pt structure.

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There have been innumerable contributions to clarify bubble behaviour in glass melt, where various approaches have been carried out. Experimental results show bubble quality is represented by bubble number density, bubble diameter, and standard deviation of the diameter, which depend on time and temperature. The latest experiment implies growth of bubble is strongly dependent on temperature, and the standard deviation is independent of time and temperature. Not only appeared location but also number density of small bubble (seeds) is of major concern for manufacturers to produce high quality glass. A new mathematical model is developed to predict bubble number density, which quantifies effect of both fining and refining on the density by introducing an exhausting effect of bubbles from upstream of the highest temperature area, i.e. hot spot, and the downstream in melter, i.e. stagnant. Inlet bubble number density with melting down is extrapolated from the published data. Monitored diameter obtained in experiment is applied to calculation. Calculated bubble number density is compared with measured one in an actual flat glass furnace, which makes it clear that the mathematical model is valid to predict order of the density in the glass melt. Numerical simulation gives reasonable suggestion about fining effect.

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Strength variation of alumina ceramics formed by dry-pressing of granules was examined by the number density of coarser defects. The Weibull modulus m was related to the exponent n of the power function of the number density of coarser defects by strength simulation; m = 1.82n - 1.92. The Weibull modulus was determined by a series of strength data, which were calculated by the simulated bending tests of the samples. The number density of coarser defects was given by the assumed power function. The various Weibull moduli were obtained for some kinds of series. The experimental results of the number density of coarser defects by direct observation of alumina ceramics and the Weibull modulus from strength tests were plotted well on the calculated line except a series of sample containing coarser defects with ambiguous boundaries. The relationship between the Weibull modulus and the parameter of the power function concurred with past studies; m = 2n - 2.

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Two kinds of zeolites with different crystal structures with the same chemical composition of SrO·Al₂O₃·2SiO₂·xH₂O prepared by an ion-exchange technique were used as a precursor of Sr-celsian. One was Sr-exchanged zeolite A (Sr-A), the other was Sr-exchanged Linde F zeolite (Sr-F). The Sr-A almost became an amorphous material at 400°C, and then generates a small amount of Sr-hexacelsian from the amorphous material at 500°C. The amount of Sr-hexacelsian steeply increased and a small amount of Sr-monocelsian also formed at 1000°C. On the other hand, the Sr-F nearly becomes an amorphous material at 300°C, and then Sr-hexacelsian mainly formed along with a small amount of Sr-monocelsian above 1000°C. In both of the Sr-exchanged zeolites, a single phase of Sr-monocelsian was obtained finally at 1300°C, owing to the hexacelsian - to - monocelsian phase transformation. The reason for the crystallization of Sr-hexacelsian at 500°C only from Sr-A was explained in terms of the similarity in framework structures of zeolite A and Sr-hexacelsian.

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This study investigates and compares the efficiency of visible-light-driven routes of anion-doped TiO₂ and composite photocatalyst by using preparation conditions as controls for crystal phase, crystallite size, and optical properties. Anion-doped TiO₂ was formed by doping nitrogen, and the composite photocatalyst was made from TiO₂ combined with Multi-Walled Carbon Nanotubes (MWCNTs) via the sol-gel process. The results of the evaluated performances of the photocatalysts with the photodegradation of methanol under visible-light radiation demonstrated that the anion-doped TiO₂ exhibited higher photocatalytic activity than that of the composite photocatalyst. It is concluded that the composite photocatalyst was induced into the visible-light region by the photosensitizer, which may decrease the efficiency of electron transfers between photosensitizer and TiO₂ phases, or that photosensitizer could not effectively induce the valance band electron of TiO₂ into photosensitizer to form positive holes. On the other hand, the anion-doped TiO₂ directly formed a new energy band gap, which indicates a superior route to visible-light response.

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Conditions were investigated for preparing needle-like hydroxyapatite (HAp; Ca₁₀(PO₄)₆(OH)₂) by hydrothermal processing of mixed calcium phosphate powders consisting of dicalcium phosphate dihydrate (DCPD; CaHPO₄·2H₂O) and beta-tricalcium phosphate (β-TCP; β-Ca₃(PO₄)₂). The powder mixture was subjected to two-step hydrothermal processing in which the compacted powder was treated first by exposure to vapor of the liquid and subsequently by immersion in the liquid. High aspect ratios were obtained in samples with crystal sizes around 60 μm in length from the reactant mass ratio composition of β-TCP/DCPD = 1/9 by treatment at 160°C for 0.5 h under vapor conditions, followed by liquid conditions for 24 h with renewal of the liquid at 12 h. Initial compositions and pH conditions were the main parameters determining the formation of needle-like HAp by hydrothermal processing.

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Sintering of (1 mol%Ni²⁺-1 mol%Er³⁺) or (1 mol%Mn²⁺-1 mol%Er³⁺) -doped Y₂O₃ polycrystal was investigated by conventional sintering at the sintering temperature in a range from 1200 to 1600°C. The sintering temperature required for full-densification decreased from 1600 to 1300°C by the doping. The average grain size in Ni²⁺ or Mn²⁺-doped Y₂O₃ is twice as large as that in undoped Y₂O₃ at the examined sintering temperature. HRTEM observations and EDS analyses with a nano-sized probe indicated that the doped transition metal ions segregated along the grain boundaries without amorphous layers and secondary phase particles. The segregated transition metal ions probably enhance the grain boundary diffusion, and the sinterability of Y₂O₃ was accordingly improved.

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Recently, it has been reported that the spherical core-shell type cerium oxide/polymer hybrid nanoparticles which has a good dispersibility for water or alcohol can be obtained by using cerium nitrate hexahydrate and polyvinylpyrrolidone as source materials in the polyol method. This article presents 1) examination concerning raw materials for synthesis of the core-shell type nanoparticles, 2) flow properties of a dispersion sol of the core-shell type nanoparticles, and 3) experiment of ink-jet printing of the dispersion sol as an ink. First, we investigated whether the core-shell type nanoparticles were able to be obtained by using cerium (IV) ammonium nitrate instead of cerium (III) nitrate hexahydrate or hydroxypropyl cellulose instead of polyvinylpyrrolidone in the synthesis. As a result, in the case of using cerium (IV) ammonium nitrate, the spherical core-shell type nanoparticles were not able to be obtained. However, in the case of using hydroxypropyl cellulose, the core-shell type nanoparticles similar to the reported nanoparticles were able to be obtained. Therefore, it became clear that the synthesis condition for obtaining the core-shell type nanoparticles was not limited to using polyvinylpyrrolidone as a polymer. Next we investigated the flow properties of dispersion sols of the core-shell type nanoparticles synthesized by using cerium (III) nitrate hexahydrate and polyvinylpyrrolidone as starting materials. In the case of the dispersion sol with 4.3 vol% nanoparticle concentration using a mixing solution of water and ethylene glycol as a dispersion medium, the viscosity and surface tension were 5 mPa·s and 55 mN/m, respectively. Finally, it also became clear that the dispersion sols were able to be used for the ink-jet process for making patterns.

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Recently, core-shell type spherical nanoparticles (nanospheres) (core: cerium oxide, shell: organic polymer) that have a monodisperse size distribution and disperse easily in water and alcohol have been reported. Core-shell type cerium oxide/organic polymer nanospheres were characterized with respect to physicochemical properties and microstructure. As-prepared nanospheres have no pores with a size of 4 nm or less, while the nanospheres calcined at 600°C had the pores with a size of 4 nm or less. These pores are considered to be on the surface of the core. The as-prepared nanospheres and those calcined at 600°C had size distribution peaks in the range of 20-60 and 70-110 nm, respectively. The specific surface area and total pore volume of the as-prepared nanospheres were 82.8 m²/g and 0.211 cm³/g, respectively. For core-shell type nanospheres with a size of 114 nm, the diameter of the core particles was 88-92 nm and the thickness of the shell was 11-13 nm. Transmission electron microscopy images revealed that the core had dense structure. The average density of the core-shell type nanospheres was in the range of 4.2-4.6 g/cm³.

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The influence of diluent addition on purities of β-Si₅AlON₇ powders synthesized by mechanically activated combustion synthesis (MA-CS) under a very low nitrogen atmosphere of 1 MPa was investigated. The purity of β-Si₅AlON₇ powders increased with diluent concentrations in raw materials and had a maximum value of 91% when 40 mass% of diluents were added, a 25% more pure when compared to powders procured without diluents. In contrast, when diluents were included 50% or more, the combustion synthesis (CS) reaction did not occur due to reduced exothermic heat. The results also showed that the particle sizes of β-Si₅AlON₇ powders synthesized with 40 mass% of diluents were only one-tenth when compared to powders synthesized without diluents.

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MgO films were synthesized on stainless steel electrodes by a chemical-vapor-deposition method operated under atmosphere to reduce a discharge inception voltage in diode type discharge system under 6%Xe + 94%Ne atmosphere. The relationship between crystalline perfection of the MgO film and discharge inception voltage was investigated. In this study, crystalline perfection is quantified by the true density of the film. The discharge inception voltage was varied with the true density of the MgO film. The MgO film with 87% of the theoretical density indicated a minimum discharge inception voltage under various gas pressures and electrode distances.

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Thermal imprinting conditions of low-softening tin phosphate glass with a composition of 67 mol% SnO-33 mol% P₂O₅ were investigated using three processing parameters of temperature, imprinting pressure, and holding time. Fabrication conditions of a micro square grid (SG) pattern with a similar depth of silica mold (∼120 nm) were optimized. AFM observations confirmed that the 700 nm × 700 nm SG pattern with ∼120 nm depth could be formed with good reproducibility.

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