Well-aligned carbon nanotube (CNT) films were found to self-organize by surface decomposition of SiC (0001) wafers. High-resolution transmission electron microscopy and atomic force microscopy revealed that hemispherical nanocaps are generated all over the surface in the initial stage from 1200 to 1250°C. The diameter of grown CNTs is determined initially with that of the initial nanocaps. Furthermore, corresponding electron diffraction patterns showed zigzag-type CNTs selectively grow by heat-treating at a small heating rate of 1°C/min. This is a unique method to synthesize CNTs with a unique structure. The CNTs are considered to be constructed by recrystallization with a slight diffusion of carbon atoms built around the skeleton of SiC. In this paper, the formation mechanism will be proposed from the view point of crystallography.

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In order to clarify the occurrence mechanism of nonlinear phenomena, dc-bias dependence and aging characteristics of the nonlinear coefficients of second-higher and third-higher terms were measured in piezoelectric rectangular vibrators. The two nonlinear coefficients of second- and third-higher terms were contrasted sharply in their dc-bias dependence and aging characteristics. These contrasting dependences originate from the difference in the occurrence mechanism of harmonic voltages, that determines the values of the second- and third-higher nonlinear coefficients. The difference in the occurrence mechanism was discussed from the viewpoint of non-180° domain-wall motion.

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Surface structures of seven different commercial Si₃N₄ powders were investigated by X-ray photoelectron spectroscopy (XPS). The evaluated powders were produced by three different methods: diimide precipitation, carbothermal reduction and nitridation of silicon using different nitriding media with final treatments. The XPS spectra of all as received powders show Si2p, C1s, N1s and O1s signals after 0, 5 and 10 s etching priods. Tetrahedral structures Si-XYZW with different atoms (Si; H; N; O) or groups (NH; NH₂; OH) in XYZ and W, from here after substituted by them, were observed for all as received commercial Si₃N₄ powders. For five out of the seven Si₃N₄ powders, the two main tetrahedra present on the most outer surface layer are Si-SiSiN(OH), and tetrahedra containing O; Si-O(NNN; SiSiH; SiNN; NNO). The two powders produced by nitridation of silicon with HF acid washing in the final treatment present Si-SiSiN(NH₂) and tetrahedra containing OH; Si-SiN(Si; N) (OH). The powder produced by carbothermal reduction process using NH₃ (g) presents the highest fraction of O containing tetrahedra. For all powders after 5 and 10 s etching periods, the main structure changed to NH₂; Si-SiN(H; Si)(NH₂) and NH groups containing configurations Si-SiN(Si; N)(NH), respectively. The surface of Si₃N₄ powders of any production method does not have structure close to SiO₂, Si₂N₂O or an intermediate between them as commonly accepted.

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The mechanism of the formation of an internal bulge appearing as a local increase in wall thickness in the slip casting of large potteries was investigated to prevent occurrence of cracks in dried green bodies. Because it is not easy to observe moisture suction and deposition inside a plaster mold, a simple plate mold was used in the experiment. Moisture suction in the joining region during the casting was enhanced by breaking the alignment of particles due to the collision between the fronts of the slurry; thus, the wall thickness in the joining region increased owing to the acceleration of the growth of deposit. An internal bulge was formed by the difference in the growth of deposits between the joining and peripheral regions. It was found in the slip casting of a model washbasin that the occurrence of internal bulge is prevented by vibrating the plaster mold during the pouring of the slurry.

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We attempted to manufacture long life span stabilizing solution for obtain PZT precursor and/or filmy lead zirconate titanate, Pb_x(Zr_yTi_1-y)O₃. The precursor solutions were synthesized by using the original solution of Pb-acetate, Ti- and Zr-alkoxide and four kinds of stabilizers, DBU, 2-ethylhexanoic acid, ammonia and acetic acid. The DBU contained precursor solution is mostly stable compared with that of the solutions contained other stabilizers, and its DBU contained solution can stand for at least over one year. Thick PZT film of (100) orientation with 0.22 μm thickness was made on PTO/Pt/SiO₂/Si substrate by using CSD-method from DBU contained precursor solution. For this film, the estimated electrical resistivity was 6.2×10¹⁰ Ω•cm, the dielectric constant of 1300 and the residual polarity, Pr, of 21.1 μC/cm².

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Nanocrystalline zinc ferrite (ZnFe₂O₄) powders have been synthesized successfully by high power, short pulse, electric discharge using Fe and Zn wires in oxygen gas. The powders were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Mean size of the particles obtained was determined by both BET and TEM was 12-56 nm depending on the oxygen pressure. XRD analysis shows that the zinc ferrite spinel was clearly obtained.

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An indirect determination of alkali metals and lead by fractional dissolution/ion chromatography of sulfates deposited on the surface of sulfur dioxide-treated lead glass was investigated. This method involves the following procedures: 1) Sodium sulfate and potassium sulfate are dissolved in 50% (v/v) ethanol. 2) Remaining lead sulfate is dissolved in 20 mM sodium hydroxide. 3) From the concentration of sulfate in each sample solution, the surface concentrations of the corresponding alkali metals and lead are calculated. From the analytical results for lead glass samples, we have ensured that treating the glass with sulfur dioxide resulted in the formation of high concentrations of sodium sulfate and potassium sulfate, in addition to traces of lead sulfate, on the glass surface.

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Fabrication conditions for high-density and fine-grained hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂: HAp) ceramic were examined; the tensile elongation of HAp ceramic during heating was measured in order to evaluate its possible superplastic behavior. The HAp compact was fired in air at a temperature between 1100 and 1200°C for 5 h. The relative density of HAp compact fired at 1100°C for 5 h showed a maximum (99.2%), whereas the average grain size was as small as 0.56 μm. The tensile elongation of this HAp specimen was tested at a temperature between 940 and 1100°C. The tensile elongations tested at 1050 and 1100°C attained 156 and 157%, respectively; the specimen tested at 1050°C contained a limited number of cavities, whereas the specimen tested at 1100°C was observed to have a large number of cavities.

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Because ceramic products are difficult to be recycled with zero emission, they are buried as industrial wastes. We retrieved successfully a used product of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) as a new ceramic product. A used Y-TZP product was hydrothermally treated in an autoclave at 200°C for 66 or 162 h. The obtained powders were pulverized, press-formed and then sintered at 1450°C for 2 h. As a result, we had densely sintered recycle Y-TZP product.

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Samples with nominal compositions of Hg_0.8M_0.2Ba₂Ca₂Cu₃O_y (M=V, Cr, Mn, Mo, Ag, In, Sn, W, Re, Pb, Hf, Ta) were prepared by a conventional quartz-tube encapsulation method at ambient pressure. The 1223 phase formed in the samples with dopants except In and W. Ag, Re and Pb-doping effectively expanded the temperature range for formation reaction of the 1223 phase. For samples with V, Cr, Mn, Mo and Re, appreciable shortening in the lattice parameter c was observed. It suggested incorporation of the dopants into the 1223 phase. Magnetization measurements at 77 K revealed that an enhancement in the critical current density was achieved in the samples with Re and Mo.

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Lithium ferrite was investigated with a view to its application as a new CO₂ absorbent capable of absorbing CO₂ at around 500°C and emitting CO₂ at temperatures of less than 750°C. From the TG analysis, equilibrium temperature of lithium ferrite, at which CO₂ absorption apparently stops and emission starts, is found to be around 530°C. This temperature is almost the same as that obtained from thermodynamic calculation and about 200°C lower than those of Li₂ZrO₃ and Li₄SiO₄. The absorption rate increased as the absorption temperature increased up to 500°C. On the other hand, CO₂ emission was completed in about 10 min even in pure CO₂ at temperatures of more than 600°C.

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The details of a novel ceramic forming process are presented in this paper. Compared to the conventional techniques, the process cuts the amount of added organic binder by half. The process can be characterized by creating a photoreactive thin-film of chemically bonded organic binder on particles' surfaces which subsequently acts as a bridge for the linkage of the whole particle assembly upon radiation by UV-light. Such thin-film use of an organic binder and significantly stronger bonding due to the chemical forces involved are the highlights of this new approach in green body forming.

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In this study, we examined the temperature dependence of the second-harmonic (SH) intensity and Raman shift in the langasite-type Ba₃Ga₂Ge₄O₁₄ (BGG) and Na₂CaGe₆O₁₄ (NCG) crystalline phases. The SH intensity curves revealed an anomalous temperature behavior around 370°C and 270°C in the BGG and NCG phases, respectively. Furthermore, as a result from the Raman spectral measurement, it was suggested that the anomaly observed in the lagasite-type phases originated in the A-site.

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Macroporous alumina materials were synthesized by using yeast cells as bio-templates. Aluminium isopropoxide (AIP) modified with triethanolamine (TEA) was first hydrolyzed by water containing the dispersed yeast cells. This resulted in the formation of slurry consisting of hydrolyzed sol and yeast cells. After centrifuging, the cake which is packed with hydrated sol and yeast cells was subjected to heat treatment. The obtained sample after heat treatment contained finely dispersed pores ranging in size from 1.5 to 2.0 μm. Under the present experimental conditions, the thickness of alumina wall was also controlled by changing the ratio of yeast cells to AIP.

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Highly c-axis-oriented aluminum nitride (AlN) thin film sensor elements were prepared on silicon single crystal by rf magnetron sputtering technique. The sensor characteristics were evaluated under pressures of 0.1 to 1.6 MPa and frequency of 0.1 to 100 Hz at room temperature. The deviation from the linearity of charges with pressures for the AlN sensor was within 1.49% of a full scale at 1.6 MPa, which indicates a good linearity between 0.1 and 1.6 MPa. The AlN sensor showed a good flat frequency characteristic between 1 and 100 Hz. It is confirmed that the AlN thin film has a good possibility as a pressure sensor.

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