The terbium (III) 2, 2'-bipyriyl complex, [Tb (bpy)₂]Cl₃, was incorporated for the first time into partially metal oxide-substituted silica matrices derived from tetraethyl orthosilicate (TEOS) and metal alkoxides (M (OR)_n, M=Zr and Ta) via sol-gel process. The optical properties of the obtained [Tb (bpy)₂]Cl₃-dispersed inorganic-organic composite materials were characterized by measurements of photoluminescence, transmittance, infrared spectra and X-ray diffraction patterns. The emission intensity of the (SiO₂-M_xO_y):Tb (bpy)₂³⁺ composite phosphors was dependent on the kind and content of metal oxide component in the matrices and maximized at the matrix composition of Si:M=9:1 in molar ratio in either case. In particular, for the SiO₂-Ta₂O₅ matrix system with the composition of Si:Ta=9:1, the complex was incorporated into the host media at concentrations up to 20mol%, which resulted in composite phosphors with a good transparency. Under the optimized preparation conditions, the emission intensity of such organically modified ceramic (ORMOCER) (SiO₂-Ta₂O₅):Tb (bpy)₂³⁺ phosphors maximized at ca. 75% vs. LaPO₄:Ce, Tb (a commercially available lamp phosphor as the standard substance) with complex concentrations of 10-15mol%.

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Interaction parameter, A, proposed in Yamashita-Kurosawa's theory of dielectric constant, has been calculated for numerous binary oxide glasses on the basis of polarizability of oxide ion determined from refractive index. It has been established that the interaction parameter is closely related to the oxide ion polarizability and the optical basicity of the glasses. The almost linear distribution of the optical basicity obtained in the oxide glasses against the interaction parameter could be used as an optical basicity scale for the oxide glasses. It was established that the interionic interactions are strong in glasses formed by two acidic oxides and they become weaker in glasses formed by acidic and basic or two basic oxides. Generally, the interaction parameter decreases and optical basicity increases according to the sequence: phosphate, borate, silicate, germanate, tellurite, titanate glasses. It has been assumed on the basis of the known structural models and experimental results on the core level and valence band spectra of glasses that the interaction parameter represents the interionic interaction between cation and an averaged oxide ion due to overlapping of their outermost electronic orbitals to form a chemical bond. It was found that the decrease of interaction parameter correlates with small charge overlap and large cation and oxide ion polarizabilities, giving rise to an enhanced unshared oxide ion 2p electron density available for donation. The results obtained probably provide a good basis for prediction of interionic interaction in oxide glasses on the basis of refractive index.

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Fine platinum (Pt) particles-dispersed lead zirconate titanate, Pb (Zr, Ti)O₃ (PZT) nanocomposites were prepared by an electroless plating method which enabled to obtain a PZT nanocomposites homogeneously dispersed with fine platinum particles. Platinum particles with the size up to a few tens nanometer were precipitated on the surface of the PZT matrix. According to transmission electron microscope (TEM) observations, both the size and dispersion of the platinum particles may depend on the pH value of the aqueous platinum solution during electroless plating. After sintering, the platinum particles were found to be homogeneously dispersed in the PZT matrix. Fracture strength and toughness of the PZT nanocomposites were improved with retaining their electrical properties. Scanning electron microscope (SEM) observations revealed that the fracture mode of the PZT/platinum nanocomposites was transgranlar, in contrast with the intergranular fracture mode of the monolithic PZT. This result suggests that the grain boundary structure of the PZT nanocomposites may be modified by the platinum, leading to improved mechanical properties.

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Cracking of a cristobalite-containing mullite body at the middle stage of crystallization during cooling was investigated by acoustic emission (AE) and the crack formation was discussed. The specimen was composed of an outside layer of crystalline cristobalite and the inner part remaining as a glass phase. There are two kinds of cracks, of which the one is almost parallel to the surface of specimen at the boundary between the outside layer and the inner part and the other is perpendicular to the surface. AE signals indicated that the cracks occurred in two stages, the first stage at the temperature range 750-650°C and the second stage below 250°C. Cracks parallel to the surface were formed at the first stage due to a mismatch in thermal expansion coefficient between the outside layer and the inner part. Those perpendicular to the surface were generated at the second stage under a tensile stress developed in the outside layer, which was caused by the β-α phase transition of cristobalite, in the direction parallel to the surface

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(1) Poly-titanosilazanes were synthesized by chemical modification with Ti(X)₄ [X=N(CH₃)₂, OCH(CH₃)₂]. The chemical structure of the synthesized precursors was studied using IR and ¹H NMR techniques. The polytitanosilazanes were found to contain some N-Ti bonds.
(2) [Si-Ti-O-C-N] multicomponent amorphous powders were synthesized by pyrolysis of the poly-titanosilazanes at 1000°C in NH₃.
(3) Amorphous Si₃N₄ in the [Si-Ti-O-C-N] was rather stable below 1400°C and titanium was found to be effective to suppress crystallization of Si₃N₄. Above 1600°C, the Si-Ti-O-N liquid phase enhanced the α-/β- phase transformation of Si₃N₄.
(4) The poly-titanosilazane derived from PHPS and Ti(N(CH₃)₂)₄ yielded Si₃N₄-TiN ceramics by heat treatment at 1800°C in N₂. TiN was observed as particles with diameter of smaller than 100nm. The poly-titanosilazane was found to be suitable for the synthesis of TiN nanopartitle-dispersed Si₃N₄-based ceramics.

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The mass loss reaction during sintering of Si₃N₄ ceramics with 5mass% Y₂O₃ and 3mass% Al₂O₃, which was reported in the former paper, was discussed in greater detail, including the observation of cross-sectional morphology and the analysis of the distributions of crystal phases and elements. Differences in the conditions of the powder bed and N₂ gas pressure (0.1 and 1MPa) during sintering caused significant differences in cross-sectional structures. A porous layer was formed in the surface of samples sintered under 0.1MPa N₂ at more than 4h of soaking, while a pore-free densified layer was formed at the surface of samples sintered under 1MPa N₂ at more than 4h of soaking. It was found that the packing powder not only suppressed mass loss reaction, but also drew Y-Si-Al-O-N glass from the grain boundary phase via capillary force. With increasing mass loss with longer soaking times, the oxygen content in specimens decreased and α-SiAlON, melilite and other crystals including Y, Si, O and N were formed. As a result, we concluded that mass loss reaction during sintering of Si₃N₄ ceramics occurred mainly through the following reaction: Si₃N₄(s)+3SiO₂(l)→6SiO(g)+2N₂(g).

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Silica-titania films with a concave-convex surface were prepared from a mixture of polymerized tetraethoxysilane (TEOS) sol containing tetraisopropoxytitanate and polymerized methyltriethoxysilane (MTES) sol in a molar ratio MTES/TEOS of 6. Film hardness was dependent on the composition of the coating sol, heat treatment temperature and time. The film obtained by introduction of 4mol% TiO₂ to SiO₂ and by heat treatment at 620°C for 10min was hard to be usable in engineering practice. New-type water-repellent glasses were produced y using these SiO₂-TiO₂ films as an under layer combined with fluoroalkylsilane; the glasses showed an abrasion resistance for practical application as automotive windows.

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Impedance spectroscopy has been used to investigate a correlation between the microstructure and electrical properties of a phase-separated Li(Fe_0.5Al_0.5)₅O₈ solid solution. The phase separation of the Li(Fe_0.5Al_0.5)₅O₈ single-phase solid solution, which was caused by annealing at 1000°C, resulted in a continuous compositional variation, suggesting that the phase separation proceeded spinodally. An equivalent circuit proposed for modeling a modulated microstructure of the spinodally decomposed Li(Fe_0.5Al_0.5)₅O₈ successfully explained the change in the electrical properties during the phase separation. Impedance and electric modulus data suggested that a well-defined phase boundary between separated phases was formed after annealing for 40h. The bulk conductivity was dominated by the Fe-rich phase at the early stage of the phase separation, whereas the conductivity of the phase boundary was dominant after its formation. For interpreting the electric modulus spectra, the activation energy of its peak frequency was useful.

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Al₈B₄C₇ has been synthesized and its oxidation properties have been evaluated in both powder and sintered state. Al₈B₄C₇ can be synthesized at above 1250°C by using Al+B₄C+C as a starting material mixture. At 1800°C, no other phase could be identified. The process is achieved via gas phase. In the temperature range 700-1000°C, the results show that oxidation occurred by a parabolic kinetic process, the activation energy of the process is 25.8kJ/mol, indicating that Al₈B₄C₇ powder is liable to oxidation. A sintered pure Al₈B₄C₇ body cannot be satisfactorily used in air at temperatures higher than 1200°C because of its low oxidation resistance.

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Thermal conductivity of several soda-lime-silicate glasses, which are called float glasses, has been measured by a needle probe method in the temperature ranges from room temperature to 1173K. Kinds of the samples were the ordinary clear float glass (CFL), bronze (BFL), gray (GFL), blue (HFL) and green (MFL) Masses. Experimental results showed that the thermal conductivity of the glasses increased gradually with rise of temperature in the ranges from room temperature to 1173K. Thermal conductivity values of the glasses measured do not depend on the kinds of samples, and it is considered that the measured values are real thermal conductivity. The values of conductivity of the glasses measured were about 1.0W/(m·K) at 303K, 1.3W/(m·K) at 773K, 1.4W/(m·K) at 973K and 1.7W/(m·K) at 1173K.

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La-doped lead magnesium niobate (Pb_1-xLa_x[Mg_(1+x)/3Nb_(2-x)/3]O₃, PLMN, x=0.1, 0.2) was prepared by a polyethylene glycol-based process (PEG method) as follows: PEG-cation (La³⁺, Mg²⁺, Nb⁵⁺) complex was oxidized and the obtained oxide was mixed with PbO. This oxide mixture was fired to obtain PLMN. This PEG method enabled to prepare the single phase of perovskite structure of PLN at 1023K. This temperature is lower than that used in the solid state reaction method. The PLMN prepared by the PEG method had quite little compositional fluctuation and structural strain. PLMN has an ordering domain with the super lattice structure of B site cations in the perovskite structure. The crystallite size of the ordering domain in the PLMN obtained by the PEG method increased when the molecular weight of the initial PEG increased (from 150 to 7500). The formation process of the ordering domain was under the influence of the cation distribution in the PEG-cation complex.

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Hydration reaction of a calcium sulfoaluminate-type expansive additive (CSA)-Alite system was investigate at a quantitative viewpoint. Free lime and anhydrite rapidly reacted at initial period but hauyne did slowly. In special, at early days, the anhydrite showed extremely high reaction ratio. As the formed hydrates, calcium hydroxide and ettringite could be identified. And, from materials balance of the hydration, presence of a large amount of gel was presumed. SO₃ contents in the gel showed a high value within 1 in reaction period, and after reducing to half value by 3d in reaction period, it showed a nearly constant value. As a result of investigation on forming mechanism of the ettringite, it was thought that at initial period SO₄^2- was adsorbed on C-S-H, and that after a matrix was formed, it reacted with hauyne and aluminate hydrates to form the ettringite in the matrix.

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SiC-fiber/Si₃N₄-matrix composites (CMC) which contained W fiber (W_f), Ti fiber (Ti_f) or Si₃N₄-TiN phase ([SiN-TiN]) as an electrically conductive phase were fabricated by hot-pressing in N₂. Electrical resistance change (ΔR) was measured in bending tests including loading-unloading and cyclic tests. The CMC-W_f showed little ΔR in deformation regions and discontinuous ΔR at the fracture of whole material. The ΔR of the CMC-Ti_f was observed in small displacement because of brittle TiN formation during the hot-pressing, but residual ΔR after loading-unloading and cyclic tests was slight in this material. The CMC-[SiN-TiN] possessed the best sensitivity of ΔR among the three kinds of materials. At unloaded state, the CMC-[SiN-TiN] had clearly residual ΔR, which increased obviously with increasing the number of cycles. These results could be qualitatively understood by conductive pass amputation in percolation structure of TiN particles in the matrix phase of the CMC. The self-diagnosis function of fracture detection in the CMCs would be applicable into the damage evaluation of important materials and structures.

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Coarse white polyethylene particles were coated by fine pigment particles of red iron oxide by high-speed rotational impact blending and by hand mixing in a mortar. As the dark pigments became progressively distributed over the coarse particle surfaces, the color characteristics of the resulting powder changed. First, the effects of the mixing ratio of fine particles, the treatment time, the rotational speed of a rotor and the mean diameter of coarse particles were investigated with respect to the degree of mixing of the total mixture. The value of the degree of mixing was determined directly and precisely by chemical analysis. It was found that the degree of mixing increased with the treatment time at a certain mixing ratio of fine particles, corresponding to a coating ratio over coarse particles of less than 100% of closest packing on a number basis, but decreased at the mixing ratio of more than 100% by rotational impact. Micromixing to coat individual coarse particles was more easily and rapidly achieved by rotational impact blending as compared with hand mixing. Coating coarser particles at higher rotor speeds was more suitable for achieving homogenous mixing. In addition, it was found that the lightness of mixed particles decreased to lower than that by hand mixing due to the increased degree of mixing, but remained almost constant during the process of rotational impact blending, with its slight increase being due to embedment of fine particles by frequent impact. This means that the lightness of particles reached a steady state in a very short mixing time, resulting in the reduction of the amount of fine particles for the same lightness effect when using the high-speed rotational impact blender.

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Two slags of different CaO content from municipal waste were heat-treated. The structure and properties of the products were revealed. The main crystalline phase in the specimen with high CaO content (high basicity) was gehlenite when it was heated above 1073K. When heated above 1123K, fully crystallized materials were obtained. The specimen with low basicity yielded porous materials on heating above 1173K and the effective foaming was observed in the temperature range between 1223-1233K. The porous materials were composed of gehlenite, anorthite and glass. The difference in crystals formed on heating with the difference in basicity was interpreted according to a three-phase triangle diagram defined by gehlenite, anorthite and wollastonite.

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The densification behavior and the mechanical properties of NiO-CoO and NiO-CoO MgO systems were investigated. Al₂O₃ of 2mass% was added in those systems as a sintering aid. Samples were prepared by hot isostatic press (HIP) treatment performed after a conventional ressureless sintering. The density of the NiO-CoO system did not depend on CoO content. On the other hand, the densification of NiO-CoO system was slightly prevented by the addition of MgO. Those samples have microstructure dispersed with (Ni, Co) Al₂O₄ or (Ni, Co, Mg) Al₂O₄ spinels in a NiO-CoO or NiO-CoO-MgO solid solution matrixes and the addition of CoO or MgO had no effect on the microstructure. In the NiO-CoO system, the bending strength increased, and the Vickers hardness increased with increasing the CoO content. Swelling around the Vickers mark, which is often observed in materials with plastic deformation ability, was observed. In the bending strength and the Vickers hardness of the NiO-CoO-MgO system increased with increasing the MgO content. These results suggested that the addition of CoO improved a brittle property of the NiO ceramic and the addition of MgO increased both the strength and the hardness of the NiO-CoO solid solution ceramic.

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Residual stress field around a Vickers diamond indentation was studied using float glass as a model specimen. The basis of the experimental technique is to use cracks from a small indentation as a microprobe to measure the residual stress at a specific point around a large indentation and to study the change of the residual stress by heat treatment. Residual tensile and compressive stresses around a large indentation produced by applying the load of 19.6N were distributed up to the distance of about 300μm from the indentation center. The tensile and compressive stresses were 10MPa and -40MPa, respectively, at a distance of 200μm from the indentation center. The residual stress decreased y heat treatment and became zero by keeping the indented specimen at 550°C, a temperature which is close to the annealing point of the glass, for 2h. The depth of the indentation also decreased by heat treatment. This technique can be widely applied to study residual-stress-related phenomena in ceramics as well as in glass.

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Precursor structure of chemically modified Al(O-sec-Bu)₃ with ethyl acetoacetate or diethanolamine, dissolved in diethylene glycol (DEG), ethylene glycol monoethyl ether (EGE), and sec-butyl alcohol (sec-BuOH), was investigated using ²⁷AlNMR. ²⁷AlNMR spectra revealed that the reaction of DEG or EGE with Al(O-sec-Bu)₃ led to the formation of six-coordinated structural units. The precursor structure of Al(O-sec-Bu)₃ modified with ethyl acetoacetate in EGE, which consisted of six- and five-coordinated structural units, was almost the same as that in DEG, but different from that in sec-BuOH, where four-coordinated structural units were also observed. In Al(O-sec-Bu)₃ modified with diethanolamine, five- and six-coordinated structural units were present in all the solvents used in this study and the effect of solvents on the coordination state was very small.

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Residual stress distribution around the woven fiber bundles was analyzed by a Finite Element Method to understand the fracture behavior of the laminated Si-Ti-C-O fabrics (10vol%)/mullite matrix composite under anticlastic bending test. The analysis revealed that the residual stress was concentrated on the fabric node, a cross point of the longitudinal and horizontal fiber bundles. The result could explain the formation of surface cracks in the mullite layer during anticlastic bending test, which originated from the fabric node. We have conducted the anticlastic bending test on 0°/90° crossply laminate composites of the Si-Ti-C-O fibers (10vol%)/mullite system to evaluate the influence of fabric node on the fracture behavior. No surface crack was formed in the crossply laminate composites with no fabric node. The fracture strength of the crossply laminate composite was twice that of the layered composite with woven fabric. In other words, the fabric node of the fiber bundles greatly affects the mechanical reliability of layered composites.

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Nd-heavily-doped-YAG ceramic with high transparency was fabricated by a simple solid-state reaction method using high purity powders of Al₂O₃, Y₂O₃, and Nd₂O₃. The optical absorption coefficient of 4.8 at% Nd: YAG ceramic (at wavelength of 808nm) was 16.5cm^-1, which was remarkably higher than that of 1.0 at% Nd: YAG single crystal by the Czochralski method. Laser output power of the polycrystalline 4.8 at% Nd: YAG ceramics was about 4 times higher as compared with that of high-quality commercial 1.0 at% Nd: YAG single crystal.

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In the late 19th century, T. A. Edison, a great inventor, applied a carbon filament made from bamboo fibers grown in Kyoto to an incandescent lamp, which was one of the earliest technical applications of carbon fiber. The need for carbon fiber for use in military aircraft originated shortly after World War II in the U.S.A. as carbon fiber reinforced structural materials. Since the early 1950s, many varieties of reinforcing fibers have been developed and the UCC demonstrated high-performance carbon fiber made from rayon. However, its tensile strength and elastic modulus were not particularly high. A technical and commercial breakthrough for high-performance carbon fibers occurred in the mid 1960s-the production of carbon fibers from polyacrylonitrile (PAN) precursor fibers. This process proved to be more economical due to the lower cost of the PAN precursor fiber and the simpler process required to convert PAN fiber to carbon fiber. Shindo first reported the use of PAN as a precursor for carbon fibers. At that time almost no military application of engineering materials was considered in Japan. The history of these carbon fibers can be found in “Carbon Reinforcements and Carbon/Carbon Composites, ” by E. Fitzer and L. M. Manocha, Springer-Verlag (1998).
Shindo's invention appeared as Japanese Patent No. 304892 (1963, applied for in 1959). His claim was a method of manufacturing carbon or graphite materials, which comprises heating PAN polymer up to 350°C in an oxygen-rich atmosphere followed by heating to a temperature above 800°C. The heating PAN fiber at lower temperatures in an oxidizing atmosphere does not cause melting or deformation of the fiber during subsequent heating. This heat treatment was referred to as a stabilization process and became a fundamental process for conversion of organic precursors to inorganic fibers.
Shindo's paper describes, (1) the growth of crystallites in two kinds of PAN-based carbon fibers, (2) changes in the mechanical properties and (3) changes in the electrical resistance by heat treatment in the temperature range, 1000 to 3000°C. From the viewpoint of the remarkable development of carbon fiber applications subsequently, the available data on mechanical and crystallite growth must be significant. High grade of preferred orientation of graphite layer planes parallel to the fiber axis, which is shown in X-ray diffraction photos and electron diffraction pattern, could be due to the high-strength and high-modulus of the fiber. Furthermore, after heat treatment at a temperature as low as 1000°C, the fiber assumed significantly higher preferred orientation. This shows that a high-modulus carbon fiber can be more easily manufactured from PAN fiber than rayon-based fiber.
The density of the carbon fibers vs. heat treatment temperature curve (Fig. 8) shows a fairly large increase above 2000°C. The electrical resistivity vs. heat treatment temperature curve (Fig. 9) shows three regions: a steep decrease below 1000°C, a slight decrease from 1000 to 2300°C and a very small decrease above 2300°C. Figure 10 shows that the tensile strength of the fibers decreases steadily from 5000-10000 to 2000-5000kgf/cm² with raising heat treatment temperature from 1000 to more than 2500°C. The elongation at the breaking point decreases from 1 to 0.3% with raising heat treatment temperature, as shown in Fig. 12. Young's modulus, as determined from these curves, increases from about 11000kgf/mm² at a heat treatment temperature of 1000°C to 15000kgf/mm² at 3000°C with a maximum at 2000°C, as shown in Fig. 13. The content of the Shindo's paper appeared in Govt. Res. Inst., Osaka, Report No. 317 (1961) in English, which has been widely cited in many articles concerning carbon.

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