Bi-layered oxides SrBi₄Ti₄O₁₅(SBTi) and Nd-substituted SrBi₄Ti₄O₁₅(SBNTi) ferroelectric ceramics were prepared by solid-state reaction methods. At an applied field of 200 kV/cm, the remnant polarization and coercive field (2P_r, E_c) of the SBNTi and SBTi ceramics were (21.1 μC/cm², 101.4 kV/cm) and (10.9 μC/cm², 82.9 kV/cm), respectively, showing a significantly increase of P_r. Both ceramics demonstrated fatigue-free properties up to 1.44×10¹⁰ cycles. The improved temperature-independent dielectric constant and dissipation factor (ε, tan δ) of the SBNTi ceramics than the SBTi ones were also demonstrated experimentally These results provide some guideline to search for new material with large P_r, high T_c, fatigue-free characteristics, and high resistivity.

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The effects of co-doping with Y₂O₃ and Ta₂O₅ on the capacitance-voltage (C-V) characteristics and the SiO₂ interlayer growth of ZrO₂ based gate dielectrics has been examined. The width of the hysteresis window of 8 mol%Y₂O₃ and Ta₂O₅ stabilized ZrO₂(YTaSZ) gate dielectric has been almost 0 V, on the other hands, that of conventional 8 mol%Y₂O₃ stabilized ZrO₂(YSZ) gate dielectric has been 0.5 V. The density of interface trapped charge has increased than that of YSZ. Flat band voltage has been -1 V in YTaSZ larger than that of YSZ (∼0 V). High resolution transmission electron microscope (HRTEM) analysis has indicated that the growth of SiO₂ interlayer and the roughness of interface of YTaSZ are accelerated with the segregation of Ta oxide grains. It is found that this interface reaction cause these problems.

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Undoped ZnO thin films were epitaxially grown on sapphire (0001) substrates by reactive radio-frequency magnetron sputtering using a Zn target and Ar+O₂ gas mixture. The undoped ones with an AlN buffer layer were also grown by the same sputtering apparatus using an Al target and Ar+N₂ atmosphere. Epitaxial ZnO films with a very smooth surface were grown at 600°C. Photoluminescence spectra obtained from ZnO films at a suitable sputtering condition showed dominant band-edge UV emissions with little green luminescence at room temperature. Very strong exciton emissions were observed at low temperatures less than 70 K. Rare-earth elements were doped by simultaneous sputtering oxide pellets or the target. Eu and Er-doped ZnO exhibited emissions from Eu at about 615 and 623 nm and from Er at about 664 nm, respectively.

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Er-doped epitaxial ZnO thin films were prepared on the Al₂O₃(0001) substrates by reactive RF magnetron sputtering using a metal Zn target and a gas mixture of oxygen and argon at 600°C. Er was doped by sputtering an Er₂O₃ target during the ZnO deposition. 1.54 μm light emission intensity was ten times larger than that of Er₂O₃ powder. Dependence of the photoluminescence intensity on excitation light power and wavelength concluded that indirect excitation by energy transfer from the ZnO to the Er is effective in enhancing light emission.

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Finite element method was used to simulate the thermal and stress fields in zirconia thermal barrier coatings on superalloy during the cooling process. The correlations of cooling rate, thermal gradient, crack, sintering and stress were studied. The calculated results show that there is a large thermal gradient in the ceramic layer during initial cooling period. The thermal gradient increases with the increasing of cooling rate. The gradient results in delaminating stress at the edge of the sample with thermal barrier coating (TBC). The results show that cooling rate, sintering of zirconia and preexisted crack length impact the crack propagation during thermal cycles. In the case of thermal cycles, cooling rate is crucial to lifetime of TBCs.

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Dielectric, ferroelectric and piezoelectric properties of barium titanate, BaTiO₃-based solid solution, (1-x)BaTiO_3-x(Bi_1/2K_1/2)TiO₃ (BTBK100x) were studied as a lead-free piezoelectric material. Curie temperature, T_c, of the BTBK100x ceramics shifted to higher temperature with increasing the amount (x) of (Bi_1/2K_1/2)TiO₃ and the T_c at x=0.2 was higher than 200°C. Electromechanical coupling factor, k₃₃, and piezoelectric constant, d₃₃, of BTBK20+MnCO₃ (0.1 wt%) were 0.33 and 54.6 pC/N, respectively.

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A piezoelectric transformer used for AC-DC converters is described that has a multilayered construction in the thickness direction and operates in contour-extensional vibration mode. By using a finite element method, the internal electrode shape was analyzed. The output impedance is designed to be low, approximately several tens of ohms. Tape-casting technique was used to fabricate the multilayer piezoelectric transformers. Testing of a fabricated transformer 14 mm long, 14 mm wide, and 5.8 mm thick showed that it had a 0.4 gain, 30 W output power, and 97% efficiency at 135 kHz when the temperature increase was 30 degrees centigrade. A fabricated AC-DC converter with this transformer had good load regulation and a maximum efficiency of 90.2%. Furthermore, the electrical drive of two piezoelectric transformers with parallel connection was fundamentally investigated, in order to achieve higher electrical capacity of AC-DC converter.

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Electrophoretic deposition (EPD) is a powder forming process in which charged particles in a liquid medium migrate to an electrode under an applied DC electric field (electrophoresis) and deposit on the electrode to form a thick film-like deposit. Various applications in the field of ceramic processing, for monolithic and/or film-like materials and composite and/or three-dimensionally shaped bodies, have previously been reported. For example, excellent applications of EPD include the preparation of laminated composite materials, the deposition of high-Tc oxide superconductors on various metal substrates, the deposition of phosphor materials for display devices and the preparation of fiber-reinforced materials by infiltration of matrix materials into fibers. On the other hand, the theoretical interpretation of EPD, based mainly on colloid chemistry, is not completely understood, especially with respect to the deposition mechanism of the particles. Although a number of theories have been reported in excellent studies of the mechanical, hydrodynamical and chemical effects on the deposition of particles in EPD, there are controversial experimental results which are difficult to explain by these theories. This review paper presents new interpretations of particle deposition in the EPD process, concentrating on the effect of the powder properties, i.e. dispersibility, particle size distribution and packing state. Two novel hypotheses, which focus on the importance of (1) timelag phenomenon in the deposition of particles and (2) packing density and structure of particles, are proposed. Furthermore, experimental proof is presented for the hypotheses using Al₂O₃ powder in measurements of the deposition efficiency under EPD and its relation to the particle size distribution of starting material.

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A classification method of particle size distribution and a quantification method of smaller-sized particle-content distributed between the larger particles were presented. Filler-powder of semiconductor-packaging compound was comprised of the 3 kinds of fillers, i.e., small, medium and large sized filler-powders; but their evaluation work was limited. We considered an intrinsic classification ability of conventional particle size analyzers. Small & large filler-powder ratios were calculated from the ratios of 10% and/or 90% diameters of cumulative under-size distributions of electrical sensing zone and light diffraction/scattering methods. The small & large filler-powder ratios enabled to describe the difference of moldability between conventional-purity and high-purity silica-fillers. The small filler-powder ratio was in proportion to the viscosity of conventional-purity filler-powders, and the large filler-powder ratio was proportional to the viscosity of high-purity ones. However, the previous-used indices, i.e., mean diameter, surface area, exponent-number of Rosin-Rammler distribution, failed to quantify the moldability change.

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This paper investigated the preparation of Mg-α SiAlON ceramic from mixtures of talc (Mg₃(Si₂O₅)₂(OH)₂) and halloysite clay (Al₂Si₂O₅(OH)₄). Firstly, Carbothermal Reduction-Nitridation (CRN) of these raw materials mixtures was used to synthesize Mg-α SiAlON powders. Subsequently, densification of Mg-α SiAlON ceramic using these as-synthesized powders was attempted through gas pressure sintering (GPS) method. The effects of sintering additive on the density and phases of sintered bodies were investigated. As a result, in the case of without sintering additive, phase transformation to β-SiAlON was enhanced with elevating temperatures. In contrast, the sample doped with α-Si₃N₄ was fully densified after sintering at 1950°C for 2 h and a main phase was α-SiAlON. The sintered density of Mg-α SiAlON ceramics composed of fine and uniform grains was higher than 3.10 g/cm³, hardness was above 1700 MPa, and fracture toughness (K_IC) reached 4.6 MPam^1/2.

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Halloysite is one of the kaolin minerals with a tubular form. High-resolution transmission electron microscope (HR-TEM) images of tubular halloysite could be taken, but this required extreme care because its structure easily changes to an amorphous state by the equipment's thermal-electron beam. The selected area diffraction (SAD) pattern showed that the halloysite has a monoclinic structure as a dehydrated form of halloysite (0.7 nm of (001) spacing). Along the c-direction, two types of lattice fringes were observed in the HR-TEM images: one is a lattice image with a periodical distance of 0.7 nm spacing and the other consists of stripes caused by domains with 5-10 nm thickness.

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To data, the quartz-glassy crucible waste, which is obtained in the production of silicon-single-crystal ingot, has been simply reused as a refractory raw-material, or discarded. The present study is concerned on the advanced recycling-technology, which is based on a micro-particle preparation process in order to produce fine amorphous silica filler for EMC (Epoxy Molding Compound). The paper deals with the physical, chemical and thermal pre-treatment processes to remove impurities effectively, and the micro-particle process for producing the amorphous silica-filler.
The results have shown that, if the contained impurities were eliminated through the application of above mentioned pre-treatment processes, the purity of the product is almost equal to the original anhydrous quartz glass. Therefore, the spent fused glassy crucible has sufficient value for recycling. Examination of the poured ingot has shown that there is no phase transformation of crystallization by the heat treatment (heat hysteresis phenomenon). Since the fused silica is in the amorphous state, the possibility of re-cycling of the material is considered to be very high.

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Recent studies on creation of photonic crystallized structures in glass will be described in this review. Concept for photonic crystallized glass and several interesting topics in related with the subject will be presented as following: 1) The largest second-order optical nonlinearity in thermally crystallized Ba₂TiGe₂O₈ (BTG) glass has been obtained ever reported. 2) Novel processing of ultraviolet laser-induced nano-crystallization has been developed, and single-crystalline patterning by CW-YAG laser irradiation through the atomic heating has been investigated and demonstrated for the first time in glass-based materials with second-order optical nonlinearity. 3) Origin of permanent second-harmonic generation (SHG) in GeO₂-SiO₂ crystallized glass films has been found and clarified. In addition, a new technique for enhancement of the permanent SHG by means of modification on defects state has been demonstrated.

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Transparent crystallized glass consisting of nonlinear optical crystal is a promising material with permanent properties on second-order optical nonlinearity. Challenges, to obtain the largest second-order optical nonlinearity ever reported, have been performed by taking account of novel glass composition for crystallization, i.e., systems and stoichiometry in crystalline/glass phases. New transparent crystallized glasses have been successfully fabricated from the glasses with the exact or close stoichiometric composition corresponding to crystals, and their second-order optical nonlinearities are presented in this article. We found that the d₃₃ value of a transparent crystallized glass with stoichiometric composition of optical nonlinear crystal was equivalent to that of corresponding single crystal. Moreover, the very large d₃₃ value, being comparable to that of LiNbO₃, was achieved in the newly developed transparent crystallized glass with Ba₂TiGe₂O₈ crystal.

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Recent studies are reviewed on nucleation and growth mechanism, method of evaluation of nucleation rate and its application for the development of functional glass-ceramics. The functional glass-ceramics include optical, photonic, electric, magnetic, mechanical and thermal properties. Crystallization proceeds via surface and bulk nucleation, and oriented or randomly oriented crystal growth, and in finely distributed structure or densely packed crystal package. In the present paper some of the typical applications are reviewed. Infrared transmitting chalcogenide glass-ceramics and dental glass-ceramics are applications fully or partially optical use. CuCl and CuBr particle precipitation from glass on heating and BaTiO₃ crystal or silver particle deposition on an irradiation of glass by femtosecond laser are photonic applications. Barium hexaferrite (BaFe₁₂O₁₉), lead titanate (PbTi₄O₉) precipitation and frozen-in α-AgI glass are included in the electro-magnetic applications. Anorthite (CaAl₂Si₂O₈) and gehlenite (Ca₂Al₂SiO₇) glass-ceramics from glass sintering method, additive influence in the fluorphlogopite machinable glass-ceramics, oxynitride glass-ceramics and glass-ceramics from industrial wastes (by-product cement dust) are involved in the mechanical and thermal properties application. Crystallization mechanism of tape cast bioactive glass is of a special concern. Pressure induced nucleation and electrically activated crystallization and oriented crystal growth on ultrasonic treated glass surface are of general interest.

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Lead germanate glass of good optical quality was synthesized by fusion of components and subsequently casting in air atmosphere. The absorption spectrum from near-infrared to visible was obtained and the Judd-Offelt parameters were determined from the absorption bands. Emission cross section at 1.53 μm and the excited state lifetime were determined from the measurements. Pumping with 976 nm beam from a LD pump resulted in the emissions centered at 547 and 659 nm due to the ⁴S_3/2→⁴I_15/2 and ⁴F_9/2→⁴I_15/2 transitions in Er³⁺ ions, respectively. Theoretical and experimental lifetimes were determined and the results were discussed.

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Er³⁺-doped 50SiO₂-(50-x) PbO-xPbF₂ glasses were prepared. The effect of PbF₂ content on refractive index, density, absorption spectra, the Judd-Ofelt parameters Ω_t (t=2, 4, 6), fluorescence spectrum and the lifetime of 4I_13/2 level of the glass samples were investigated, and the stimulated emission cross-section was calculated from McCumber theory. With increasing PbF₂ content in the glass composition, the Ω₆ parameter, fluorescence full width at half maximum (FWHM) and lifetime of 4I_13/2 level of Er³⁺ increase, while refractive index and density decrease. The FWHM value is related to the Ω₆ parameter, and the lager the Ω₆ parameter, the broader the FWHM. Compared with other glass hosts, the gain bandwidth properties of Er³⁺-doped 50SiO₂-50PbF₂ glass is close to those of tellurite and bismuth glasses, and has advantage over those of silicate, phosphate and germante glasses.

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A continuous-wave (CW) Nd:YAG laser operating at a wavelength of 1064 nm is irradiated to Sm₂O₃ and Dy₂O₃ doped glasses under various conditions in the systems of Ln₂O₃-Bi₂O₃-B₂O₃ and Ln₂O₃-BaO-B₂O₃ (Ln: Sm and Dy), and nonlinear optical Bi_1-xSm_xBO₃ and β-BaB₂O₄ (β-BBO) crystals with the shape of dot or line are formed on the surface of glass substrates. It is demonstrated from the azimuthal dependence of second harmonic intensity that β-BBO crystal-lines are single crystals with the c-axis orientation along the laser scanning direction. The photoluminescence spectra indicate that Sm³⁺ and Dy³⁺ are incorporated into β-BBO single crystal-lines. The present study proposes that CW Nd:YAG laser irradiation to glass with Sm³⁺ and Dy³⁺ is a novel technique for a spatially selected crystallization in glass.

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The glasses containing a large amount of TiO₂ are considered as eco-optical glasses with high refractive index and low density. In the present work, the phosphate glasses with high TiO₂ content, which have been developed as electronic conduction glasses and are black in color due to the inclusion of relatively large amount of Ti³⁺ ions, were attempted to be made applicable as novel eco-optical glasses. Colorless and transparent Ti³⁺-free titanophosphate glasses (60-74 mol% TiO₂) were successfully obtained by re-heat-treating the black glasses near glass transition temperature in the air. Binary glasses thus obtained possessed high refractive index (1.8-2.0), high dispersion and low density (3.0 g•cm^-3 at most). Furthermore, the Abbe number, glass transition temperature and thermo-optic coefficient were modified by the introduction of La₂O₃, ZnO and K₂O, respectively, into the 60TiO₂•40P₂O₅ glass.

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The surface tension in xBi₂O₃-(100-x)B₂O₃ (x=0∼100 mol%) binary melts has been measured by the ring method in the temperature range, 973 to 1373 K. The compositional dependence of surface tension has been investigated. The surface tension values of the phase-separated region (0∼20 mol%Bi₂O₃) were close to that for pure B₂O₃. Beyond this region the surface tension increased sharply with the increasing Bi₂O₃ content, showing a maximum at 70∼80 mol%Bi₂O₃, and then decreased with further addition of Bi₂O₃. The behaviour of surface tension was discussed on the basis of the Gibbs' adsorption rule and the ionic potential of bismuth ion. In the phase-separated region (0∼20 mol%Bi₂O₃), the temperature coefficient of surface tension in Bi₂O₃-B₂O₃ binary melts had the values of pure B₂O₃ with positive value. It changed from positive to negative in the range of 30 to 80 mol%Bi₂O₃, with the minimum value at 40 mol%Bi₂O₃ and decreased with further addition of Bi₂O₃ over 80 mol%Bi₂O₃. The temperature coefficient of surface tension was discussed in terms of the coordination number of boron in crystalline polymorphs and the volume expansion coefficient of the melt.

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Crystallization process of ZnAl₂O₄:Cr³⁺ and variation of optical absorption and fluorescence spectra accompanied by the crystallization have been examined for Cr³⁺-doped aluminosilicate glasses in ZnO-Al₂O₃-SiO₂ system with and without TiO₂ and ZrO₂. By the heat treatment of glasses, ZnAl₂O₄ is precipitated as a main phase for both compositions. It is clear that addition of TiO₂ and ZrO₂ as a nucleation agent is effective for the reduction of size of crystalline phase, leading to transparent glass-ceramics. In the crystallized specimens, the fluorescence due to the transition from ²E_g to ⁴A_2g is clearly observed and an increase in crystal field strength for Cr³⁺ caused by the crystallization is revealed on the basis of variation of optical absorption and fluorescence spectra, suggesting that the Cr³⁺ ion are predominantly present in the ZnAl₂O₄ crystalline phase in the glass-ceramic specimens.

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We have developed a system for in-situ observation of glass melts under high magnetic field up to 10 T. Thermal convection in binary potassium phosphate melts was observed under vertical and transverse magnetic fields. Above 1 T, the flow velocity of the convection decreased to one-third of the velocity at 0 T in the melt of low potassium content glass by applying vertical and transverse magnetic fields. Contrary to this, the flow velocity increased in the melt of high potassium content glass by applying transverse magnetic fields of around 1 T. It was deduced that different electro-magnetic forces act on positively charged potassium ions and negatively charged clusters consisting of PO₄ tetrahedra resulting in the attenuation or acceleration of the flow velocity of the melts.

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The low alkali-containing glasses (5 mol%) based on Alkali-Alumino-Borosilicate glass system, SiO₂-B₂O₃-ZrO₂-Al₂O₃-R₂O(Na₂O+K₂O)-RO(MgO+CaO+SrO+BaO)-ZnO were prepared for plasma display panel (PDP) application. Then, viscosity and thermal, mechanical, and optical properties were characterized by using Rotation Cylinder Viscometer, thermal mechanical analyzer (TMA), 3 point bending strength tester, Vickers hardness tester, and spectrophotometer. The glass transition temperature and coefficient of thermal expansion of the parent glasses were 637∼661°C and 85.7∼90.7×10^-7/K. Working temperature (log η=4/dPa•s) and melting temperature (log η=2/dPa•s) were 1048∼1062°C and 1297∼1329°C respectively. Liquidus temperature was 1023∼1047°C. Bending strength and hardness were 54.9∼58.8 MPa and 4.7∼4.9 GPa. Transmittance of S2 glass was 90∼92.6% in the range 400∼800 nm and the highest value was 92.6% at 698 nm. The results support that these glasses would be suitable as a new glass substrate for PDP application.

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Thick film photolithography enables finer line and space resolution compared to the conventional thick film process and a similar level of packaging density can be achieved when compared to thin film or etched thick film circuits. Because of the better line-edge definition than that of the screen-printed line, improved characteristics can be obtained at RF and microwave frequencies. In this paper, small size, fine line inductors buried in LTCC were fabricated by thick film photolithography. Photosensitive silver conductor paste was developed, which could be matched with the shrinkage of low temperature co-fired glass-ceramic composite. The test coupon showed line and space resolution below 30 μm and clear edge definition compared with screen-printed patterns. Buried inductors with fine lines were fabricated using the developed photosensitive silver paste and measured by a network analyzer. Inductance at 100 MHz, self-resonant frequency, and the quality factor of buried fine-line inductors were calculated from the measured data. Small-size, fine-line buried inductors showed reliable inductance and quality factor, and enabled the miniaturization of the LTCC body.

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Elastic moduli of some binary tellurite glasses were measured by using a cube-resonance method. The glass systems employed were MgO-TeO₂, ZnO-TeO₂, MoO₃-TeO₂, and WO₃-TeO₂. Young's moduli of most glasses can be predicted using the compositional parameters based on the Makishima-Mackenzie theory. In the systems containing divalent cations (Mg²⁺ or Zn²⁺), Young's modulus of MgO-TeO₂ glass was larger than that of ZnO-TeO₂ glass because of the higher dissociation energy of MgO. In the case of the glasses containing hexavalent cations (Mo⁶⁺ or W⁶⁺), although the dissociation energy and the packing factor of MoO₃ and WO₃ are comparable with each other, Young's modulus of MoO₃-TeO₂ glass was smaller than that of WO₃-TeO₂ glass. This is due to the change in oxygen coordination state of a hexavalent cation. A less contribution of doubly bonds around Mo⁶⁺ to the mean bond-strength in glass would be one of the reasons for the difference in Young's modulus. The larger molar volume of MoO₃-TeO₂ glass also supports this loose structure.

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Mn²⁺-doped GeO₂-B₂O₃-ZnO (GBZ) glasses were investigated and developed as efficient long-lasting phosphorescence host materials. Surface crystallization phenomenon occurred when the Mn²⁺ doped 25GeO₂-25B₂O₃-50ZnO glasses were heat-treated at 706°C for 30 min. By X-ray diffraction measurement, it is clarified that Zn₂GeO₄ crystallites with a diameter of about several μm are precipitated on the sample's surface after heat-treatment. A red long-lasting phosphorescence from Mn²⁺ was observed in the 25GeO₂-25B₂O₃-50ZnO glass matrix, however, a very strong long-lasting green phosphorescence was observed in the phase of Zn₂GeO₄ crystallites. This phenomenon is considered due to the different ligand field environment surrounding Mn²⁺ ions in the glass and the glass-ceramics. A possible mechanism for the long-lasting phosphorescence in the Mn²⁺-doped glass was discussed.

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With the aim of developing a simulation technique usable for a glass refining process, the possibility to reproduce the redox reaction of arsenic ions in a soda-lime glass with molecular dynamics simulation was explored by two charge transfer models based on an empirical charge-transfer function and a theoretical concept of electronegativity equalization. In the former model the charge increases as temperature is raised. While, the latter gives the charge a decreasing trend with increasing temperature. The final conclusion for a suitable model for the refining process is not yet given because it turned out that much further effort is necessary. As far as known to the authors this study is the first approach to investigate the refining phenomenon by an atomic-scale simulation.

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Liquid-liquid phase separation in glassy thin films prepared by a Sol-Gel method has been studied in Na₂O-SiO₂ systems. 18Na₂O-82SiO₂ (mol%) films were coated on SiO₂ substrates using a spin coating method. The effects of the heat treatment, sodium content and thickness of the coatings on the morphology of the phase separation were examined. The distribution of sodium concentration in-depth profiling in the film was measured by X-ray photoelectron spectroscopy (XPS). Although the phase separation was not observed on the surface of the annealed film, it was observed on the surface of the film etched by HF solution. The microstructure of the phase separation was different from that of the bulk glasses with similar composition and was strongly influenced by the Na distribution along the depth of the film. It was noted that the diameter of the droplets prepared by phase separation increased with the thickness of the films.

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Surface passivation with glass frits, which is aimed at reducing the unstable influence of the semiconductor surface on the electrical behavior, is used for high voltage silicon power devices. In this study, PbO-Al₂O₃-SiO₂ glass was prepared by sol-gel process, and its properties were studied by differential thermal analysis (DTA), X-ray diffraction (XRD) and particle size analysis (PSA). Glass passivation films were made on the silicon surface by screen-printing. Heat-treated glasses and glass/silicon interfaces were analyzed by XRD, thermal mechanical analysis (TMA), and capacitance-voltage (C-V) curve of a metal-insulator-semiconductor (MIS) structure. The coefficient of thermal expansion (CTE) of the heated glass at 820°C showed the value of 3.0×10^-6 K^-1 equal to that of Si wafer. It is found that the CTE of the glass similar to that of the Si wafer is important factor to obtain reliable C-V curves with MIS structure.

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A molecular dynamic simulation with 2+3 body interactions was performed to investigate the structural changes in the sodium germanate melts. It has been widely accepted that the octahedral GeO₆ units change into tetrahedral GeO₄ units and non-bridging oxygen is formed while the glass is melting. Such the structural changes were confirmed in the simulations. Furthermore, oxygen atoms surrounded by three Ge atoms were also formed in the structural models, and the relative amount of the 3-fold oxygen decreased during the heating simulations. From these results, the glassy and molten states could be characterized by the edge-sharing connections by GeO₆ units and the corner-sharing open structures by GeO₄ units, respectively.

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ZrO₂-WO₃-Al₂O₃ glasses were prepared by means of the melting and quenching method, and their thermal expansion, together with density and infrared absorption spectra, were measured. The thermal expansion was determined by using thermomechanical analyzer (TMA). The glass-forming region was in the range of ZrO₂ 5-25, WO₃ 65-75, Al₂O₃ 5-15 mol%. The thermal expansion coefficients of the glasses in the system ZrW₂O₈-Al₂(WO₄)₃ were 25×10^-7 K^-1, which is lower than that of pyrex. The results of density and infrared absorption spectra indicated that tungsten ions in these glasses take the 6-coordinated state, and aluminum ions the mixture of 4- and 6-coordinated states.

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TeO₂-based glass ceramics was prepared by crystallizing the glass. Strength and toughness of the glass ceramics were higher than those of the glass. Intrinsic fracture toughness of the glass ceramics could be evaluated by the SEPB (Single Edge Pre-cracked Beam) method, while fracture toughness evaluated by the IF (Indentation Fracture) method depended on indenting load. The glass did not show second harmonic generation (SHG) but the glass ceramic did. Intensity of SHG decreased with polishing the specimen surface and with decreasing the cooling rate during the crystallizing process. Residual stress on the specimen surface was measured by the indentation method. Effects of surface polishing and cooling rate on residual stress accorded with those on intensity of SHG. Applied compressive stress also affects on SHG. Therefore, distortion of crystal structure due to residual stress and applied compressive stress may take an important role on SHG.

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Second-order optical nonlinearity induced in thermally crystallized Ba₂TiGe₂O₈ glasses with a stoichiometric composition, 40BaO-20TiO₂-40GeO₂ (BTG-40), has been investigated for the first time. Induced second-order optical nonlinearity, d-coefficient, was approximately 10 pm/V in crystallized BTG-40 for the largest case in our experiment. Measured d-coefficient was increased with increasing temperature of heat-treatment for crystallization, and then saturated. Similar temperature dependence of d-coefficients was also observed in Sr-doped BTG-40 to clarify a change of d-coefficients by means of systematically structural modification in crystalline phase. It has been found that the increase and/or optimization of d-coefficients can be caused by Sr-doping, which is characterized by anisotropy of lattice constant parameter, c/a, in crystallized glasses.

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Sintering behavior and pore structure of 60 mass% kaolin-40 mass% Al₂O₃ ceramics have been studied. Linear shrinkage of the heated sample occurs during the dehydration and transformation of kaolin, sintering process and mullite formation. The sintered sample shows a normal pore size distribution in which the average pore diameter increases from 0.6 to 1.5 μm with the sintering temperature increasing from 1373 to 1873 K for 1 h. Apparent density is about 2.97∼3.07 g cm^-3 and reveals an opposite trend to open porosity. Open porosity decreases from 48.5 to 37.2% when the sintering temperature increases from 1373 to 1673 K; but it increases to 39.6% as sintered at 1773 K. Both of the linear shrinkage and open porosity reveal a decrease trend as sintered at 1473 K for duration from 1 to 7 h; however, they show an increase tendency as sintered at 1723 K.

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In Japan, various wastes are used in cement rotary kilns as raw materials or fuel, and their types and throughput has increased recently. More usage of wastes causes rapid wear of basic bricks. According to postmortem analysis data of used basic bricks in the burning zone and the transition zone of cement rotary kilns, causes of the brick wear were studied. In the burning zone, thermal spalling would occur during heating-up and initial operation period and/or heavy erosion would take place in service. In the transition zone, bonding strength of the heated surface-layer of the basic bricks was lowered by repetitive temperature fluctuation and the reaction with sulfur oxide. Then the deteriorated bricks were exposed to external stress and spalling takes place.
Wear mechanisms of the bricks in the burning and the transition zones of cement rotary kilns were presented and the reaction of the bricks with sulfur oxide was especially noticed.

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In the function and performance of the cement and concrete, or in its time-dependent changes under the service environment, the distribution of elements, microstructure, and material transfer in the region of the nanometer digit take part deeply. In order to realize “material design” of the cement and concrete exhibiting the designated performance, and to realize a reliable concrete structure, it is indispensable to control its material transfer, chemical reaction, and structure formation in the region of nanometer under manufacturing condition and the service environment. Recently, together with the development of science and technology, characterization methods in the region of nanometer were developed, and the analysis of the phenomena in the nanometer region using these nano-technologies, was being advanced. In this report, the application in the nano-technology in the field of cement and concrete research in recent years, is reviewed.

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Since cracks induced by thermal stress or shrinkage stress cause initial defects in concrete structures, measures against the cracks have so far been taken by material used, construction methods, and so forth. This research evaluated reduction effect of thermal stress using a temperature-stress testing machine (TSTM) when expansive admixture or shrinkage-reducing agent was added to low heat portland cement. Furthermore, effective Young's modulus used for thermal stress analysis was calculated based on test results.

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A cement suitable for the Autoclaved aerated concrete (AAC) was developed. The cement in which the C₃S, fineness (Blaine), and hemihydrate (H)/gypsum (G) ratio (H/(H+G)) changed was produced experimentally. Using this cement, the effect of the cementitious property on the viscosity of the AAC slurry and the hardening of the AAC green cake was clarified. Though H/(H+G) influences viscosity, C₃S and Blaine do not. On hardening, it quickens, as C₃S is more abounding as Blaine is higher, and as H/(H+G) is lower. Since the cuttable time shortens on Blaine 4300 cm²/g, and H/(H+G)=0% is not desirable. The effect of H/(H+G) on slurry viscosity and hardening was regarded as the reactivity of C₃A and generation of the ettringite. The hydration temperature of the cement in AAC is higher than ordinary cement paste, and the rapid supply of SO₄ ^2- from hemihydrate of which the solubility is high is required, since the hydration of C₃A is extremely active. The characteristic of the cement suitable for AAC consists like as follows; a) HC with many C₃S is made as a base. b) The Blaine is desirable at around 3800 cm²/g. c) Hemihydrate and gypsum are coexistence. The adaptability was confirmed by the factory scale test.

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Comb-type superplasticizers are used for producing self-compacting concrete and high strength concrete, and improving concrete durability. To establish the fluidity control technology for concrete with these polymers, it is necessary to clarify the relationship between the adsorption mechanisms, dispersion mechanisms and molecular structures of comb-type superplasticizers.
In a previous paper, we reported the influence of various types of inorganic electrolytes on the adsorption mechanism of comb-type polymers. When the dosage of inorganic electrolytes that form insoluble calcium salts increased, the apparent viscosity of CaCO₃ suspension rapidly rose, and the Ca²⁺ concentration in the liquid phase of suspension was rapidly decreased. Furthermore, the comb-type polymer with the larger content of carboxyl groups on the main chain may be adsorbed more, even though the adsorption sites decreased.
This paper discusses the influence of molecular structure and composition of copolymer for comb-type polymers on the fluidity of CaCO₃ suspension with K₂CO₃ or K₂SO₄. When a larger amount of functional groups (-SO^3-/-COO^-) was introduced onto the main chain, or when the distance between the grafted chains was extended, the influence of inorganic electrolytes on the fluidity of CaCO₃ suspension with comb-type polymer was decreased. These comb-type polymers can be adsorbed onto limestone powder even though the adsorption sites were decreased when inorganic electrolytes were added. In contrast to the case of CO₃ ^2-, the addition of SO₄ ^2- may possibly cause shrinking of the polymer chains as well as hindering the adsorption of the comb-type polymer. Comb-type polymers containing graft chains with some extent of chain length are effective for preventing the fluidity decrease when SO₄ ^2- is added. It is clear that the interval of the graft chain, the composition of copolymer, and the chain length of the grafted polymer for comb-type polymers is important for controlling the fluidity of the suspension with comb-type polymers.

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Many amorphous hydrates layers are produced in the process of cement hydration, who control the rate of hydration. It is well known that the induction period in the hydration of C₃S or alite is the result of the protective layer produced. Here, we will report that the amorphous layer was produced and affected the rate of hydration in several cases. They are in the case of the hydration of C₃A with gypsum, the hydration of crystalline or amorphous C₁₂A₇, the hydration of C₄A₃S with H₃BO₃ and the hydration of C₄AF with SiO₂.

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A major factor in energy consumption associated with concrete and other cement-based building materials is that used on producing portland cement. Increasing the reactivity of less reactive materials is one way to reduce energy consumption, and also to reduce CO₂ emissions. The other way is to produce cement-based materials with higher performance and so use less material overall. This paper discusses various strategies to achieve these goals. Producing more reactive dicalcium sillicate (C₂S) during clinkering reactions, or forming highly reactive, high surface area C₂S by chemical synthesis, are two approaches that have received much attention. Autoclaving lime-silica mixtures is a well established technology which has been re-examined recently, and alkali-activated aluminosilicates are widely used in some countries. Mechano-chemical processing is a promising new route to benign processing of construction materials. Finally, extrusion of high-volume, fiber-reinforced cement-based composites is a promising new technology.

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Increasing environmental concerns highlight the need to build up a sustainable society based on recirculation of our limited natural resources. The authors have been studying the application of hydrothermal solidification for the recirculation of inorganic waste materials with lesser energy at the waste heat level. The wastes generally contain higher amount of Al₂O₃, yielding the formation of large hydrogarnet crystals as the prevention factor of the strength development of hydrothermal solidification. It was found that the formation of nano-size hydrogarnet crystals by the controlling of reaction condition enables the strength development on the hydrothermal solidification of wastes. Similarly, the formation of nano-size zeolite crystals gives high strength. It was expected that these solidified waste materials show the self-humidity controlling property and the fixation of heavy metals through ion exchange.

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As a step towards sustaining our present life style into the future, it will be necessary to develop cycles involving the conversion of various industrial wastes into functional ceramics, encouraging and enhancing re-cycling and re-use of materials. This paper presents a case study on the preparation and properties of products from waste paper and paper sludge. Since paper contains cellulose fibers and ceramic powder fillers and coating materials (kaolinite, calcite, talc, etc), we have developed methods for producing activated carbon from the cellulose and calcium aluminosilicate from the ceramic powder components of waste paper and paper sludge. The activated carbon showed excellent adsorption properties for various gases and ions. The amorphous calcium aluminosilicate showed a high uptake selectivity for heavy metal ions and the ability to maintain a neutral pH.

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TEM observation showed that densely assembled TiO₂ nanorods have been synthesized by heating-sol-gel template process in a diameter of 150∼200 nm and a length of several micrometers by adjusting the dip coating time, dry temperature, dry time, aging period of TiO₂ sol and the molar ratio of precursors. XRD proved that the obtained nanorods were anatase-TiO₂ nanorods. TEM image revealed that the nanorods were the aggregates of many nanoparticles with about 10 nm in diameter and indistinct polygonal shape. The results of SAED and EDS under TEM confirmed that the obtained nanorods were single-phase anatase-TiO₂ with good compositional uniformity in the entire length along the rod axis.

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An investigation of the reduction of magnesia and chromia by graphite and aluminum was carried out using a nonisothermal gravimetric technique under an argon atmosphere, in a temperature range from 600 to 1973 K. In the case of MgO-C system, the reduction ratio obtained by using charcoal is larger than that by using graphite. An excess charcoal addition increases the reduction ratio. The activation energy is 192.4∼208.1 kJ/mol. The Boudouard reaction has a large influence on the reaction rate. In the case of MgO-Al system, magnesia is reduced by aluminum to form magnesium and spinel at first, and then the excess aluminum reacts with the spinel slowly. The reaction rate is affected by pellet-forming conditions. The activation energy of the reduction of magnesia by aluminum is 151.2 kJ/mol. In the case of Cr₂O₃-C system, the reduction reaction proceeds through two steps. At first, chromia is reduced by graphite to form chromium carbide, and then the rest of chromia by the chromium carbide. The excess graphite addition increases the reduction ratio, but chromium carbide and not chromium is obtained.

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For the purpose of carbon dioxide (CO₂) capture at high temperature, Toshiba developed a series of novel CO₂ absorbents using lithium-containing oxides. Among these absorbents, lithium orthosilicate (Li₄SiO₄) shows highest reaction rate of CO₂ absorption and emission, which result in weight change of up to 36%. Furthermore, the emission was performed at a much lower temperature than that of CaO.
This paper is our first report regarding reproducibility of CO₂ absorption and emission using Li₄SiO₄ absorbent in the shape of cylindrical pellet. The pellets were heated at 600°C for absorption and 800°C for emission in a gas flowing condition of 20% CO₂ up to 50 cycles. The reproducibility was evaluated by the retention ratio of absorption rate to the initial one. In addition, the degradation mechanism of reproducibility was investigated in term of the change of microstructure.

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In a loose abrasive polishing of a silicon wafer, the polishing slurry is discarded as waste. In This study, we have devised a new polishing pad (the LHA Pad) that reduces the amount of waste. We examined the amount of waste and the polishing performance of the LHA Pad. The LHA Pad is found to reduce the amount of waste to 1/200 to 1/10,000, in comparison with the loose abrasive polishing. The removal rate and surface roughness of the LHA Pad is almost equivalent to the loose abrasive polishing, and the temperature dependence of the LHA Pad is smaller.

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Gas adsorptive properties of dust, which is exhausted from cupola, have been investigated at room temperature. The cupola dust adsorbed some gases, and in particular hydrogen sulfide (H₂S). The adsorptive mechanism for H₂S has been examined through the characterization of the dust by X-ray fluorescence analysis, X-ray diffraction, transmission electron microscopy, measurement of adsorptive capacity, etc. Consequently, it was found that the property was induced by the spinel nanocrystals with 10-50 nm in dimension such as (Mn_xZn_1-x)(Mn_yFe_1-y)₂O₄ solid solutions in the dust. Furthermore, the characterization revealed that the adsorptive capacity of the dust for H₂S was promoted by the NaOH treatment. In addition, it was found that the Mn content of the dust correlates with the adsorptive capacity for H₂S.

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ZnMn₂O₄ spinel ceramics with NTC character were fabricated using a powder recycled from used dry batteries. The recycled powder (IZC) consisting of oxides of Zn and Mn as major solid phases was mixed with given amounts of hydrous MnCO₃ and heated in the temperature range 900°C-1300°C. The ZnMn₂O₄ spinel powders were produced from mixtures with mass ratio of MnCO₃/IZC larger than 1/2 above 900°C. The densification of the spinel powders thus obtained was considerably improved by washing the starting IZC powder with distilled water, which substantially reduced the concentrations of K, S and Cl components contained as impurities. Among oxide additives used to modify the densification and/or electrical properties of the spinel ceramics, the NiO additive (5 mass%) caused a drastic lowering in the electrical resistivity of the spinel sample by about four orders of magnitude at room temperature. Thus, the NiO-doped spinel ceramics obtained from a recycled IZC powder could be applied to a practical NTC thermistor with B=5650 K.

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Pollucite compounds, Cs_1-XAl_1-XSi_2+XO₆ (X=0.0, 0.1, 0.2, 0.25) with cubic symmetry at 298 K, were synthesized by multi-step heat treatment. The synthesized CsAlSi₂O₆ and Cs_0.9Al_0.9Si_2.1O₆ were tetragonal below 223 K and 173 K, respectively, while the synthesized Cs_0.8Al_0.8Si_2.2O₆ and Cs_0.75Al_0.75Si_2.25O₆ were cubic even at 123 K. Cubic Cs_0.75Al_0.75Si_2.25O₆ showed low thermal expansion in the temperature range of 123 to 1173 K, of which the mean linear thermal expansion coefficient in the range of 123 to 1173 K was 1.47×10^-6 K^-1. From the relationship between the thermal expansion properties and lattice volumes of the synthesized pollucite compounds, it was considered that the low thermal expansion properties of Cs_0.8Al_0.8Si_2.2O₆ and Cs_0.75Al_0.75Si_2.25O₆ were due to smaller distortion of the aluminosilicate framework compared to Cs_1-XAl_1-XSi_2+XO₆ (X=0.0, 0.1), and that the formation of space around Cs sites in the unit cells resulted in the cubic structure at 123 K for Cs_1-XAl_1-XSi_2+XO₆ (X=0.2, 0.25).

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