Grain growth behavior in Alumina-Zirconia with small zirconia contents (≤ 5vot%) was examined. The grain growth of alumina was effectively retarded by zirconia particles, regardless of small zirconia contents. The amount of the zirconta particles in the alumina grains increased with decreasing zirconia content and increasing sintering temperature, without abnormal alumina grain growth. Grain growth inhibition of atumina in the Alumina-Zirconia with small zirconia content cannot be simply explained by the model of Zener’s pinning effect.

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PSZ powders were fully densified by microwave heating a microwave oven for cooking. The pressed powder compacts of PSZ were sandwiched between two ZMA ceramic plates acting as preheaters and put in the oven. The PSZ pellet pre-heated by the ZMA ceramics more easily absorbed the miorowave energy and self-heated to a higher temperature. PSZ ceramics fabricated with a microwave oven for 16min exhibited a density of 6.04g/cm³, which is approximately equal to the density of materials sintered at 1450°C for 4h or at 1500°C for 16min by the conventional furnace method. The enhancement of the grain growth was observed in the materials sintered by microwave oven.

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Yttria-stabilized zirconia (YSZ) films were prepared by MOCVD using Zr(dpm)₄, Y(dpm)₃ and O₂ gas, and placed on a PZT piezoelectric actuator. The effect of piezoelectric vibration on the ionic conduction of YSZ was studied at room temperature. The ionic conductivity of YSZ films with the vibration by the actuator increased with increasing the amplitude of vibration.

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Ba(Ti_1-xZr_x)O₃ (x=0-1.0) films were prepared at 973 K and 400 kPa by MOCVD using Ba(DPM)₂, Ti(O-i-C₃H₇)₂(DPM)₂ and Zr(DPM)₄ as sources. Ba(Ti_1-xZr_x)O₃ films showed significant (100) orientation at x≤0.15. The (100) orientation of Ba(Ti_1-xZr_x)O₃ films decreased with increasing x. The dielectric constant (e_r) of Ba(Ti_0.85Zr_0.15)O₃ films showed the highest value at room temperature. The dielectric constant of Ba(Ti_0.85Zr_0.15)O₃ films showed a broad peak around 350 K, and decreased with increasing frequency at less than 350 K. The temperature showing the maximum e_r of Ba(Ti_0.85Zr_0.15)O₃ film shifted from 353 to 363 K with increasing frequency from 1 k to 100 kHz.

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Pb(Zr, Ti)O₃ (PZT) thin films were deposited by pulsed metal-organic chemical vapor deposition (MOCVD) on the MgO, LaAlO₃ and SrTiO₃ substrates. The microstructure of PbTiO₃ thin films were improved by the changing of pulsed MOCVD sequences. In the sequence which has vacuum duration after deposition of PT, Ti-rich composition of PT on MgO was obtained. The PT thin films deposited on SrTiO₃ with vacuum duration showed the lowest surface roughness RMS=0.390nm.

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Epitaxial Pb(Mg_1/3, Nb_2/3)O₃ (PMN) thin films were fabricated on various buffered-Si substrates by pulsed laser deposition (PLD), and the growth behaviors and dielectric characteristics were investigated. For La_0.5Sr_0.5CoO₃ (LSCO)/CeO₂/YSZ/Si and SrTiO₃/CeO₂/YSZ/Si substrates, PMN films were epitaxially grown with (001) and preferred-(001) orientation, respectively. On the other hand, for CeO₂/YSZ/Si substrate, Pb-Mg-Nb pyrochlore was epitaxially grown instead of perovskite phase. This phenomenon was considered from the viewpoints of crystal structural matching and interface stability between film and substrate.

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Single Crystals of xPb(In_1/2Nb_1/2)O₃-yPb(Mg_1/3Nb_2/3)O₃-zPbTiO₃ (PIMNT 100x/100y/100z) have been grown by a flux method. The crystals were grown in a platinum crucible by mass crystallization achieved by the slow cooling of a 50PIMNT:40PbO:10B₂O₃ (mol%) molten solution from 1230°C to 900°C at 1.2°C/h. Obtained crystals had a perovskite structure as in the case of PIMNT ceramics. One of the single crystals near the morphotropic phase boundary (MPB) sbowed a dielectric constant peak of 187°C with a high piezoelectric constant, d₃₃=2,200pC/N.

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Silicon carbide ceramics has been studied as a potentially important structural and an electronic material. In this work, silicon carbide ceramics has been prepared by hot isostatic pressing (HIP) method (capsule free method) under nitrogen atmosphere. The electric property (piezoresistance effect) was discussed from the view points of n-type semiconductor with nitrogen doping.

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Barium titanate powder was CIPed under 1.0 GPa repeatedly up to 60 times. The crystallite size decreased and lattice strain increased with CIPing times. However, the specimen was characterized to belong to the tetragonal phase even after CIPed 60 times. The integrated diffraction intensity of barium titanate was revealed to increase notably by CIPing. The tweedy and/or squeezed texture was analyzed having collapsed boundary zones and modulated array of lattice.

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BaTiO₃ solid solutions containing rare-earth elements used for capacitors with multi-layer structure were prepared and their crystal structure was examined in order to determine preferential solubility site of rare-earth ions in perovskite structures. Since the ionic radius of Sm is in intermediate range between those of Ba and Ti, both Ba and Ti-site replacements can be considered in this study. The occupational site of Sm affected the lattice parameters. Transition mode of Sm incorporation between Ba and Ti-sites was discussed.

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The domain structure in the single crystals of (Bi₄Ti₃O₁₂:BiT) and vanadium-containing BiT was investigated by optical microscope combined with Micro-Raman spectroscopy. The strong anisotropy of the soft mode(s) at 25-30 cm^-1 was observed and the intensity of the soft mode along a axis was much higher than that along b axis. The complex 90-deg domain structure was determined in a-b plane of single crystals. The mobility of the domain wall in V-containing BIT was much higher than that in BIT, and the speed of domain wall motion near Curie temperature (=675°C) was roughly estimated to be 20μm/s, which was four times as high as that in BIT.

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SrBi₄Ti₄O₁₅(SBT) is a candidate for the lead-free piezoelectric materials. The electric properties of SBT are improved by applying a grain orientation technique. SBT was fabricated by OCAP, TGG and RTGG method, and the grain orientation and relative density were evaluated in order to examine the effect of processing methods on grain orientation.

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(Bi, La)₃Ti₄O₁₂ (BLT) thin films were prepared by chemical solution deposition method. The films were grown on various size of Pt-coated Si (Pt/Ti/SiO₂/Si(100)) substrates. The effect of substrate size for structural and electrical properties of BLT thin films was investigated. The drastic orientation changes were observed with the changing of substrate size. The films deposited on lager substrate were c-axis preferentially oriented. However, the film deposited on 1.0 × 1.0 cm substrate was randomly oriented.

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Bi-site ions of BIT were substituted by Nd ions. BNT thin films prepared on Pt/TiO_x/SiO₂/Si substrate were investigated by chemical solution deposition. BNT thin films prepared at 700°C exhibited a high crystallinity. BNT thin films showed a dense microstructure with grain sizes of approximately 200nm. 700°C-annealed BNT thin films showed a well-saturated P-E hysteresis loop. The Pr and Ec values of the BNT thin films were 22.1μC/cm² and 70.5kV/cm, respectively.

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Defect engineering to design for remanent polarization (Pr) and coercive field (Ec) in SrBi₂Ta₂O₉ (SBT) is proposed. Cation vacancies coupled with substituents or oxide vacancies are shown to play an essential role in the polarization properties. High-resolution neutron powder diffraction revealed that trivalent-cation (Bi, La, and Nd) substitution induces Sr vacancies for the requirement of charge neutrality. La substitution with Sr vacancies increased Pr slightly, but the 2Ec value (41 kV/cm) of La-SBT was much smaller than that in SBT (57 kV/cm). Nd-SBT showed almost the same Pr of La-SBT, while the very high 2Ec (125 kV/cm) was attained for Nd-SBT.

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Thin films of BaTiO and SrTiO₃ and their artificial superlattices on SrTiO₃(001) substrate were fabricated by molecular beam epitaxy process. The capacitance and the complex admittance of superlattices were measured by the impedance analyzer at 5MHz-110MHz. The electromagnetic analysis software has been used for the evaluation of the dielectric properties for the ultra thin film with interdigital electrodes formed by the electron beam lithography technique. In this study, it was cleared that the dielectric permittivity was changed by the period of the superlattice. The dielectric permittivity of [(BaTiO₃)₁₀/(SrTiO₃)₁₀]₄ superlattice was lager than those of other specimens.

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(Bi, La)₄Ti₃O₁₂ (BLT) is one of the most suitable materials for nonvolatile ferroelectric random access memories (FeRAMs), because this substance has excellent ferroelectric and fatigue-free properties. In this work, fabrication and characterization of (Bi, Ln)₄Ti₃O₁₂ [Ln:La, Nd, Sm, Gd,] thin films on substrates have been carried out by the chemical solution deposition process. Homogeneous and stable precursor solutions could be are prepared by controlling the reaction of starting metal alkoxide. A heat treatment above 600°C was required for the fabrication of (Bi, Ln)₄Ti₃O₁₂ thin films on Pt/Ti/SiO₂/Si substrates with high crystallinity. A crystallinity of the thin films was found to depend on substituent ions. Dielectric and ferroelectric properties of synthesized films were also evaluated.

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Spray freeze drying (SFD) method was developed to fabricate ceramic powder granules with high homogeneity for high performance ceramics. In this study we prepared high density granules from high solid loading slurry through the SFD technique. Granules obtained through SFD were characterized with SEM, immersion liquid technique and powder tester. The ceramics prepared from the spray freeze dried granules (SL 40vol%) had the mean strength of 510MPa and the Weibull modulus m=17.5.

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First, alumina powder was synthesized from aluminum nitrate solution using a spray-pyrolysis aparatus. Obtained alumina powder was compacted and calcined at different temperature. Then, YAG solution was impregnated into the calcined compact. After that, these compacts were dried. This process repeated several times. Finally, they were hot-pressed. Concentration of YAG after 5 times impregnation and then hot-pressed at 1500°C was about 43vol.%. The bulk density of the composite was 4.07g/cm³ and bending strength was about 800MPa.

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Enlarged particles are aligned in the perpendicular direction of pressing. This particles alignment or particles orientation causes the anisotropy in the sintering shrinkage. The aim of this study is to correlate granules packing structure with particles alignment in the pressing and shrinkage anisotropy. In the initial stage of sintering, Notable difference was observed in the sintering shrinkage of samples fabricated by loosely and densely packed granules. Loosely packed granules presented more anisotropic shrinkage than densely one. In the final stage of sintering, both samples showed isotropic shrinkage.

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The alumina granules were produced with the various quantities of PVA. All granules created so far were almost solid spheres. The strength of individual granule was directly measured by the micro compression-testing machine, and the influence of the granule characteristic on the green bodies was studied. It turned out that the strength of a granule was influenced in the range of these granule produotion conditions by only the quantity of PVA. It was found that the compaction behavior was strongly affected by the granule characteristic.

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TiO₂ was HIPped at 1100,1200,1300°C under 50,200MPa. Grain sizes in the HIPped TiO₂ were measured. The effect of HIPping pressure on the grain growth was discussed. As the results, in the initial stage of sintering, HIPping pressure promoted grain growth. But in the final stage of sintering, HIPping pressure suppressed grain growth.

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Pore structure was directly observed by dyeing of fluorescence in pores. The mixture of fluorescence dye and immersion liquid was filled into pores of alumina green body which was thinned previously. Images were obtained by a confocal laser scanning microscope. Several pictures were taken at a specific change of focusing position in the specimen. Three-dimensional pore structure was reconstructed from these pictures in a computer.

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Influence of coarser grains on sintering of AlN was investigated. Densification of AlN was limited by addition of coarser grains. Large pores were observed near the coarser grains. Local porosity showed higher value in the vicinity of coarser grain than any other area. It was found that the pore grew up during sintering. These phenomena probably resulted from not only inhomogeneity of density of green body but also insufficiency of oxygen near coarser grain.

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Two different slip casting methods(the vertical and rhombus casting) were tested to examined the relationship between the casting methods and cracks or deformation on the plate after firing. The crack was observed on the plate oast by the vertical casting. The slight deformation was observed on the upper sides of the plate by the rhombus casting.

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Industrial powders were ground to eliminate aggregates using an attrition beads mill. The effect of grinding was studied on characteristics of green body with slip casting method. Eliminating aggregates in green bodies by beads milling were observed using a laser scanning fluorescence microscope. Porosity of specimens made using ball milling and beads milling were 40% and 37%, respectively.

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The particle packing structure with regard to the particle orientation of the green sheet was examined with a polarized light microscope. The particle orientation was found in the cross-sectional plane. There is almost no particle orientation in the surface plane of the green sheet.

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Oriented zeolite films were successfully synthesized on ceramic substrates using bulky glasses as a source material of Si element. The silicalite-1 films obtained by hydrothermal treatment at 473 K for 14 days strongly oriented to the (0k0) face, i.e., micropores of silicalite-1 were vertically aligned on the substrates.

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Cs_0.9Al_0.9Si_2.1O₆ is an aluminosilicate compound showing a low thermal expansion property. In this work, the porous body of Cs_0.9Al_0.9Si_2.1O₆ was fabricated by an addition of PMMA. When 40wt% PMMA was added, the porous body fabricated by a heat treatment of 1400°C for 20h, had the relative density of 46% and showed the thermal expansion rate of 0.105% with a small hysteresis. Thus it was found that the porous body of Cs_0.9Al_0.9Si_2.1O₆ showed a further low-thermal expansion property.

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Porous alumina-based ceramic with high open porosity was fabricated by using the hydraulic alumina-based inorganic binder. Hydraulic properties of the alumina-based binder and forming and sintering of the binder mixed powder was studied.

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Although hydroxyapatite is a major inorganic constituents of bones and teeth, it is known that the hydroxyapatite can exchange various ions with the ions of the hydroxyapatite lattice. Apatite based materials are expected to apply for absorbents of harmful metal ions. Various types of hydroxyapatites were prepared by sintering technique. The ability of Cd ion and Cr ion into hydroxyapatite structure and surface was investigated.

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We have reported that amorphous CaAl₂Si₂O₈ prepared by mechanochemical mixing for 24 h and firing of kaolinite and CaCO₃ at 800°C shows good uptake ability and high selectivity for heavy metal ions. In this report, the uptake ability of the amorphous CaAl₂Si₂O₈ was investigated using mixed ion solutions, i.e. four ion mixing (Ni²⁺, Co²⁺, Zn²⁺ and Cu²⁺), three ion mixing (Ni²⁺, Co²⁺ and Zn²⁺) and two ion mixing (Ni²⁺ and Co²⁺). As a result, uptake becomes higher as Co²⁺ < Ni²⁺ < Zn²⁺ < Cu²⁺ in order. This relation is thought to be relating with their ion products.

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Calcium hydroxide powder was fabricated from calcium nitrate solution. The powder was heated in CO₂ atmosphere at different pressures and the change in weight was measured to monitor the reaction between hydroxide and CO₂. At high Pco₂, the direct reaction between hydroxide and CO₂ took place to form calcium carbonate. At low Pco₂, the hydroxide first decomposed into oxide and then reacted with CO₂ to form calcium carbonate. The decomposition could not be suppressed in CO₂ which was saturated with H₂O at room temperature.

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Continuous Al₂O₃ fiber reinforced mullite composites with both excellent damage tolerance and corrosion resistance to fly ash were developed for use as hot gas particulate filters in advanced coal-based power generation systems. Filtration layer with mullite whiskers leads to excellent separation efficiency and low pressure drop.

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Durability of SiC porous materials for diesel particular filter(DPF) was investigated. Evaluated SiC materials were newly developed material, Si-bonded SiC(Si-SiC) and conventional material, recrystallized SiC(Re-SiC). Si-SiC had invariable properties before and after oxidation test, while Re-SiC had variable properties, and were sensitive to oxidation. It would be caused by difference of each microstructure. Si-SiC had good thermal shock resistance, compared with Re-SiC. It would be caused by plastic deformation of matal-Si.

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Mixtures of HZr₂(PO₄)₃ with M^INO₃ (M^I=Li, Na, K, Rb, Cs) or M^II(NO₃)₂ (M^II=Mg, Ca, Sr, Ba) were thermally treated at 973K, in order to investigate the immobilization of M^I or M^II. Leaching tests for M^IZr₂(PO₄)₃ and M^IIZr₄(PO₄)₆ were carried out at 433K for 24 hours in 1mol·dm^-3-HCl. The leaching rate decreased with an increase of ionic radius of M^I or M^II, except for the case of Rb and Cs in M^IZr₂(PO₄)₃.

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The fixed small incident angle of the X-ray beam in the thin film diffraction condition contributes to a shallow X-ray penetration depth into the coating layer, and the signals from the layer can be efficiently detected in comparision to signals from the substrate. Moreover, the independent peak patterns of inside layer were considered to be obtained by an extension of TF-XRD method. The bio-functional HAp coating had been applied to this method, and then the less crystallinity was revealed in the inside layer of the coating near the substrate compared to the surface layer. The broad peaks were observed at the higher incident angles, and independent peak pattern of the inside layer was obtained by the subtraction the peaks of the shallow layer.

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Reciprocal space maps of CeO₂/YSZ/Si(001) grown by PLD method were obtained at high temperature by adding a heater to the sample stage. CeO₂ and YSZ thin films were epitaxally grown. By measuring lattice constats at high temperature it is conducted that a-axes of CeO₂ and YSZ thin films parallel to the substrate surface showed smaller thermal coefficients than bulk reference and a-axes perpendicular to the surface showed larger thermal coefficients. And in YSZ films a-axes parallel to the substrate surface showed decreasing with temperature around 200-300°C which thought to be the relaxation of thermal stress by generation of dislocations.

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Zirconium dioxide whiskers were synthesized using a chemical vapor deposition technique operated under atmospheric pressure. The whiskers were deposited on a silicon substrate under substrate temperature in the range from 650°C to 700°C for 120 min. The characterization of the whiskers by X-ray diffraction reveals that the whiskers are highly oriented along the (002) planes and ascertains the presence of a tetragonal structure. The observation of the morphology of the zirconium oxide whiskers indicates that the ZrO₂ whiskers have an average growth rate of 0.6nm/s, an aspect ratio of 11 and a diameter of 430nm.

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The oxide films were obtained by an atmospheric chemical-vapor-deposition (CVD) method, Relatively high reaction temperature was required for formation of the oxide films. In this study, we tried the synthesis of titania films using the CVD method assisted by the surface discharge. The films were evaluated using FT-IR and Raman spectroscopy. The shiny films were obtained using this method. The infrared absorption at the wave number in the range of 3500cm^-1 can be assigned to the stretching vibration mode of -OH. The absorption obtained from the sample deposited by this method was lower than that formed by the thermal CVD method. The polymerization of the structure of TiO₂ progresses by assist of by the surface discharge.

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The hydroxile compound, TiO_xH_y was the material with the amorphous TiO₂ cluster terminated by the OH group. The structure of this material transforms to the crystalline form of the anatase type of TiO₂ by the anneal treatment. This study focuses on the time dependent property of microstructural changing of TiO_xH_y during the anneal treatment. The TiO_xH_y film was deposited using an atmospheric chemical-vapor-deposition reactor with tetraisopropyl titanate. The deposited films were annealed in the furnace heated at 250°C. The structure of this material transforms to the crystalline form of the anatase type of TiO₂ for the 36 hours. The average cluster size of the sample was determined as 5 nm and 36 nm, using the result of Raman spectroscopy, for annealing time of 24 hours and 48 hours, respectively. The cluster size suddenly increases to 5∼36 nm when the structure of the material changes from amorphous to crystalline states detected by Raman spectroscopy and X-ray diffractometry, respectively.

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This study focuses on the size effect for lead zirconate titanate. Pb(Zr_0.3Ti_0.7)O₃(PZT30) nanopowders with different sizes were prepared by chemical solution deposition. The crystal size of the prepared samples was determined by X-ray diffraction (XRD) and transmission electon microscope (TEM). The crystal structures were identified by XRD. The c/a ratio for PZT30 nanocrystals close to 1 with decreasing crystal size. Raman spectra for PZT30 nanocrystals with various grain sizes have been observed to show the sudden decrease in the soft mode frequencies of E(1TO) and A₁(1TO) at around 25 nm, suggesting the existence of the critical size for PZT30 nanopowders. The intrinsic dielectric constant calculated from the phonon mode shift by using LST relation increased with decreasing crystal size. The temperature dependence of raman spectra clearly revealed that T_c for PZT30 nanopowder shifted by the size effect.

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Recently, it has been found by our group that the ZnO crystals grow on ZnO ceramic bar heated by electric current. The crystal shapes were related to the surrounding atmosphere and temperature during the growth. In this report, aluminum powder was placed on the ZnO ceramic bar. When a certain current run through the ceramic bar, a rod consisting of ZnO crystals grew from the aluminum powder. Photoluminescence spectra of obtained crystal rod were measured at room temperature (300 K) and low temperature (77 K).

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The reference materials are necessary to evaluate exactly the fundamental properties of materials. Two kinds of reference materials on thermal diffusivity are investigated. One is for the measurement of monolithic ceramics by the laser flash method and the other is for the measurement of coating materials. Moreover, we examine the simultaneous measurements of thermal diffusivity and specific heat capacity.

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A new method of elastic modulus measurement by use of dynamic resonant method was developed for the study of mechanical property of the thin films. This method was practicable by applied weights on the nodes of a specimen. The measurements of Young’s modulus by new method are good agreement with the result of standard dynamic resonant method.

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Analytical approaches to the simultaneous estimate of elastic modulus E’ as a measure for elasticity and the true hardness H as a measure for plasticity are discussed on the basis of a simple elastoplastic model under an indentation contact. Two different methods, Method I and Method II, for the experimental determination of E’ and H are examined. Extensive finite element analyses in elastoplastic indentation contact with linear strain-hardening give an important physical insight into the true hardness H.

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The size of frontal process-zone at a crack tip is important to estimate toughening mechanisms of ceramics. Three-point flexural test was carried out for porous silicon carbide containing a sharp V-notch with different size. The critical size was determined as the distance between the notch tip and the characteristic point, where the critical local stress was equal to the flexural strength of the specimen. Porous ceramics showed obviously the enlarged critical frontal process-zone, compared with dense ceramics.

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Ceramic matrix nanocomposites have the attention as high strength and high toughness materials. However, there is no quantitative analysis of strengthening and toughening mechanism still now. In this paper, we discuss the strengthening and toughening mechanisms in ceramic/metal nanocomposites referring to relationship between analysis of residual thermal stress and experimental results.

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Mechanical properties of ZrO₂, HfO₂, Al₂O₃ and Y₂O₃ thin films synthesized using a chemical vapor deposition technique operated under atmospheric pressure were investigated. X-ray diffraction reveals the existence of tetragonal, monoclinic, amorphous and cubic structure for zirconia, hafnia, alumina and yttria respectively. The nanoindentation test points out that the films of zirconia possess the highest values of elastic modulus and hardness. Elastic modulus and hardness of the hafnia films are in a good agreement with those in the reference (Ceramics fundamentals, M. Barsoum).

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The proposed constant force-feeding grinding method modifies automatically the feeding rate depending on grinding conditions. Forces of a grinding wheel on a specimen are easily controlled by the present method. We have developed a system and proved an effect of constant-force-feeding grinding by this experiment. We used silicon wafers of 4-inch diameter and sintered-Al₂O₃ plates of 50×25×1mm to evaluate grinding forces, feeding rate and grinding defects. The present system takes only 50min to thin the silicon wafer to 40μm from 520μm thickness and the sintered-Al₂O₃ to 40μm from 1mm thickness by grinding.

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