YSZ thin films were deposited by pulsed laser deposition (PLD) on Si(001) with native SiO₂, H-terminated Si(001) and ablated Si on H-terminated Si(001) at various temperatures (800, 600, 400, 200°C and RT (room temperature)). The crystallinity of YSZ thin film on Si(001) with native oxide was the highest among the three substrates. YSZ thin film on ablated Si on H-terminated Si(001) was amorphous. We suggest that an ultrathin SiO₂ layer (<1.1nm) is necessary for crystal growth of YSZ thin film. A two-step process was attempted to prepare epitaxial YSZ thin films. First, YSZ thin films were deposited on Si(001) with native SiO₂ at 800°C in 8.0×10^-5Pa O₂ (reduction condition). Second, YSZ thin films were deposited on Si(001) with native SiO₂ at various temperatures (800, 600, 400, 200°C and RT) in 7.3×10^-2Pa O₂. All YSZ thin films deposited by a two-step process were epitaxial. The reason for this mechanism is discussed.

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The role of an ultra thin SiO_x layer for the epitaxial growth of the YSZ (Y stabillized ZrO₂) thin film on (001) Si substrate through the SiO_x layer was investigated by high resolution transmission electron microscope (HRTEM) method, in-situ heating transmission electron microscope method and nano-beam diffraction methods. An ultra thin SiO_x layer 1-2nm in thickness has the effects of inducing crystallization strain relaxation at the YSZ/Si interface; therefore an ultra thin YSZ layer in the very initial stage of the thin film growth could be epitaxially crystallized. The nano-beam (0.4nm) diffraction analysis, focused on the SiO_x layer of the (001) epitaxial YSZ/SiO_x/Si thin film, showed a no complete halo pattern, but the diffraction spots convoluted into a halo pattern. The diffraction pattern was not so sharp than YSZ and Si, however there existed an epitaxial relationship the YSZ, SiO_x and Si layers. On the other hand, an amorphous-like phase contrast was observed by high coherent HRTEM imaging. This indicates that the ultra thin SiO_x layer formed just above the Si surface has a nano-crystalline structure below 1nm order. Our results indicate that the SiO_x layer plays two important roles: (a) it enables strain relaxation in the crystallization process of YSZ layer with increasing the crystallinity of the YSZ layer; (b) it enables the transmission of an epitaxial relationship from the Si (semiconductor) toward the YSZ (oxide) layer.

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Epitaxial heterostructures of ZnO/AlN have been fabricated on both sapphire (0001) and Si (111) substrates with a 3C-SiC buffer. AlN underlayers with heterostructures were epitaxially grown by radio-frequency (RF) plasma-assisted molecular beam epitaxy (MBE). ZnO top layers were grown by direct-current (DC) sputtering using a Zn target and oxygen atmosphere. Analysis using X-ray diffraction, reflection highenergy electron diffraction (RHEED), and transmission electron microscopy (TEM) showed that both ZnO and AlN films have a monocrystalline wurtzite structure with epitaxial relationships of ZnO[0001]//AlN [0001]//sapphire[0001] and ZnO[0001]//AlN[0001]//3C-SiC[111]//Si[111] along the growth direction, ZnO[1120]//AlN[1120]//sapphire[1120] and ZnO[1120]//AlN[1120]//3C-SiC[110]//Si[110] within the growth plane, respectively. The successful growth of epitaxial ZnO/AlN films on sapphire and Si substrates demonstrates the feasibility of integrated devices consisting of these substrates.

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Single crystals of sodium bismuth titanate, (Na, Bi)TiO₃ (NBT), and its solid solutions were grown by a liquid phase epitaxy (LPE) using strontium titanate, SrTiO₃ (ST), single crystals as substrates. X-ray diffraction measurements and polarized optical images revealed that the crystals could be epitaxially grown on both the (001) face and the (111) face of the ST substrate. However, due to lattice mismatch, the grown crystals had a multi-domain structure with domain boundaries at both 90 and 180°. The NBT crystals grown by using unsealed platinum pan had an inhomogeneous chemical composition, while homogeneous crystals were grown by using sealed platinum capsules for the growth cell. It is concluded from the results of several experiments on inter-diffusion between the substrate and the grown crystal that liquid phase epitaxy is appropriate for the growth of NBT.

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A new range of oxygen pressure for the preparation of La_0.5Sr_0.5CoO₃(LSCO) thin films was proposed. In this work, heteroepitaxial LSCO thin films were prepared on CeO₂/YSZ/Si(001) substrates in 7.3×10^-2PaO₂ atmosphere, while LSCO thin films have been prepared in a higher oxygen pressure around 1.3-4.0×10¹Pa in the literature. The film has smooth morphology and high crystallinity as well as low resistivity (2×10^-3Ωcm). The reason may be related to the long mean free path (MFP) in the depositied LSCO thin film. The film showed semiconductive property due to oxygen vacancies. By the post annealing in O₂, the lattice parameter of LSCO thin film was increased and the resistivity was lowered.

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It has been reported that preparation of crystallized single phase Pb(Zr, Ti)O₃ (PZT) (perovskite structure) thin film on Pt/Ti/SiO₂/Si and Pt/Ir/SiO₂/Si substrates by pulsed laser deposition (PLD) method is difficult, and a pyrochlore-type compound forms instead of PZT; however, the reason for this has not been clarified. In this work, it was found that such instability of PZT is caused by the evaporation of Pb during the deposition. It was also found that the evaporation of Pb can be suppressed by introducing a very thin SrTiO₃ (ST) seed buffer layer to the surface of Pt/Ti/SiO₂/Si and Pt/Ir/SiO₂/Si substrates. Moreover, it was found that the peak intensity of PZT changes with the thickness of the ST seed buffer layer, and maximum peak intensity was obtained when the thickness of ST was 2nm. When the thickness of the ST seed buffer layer was less than 1nm, considerable coexistence of the pyrochlore-type compound was detected, therefore the remanent polarization (P_r) was lowered. Single-phase PZT thin films can be obtained if the thickness of ST is over 2nm, however, if the thickness of ST is over 4nm, the P_r value is decreased.

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The introduction of various seed layers produced thin films with different properties on the same substrate. PbTiO₃ (PT) and Pb(Zr_0.52Ti_0.48)O₃ (PZT) thin films with different crystallinities, crystal orientations and phases were successively fabricated on Nb doped SrTiO₃ (Nb-ST) and Pt/Ti/SiO₂/Si (Pt/Si) substrates, respectively, by introducing the SiO₂ and TiO₂ seed layers using a chemical solution deposition process. The optimum processing conditions for each combination of film, substrate and seed layers were examined from the viewpoint of the compatibility of the target film formation and the patterning process for realizing different cells on the same substrate. The c-axis oriented epitaxial PT film was formed on the Nb-ST substrate. By introducing TiO₂ and SiO₂ thin layers onto the Nb-ST substrate, the polycrystalline PT and amorphous film with PT composition were obtained, respectively. The (111) oriented PZT film, and the pyrochlore phase and PZT (110) were formed on Pt/Si without and with the SiO₂ seed layer, respectively. Combining the introduction of the seed layers and the photolithography technique, we succeeded in fabricating the thin films with different cells having various electrical properties on the same substrates. In the Pt/PZT/ (with and without seed layer)/Pt/Si system, 200μm^φ cells with ferroelectricity or dielectric properties were obtained on the same substrate.

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Sr_0.5Ba_0.5Nb₂O₆ (SBN) thin films were prepared on Pt-coated Si (Pt/Ti/SiO₂/Si(100)) substrates by pulsed laser deposition. The influence of ambient gas type on the preparation of SBN thin films was studied. N₂O gas was found to be more effective for improving the oxidation reaction during deposition under lower pressure than O₂ gas because, under lower gas pressure, the ablated species can keep higher energy for improving the crystallinity of SBN thin films. Structure changes in SBN thin films have been investigated as a function of film thickness in the range of 0.1-1.2μm. Highly (001) oriented SBN layers have been obtained in thicker films.

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Strict control of the crystallization of TiO₂ is one of the most important factors in forming mesoporous structured TiO₂ thin films. Effects of the crystallization of TiO₂ on the formation of mesoporous structures have been studied by transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) observation and X-ray diffractometry (XRD) analysis. The obtained well-ordered mesoporous TiO₂ thin films, calcined at 450°C to remove the template, are composed of a continuous non-crystalline TiO₂ matrix containing TiO₂ nanocrystals, whose mean size is sufficiently small to support the mesostructure. In the mean time, the mesoporous TiO₂ materials that almost lose their ordered structure after calcination consist of large TiO₂ crystallites (over 6 nm), and the overgrowth of TiO₂ crystallites cause a collapse of the mesoporous structure.

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Naβ-alumina is a two-dimensional ionic conductor in which conducting planes of Na⁺ ion are separated by insulating spinel block layers. For practical use, Naβ-alumina needs not only high ionic conductivity but also mechanical reliability. Therefore, we prepared preferentially oriented Naβ-alumina ceramics by hot pressing and evaluated the ionic conductivity and mechanical strength. The ionic conductivity perpendicular to the c-axis-oriented plane was five times higher than that parallel to c-axis. From the preferentially oriented Naβ-alumina ceramics three types of test pieces were cut for a three-point bending test. In one type of test piece, the longest side was parallel to the hot-pressing direction, while the longest sides were perpendicular to that direction in the other types of test pieces. The latter test pieces showed mechanical strength 1.5 times that of the former.

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Zirconia thin films were successfully micropatterned on octadecyltrichlorosilane (OTS)-self-assembled monolayers (SAM) in ZrOCl₂⋅8H₂O-ethanol solution at room temperature. OTS-SAM was modified by UV-irradiation through a photomask to change into a SAM template patterned with silanol and octadecyl groups. The films were selectively deposited in the silanol regions through hydration-alcoholysis and condensation reactions. The as-deposited film was amorphous with a complex composition, decomposed into tetragonal-zirconia at 500°C, and further transformed into monoclinic-zirconia at 600°C. The as-deposited film demonstrated a dielectric permittivity of 14 at 100kHz, but a resistivity of 3.1×10¹¹Ωcm and a leakage current density of 9.0×10^-7Acm^-2 obtained for a MOS device indicated that the film quality needed to be improved.

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ZnO micropatterns were fabricated through site-selective electroless deposition using self-assembled monolayer template terminated with phenyl/OH-surface functional groups. ZnO was deposited only on the Pd-catalyzed phenyl-regions of the substrate. The feature edge acuity of the ZnO patterns was estimated as several times of the particle size of -0.2μm. ZnO single crystal particles were grown on the substrate forming a dense, mono-particulate layer. The broadening of X-ray diffraction peaks was attributed to the strain due to the defects originated in an aqueous solution. Transmission electron micrographs revealed that ZnO particles were continuously grown on the catalyzed substrate.

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Two-dimensional (2D) photonic crystals (PCs) of transparent TiO₂ gel rods, with a diameter in the range of 0.5 to 2.0μm, arrayed in a triangular lattice with a lattice constant between 1.0 and 4.0μm, were successfully fabricated from a titanium tetra-isopropoxide (Ti(OⁱPr)₄) ethylene glycol monomethyl ether (EGMME) solution using resist molds. The resist molds were fabricated on a Si wafer by electron-beam lithography. By casting the solution into the resist molds, we obtained TiO₂ gel PCs, which contained polyethylene glycol (55-60 mass%) used as a plasticizer, formed on gel plates with the same composition over an area of 500μm×500μm. This method enabled the preparation of dense, highly transparent TiO₂ gel PCs. Distinct changes in both reflected and transmitted colors were observed in the present gel PCs, demonstrating that they function as photonic crystals in the visible region.

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The chemical etching mechanism of ZnO (0001) and (0001) polar surfaces was experimentally investigated by a scanning electron microscope, and applied to the control of surface morphology. The (0001) and (0001) surfaces of ZnO single crystal were periodically patterned using Pt masks, and were etched in HCl solution for 1-6 d. The etched patterns could not exactly reflect the shape of the masks due to side etching on the (0001) surface. With respect to the (0001) surface, many hillocks periodically formed with keeping the original square shape. The difference in the etching behavior was caused by the difference in the uppermost surface structure. The (0001) surface was etched at step or kink sites because of the existence of oxygen ions at only the steps or kinks, and therefore the step flow etching occurs. However, the (0001) surface is etched not at steps and kinks but at the terraces in which only the oxygen ions exist, and the etching direction is vertical to the crystal surface. After long-duration etching, the pattern changed into a pointed pyramidal shape on the (0001) surface.

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New transparent surface crystallized glasses in the system of Sm₂O₃-Bi₂O₃-B₂O₃ have been successfully fabricated. The second harmonic generation (SHG) from the crystalline phase at the surface layers has been confirmed from Maker fringe measurements. The irradiation of CW YAG laser with a wavelength of 1064 nm induces sharp refractive-index changes or crystalline dot formation, depending on Sm₂O₃ content in the glasses. In 10Sm₂O₃⋅30Bi₂O₃⋅60B₂O₃ glass, refractive-index changes (not crystallites) are induced by laser irradiations (power: 1W, time: 1-250 s), and spherical spots with 2-45μm are formed. In 12.5Sm₂O₃⋅30Bi₂O₃⋅57.5B₂O₃ glass, crystalline dots with the diameters of 5-65μm are formed by laser irradiations (power: 0.5-0.7W, times: 1-250s). It is found that the crystalline dots generate second harmonic waves. Refractive-index changes by YAG laser irradiations were confirmed in 10Dy₂O₃⋅30Bi₂O₃⋅60B₂O₃ glass, supporting the model proposed by Sato et al. New Sm₂O₃-Bi₂O₃-B₂O₃ glasses have a high potential as materials for “Ceramics Integration.”

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Ca₂Bi₄Ti₅O₁₈ (CBTi245) thin films were deposited by spin-coating a precursor solution of metal alkoxides on Pt-passivated Si substrates. Thickness of the as-deposited amorphous layer affected the nucleation site, microstructure and electrical properties. The onset of crystallization of thin films to a pyrochlore phase was below 550°C via rapid thermal annealing in oxygen. A perovskite phase developed by further annealing at temperatures of 650°C or higher. The CBTi245 thin films which were prepared by multi-coating and multicrystallizing of the 20 nm-thick amorphous layer showed random orientation, a columnar-like structure, and P-E hysteresis loops.

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Strontium titanate (SrTiO₃) perovskite oxide thin films have been investigated for use as a dielectric material for by-pass (RF-shunt) capacitors in microwave monolithic integrated circuits (MMIC). This paper describes the structural and electrical features of SrTiO₃ thin films and some issues related to the integration of SrTiO₃ thin film on a silicon substrate, as a planar capacitor structure. The specific properties of the capacitors are found to be strongly dependent on the SrTiO₃ deposition conditions, post thermal treatment and choice of the bottom electrode.

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Nb-doped semiconductive SrTiO₃ film and Bi and Nb co-added SrTiO₃ film were grown on (001) MgO substrates by metal-organic chemical vapor deposition (MOCVD). The (001)-oriented SrTiO₃ phase was grown epitaxially with cube-on-cube structure in relation to the MgO substrate. In the case of the Nb-doped SrTiO₃ film, the film exhibited a semiconductive nature with a low electrical resistivity (0.11Ω·cm) that is three orders of magnitude lower than that in bulk SrTiO₃ ceramics by adding a much higher Nb addition (1.6-3.5mol%). Most of the added Nb is thought to substitute for the Ti⁴⁺ as valence 4⁺, as suggested by the dependency of the cell volume change. In the case of Bi and Nb co-added SrTiO₃ film, the lattice parameter was somewhat increased with the addition of Bi, but the amount of Bi was undetectable. The addition of Bi did not produce a thin film with nonlinear electrical resistivity. Introducing a SrO seed layer with -2nm thickness onto (001) MgO substrate produced weak nonlinear I-V (varistor) properties. It might be thought that the grain boundary between the two kinds of in-plane oriented grains, i.e., 45° rotating and cube-on-cube grains, acts as a barrier against varistor characteristics.

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Effects of Pb(Zr_0.5Ti_0.5)O₃ (PZT) thickness on the residual stresses and the electrical properties of a PZT thin-film layer were discussed for the PZT/Pt/SrTiO₃ or PZT/(La_0.5Sr_0.5)CoO₃/SrTiO₃ system. Bottom electrodes, i.e., Pt and (La, Sr)CoO₃ (LSCO) thin films, were deposited by DC magnetron sputtering and pulsed laser deposition (PLD), respectively. PZT thin films with thicknesses of 30nm and 60nm were fabricated using the pulsed metal-organic chemical vapor deposition (MOCVD) apparatus. PZT films deposited on the LSCO electrodes were all epitaxially grown. The residual stress measurements by XRD revealed that all PZT films received the in-plane tensile stress from the substrate or the electrode/substrate. When the Pt and LSCO electrodes were introduced between the PZT film and the STO substrate, in-plane tensile stress in PZT was enhanced. With decreasing the PZT film thickness, the in-plane tensile stress in PZT film was enhanced. Remanent polarization decreased with increasing residual tensile stress in PZT film in all cases. The change of residual stress in the PZT/LSCO/STO system was discussed on the basis of the thermal expansion coefficient of the constituent layers.

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Epitaxial (Ni-Zn)Fe₂O₄ thin film was prepared on Si(001) substrates using (MgO-Al₂O₃)/CeO₂/YSZ triple buffer layer. In this work, to increase remanent magnetization (M_r) and decrease coercive field (H_c), for epitaxial (Ni-Zn)Fe₂O₄ thin film, the effect of substrate temperature, oxygen pressure and composition on the magnetic properties was examined. It was clarified that the remanent magnetization and coercive field were strongly influenced by temperature and oxygen pressure. In order to obtain high M_r and low H_c, it was thought that a substrate temperature of 800°C and oxygen pressure 1.3Pa were optimal conditions. As regarding the composition, M_r could be obtained to a maximum of 3.96×10^-1Wb/m² by changing the quantity of Zn and Fe(M_s=5.31×10^-1Wb/m², H_c=1.35×10¹kA/m).

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CoFeAlO nano-granular magnetic thin films were prepared by means of the inductively coupled radio frequency sputtering method. The self-resonant frequencies of the films were higher than 2GHz, and magnetic permeability was higher than 100 even in the GHz region. Spiral inductors were fabricated on the (Co₇₂Fe₁₇Al₁₁)-O thin film and their high-frequency inductance was measured to confirm the effect of insertion of the film. At frequencies up to 2GHz, the inductance of the spiral inductor on the film was increased to 20 percent. The films are suitable for magnetic applications in high-frequency circuitry.

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The highly integrated monolithic microwave power amplifier module for W-CDMA (wideband code division multiple access) cellular phones were designed and fabricated taking advantage improvements in microwave materials and new developments in processing methods of thin films for applications in decoupling capacitors and choke inductors. The obtained module is ultimately downsized into 3.0mm by 3.5mm with 0.5mm in thickness. The volume is about 10 times smaller than that of the ceramic chip components assembled conventional power amplifier module.

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Focused ion beam (FIB) system was applied to sample preparation for local microscopic observation of passive thin-film elements integrated into a semiconductor substrate. The newly developed microsampling method is suitable not only for scanning electron microscopy (SEM) observation but also for transmission electron microscopy (TEM) observation. By adopting this method, microstructures and their ramifications in SrTiO₃ MIM (metal-insulator-metal) thin-film capacitors fabricated on integrated circuits were clearly revealed.

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Compositionally graded AlN/TiN and SiN/TiN films were prepared on Si substrates at about 700°C by plasma CVD capable of injecting mixed solutions of Ti(OC₂H₅)₄, Al(OC₄O₇)₃, and/or (CH₃)₃SiOSi(CH₃)₃ containing stabilizing solution of N(CH₂CH₂OH)₃ into thermal Ar/N₂/H₂ plasma. A complementary change of Ti and Al, and Si and Ti contents with depth was achieved by changing the feeding rate of each alkoxide solution with time. By this means, it was possible to prepare the CGed AlN//TiN films with the AlN and TiN compositions on the respective surface and substrate, accompanied by complementary changes of Al and Ti with depth, and vice versa. Similarly, the CGed SiN_x//TiN and TiN//SiN_x films were prepared by this liquid injection CVD method. The films achieved a thickness of 1-3μm and show the formation of cauliflowerlike agglomerated particles consisting of fine 0.2-0.3μm-sized particles on the surface. Columnar and dense microstructure was observed in the deeper region of the CGed AlN//TiN and SiN_x//TiN films, respectively. The electrical resistivity of the films changed from 300 to 7×10⁴μΩcm, depending on the type of the CGed films.

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To characterize a photo-catalytic SiO₂/TiO₂ multilayer film prepared by vacuum-deposition method, kinetic measurements of the photo-catalytic activity were carried out, and the interface structure and photo-conductivity of the film were also investigated. By the kinetic analyses of self-cleaning of stearic acid and de-colorization of methylene blue, it was proved that the SiO₂/TiO₂ multilayer film with the 20nm set-thick SiO₂ overlayer exhibited an improved photo-catalytic activity as compared to the TiO₂ film. The multilayer film had a heterogeneous interface structure, whereas the photo-catalytic reaction seemed to occur on the photo-catalytically inactive SiO₂ surface. A sufficient overlaying by the SiO₂ thin film on the TiO₂ film improved the photo-catalytic properties of the film. The multilayer film with improved photo-catalytic activity exhibited a significantly increased photocurrent compared to a TiO₂ film. Both improved photo-catalytic activity and photocurrent amplification of the multilayer film might be strongly correlated to an increase of photo-generated carriers at the interface of the film. A nanometer-sized insulating overlayer can synergistically form integration to improve photo-catalytic activity, an attractive function for photocurrent amplification of the multilayer film.

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Perovskite type lead magnesium niobate Pb(Mg_1/3Nb_2/3)O₃ (PMN) films with BaTiO₃ buffer layers on Pt/Ti/SiO₂/Si substrates were prepared by Pulsed Laser Deposition. Effect of PMN thickness on the film structural and dielectric properties were investigated mainly by high-resolution X-ray diffraction. The average lattice constant of the whole PMN layer increased with increasing the film thickness. In addition, the surface of PMN has a smaller lattice constant comparing with the inner part of the PMN layer. These two effects can be explained by the thermal expansion coefficient mismatch between the PMN and the bottom layers. The overall dielectric constant of Pt/PMN/BT/Pt/Ti/SiO₂/Si exhibits film thickness dependence and has a similar distribution with the average lattice constant. After a simulation with a two-capacitor model, the PMN dielectric constant was distinguished from the overall one. Depending on the thickness, the dielectric property of PMN layer obeys two different mechanisms.

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Several (Bi, La)₄Ti₃O₁₂/Pb(Zr, Ti)O₃ composite thin films, including a sandwich structure (Bi, La)₄Ti₃O₁₂/Pb(Zr, Ti)O₃/(Bi, La)₄Ti₃O₁₂, a multilayer structure (Bi, La)₄Ti₃O₁₂/Pb(Zr, Ti)O₃/LaNiO₃, and two bilayer structures of (Bi, La)₄Ti₃O₁₂/Pb(Zr, Ti)O₃ and Pb(Zr, Ti)O₃/(Bi, La)₄Ti₃O₁₂, were fabricated on Pt/Ti/SiO₂/Si substrates. Both (Bi, La)₄Ti₃O₁₂ and Pb(Zr, Ti)O₃ layers were prepared by a chemical solution deposition technique. The electrical properties of the composite films are affected not only by the stacking configuration of the composite films but also by the electrical properties of individual layer in the composite films. The experiments demonstrated that the (Bi, La)₄Ti₃O₁₂/Pb(Zr, Ti)O₃/(Bi, La)₄Ti₃O₁₂ sandwich structure and the (Bi, La)₄Ti₃O₁₂/Pb(Zr, Ti)O₃/LaNiO₃ multilayer structure showed fatigue-free characteristics at least up to 10¹⁰ switching bipolar pulse cycles and excellent retention properties. The room-temperature dielectric constants of all composite thin films ranged between 200 and 300, at a frequency of 100kHz.

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Multi-layered electrochemical cells for exhausts gas purification, which consist of a LSCF/CGO composite catalytic electrode, a CGO buffer layer, and ScSZ solid electrolyte, were prepared, and their electrochemical properties and NO decomposition behaviors were investigated. Owing to the presence of a CGO buffer layer, the harmful interfacial reaction between LSCF and ScSZ, which resulted in a resistance increase of the electrochemical cell, could be prevented. Consequently, it was possible to reduce the electrode/electrolyte interfacial resistance of the cell by integrating the LSCF/CGO electrode and ScSZ electrolyte covered by CGO buffer layer. The CGO buffer layer was deposited on the ScSZ electrolyte by two different methods: a screenprinting and a pulsed-laser deposition (PLD) process. The screen-printed CGO buffer layer showed a porous microstructure, while a dense CGO layer could be obtained by PLD process. It was found that the microstructure of the CGO buffer layer influenced strongly the ohmic resistance of the electrochemical cells. A consuming electrical power for NO decomposition was reduced by constructing multi-layered electrochemical cell, LSCF/CGO (cathode)|CGO (buffer layer deposited by PLD)|ScSZ (electrolyte)|CGO (buffer layer)|LSCF/CGO.

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Dense Al₂O₃-ZrO₂ continuous graded hollow tubes were achieved and characterized using Centrifugal Molding Technique by pressureless sintering at 1550°C (3h) in normal atmospheric conditions. There was a uniform change in the compositions of zirconia in alumina matrix along the radial direction of graded hollow tube. Electron microscopy showed that zirconia concentration was high in outer radial regions due to the centrifugal action. Agglomerations of zirconia were found in alumina matrix due to inadequate dispersion of their fine particle sizes in sub-micron level. Vickers measurements along the cross section of graded hollow tube confirmed the gradient of zirconia inclusions. This forming technique is very simple and cost effective method compared to other techniques prevailing for the fabrication of graded hollow tubes.

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Several nano liters of tellurite glass melt was inserted and quenched between two ends of silica glass optical fibers to form a optical coupling structure, whose length was several hundred micron meters. Dispite the large gap of thermal expansion coefficient between these glass materials, neither fracture nor bubbles were observed, which usually lead to a large optical propagation loss. The insertion was less than 10dB, which was mainly due to the lack of an optical waveguide structure in the tellurite glass segment. Further loss decrease is expected to be possible by introducing a refractive index modulation.

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A porous La_0.6Sr_0.4Co_0.2Fe_0.8O₃-Ce_0.9Gd_0.1O_1.95 (LSCF-CGO) green body was prepared from a water-based slurry by a freeze-drying process. The LSCF-CGO slurry was frozen, controlling the growth direction of ice, and it was sublimated at a reduced pressure. After sintering the green body at 1350°C, the obtained porous substrate has macroscopically aligned open pores parallel to the ice growth direction, and micro pores on their surfaces. It was found that a porous body with such a unique pore structure is the most suitable for integrating a thin film with a porous substrate. A bi-layer consisting of a dense thin-film of CGO on the porous LSCF-CGO substrate has been then fabricated using a slurry-coating process.

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A new type of thin film module, using SrTiO₃ (STO) as thin film metal-insulator-metal (MIM) capacitors was developed. The module consisted of a GaAs heterojunction bipolar transistor (HBT) and aluminum thin film inductors along with STO MIM capacitors. To connect these devices, the most suitable interface condition between aluminum interconnects and the above devices was optimized to achieve good interlayer conducting properties. In optimizing the connection of aluminum interconnects and the platinum electrodes of the STO capacitors, oxygen plasma cleaning was effective to remove the insulating film on the platinum surface. This film was formed when the SiO₂ thru-hole was made by reactive ion etching (RIE) process with CF₄. As for the connections of aluminum interconnects and thin film inductors, Au/Ti covering of aluminum surface was effective for preventing the surface oxidation of the aluminum inductors.

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ZnO thin films were grown on TbAlO₃ single crystal substrates by pulsed laser deposition. In photoluminescence (PL) measurements, strong emissions from TbAlO₃ were observed with the emission from ZnO when the film thickness was less than 100nm. The relationship between the ZnO film thickness and the emission intensity from TbAlO₃ was investigated in order to determine the penetration depth of excitation light. Information on the heterostructures ranging from the surface to a depth of 300nm was obtained by PL measurements in this study, and the absorption coefficient for a wavelength of 325nm was estimated to be 1.31×10⁵cm^-1.

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This paper reported the development of lead-free Sr_2-xCa_xNaNb₅O₁₅(SCNN, x=0.1) piezoelectric ceramics with tungsten bronze structure that are potentially served as sensors in sensing patches. These ceramics were prepared using the conventional solid-state synthesis method, and their dielectric, ferroelectric and piezoelectric properties were investigated. The dual-stage sintering was used to density SCNN ceramics, i.e. prefiring at 1240°C for 6h and finally firing at 1280-1360°C for 25h. The sample sintered at 1320°C exhibited the maximum density (4.96g/cm³) and thus had the maximum dielectric constant (1455) and the Curie temperature (288°C). The spontaneous polarization and the piezoelectric constant of this sample were 7.9μC/cm² and 118pC/N, respectively. The electric properties of SCNN were improved by doping with 1 mass% La₂O₃, with the dielectric constant of 1662, the Curie temperature of 298°C, spontaneous polarization of 10.7μC/cm² and the piezoelectric constant of 138pC/N, respectively. The good piezoelectric properties of the SCNN-based ceramics indicate that they are good candidates for sensor applications.

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The oxygen diffusion coefficients of nondoped, Ho-doped and La-doped BaTiO₃ polycrystals were evaluated by secondary ion mass spectrometry (SIMS). The La-doped and Ho-doped systems have a greatly reduced oxygen diffusion coefficient compared to nondoped BaTiO₃. The oxygen diffusion coefficient of La-doped BaTiO₃ was dependent on the amount of La dopant, while the amount of Ho did not influence oxygen diffusion. According to the change of the cooling rate during the fabrication process, the oxygen diffusion of the La-doped BaTiO₃ was influenced but that of Ho-doped BaTiO₃ changed little.

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A five-volt lithium insertion material of Li[Ni_1/2Mn_3/2]O₄, having a spinel-framework structure, was prepared from nickel manganese double hydroxide with LiOH and characterized by XRD, FT-IR, TG, SEM and electrochemical methods. Heating a reaction mixture below 600°C did not give good results in terms of polarization and cycleability during charge and discharge in lithium nonaqueous cells. Higher heating temperatures gave lower polarization and better cycleability, while rechargeable capacity at 4.75V vs. Li reduces as heating temperature rises. After several trials, an optimum condition to prepare a five-volt lithium insertion material of Li[Ni_1/2Mn_3/2]O₄ is found to be a two-step solid state reaction, i.e., crystallization at 1000°C followed by oxidation at 700°C. By this process Li[Ni_1/2Mn_3/2]O₄ showed an excellent performance in a five-volt nonaqueous lithium cell and also in a three-volt lithium-ion cell with a Li[Li_1/3Ti_5/3]O₄-negative electrode.

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