Beta-Spodumene based matrix composites with ZrB2 dispersions were fabricated. The electrical resistivity value was decreased with increasing the amount of ZrB2, and was saturated about 40 vol% ZrB2 by the formation of percolation structure. The temperature coefficient is 0.29%/degree C, and is quite low compared with metal. Although the magnetic permeability that specifies the osmosis depth in which high-frequency current flows was low compared with a magnetic material. In order to make it generate heat with the whole material, it turned out that it is effective.

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T1:The several materials such as ZnO:Al and In₂O₃:Sn(ITO) are proposed as conductive oxide materials synthesized by the chemical-vapor deposition method operated under atmosphere. We fabricated ITO whiskers on the n-type Si(100) substrate with coating of the low work function material, hydrogenated carbon nitride(a-CNx:H) to evaluate field emission properties of the ITO whiskers. The threshold electric field at 10^-6 A was determined to be 1.46 kV (0at%Sn), 1.76 kV (,1.0 at%Sn) and 2.26 kV(4.7 at%Sn). The inclination of the Fowler-Nordheim plot was the smallest at the sample without Sn doping. Since the radius of curvature at the ITO whisker tip was independent on the Sn dope, the work function of whiskers might be changed with the Sn content.

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High quality metal-oxide crystals are synthesized using the chemical-vapor deposition apparatus operated under atmosphere. For example, intense ultraviolet emission induced as cathodoluminescence is obtained from ZnO whiskers formed by this CVD system. In this study, indium tin oxide (ITO) crystals were formed on the yttrium stabilized zirconia (YSZ)(100) single crystalline substrate. X-ray diffraction revealed the epitaxial relationship to be ITO [100](001)//YSZ [100](001). Cathodoluminescence of the ITO crystals consists of the peaks at 470 nm and 520 nm. The maximum peak position locates at 470 nm (0 at%Sn) and 520 nm (5.1 at%Sn and 12.3 at%Sn), suggesting that peak shift occurs with Sn doping.

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In this study, realizing blue-emitting from YNbO4 thin film is objective. For realizing it, deposition condition and substrate were optimized and ITO thin film as upper electrodes was used. YNbO4 thin films were deposited on Pt/lr02/Si02/Si(100) and SrTi03(100) by RF magnetron sputtering method. ITO (Indium-Tin oxide) thin films as upper electrode were deposited on YNbO4 thin film by PLD (Pulsed laser deposition) method. The electro luminescence (EL) in YNbO4 thin films was measured by the photonic multi-channel analyzer.

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Electric properties of La-(Mn, Fe)-codoped BaTiO3 ceramics sintered in air or Ar were studied. PTCR jump of 0.2mol%La-0.04mol%Fe-codoped BaTiO3 sintered in Ar was 3 orders of magnitudes, being much higher than that of La-Mn-codoped sample.

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Fe_1-xCo_xB powders were prepared by solid state reaction of iron, cobalt and boron at 950°C in vacuum. The specimens for the measurement were fabricated by HIP at 900°C for 2h under a pressur of 100MPa. Electrical conductivity and Seebeck coefficient were measured as a function of temperature up to 400°C. Electrical conductivity of the samples of Fe_1-xCo_xB (x=0, 0.05, 0.1, 0.2, 0.5) showed metal, and that of Fe_1-xCo_xB (x=0.7, 0.9, 0.95) showed semiconductive. CoB showed metal-semiconductor transition. Seebeck coefficient were negative for x=0,1, and positive for x=0.5.

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Recently, hyperthermia has been expected for a treatment of cancer tissues. In this case, the heating of cancer tissues keeps at about 42°C using AC magnetic field, since the heating at this temperature affects only the cancer cells and does not give a damage to normal cells. Heating properties under AC magnetic field were investigated for various ferrite powders. The maximum temperature was obtained when a frequency of AC magnetic field was about 370 kHz for all the samples examined. Mg-ferrite (MgFe₂O₄) showed the excellent temperature ehnancement compared with those of other ferrites.

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Fine MgFe₂O₄ ferrite powder for local hyperthermia was synthesized by a glycothermal method. The single phase of MgFe₂O₄ powder was obtained when the precursor decomposed above 800°C which was confirmed by TGA and XRD. The temperature enhancement by AC magnetic field was increased with an increase in the particle size for the MgFe₂O₄ ferrite powder.

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Epitaxial nickel-zinc-ferrite (NZF) thin films were deposited on various buffer layers and the effect of lattice mismatch on the magnetic properties, especially, squarness (Mr/Ms) was systematically examined. It was suggested that Mr/Ms was increased with lattice mismatch. NZF thin film deposited on ZnCo2O4 composition buffer layer showed high Mr/Ms value.

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We have investigated novel optoelectronic properties in Cu-based Oxides. At focus are photoinduced structural changes in Cu-based high-T_c superconductors, which may occur though electronic excitation by light irradiation. We found photo-induced structural changes and persistent photoconductivity in Y-, Bi- and Tl-based high-T_c superconductors, which indicates that photo-induced structural changes might be a common phenomena in high-T_c superconductors.

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Thin film of YBa₂Cu₃O_7-δ (YBCO) was deposited on a MgO substrate by the visible light (532nm) pulsed laser ablation method using a Nd:YAG laser. The purpose of this study is to find out the best composition of target and the deposition conditions. Thin film deposited in O_2 gas at substrate temperature of 600°C and thermally annealed at 925°C in the air using a target with mol ratio of 1:2:4 of Y, Ba, and Cu (1:2:4 target) changed to the super conducting state at 69K, which was higer than those of thin films deposited using targets with different compositions. Thin film deposited in O₂ gas including O radicals produced by the oxygen plasma using a 1:2:4 target changed to the superconducting state at 75K. Resistance decreased rapidly with decreasing temperature near superconducting transition temperature. Thin film deposited in O₂ gas including O radicals at 730°C using a 1:2:4 target without thermal annealing changed to the superconducting state at 50K. Composition of YBCO thin films deposited O₂ gas and O₂ gas including oxygen radicals using a 1:2:4 target was approximately 1:2:3.

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GdBa₂Cu₃O_7-δ and BaZrO₃ composite ceramics was prepared by solid state reaction. The stability on electrical properties of the composite was investigated. A hot spot appeared on the rod with 0-70 mol% BaZrO₃ when a certain voltage was applied at room temperature in air. It is found that GdBa₂Cu₃O_7-δ-BaZrO₃ composite ceramics has a high stability compared with GdBa₂Cu₃O_7-δ ceramics.

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A hot spot appeared in SmBa₂Cu₃O_7-δ ceramic rod when voltage above a threshold was applied in room temperature. Under low oxygen partial pressure, a damped sinusoidal oscillatory current was generated after the appearance of the hot spot. In this work, the effect of applied voltage on the oscillatory current was investigated. The decay of the amplitude decreased with increasing voltage. The decay of the amplitude was considered to be related to the size of the hot spot.

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Recently, it has been found by our group that ZnO crystals grow on ZnO ceramic bar heated by electric current. In this research, Zn wire was heated by electric current under 0-100% O₂ concentration in the ambient atmosphere. As a result, crystals grew on the Zn wire surface. The shape of the crystals was needle under an atmosphere containing O₂. Under Ar atmosphere, crystal shapes were mainly rod and partly hexagram. From X-ray diffraction pattern, the grown crystals were considered to be ZnO.

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Effect of O₂ concentration of ambient atmosphere on crystal growth of ZnO by electric current heating method was investigated. Zinc oxide crystals were fabricated under atmosphere containing O₂ (20-100% in Ar). The form of grown crystals tended to be hexagonal hollow prism. The diameters of ZnO hexagonal hollow prisms increased with increasing O₂ concentration. It was found that size of ZnO crystals depended on O₂ concentration of atmosphere.

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Recently we have found a phenomenon that a cluster consisting of ZnO crystals grows on the aluminum powder placed on a ZnO ceramic bar when a certain current runs through the bar. In this report, conditions of the current density and oxygen partial pressure for the cluster growth were investigated. As a result, the cluster grew in current density 70-100 A/cm2 and oxygen partial pressure 10 - 30 kPa.

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Barium titanate gel was prepared from highly concentrated alkoxides solution. A mixture of 2-methoxyethanol and Acetylacetone was added to the gel. The gel was dispersed in the suspension medium by ultrasonication. We obtained transparent barium titanate nanoparticle suspension by this method. Barium Titanate thin films were fabricated by electrophoretic deposition on cathode electrode. From TEM observation, the particle size was estimated around 10∼15nm. The particles were conformed to be cubic barium titanate by diffraction pattern.

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LaNiO3(LN) and BaTiO3(BT) thin film was deposited on Si(001) substrate by RF-magnetron sputtering. BT thin film was deposited at R.T. and tried to crystallize by post annealing. Crystallized BT was obtained in the annealing temperature range above 600°C. Relative permittivity of BT annealed at 600°C was obtained from 20 to 150 at respective annealing time.

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Non-doped and rare-earth metal doped ZnO films with/without AlN buffer layer were fabricated on (0001) sapphire substrates by reactive rf magnetron sputtering. The films were investigated by measuring photoluminescence(PL), SEM and XRD. The PL spectra showed dominant UV emission at about 380 nm and the emissions from Eu.

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The influence of electric field induced ferroelectricity (piezoelectricity) in SrTiO3 thin films on the capacitance of the Pt/SrTiO3/Pt MIM capacitors were investigated. The SrTiO3 thin film MIM capacitors show electric field induced resonance under dc electric field at specific frequencies. These piezoelectric resonant frequencies depend only on the stack structure of the capacitor, but are independent of the MIM area and the applied dc electric field strength.

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YSZ-MO₂ (M=lr,Ru)nano-composite films were prepared by MOCVD. The films were dense and consisted of spherical grains in diameter of several tens nano-meters. The electrical conductivity of zirconia/electrode interface was increased with increasing Ir or Ru content in the nano-composite films and became the maximum at 15-25vol%MO₂. This trend could be explained by a percolation of MO₂ particles in the composite films. The emf values of the oxygen concentration cell constructed from the composite film electrode and YSZ electrolyte showed the Nernstian theoretical values at 650°C.

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The effect of the Ta doping on the growth of the SiOx layer in YSZ/Si gate dielectrics was investigated by HRTEM method. Most of the YTaSZ layer epitaxially grown like as YSZ layer. It was, however, out of expectation that the SiOx thickness of Ta doped YSZ/Si became thicker than YSZ/Si, and that the roughness of the interface between SiOx/Si was increased.

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AlN growth on SiC is a good candidate as the substrate for nitride high-power devices because of high thermal conductivity. However a large number of defects appear in AlN film, because commercially available SiC substrates have many scratches arising from polishing damages. The AlN film on atomically flat 6H-SiC surface, etched by removing the graphite layer formed in vacuum annealing, had no pits and the steps corresponding to the 6H-SiC unit cell height. The morphology of AlN film was significantly improved compared to that on the as-received SiC surface.

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Indium oxide films were deposited using an atmospheric CVD reactor on the Si(100) substrate. X-ray diffractometry revealed that the cluster size of samples deposited at substrate temperatures of 350°C, 450°C and 550°C were 9 nm, 14 nm and 41 nm, respectively. On the other hand, the sample obtained at a temperature of <250°C had amorphous structure. For the sample deposited at 350°C∼450°C, the cluster was terminated by OH group. The In2O3 crystal without OH group was formed at a temperature of 550°C.

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Y3Fe5O12, LaCoO3 and NiFe2O4 were prepared from aqueous solutions of metal salts containing polyvinylpyrrolidone (PVP) in an attempt to examine if the PVP-assisted aqueous solution route is available for fabricating complex oxide coating films. The solutions contained Y(NO3)3H2O, Fe(NO3)3H20, La(NO3)3H2O, Co(NO3)2H2O and Ni (CH3COO)2H20 as the metal source, water as the solvent, PVP, and nothing else. Dip-coating was conducted on silica glass substrate, and the gel films were just placed in an electric furnace of 700°C or 1000°C. The films were crystallized in single-phase target compounds.

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Selective deposition process of metal oxide thin film was researched for the application to the direct production on chip. In addition, the microstructure, e.g. crystalline degree, of the as-deposited film was also controlled in aqueous solution containing different kinds of precursors. We have succeeded in fabricating patterned alkyl monolayers directly formed on Si for the first time. The patterned alkyl monolayer substrate with both silanol- and methyl regions was used as the template for the selective deposition. This report suggests a reliable approach for fabricating micro-sensor from aqueous solution processing. Additionally, the effects of film thickness and crystallized degree on the electrical and gas sensing properties were investigated.

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Electroless plating solutions were employed to fabricate the tiny particles of copper or copper(I) oxide in the volume of solutions by controlling the pH values and additives. Selective deposition of both copper and copper(I) oxide particles were observed in the appropriate aqueous solutions onto self-assembled monolayers (SAM) terminated with NH2 instead of OH headgroups individually, as a result, micro patterns were successfully fabricated on the UV-patterned SAM with NH2 and OH terminals. Considering the difference in charged conditions between copper and copper(I) oxide tiny particles (negative) formed in the volume of solutions and SAM surfaces (NH2-SAM: positive; OH-SAM, negative), it is conceivable that the electrostatic interactions should be strongly responsible for the selective deposition.

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Kaolinite was organically modified with butanediols by the reaction between methoxy-modified kaolinite and 1,2-(and 1,3-)butanediols. Butanediols were grafted onto the interlayer surface of kaolinite by transesterification of methoxy-modified kaolinite, which was shown by XRD, TG-DTA, and ¹³C CP/MAS NMR data. During the reaction, the amounts of the alkoxy groups per Al₂Si₂O₅(OH)₄ increased. This finding suggests that further esterification of AlOH groups with butanediols also occurred.

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The alkoxyl derivatives of layered perovskite, H_1.8Sr_0.8Bi_0.2Ta₂O₇, were prepared using n-alkylamine layered perovskite intercalation compounds as intermediates. After the reaction of n-alkylamine intercalation compound of HST with n-decanol in an autoclave at 150°C the basal spacing increased. Carbon-13 NMR showed the presence of signals due to n-decoxyl groups and downfield shift of a a-carbon signal, indicating of the formation of Ta-O-C bond. These results suggest successful modification of H_1.8Sr_0.8Bi_0.2Ta₂O₇.

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The hydrosilylation between layered perovskite, HLaNb₂O₇, possessing C=C bonds and hydride-terminated polydimethylsiloxane was investigated. XRD analysis showed the basal spacing was increased from 1.84 nm to 2.54 nm after the reaction. IR spectroscopy exhibited the presence of dimethylsilyl groups in the resultant product. Carbon-13 CP/MAS NMR spectroscopy showed the new signals(17.7 and 24.2 ppm)attributed to the Si-CH₂-CH₂- and Si-CH₂-CH₂-. Silicon-29 CP/MAS NMR spectroscopy showed the present of (CH₃)₂Si(OSi)CH₂ groups and (CH₃)₂Si(OSi)₂ groups. These results suggest hydrosilylation proceeded, leading to the formation of the new organic derivative of layered perovskite.

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Intercalation compounds of MoO₃-pyridine derivative were prepared by closed tube and ultrasonic wave processes. Pyridine, 4,4' -bipyridine and 2,2' -bipyridine were used as the reactants with MoO₃. Intercalation compounds were analyzed using XRD, IR and TG/DTA. Unit cell parameter of MoO₃-pyridine compound prepared by closed tube process is b =1.13 nm, while b =1.17 nm by ultrasonic wave. Peak intensity of Mo=O stretching in IR spectra decreased and a new peak appeared at 940 cm^-1 for intercalation compounds prepared by both processes. (MoO₃)(4,4' -bpy)_0.31 was obtained by closed tube process and (MoO₃)(py)_0.68 by ultrasonic wave.

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Novel porous titania-hydrotalcite composites were synthesized by intercalation of [CH₃CH(O-)CO₂NH₄]₂Ti(OH)₂.The product showed microporosity with large surface areas (>300 m²/g).

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Layered double hydroxide, Hydrotalcite, was anion-exchaned by hexachloroplatinate ion and reduced by H₂ to produce porous pillared structure having a specific surface area of >200 m²/g and pore distributions centered at 1.8nm.

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The method of oxidative polymerization using pyrrole vapor was investigated to prepare the composite powders of ion exchanged hectorite/polypyrrole. The obtained powders were evaluated by XRD, FT-IR and TG-DTA. The results of these measurements were suggested the existence of interlayer reaction products of penetrated pyrrole in the prepared powders, and the improvement of heat resistance of polypyrrole was observed.

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In most of the known ternary systems RE-Mn-Si (RE=rare earth), three types of ternary structures have been reported. However, the information on their physical and chemical properties is not complete. In this work, we report experimental conditions for growing relatively large crystals of REMn₂Si₂ (RE=Sm,Eu,Gd) compounds from lead flux. The crystal morphology and crystallographic data of REMn₂Si₂(RE=Sm,Gd) crystals were determined and micro-Vickers hardness and magnetic susceptibility of the compounds were studied.

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New inorganic materials have been searched in ternary system, A₂O - Ln₂O₃- M₂O₅ and A₂O- BO-M₂O₅ (Ln = Rare earths; A = Rb, K, Na and Li; B = Ca, Sr and Ba; M = Ta and Nb). Oxygen-deficient orthoniobate and fluorite-related strucrture were newly synthesized in the ternary system Rb₂O- Ln₂O₃ - Nb₂O₅.

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Octahedral CrN single crystals with a size of 75 μm were obtained by heating Cr-Ga-Na ternary melt at 850°C and 3 MPa of N₂ for 200 h. X-ray diffractometry revealed that the CrN single crystals had the cubic rock-salt structure with the lattice parameter a=4.1467(8)Å. The CrN single crystals exhibited antiferromagnetism below the Neel temperature of 290 K.

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Needle-like GaN crystals were grown on various substrates by reaction with NH3 of Ga2O gas formed by reaction of Ga2O3 with carbon. The reaction of Ga2O3 with carbon was performed at 950°C. The generated Ga2O gas was transported by Ar in the inner silica tube. The Ga2O gas was reacted with flowing NH3 in the other silica tube at 1000°C. The crystals were identified as wurtzite GaN by XRD and Raman spectroscopy. It was found that the morphology of GaN crystals is affected by the kind of substrates.

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The GaN nanoparticle mono-dispersed h-BN composite was successfully fabricated by ure-nitriding process in which urea, Ga(NO3)3 and H3BO3 as starting materials were reduced in H2 at 500-800°C. In order to synthesize GaN from Ga(NO3)3 and urea, urea of 5-10 times molar ratio of Ga(NO3)3 was required. The TEM observation of the reduced powder showed the typical nanocomposite structure that GaN nanoparticles with average grain size of 7-10nm were mono-dispersed within h-BN grain.

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(Bi,La)4Ti3O12 (BLT) thin films were prepared on Pt-coated Si (Pt/Ti/SiO2/Si(100)) substrates by chemical solution deposition method. The effect of heating process on structural and electrical properties of BLT thin films was investigated. The orientation of the thin films changed with the drying temperature and drying methods. The c-axis preferentially oriented films were obtained by lower drying temperature with heating from bottom by a hot plate. On the other hand, randomly oriented films were obtained by higher drying temperature or by tube type IR-lamp heater.

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Gel films were deposited on Pt/Ti/SiO2/Si substrates by spin-coating using a Ba(CH3C00)2-Bi(CH3(CH2)3CH(C2H5)C00)3-Ti(OC3H7i)4-PVP-CH3(CH2)3CH(C2H5)C00H-H2O-CH30C2H40H-CH3COOH solution. The gel films were heated successively at 300°C for 10 min and 700 or 800°C for 10 min, and the gel film deposition and heat-treatment were repeated. When the post-heating was conducted at 700°C, the film contained Bi2Ti2O7 impurity phase, while single-phase BaBi4Ti4O15 was obtained at 800°C. A BaBi4Ti4O15 film 3.0 μm in thickness was obtained via 5 times coating with post-heating at 800°C, which exhibited P-E hysteresis and had a dielectric constant of 254 at 1 kHz.

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This method includes deposition of Self-Assembled Monolayer(SAM) followed by the optical etching by exposing the SAM to the UV-light, leading to the patterned SAM as a selective deposition template. The pattern of SAM was formed by irradiating UV-light to the SAM on substrate through a metal mask for the selective deposition of patterned PZT precursor films from alkoxide precursor sols. As a result, patterned ferroelectric PZT films in micrometer size could be successfully deposited.

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Lead zirconate titanate (PZT) thin films were deposited by spin coating on Pt/Ti/SiO2/Si substrate with chemical solution deposition(CSD) . We investigated the influence of applied electric field during annealing and seeding layer on orientation to control the film orientation. The resultant thin film by annealing with electric field exhibited higher degree of (001)- orientation than that of the film by normal annealing process.

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Effect of the surface atomic layers of SrTiO₃ (STO) substrates on the stabilization of perovskite phase and the epitaxial growth of Pb(Mg_1/3Nb_2/3)O₃(PMN) and Pb(Zn_1/3Nb_2/3)O₃(PZN) based thin films was investigated. The films were deposited on various STO(001) substrates with TiO₂ and/or SrO surfaces by pulsed laser deposition (PLD). Although all PMN films were epitaxially grown with (001)-orientation, in the case of TiO₂- and TiO₂/SrO-covered STO substrates, pyrochlore phase was also formed together with perovskite phase. On the other hand, PMN films with almost no pyrochlore phase could be grown on SrO- covered STO substrates. These phenomena would be explained in terms of the interface stability between PMN films and STO substrates with TiO₂ or SrO surfaces.

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Pb(Zr,Ti)O3 (PZT) thin films were deposited by pulsed metal-organic chemical vapor deposition (MOCVD) with PT and PZ alternate supply on the MgO and Pt/MgO substrates. With increasing the pulse width of the alternate supply of the raw vapor gases, PZT(001) peak was splited into PZT, PT and PZ peaks. Interdiffusion between adjacent layers might be difficult with increasing the pulse width. In addition, polarization with applied voltage was decreased and increased again with increasing the pulse width.

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Lanthanum modified lead zirconate titanate [(Pb,La)(Zr,Ti)O₃:PLZT] is famous for its high transparency and large electrooptic coefficient and is expected to be a candidate for the material of a photonic crystal which has new function. At first, we fabricated resist mold contains periodic array of square and circle holes Nb-doped (001)SrTiO₃ substrate using EB lithography. After cast PLZT precursor into the mold, dried it, and polished unnecessary upper dry gel. After removed resist, there were periodic array of pillars of PLZT dry gel on the substrate. Fired them at 725°C in air, PLZT crystalline pillars grown epitaxially on the substrate were obtained. We report about cystalline, optical and electrical properties of them.

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Pb(Zr,Ti)O3 (PZT) thin films were deposited by MOCVD on SrTiO3 seeded (111)Pt/IrO2/SiO2/(100)Si substrate. SrTiO3 seed layers were prepared by Pulsed laser deposition (PLD) at 600 and 800°C. PZT thin film was prepared at 290°C by MOCVD. It was observed by RHEED that SrTiO3 seed layers were crystallized. The relationship between PZT thin films and SrTiO3 seed layers was examined by XRD, AFM and XPS.

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Change in the compositional fluctuation in Pb(ZrxTi1-x)O3 (PZT) during sintering was examined. As a sintering method, normal sintering, hotpressing and spark plasma sintering (SPS) were examined. With the increasing of the density of sample by normal sintering, the compositional fluctuation in PZT was notably decreased. By hotpressing, the change in the compositional fluctuation was slight. SPS produced a highly sintered body without changing the initial compositional distribution.

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