Innovation in Ceramic Science and Engineering

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Authors: Mitsutaka Sato, Rong Tu, Takashi Goto, Kyosuke Ueda, Takayuki Narushima
Abstract: Ca-Ti-O films were prepared by MOCVD using Ca(dpm)2 and Ti(OiPr)2(dpm)2 precursors. The phases, composition and morphology of Ca-Ti-O films changed depending on the molar ratio of Ca to Ti precursors (RCa/Ti), total pressure (Ptot) and substrate temperature (Tsub). CaTiO3 films in a single phase were obtained at Tsub = 973 and 1073 K. CaTiO3 films prepared at 873 K had a dense structure and smooth surface. CaTiO3 films prepared at Tsub = 1073 K had complicated rough surface with a cauliflower-like texture. Hydroxyapatite (HAp) formed in 3 days on the CaTiO3 film prepared at Tsub = 1073 K.
Authors: Kyosuke Ueda, Takayuki Narushima, Tomoyuki Katsube, Hiroshi Kawamura, Takashi Goto
Abstract: Calcium phosphate coating films were fabricated on mirror-polished or blast-treated titanium substrates using radio-frequency (RF) magnetron sputtering and they were evaluated in vitro. Immersion tests for the films were conducted using phosphate-buffered saline (PBS(-)), and apatite formation and the elution of calcium ions from the films were investigated. The bonding strengths between the calcium phosphate films and titanium substrates before and after the immersion tests were evaluated. After the immersion tests, a decrease in the bonding strength was observed for the coating films on the mirror-polished titanium substrates, while that for the blast-treated titanium substrates was almost the same as that before the immersion tests.
Authors: Chuan Bin Wang, Rong Tu, Takashi Goto
Abstract: A new lead-free ferroelectric BaTi2O5 film was first prepared by laser ablation. BaTi2O5 films in a single phase were obtained at substrate temperatures (Tsub) from 900 to 1050 K and oxygen partial pressures (PO2) from vacuum (10-6 Pa) to 30 Pa. The films exhibited a (710) and/or (020) preferred orientation, depending on Tsub and PO2. At PO2 = 12.5 Pa and Tsub = 950 - 1000 K, the BaTi2O5 film was b-axis oriented and epitaxially grown on MgO (100) substrate with a rectangularly crossed texture. The epitaxial growth relationship between the film and the substrate were BaTi2O5 (020) [100] // MgO (100) [001] and BaTi2O5 (020) [100] // MgO (100) [010].
Authors: Akihiko Ito, Hiroshi Masumoto, Takashi Goto
Abstract: Epitaxial BaRuO3 (BRO) and CaRuO3 (CRO) thin films were prepared on (001), (110) and (111) SrTiO3 (STO) single-crystal substrates by laser ablation, and their microstructures and anisotropy of electrical conductivity were investigated. The (205) (104), (110) and (009) oriented BRO thin films, and (001), (110) and (110) oriented CRO thin films were grown epitaxially on (001), (110) and (111) STO substrates with in-plain orientation, respectively. The (009) BRO thin film and (001) CRO thin film has a flat surface result from a good lattice matching to STO substrates. The (205) (104) BRO thin film and (111) CRO thin film exhibited orthogonal- and hexagonal-shaped texture, respectively. The (110) BRO thin film and (110) CRO thin film showed an island growth due to (110) surface feature of cubic perovskite structure. Epitaxial BRO and CRO thin films have a high electrical conductivity with a metallic conduction, the (111) CRO thin films exhibited the highest conductivity of 1.4×105 S·m-1.
Authors: Masato Sakata, Teiichi Kimura, Takashi Goto
Abstract: Ruthenium-Carbon (Ru-C) nano-composite films were prepared by microwave-induced plasma-enhanced chemical vapor deposition (PECVD) and the effects of deposition conditions on the microstructure and electrical properties were investigated. The films consisted of agglomerated grains of 10 to 20 nm in diameter, in which Ru particles of 2.5 to 3.5 nm in diameter were dispersed in an amorphous C matrix. The C contents of the films ranged from 86 to 94 vol%. The electrical properties of Ru-C nano-composite films as a catalytic electrode for an yttria-stabilized zirconia (YSZ) solid electrolyte were evaluated by AC impedance spectroscopy. The electrical conductivity at the Ru-C/YSZ interface (σi) was 0.2 × 10-3 Sm-1 at 500 K and increased with increasing temperature. The activation energy of the σi was 70 kJ/mol. Electro-motive-force (EMF) values of an oxygen concentration cell constructed from YSZ electrolyte and Ru-C nano-composite electrodes responded to the change of oxygen partial pressure above 473 K. The response time of the concentration cell was less than 10 s above 573 K.

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