Papers by Author: Mitsutaka Sato

Abstract: C-Axis-Oriented Y₂Ba₄Cu₇O_15-δ (Y247) Films Were Prepared on Multilayer-Coated Hasterolly Tape Substrate by Laser Chemical Vapor Deposition with Ultrasonically Nebulized Liquid Precursor. At a Low Precursor Concentration of 0.01 mol l⁻¹ and Deposition Temperature of 933 K, Single-Phase Y247 Film with Significant c-Axis Orientation Was Obtained. At a Precursor Concentration of 0.1 mol l⁻¹ and Deposition Temperature 983 K, a-Axis-Oriented YBa₂Cu₃O_7-δ (Y123) Was Codeposited with C-Axis Oriented Y247 Film.

Abstract: Functionally graded Ca-Ti-O/Ca-P-O films were prepared by MOCVD. The phases, composition and morphology of Ca-Ti-O and Ca-P-O films changed depending on the molar ratio of each precursors, 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 and smooth surface, whereas that prepared at Tsub = 1073 K had complicated rough surface with a cauliflower-like texture. The graded texture of CaTiO3 films from columnar to fine grains was advantageous to good adherence for metal substrates. -TCP and HAp films in a single phase were obtained at Tsub = 973 and 1073 K. Both -TCP and HAp films had a dense and smooth surface. The maximum deposition rate of Ca-Ti-O and Ca-P-O films were 44 and 20 m/h, respectively, and several 10 times grater than that of sputtering method. Apatite formation rate strongly depended on the surface morphology of film. Apatite formed after 3 days on the CaTiO3 film, 14 days on the -TCP film and 6 hours on the HAp film in a Hanks’ solution.

Abstract: Calcium phosphate films were prepared by MOCVD using Ca(dpm)2 and (C6H5O)3PO precursors. The phases, composition and morphology of films changed depending on the molar ratio of Ca to P precursors (RCa/P), total pressure (Ptot) and substrate temperature (Tsub). α-tricalcimu phosphate (α-TCP, α-Ca3(PO4)2) films in a single phase were obtained at Tsub = 1073 K, 0.1 < RCa/P < 0.4 and Tsub = 973 K, RCa/P < 0.4. Hydroxyapatite (HAp, Ca10(PO4)6(OH)2) films in a single phase were obtained at Tsub = 1073 K, 0.8 < RCa/P < 1.0 and Tsub = 973 K, 0.5 < RCa/P < 0.6. Ca-P-O films had a dense and smooth surface. HAp formed within 1 day on the α-TCP film and wholly covered the specimens within 2 weeks in a Hanks’ solution. The surface of CVD-HAp film was covered by precipitated HAp within 6 hours.

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.