Susumu Mizuta

Crystallization and in-plane alignment behavior of YBa 2 Cu 3 O 7− y films on MgO(001) prepared by the dipping-pyrolysis process

The effects of annealing temperature and oxygen partial pressure [ p (O 2 )] were investigated on the crystallization and orientation of YBa 2 Cu 3 O 7− y (YBCO) films on MgO(001) prepared by the dipping-pyrolysis process. The c -axis oriented films without in-plane alignment were prepared by annealing in the YBCO-unstable region, i.e., at low initial p (O 2 ) of 10 −4 −10 −3 atm and 950 °C followed by O 2 treatment, through intermediate Y 2 BaCuO 5 and liquid phase. In-plane aligned c - or c/a -axis films were prepared by similar heat treatment with an initial p (02) of 10 −4 atm and 900–925 °C through a mixture of BaCu 2 O 2 and YBa 3 Cu 2 O 6+x . In contrast, nonoriented YBCO films were obtained by annealing at higher initial p (O 2 )s and lower temperatures, i.e., by direct reaction among Y 2 O 3 , BaCO 3 , and CuO.

Preparation of Epitaxial Pb(Zr, Ti)O3 Thin Films on Nb-Doped SrTiO3 (100) Substrates by Dipping-Pyrolysis Process

Epitaxially grown Pb(Zr, Ti)O3 (PZT, Pb:Zr:Ti=1:0.52:0.48) thin films were prepared on Nb-doped SrTiO3 (100) substrates by dipping-pyrolysis process with metal naphthenates used as starting materials. The alignments of the films were investigated based on X-ray diffraction (XRD) θ–2θ scans, β scans (pole figures), and asymmetric ω–2θ scans (reciprocal-space maps). Epitaxial films with smooth surfaces were obtained by heat treatment of prefired films at 600°–750° C; a film heat-treated at 750° C showed the strongest peak intensities in the XRD θ–2θ scans. These PZT films were found by reciprocal-space map analysis to consist of the c-axis-oriented tetragonal phase.

DIRECT CONVERSION OF TITANIUM ALKOXIDE INTO CRYSTALLIZED TIO2 (RUTILE) USING COATING PHOTOLYSIS PROCESS WITH ARF EXCIMER LASER

TiO2 (rutile) films have been successfully prepared by the coating photolysis process using ArF excimer laser irradiation at room temperature. The choice of the Ti-alkoxide type as the starting material and the effects of atmosphere on the product films have been studied by Fourier transformation infrared (FT-IR) and X-ray diffraction (XRD). When using Ti(O-i-C3H7)4 as the starting material, rutile films were obtained by the irradiation in a dry N2 atmosphere, whereas amorphous films were obtained by irradiation in air. When using Ti(OCH2CH(C2H5)-n-C4H9)4 as a starting material, rutile films were obtained by the irradiation even in the air atmosphere. Crystallization mechanism is also discussed.

Effect of substrate material on the crystallinity and epitaxy of Pb(Zr,Ti)O3 thin films

Abstract Pb(Zr,Ti)O3 thin films (Pb:Zr:Ti=1:0.52:0.48) were prepared on various single-crystal substrates via dipping-pyrolysis process by use of metal naphthenates as starting materials. The alignments of these films were examined by X-ray diffraction (XRD) θ–2θ scans and β scans (pole figures). The films grown on Nb-doped SrTiO3, MgO or LaAlO3 showed an epitaxial relationship with substrates after heat treatment at 750°C, while those grown on sapphire and Si wafers exhibited polycrystalline or amorphous characteristics. Epitaxial films on SrTiO3 and LaAlO3 were found to consist of a c-axis oriented tetragonal phase, to minimize the lattice misfit with the substrates. These epitaxial films exhibited very smooth surfaces by SEM and AFM observations. In addition, the fluctuation of in-plane alignment was significantly dependent on the lattice-misfit values.

PREPARATION OF EPITAXIAL LA1-XSRXMNO3 FILMS ON SRTIO3(001) BY DIPPING-PYROLYSIS PROCESS

La{sub 1{minus}x}Sr{sub x}MnO{sub 3} (LSMO) (x=0{endash}0.3)films were prepared on SrTiO{sub 3}(001) substrates by the dipping-pyrolysis process using metal naphthenates as starting materials. Epitaxially grown LSMO films were obtained by heat treatment at 800{endash}1200{degree}C; the fluctuation of alignment of these films, evaluated by reciprocal-space mapping of asymmetric x-ray diffraction, was markedly small, as comparable to that of the substrates. The LSMO films with x=0.1{endash}0.3 showed metallic conduction behavior at 25{endash}300 K, and the resistivity was as low as that of LSMO single crystals, e.g., 4{times}10{sup {minus}4} {Omega}{center_dot}cm at 150 K for the film with x=0.3. {copyright} {ital 1997 Materials Research Society.}

Direct Conversion of Metal Acetylacetonates and Metal Organic Acid Salts into Metal Oxides Thin Films Using Coating Photolysis Process with An ArF Excimer Laser

Metal oxide films of TiO2, In2O3, ZrO2, ZnO, SnO2 and Fe2O3 have been successfully prepared by the coating photolysis process using ArF excimer laser irradiation at room temperature. When using metal acetylacetonates (acac) as the starting material, TiO2, In2O3 and ZrO2 were obtained with ArF laser irradiation at 50 mJ/cm2 at a repetition rate of 5 Hz for 5 min. When using Zn-acac, Fe, Sn, or In 2-ethylhexanoate as the starting material, a two-step process consisting of preliminary weak and sufficiently strong irradiation was found to be effective for obtaining ZnO, Fe2O3, SnO2 and In2O3 films.

Effects of Heat Treatment Conditions on the Critical Current Densities of Ba2YCu3O7-y Films Prepared by the Dipping-Pyrolysis Process

The effects of temperature and atmosphere on the BYCO formation reaction of BaCO3, Y2O3 and CuO, prepared by the pyrolysis of metal acetylacetonate solution, were examined by TG-DTA, XRD and resistivity measurement. This reaction was found to proceed readily below 900°C under low oxygen partial pressures. Superconducting Ba2YCu3O7-y films with Tc,zero\cong90 K and Jc(77 K)=300–400 A/cm2 were prepared by the dipping-pyrolysis process using the above solution through heat treatments at 820°–880°C under controlled low oxygen partial pressures of ρ(O2)=1×10-3–2×10-4 atm followed by O2 annealing.

Microstructural and electrical properties of La0.7Ca0.3MnO3 thin films grown on SrTiO3 and LaAlO3 substrates using metal-organic deposition

La0.7Ca0.3MnO3 (LCMO) thin films have been prepared on LaAlO3 and SrTiO3 (STO) (001) single-crystal substrates by the metal-organic deposition process. These films were characterized by transmission electron microscopy (TEM) and temperature dependence of the resistance R(T). The microstructure of the LCMO films and LCMO/substrate interfaces were investigated through cross-sectional TEM observations. High-resolution TEM (HRTEM) observations and electron-diffraction patterns demonstrate the (001) epitaxial growth on both the LAO and STO substrates. The local structure of the LCMO film depends on the type of substrate. HRTEM observations along the LCMO/STO interface display a good epitaxy throughout the entire film without any microstructural defects. On the contrary, in the LCMO film and in the region close to the LAO substrate, we note the presence of misfit dislocations and twins. The temperature coefficient of resistance (TCR) was calculated from the temperature dependence of the resistance measurements....

Low temperature growth of epitaxial La0.8Sr0.2MnO3 thin films by an excimer-laser-assisted coating pyrolysis process

The preparation of La0.8Sr0.2MnO3 (LSMO) films on a LaAlO3 (LAO) substrate has been investigated by an excimer-laser-assisted coating pyrolysis process (ELACPP) in the temperature range from 350 to 500°C. (00l) oriented LSMO films were successfully obtained by ArF laser irradiation at 100 mJ/cm2 in the substrate temperature range from 400 to 500°C. The films prepared at 500°C on the LAO substrate were found to be epitaxially grown based on X-ray diffraction (XRD) pole-figure measurements. The temperature dependence of the resistance of the LSMO film prepared at 400°C showed a semiconducting behavior. On the other hand, that prepared at 500°C showed a metallic behavior from 310 K to 100 K and the absolute magnitude of the resistivity of the film at 300 K was 2.6×10-2 Ωcm.

Single crystal growth of the spinel-type LiMn2O4

Single crystals of the spinel-type LiMn 2 O 4 have been successfully grown by a solvent evaporation flux method at 1173 K. The maximum size of the octahedral-shaped single crystal is 0.09 x 0.09 x 0.09 mm 3 along the octahedral edges. The single-crystal X-ray diffraction study confirmed the cubic Fd3m space group and the lattice parameter of a = 8.2483(6) A of the as-grown single crystal at 297K. The preliminary single-crystal low temperature X-ray diffraction experiments confirmed the cubic-orthorhombic structure transition around 285 K on the cooling process. The tripled periodicity toward the a- and b-axis directions of the low temperature form has been also confirmed.