T. Kumagai

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 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.}

Preparation of YBa2Cu3O7− y films on SrTiO3 and MgO by the dipping-pyrolysis process under low- p(O2) heat treatment

Superconducting YBa 2 Cu 3 O 7− y (YBCO) films having a thickness of 1 μ m were prepared on SrTiO 3 (100) and MgO(100) by the dipping-pyrolysis process using a low- p (O 2 ) annealing method. Heat-treatment conditions were varied along the upper limit of the stability region of the YBCO phase. Films on SrTiO 3 (100) exhibited strong c -axis orientation with sharp rocking curves (FWHM = 0.8°). The highest T c,zero of 87 K was obtained for the film heat-treated at 750 °C. On the other hand, films on MgO(100) showed broader rocking curves and their T c s remained lower. Moreover, Ag addition was found to enhance the T c values ( T c,zero = 91 K) of films on SrTiO 3 heat-treated at 750 °C.