ИСТИНА

This study continues our previous works [1,2,3] dealing with the thin oxide films obtaining using Chemical Solution Deposition (CSD) method. In spite of high potential of the technique was demonstrated, still many problems of kinetic origin, very important for the obtaining high quality (e.g. smooth, homogeneity, heteroepitaxial) films, are not solved. In particular, the problem of residual carbon contamination of the CSD films is essential. In this work we propose to reduce the carbon contamination adding the additional pre-treatment of the precursor film with UV-irradiation (250 nm) and/or with ozone-containing atmosphere. The objects of the study were a) Zr and La propionates chosen to synthesize La2Zr2O7 as buffer layers for the 2G HT superconducting materials, and b) Fe and Lu propionates for obtaining multyferroic LuFe2O4 thin films. The coating solutions were prepared dissolving in the propionic acid a stoichiometric mixture of lanthanum oxide and zirconium acetylacetonate (case a) or lutetium carbonate and iron(II) acetate (case b).The solutions are stable at high concentrations (up to 0.3 M) and show excellent wetting ability at metal (Ni5W tapes) and oxide (MgAl2O4 single crystals) substrate surfaces. The chemistry of the precursor solutions was studied using thermogravimetric analysis and IR-sperctroscopy. At the next step a low temperature pre-treatment of the deposited films was undertaken and the effects of UV-irradiation, ozone containing atmosphere and the pre-treatment temperature were studied using IR-spertroscopy and EDX-analysis of residual carbon contamination. The pre-treated films were annealed at high temperature and very low oxygen pressure. Crystalline oxide films of La2Zr2O7 on the Ni-5W were obtained at 1000-1150oC from the precursor-coated tapes under reducing Ar + H2 atmosphere. X-ray diffraction (θ-2θ, ω- and φ-scanning), scanning electron microscopy, electron backscattering diffraction, transmission electron microscopy and auger-spectroscopy were used for oxide films characterization. For this object an important role of ozone-containing atmosphere to eliminate residual carbon was shown. The tapes were used as the only buffer layers which permitted us to make superconducting tapes with simplified architecture YBa2Cu3O7-x/La2Zr2O7/Ni-5W. In case of LuFe2O4 films the low carbon contamination obtained under UV- and/or ozone pre-treatment also was helpful for the formation of oriented films at high temperature annealing step, evidently, due to carbon hinders the cation diffusion of those metals which have high energy of carbides formation. [1] A. Kharchenko, A. Grigoriev, S. Samoilenkov, A. Kaul, Doklady Akademii Nauk, 2013, 452, 396-400. [2] A. Kharchenko, S. Schukin, V. Chepikov, XII International Conference on Nanostructured Materials, 2014. [3] A. Kharchenko, A. Grigoriev, S. Samoilenkov, A. Kaul, Organometallic and Coordination Chemistry: Fundamental and Applied Aspects, 2013. Acknowledgements This work was supported by the Russian Foundation for Basic Research grants No. 14-03-32063, 13-03-01249. e-mail: kharchenko.andrey@gmail.com