Layered thin films in the BaTiO3-SrTiO3 system have been fabricated by a hydrothermal-electrochemical method either in a closed autoclave or in a flow system using the titanium substrate and Ba- and Sr-hydroxides or acetates as sources of titanium, barium, and strontium, respectively. The synthesis conditions (temperature in the range of 120-200°C, current density of 1-20 mA/cm2, flow rates of 1-50cm3/min, duration of 1-24h) allowed an easy control of the microstructure of the titanate layers. BaTiO3 layers could be deposited easily on SrTiO3 layers at 150°C (1h, 1mA/cm2) both in the closed autoclave and in the flowing solution. To deposit SrTiO3 layers on BaTiO3 layers, a current density of 10mA/cm2 or preceding water leaching of the BaTiO3 surface were necessary. The multilayered nature of the BaTiO3-SrTiO3 films have been revealed by XRD, AFM, and XPS at various stages of their preparation. Based upon the experimental results, a growth mechanism of the BaTiO3-SrTiO3 double layers has been proposed.
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