Investigation of nucleation and epitaxial growth of Ba1-xKxBiO3 films

Abstract

Single-crystal films of the Ba1-xKxBiO3 have been successfully grown using the technique of liquid-phase epitaxy in an electrochemical cell. The FWHM of the Bragg reflection curves of the films does not exceed 0.5° and is determined by substrate quality. The films were grown from the KOH flux saturated by Bi2O3 at temperatures 230-270°C and BaO concentration 0.005-0.03 mol/mol KOH. Ferroelectric single crystals of BaBiO3 have been grown from the close to stoichiometric melt to be used as substrates. The process of film formation on the (1 0 0) substrate face were studied using a polarization optical microscope. At the first stage of the film deposition the formation of separate crystallites were observed on the film surface. Their number increases with higher electrochemical overvoltage. The optimal current density for crystallite nucleation lies in the range 20-30 A/m2. The voltammograms of the as-prepared Ba0.6K0.4BiO3 films demonstrated three particular areas: the film epitaxial growth one, the corrosion zone process area and film dissolving region. The activation energy of the film growth process have been determined. © 1999 Elsevier Science B.V. All rights reserved.