Thermodynamics of Epitaxial Ferroelectric Films.

Abstract

AbstractThe problem of phase transitions and physical properties of the BaTiO3-type films on the (001) single-crystal substrates of the cubic syngony was solved in the limits of the Landau- Devonshire thermodynamics. The thermoelastic film-substrate interaction caused by the difference between thermal expansion coefficients was strictly taken into consideration. The model was based on the following assumptions: 1) the film is closely conjugated with the substrate; 2) the film is sufficiently “thick”to find itself unstrained at the growth temperature Ts, ( growth stresses were compensated by misfit dislocations ), and 3) the film is sufficiently “thin, and the stresses arising at the temperatures T>Ts may be considered to be uniform.