Advanced Search

Browse by Discipline

Scientific Societies

E-print Alerts

Add E-prints

E-print Network

  Advanced Search  

Phase diagrams and dielectric response of epitaxial barium strontium titanate films: A theoretical analysis

Summary: Phase diagrams and dielectric response of epitaxial barium strontium
titanate films: A theoretical analysis
Z.-G. Ban and S. P. Alpaya)
Department of Metallurgy and Materials Engineering and Institute of Materials Science,
University of Connecticut, Storrs, Connecticut 06269
Received 2 January 2002; accepted for publication 7 March 2002
We develop phase diagrams for single-domain epitaxial barium strontium titanate films on cubic
substrates as a function of the misfit strain based on a Landau­Devonshire phenomenological model
similar to the one developed by Pertsev et al. Phys. Rev. Lett. 80, 1988 1998 . The biaxial
epitaxy-induced internal stresses enable phase transformations to unusual ferroelectric phases that
are not possible in single crystals and bulk ceramics. The dielectric response of the films is
calculated as a function of the misfit strain by taking into account the formation of misfit
dislocations that relieve epitaxial stresses during deposition. It is shown that by adjusting the misfit
strain via substrate selection and film thickness, a high dielectric response can be obtained,
especially in the vicinity of structural instabilities. Theoretical estimation of the dielectric constant
of 001 Ba0.7Sr0.3TiO3 and Ba0.6Sr0.4TiO3 films on 001 Si, MgO, LaAlO3 , and SrTiO3 substrates
as a function of misfit strain and film thickness is provided. An order-of-magnitude increase in the
dielectric constant with increasing film thickness is expected for films on LaAlO3 and SrTiO3
substrates. A structural instability around 40 nm is predicted in films on MgO substrates
accompanied by a substantial increase in the dielectric constant. For films on MgO substrates thicker


Source: Alpay, S. Pamir - Department of Materials Science and Engineering, University of Connecticut


Collections: Materials Science