Summary: Structural characteristics of ferroelectric phase transformations
in single-domain epitaxial films
S. P. Alpay,a)
I. B. Misirlioglu, A. Sharma, and Z.-G. Ban
Department of Metallurgy and Materials Engineering and Institute of Materials Science,
University of Connecticut, Storrs, Connecticut 06269
Received 5 November 2003; accepted 26 March 2004
Structural characteristics of phase transformations in epitaxial ferroelectric films are analyzed via a
Landau­Devonshire thermodynamic formalism. It is shown that the phase transformation
temperature, the lattice parameters, and the order of the phase transformation are a strong function
of the misfit strain and are considerably different compared to unconstrained, unstressed single
crystals of the same composition. Depending on the internal stress state, it is possible that the
structural aspects of the paraelectric­ferroelectric phase transformation may be completely
obscured in the presence of epitaxial strains. The thickness dependence of epitaxial stresses due to
relaxation by misfit dislocations during film deposition is incorporated into the model using an
``effective'' substrate lattice parameter. There is a good quantitative agreement between the
theoretical analysis and experimental observations reported in the literature on the variations in the
lattice parameters and the phase transformation temperature with film thickness in epitaxial BaTiO3
films. © 2004 American Institute of Physics. DOI: 10.1063/1.1751630
I. INTRODUCTION

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

Collections: Materials Science