Structurally frustrated polar nanoregions in BaTaO₂N and the relationship between its high dielectric permittivity and that of BaTiO₃

Abstract

This letter presents direct evidence for the existence of the same inherently polar one-dimensional (1D), displacive disorder in BaTaO₂N as occurs in paraelectric BaTiO₃ as well as in doped BaTiO₃relaxor ferroelectric systems. The inherently polar, off-center and oppositely directed displacements of Ta and neighboring O∕N ions along <001> give rise to 1D polar nanoregions (PNRs) and are responsible for the dielectric properties of BaTaO₂N. A bond valence sum analysis of the underlying crystal chemistry of BaTaO₂N shows clearly that O∕N ordering is not directly responsible for inducing the observed 1D PNRs. Show more