Geometrical polarization approach: A semi-empirical tool to estimate the intrinsic polarization of polar dielectrics

Abstract A geometrical polarization approach (GPA), where the average unit cell polarization (direction and magnitude) is obtained from diffraction-based results, is proposed as a semi-empirical tool to obtain the intrinsic polarization of polar dielectrics. In this approach, the intrinsic polarization, as a signature of the polar state, is obtained from the off-centering position of the nominal total negative and positive electric charges in an unit cell, which is achieved from the relative atomic positions of cations and anions. The GPA protocol can be used to determine the intrinsic polarization of dielectric samples without any extrinsic experimental difficulties, enabling studies for searching new and/or improved electrically polarizable materials under conventional and extreme conditions. This approach was successfully applied for determining the intrinsic polarization of the BaTiO3 ferroelectric compound as a function of temperature, which is a well-known prototype of displacive ferroelectric that shows rhombohedral, orthorhombic, tetragonal and cubic symmetries at different temperature ranges. Polarization directions and a good agreement with experimental single crystal results are indicative of the reliability factor of this approach.