Ferroelectricity in LaBGeO5 from First Principles

Published: July 21st, 2016

Category: Recent Publications

B. J. Demaske, A. Chernatynskiy and S. R. Phillpot, Ferroelectricity in LaBGeO5 from First Principles, Journal of Physics Condensed Matter 28, 165901 (2016). doi:10.1088/0953-8984/28/16/165901

Density functional theory calculations are performed to characterize the structural, electronic
and vibrational properties of both the low-temperature ferroelectric and high-temperature
paraelectric phases of LaBGeO5. Phonon dispersion calculations for the high-temperature
phase reveal an unstable mode whose zone-center eigenvector corresponds to a rigid rotation
of the BO4 tetrahedra, in agreement with previous calculations based on a short-range model
potential. A possible switching path between two symmetry-equivalent ferroelectric phases
that goes through the high-temperature paraelectric phase is identified and used to calculate
the spontaneous polarization. The theoretical value for the spontaneous polarization calculated
using the modern theory of polarization is 4.9μC cm−2 for the PBEsol + U functional, which
lies within the experimental range.