Reentrant polar phase induced by the ferroionic coupling in Bi1−xSmxFeO3

Abstract

Using the model of four sublattices, the Landau-Ginzburg-Devonshire-Kittel phenomenological approach and the Stephenson-Highland ionic adsorption model for the description of coupled polar and antipolar long-range orders in ferroics, we analytically calculated the phase diagrams and polar properties of Bi1−xSmxFeO3 nanoparticles covered by surface ions with dependence on their size, surface ions density, samarium content x, and temperature. The size effects and ferroionic coupling govern the appearance and stability conditions of the long-range ordered ferroelectric, reentrant ferrielectric, and antiferroelectric phases in Bi1−xSmxFeO3 nanoparticles. Calculated phase diagrams are in qualitative agreement with the x-ray diffraction phase analysis, electron paramagnetic resonance, infrared spectroscopy, and electrophysical measurements of Bi1−xSmxFeO3 nanopowders sintered by the solution combustion method. The combined theoretical-experimental approach allows us to explain the influence of the ferroionic coupling and size effects in Bi1−xSmxFeO3 nanoparticles on their polar properties. Published by the American Physical Society 2024