Temperature-driven phase transitions in SrBi2Ta2O9 from first-principles calculations

Abstract

The phase transition sequence of SrBi 2 Ta 2 O 9 is investigated using a shell model with parameters fitted to first-principles calculations. We show that the complex interplay between polar and nonpolar instabilities leads to the presence of two phase transitions, corroborating the existence of an intermediate orthorhombic paraelectric phase. This phase is characterized by the rotation of the TaO 6 octahedra around the a-axis. We show that this phase can be also detected from the dielectric response of the material. The present approach constitutes a powerful tool for a theoretical prediction of intermediate phases, not yet observed experimentally, in other Aurivillius compounds.

First-principles based atomistic modeling of phase stability in PMN–xPT

“…Contrary to what is believed, we show that behavior of PMN can be explained without the presence of PNRs. Recent MD simulations were able to describe the dielectric response of the relaxor PMN-0.25PT without PNRs [17], so both results raise the question about the precise role played by PNRs in the relaxor behavior [25], 0.1 [6], 0.2 [26], 0.3 [5], 0.39 [5], 0.5 [12], 0.65 [12] and 1 [27], and LDA results from PMN and PT. [55].…”

“…Model descriptions based on interatomic potentials account naturally for the presence of many factors such as chemical order or compositional heterogeneity. Among these methods, molecular dynamics simulations with shell mod-els fitted to first-principles calculations revealed powerful to predict the qualitative behavior of pure compounds and solid solutions [26,27].…”

Dielectric and piezoelectric properties of BiFeO3 from molecular dynamics simulations

“…The most widespread approaches to this problem are the effective Hamiltonians and the atomistic shell models. Atomic level simulations using shell models have been extensively used to study ferroelectric oxides [23][24] and their piezoelectric properties [25][26]. In this approach, atoms are thought to consist of an ion core coupled to an "electronic" shell in order to include its electronic polarization.…”

Phase transitions and antiferroelectricity inBiFeO3from atomic-level simulations

“…Atomic level simulations with the shell-model approach have been extensively used to study ferroelectric oxides [21][22][23]. An inherent advantage of this approach is that there is not need to know a priori which dynamical modes are relevant in determining specific material properties.…”