Examination of possible high-pressure candidates of SnTiO3: The search for novel ferroelectric materials

Florian Pielnhofer,Alberto Jiménez-Solano,Annette Bussmann-Holder,J Christian Schön,Leo Diehl,Bettina V Lotsch

doi:10.1063/5.0029968

Abstract

Following the recent successful synthesis and characterization of bulk SnTiO3, its energy landscape was studied by means of density functional theory, applying different exchange–correlation and hybrid functionals. Experimentally accessible structure candidates with composition ABX3 were identified by a database search and global exploration approach. Besides the common octahedral coordination of Ti, also fourfold and fivefold coordination spheres emerged to be reasonable structural motifs. Among the predicted high-pressure modifications, the tetragonal perovskite structure turned out to be stable at pressures between 11 GPa and 15 GPa. The possibility of a paraelectric-to-ferroelectric phase transition of the tetragonal perovskite structure was investigated by modeling the phonon spectra and soft mode behavior. Despite substantial long wavelength transverse optical mode softening, the predicted high c/a-ratio in tetragonal perovskite SnTiO3 inhibits the formation of a spontaneous reversible polarization.

Highlights

We reported about the first successful synthesis and the structural characterization of SnTiO3 as a bulk material.[1]
The polytypes that were denoted with AB, ABC, ACB, ABCB, and ABCACB contain the prominent e-[FeTiO3]-type structure (ABC) and the [α-TlSbO3]type structure (AB)
Since the energy minima and volume per formula unit of the relaxed structures are almost identical (±0.1 kJ mol−1; ΔV: ±0.3%) and all stacking variants can be derived from AB and ABC, the present study focuses on the e-[FeTiO3] and [α-TlSbO3] polytypes when comparing the experimental structures to the hypothetical structures

Summary

Introduction

We reported about the first successful synthesis and the structural characterization of SnTiO3 as a bulk material.[1]. The [α-TlSbO3]type accounts for this expansion, yet does not fully describe the crystal structure of SnTiO3 because of a different stacking sequence. Common to both structure types is the main structural motif of honeycomb layers of edge-sharing BO6 octahedra that are decorated with A2+ cations. In order to understand the similarity between α-TlSbO3 (space group P3 ̄1c) and ilmenite (space group R3 ̄), it is helpful to employ the hexagonal setting of the latter space group. Both structures are of (pseudo-)layered character, P3 ̄1c (α-TlSbO3) being a double and R3 ̄ (ilmenite) a triple layer cell, respectively. To account for these faults, SnTiO3 was described using five different polytype models that are energetically quasi-identical[1] on the level of density functional theory (DFT)

Methods

Results

Conclusion