Results for “ScFeO3” | Engineering Papers

DOE OSTI2020

Materials Data on ScFeO3 by Materials Project

ScFeO3 crystallizes in the hexagonal P6_3cm space group. The structure is three-dimensional. there are two inequivalent Sc3+ sites. In the first Sc3+ site, Sc3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Sc–O bond distances ranging from 2.17–2.37 Å. In the second Sc3+ site, Sc3+ is bonded to seven O2- atoms to form distorted ScO7 pentagonal bipyramids that share corners with three equivalent FeO5 trigonal bipyramids and edges with three equivalent FeO5 trigonal bipyramids. There are three shorter (2.13 Å) and four longer (2.26 Å) Sc–O bond lengths. Fe3+ is bonded to five O2- atoms to form FeO5 trigonal bipyramids that share a cornercorner with one ScO7 pentagonal bipyramid, corners with six equivalent FeO5 trigonal bipyramids, and an edgeedge with one ScO7 pentagonal bipyramid. There are a spread of Fe–O bond distances ranging from 1.94–1.98 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to three Sc3+ and one Fe3+ atom to form OSc3Fe tetrahedra that share corners with ten OSc3Fe tetrahedra, corners with two equivalent OScFe3 trigonal pyramids, edges with three equivalent OSc3Fe tetrahedra, and edges with two equivalent OScFe3 trigonal pyramids. In the second O2- site, O2- is bonded to three Sc3+ and one Fe3+ atom to form distorted OSc3Fe tetrahedra that share corners with ten OSc3Fe tetrahedra, corners with four equivalent OScFe3 trigonal pyramids, edges with three equivalent OSc3Fe tetrahedra, and an edgeedge with one OScFe3 trigonal pyramid. In the third O2- site, O2- is bonded to one Sc3+ and three equivalent Fe3+ atoms to form distorted OScFe3 trigonal pyramids that share corners with six equivalent OSc3Fe tetrahedra, corners with six OScFe3 trigonal pyramids, and edges with three equivalent OSc3Fe tetrahedra. In the fourth O2- site, O2- is bonded to one Sc3+ and three equivalent Fe3+ atoms to form distorted OScFe3 trigonal pyramids that share corners with six equivalent OSc3Fe tetrahedra, corners with six equivalent OScFe3 trigonal pyramids, and edges with three equivalent OSc3Fe tetrahedra.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Stromataxic Stabilization of a Metastable Layered ScFeO3 Polymorph

Metastable polymorphs--materials with the same stoichiometry as the ground state but a different crystal structure--enable many critical technologies. This work describes the development of a stabilization approach for metastable polymorphs that are difficult to achieve through other stabilization techniques (such as epitaxy or quenching) called stromataxy. Stromataxy is a method based on controlling the precursor structure during the initial stages of material growth to dictate phase formation. To illustrate this approach, we controlled the atomic layering of the precursors of ScFeO3 and stabilized the metastable P63cm phase, under conditions that previously led to the ground-state Ia3¯ bixbyite phase. Ab initio mechanistic calculations highlight the importance of the variable oxidation state of Fe and the layer stability during layer-by-layer growth. The broad applicability of a stromataxy approach was demonstrated by stabilizing this metastable phase on substrates that have previously been shown to stabilize other polymorphs under continuous growth. Stromataxy is shown as a viable option for accessing polymorphs that are close in energy, difficult to differentiate by strain, or that lack a well epitaxially matched substrate.

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