Single-crystal high entropy perovskite oxide epitaxial films

Abstract

The first examples of single crystal epitaxial thin films of a high entropy perovskite oxide are synthesized. Pulsed laser deposition is used to grow the configurationally disordered ABO 3 perovskite, Ba(Zr 0.2 Sn 0.2 Ti 0.2 Hf 0.2 Nb 0.2 )O 3 , epitaxially on SrTiO 3 and MgO substrates. X-ray diffraction and scanning transmission electron microscopy demonstrate that the films are single phase with excellent crystallinity and atomically abrupt interfaces to the underlying substrates. Atomically-resolved electron energy loss spectroscopy mapping shows a uniform and random distribution of all B-site cations. The ability to stabilize perovskites with this level of configurational disorder offers new possibilities for designing materials from a much broader combinatorial cation pallet while providing a fresh avenue for fundamental studies in strongly correlated quantum materials where local disorder can play a critical role in determining macroscopic properties.

High‐Entropy Oxides: Fundamental Aspects and Electrochemical Properties

“…However, both R‐HEO and F‐HEO comprise only one Wyckoff site for the cations. Thus, the formation of single‐phase perovskite‐based HEO (PE‐HEO) and spinel‐based HEO (SP‐HEO) materials was important in providing evidence that this design concept can be extended to structures with multiple cation sites . Figure d shows two single‐phase orthorhombic PE‐HEOs with 6 and 10 cations .…”

“…More recently, there have been reports regarding the thermal properties of HEOs, where an interesting correlation between the low thermal conductivity and the disorder in the systems (i.e., multiple cations acting as phonon scatters) has been observed . Reports are also available on thin film deposition, sintering, mechanical, magnetic, and optical properties of HEOs. Theoretical studies have not been extensively performed on all classes of HEOs, nevertheless, there are reports on R‐HEO, which correlate: (i) the lattice distortion with the Jahn–Teller effect and (ii) the phase composition with the thermodynamic parameters .…”

Long-Range Antiferromagnetic Order in a Rocksalt High Entropy Oxide

“…Recently, these materials have attracted much attention due to fundamental issues related to phase formation and materials design as well as their potential multifunctional properties that can emerge from their high configurational entropy and spin order. [3][4][5][6][7] (Mg0.2Co0.2Ni0.2Cu0.2Zn0.2)O (hereafter MgO-HEO), the first entropy-stabilized oxide, was reported by Rost et al in 2015. 3 Their choice of this system was based on the diversity in structures, coordination and cationic radii of MgO (Fm-3m), CoO (Fm-3m), NiO (Fm-3m), CuO (C2/c) and ZnO (P63mc).…”

A step forward from high-entropy ceramics to compositionally complex ceramics: a new perspective

“…Other oxide systems of significant interests include those with the fluorite [13,23,75,76,84], spinel [29][30][31][32]96], pyrochlore [14,[33][34][35][36][37], and perovskite [24][25][26][27][28] structures.…”