Investigation of the chemical versatility in high‐entropy pyrochlores

This article reports on the exploration of the chemical versatility of entropy‐stabilized pyrochlores (A2B2O7) with large chemical disorder introduced on the B site, as well as the study of isovalent and aliovalent substitution on the B site and of Ca2+‐doping on the A site. Among all the 20 new com...

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Bibliographic Details
Published in:Journal of the American Ceramic Society 2023-04, Vol.106 (4), p.2601-2621
Main Authors: Vayer, Florianne, Decorse, Claudia, Bérardan, David, Dragoe, Diana, Dragoe, Nita
Format: Article
Language:English
Subjects:
Calcium ions
Entropy
Erbium
Gadolinium
Magnetic properties
Optical properties
oxides
Physical properties
pyrochlore
Pyrochlores
Rare earth elements
scanning electron microscopy
Thermal barrier coatings
Thermal diffusivity
Versatility
X‐ray methods
Yttrium
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Summary:This article reports on the exploration of the chemical versatility of entropy‐stabilized pyrochlores (A2B2O7) with large chemical disorder introduced on the B site, as well as the study of isovalent and aliovalent substitution on the B site and of Ca2+‐doping on the A site. Among all the 20 new compounds obtained in this study, 8 are entropy‐stabilized: RE2(TiZrHfGeSn)2 (with RE = Gd–Ho and Y), Pr2(TiZrHfScNb)2O7, and RE2(TiGeSnAlNb)2O7 (with RE = Er and Y). Moreover, some physical properties (magnetic, electrical, thermal, and optical properties) of these high‐entropy pyrochlores have been screened, and some of them could be potentially interesting for applications. For example, we observed low thermal diffusivity values (between 0.4 and 0.7 m2 s−1) making them interesting for thermal barrier coating or tunable optical bandgaps in the visible region that could make them appealing as photocatalysts or in optical applications. Furthermore, single‐phased compounds were obtained for almost all the rare earths (REs) on the A site. Therefore, when five nonmagnetic cations are used for the B site, it enables to study the magnetic properties and, more specifically, the influence of the local chemical and structural disorder on the exotic ground states observed in monocationic RE pyrochlores.
ISSN:0002-7820
1551-2916
DOI:10.1111/jace.18922