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Multicomponent oxides have received significant recent attention due to their potential for improved property tunability. In simple structures, compositionally complex oxides can be stabilized by increased configurational entropy and are sometimes called “high entropy” ceramics. In phases with multiple cation sublattices or complex stoichiometries, it is more difficult to achieve high configurational entropy. However, there is limited knowledge about the factors influencing stability and solubility limits in many systems. This study investigated the limits on the stability of rare earth (RE) aluminates containing mixtures of RE cations including Gd, La, Nd, Yb, and Y in cases where (i) a fixed RE:Al ratio attempts to constrain the material into a single-phase aluminate or (ii) a two-phase aluminate, and in equilibrium with RE zirconates that readily dissolve multiple RE3+. The results show that it is difficult to form single-phase, equimolar mixed-RE aluminates encompassing a range of RE3+ sizes. Instead, the RE3+ selectively partition into specific phases based on RE-size trends in the constituent binary systems. The results are discussed in terms of the phase stability and cation partition trends and potential applications.
Bibliographical noteFunding Information:
This research was partially supported by NASA award number 80NSSC21C0071 monitored by Dr. Cameron Bodenschatz, in collaboration with QuesTek Innovations LLC. Part of this work was carried out in the Characterization Facility at the University of Minnesota, which receives partial support from the NSF through the MRSEC (DMR‐2011401) and the NNCI (ECCS‐2025124) programs. The sponsors were not involved in the detailed study design, or the data collection, analysis, or interpretation. The authors are grateful to Josselyne Berrios for assistance with materials preparation and to Dr. Clémentine Hamelin for assistance with EPMA.
© 2023 The Authors. Journal of the American Ceramic Society published by Wiley Periodicals LLC on behalf of American Ceramic Society.
- phase equilibria
- phase separation
- rare earths