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Title: Crystal growth and phase formation of high‐entropy rare‐earth monoclinic aluminates
Abstract For the first time, high‐entropy rare‐earth monoclinic aluminate crystals were grown via directional solidification using the micro‐pulling‐down method. Five high‐entropy compositions were formulated with a general formula RE4Al2O9, where RE is an equiatomic mixture of five rare‐earth elements. The rare‐earth elements included were Lu, Yb, Er, Y, Ho, Dy, Tb, Gd, Eu, Sm, Nd, and La. High‐temperature powder X‐ray diffraction and Rietveld structure refinement indicated that all crystals were a single monoclinic phase and that rare‐earth average ionic radius did not affect phase purity. At room temperature, the refined lattice parameters increased consistently with increasing average ionic radii of the five compositions. One of the crystals had a typical high‐temperature phase transition of single‐RE RE4Al2O9in the range of 1100–1150°C, which consisted of a lattice contraction upon heating. Differential scanning calorimetry indicated a thermal event corresponding to that phase transition. Electron probe microanalysis revealed Al‐rich inclusions on the surface of the crystals. Crystals containing Tb had dark surface features that became lighter after annealing in a reducing atmosphere, which indicated that Tb4+may be responsible for the dark features.  more » « less
Award ID(s):
1846935
PAR ID:
10488820
Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
Journal of the American Ceramic Society
Date Published:
Journal Name:
Journal of the American Ceramic Society
Volume:
106
Issue:
11
ISSN:
0002-7820
Page Range / eLocation ID:
7123 to 7132
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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