Journal Article

FZJ-2018-07703

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Disordered ferromagnetic state in the Ce-Gd-Tb-Dy-Ho hexagonal high-entropy alloy

Vrtnik, S. ; Lužnik, J. ; Koželj, P. ; Jelen, A. ; Luzar, J. ; Jagličić, Z. ; Meden, A. ; Feuerbacher, M.FZJ* ; Dolinšek, J. (Corresponding author)

2018
ScienceDirect Amsterdam [u.a.]

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Please use a persistent id in citations: doi:10.1016/j.jallcom.2018.01.331

Abstract: Rare-earth (RE) based hexagonal high-entropy alloys (HEAs) containing elements from the heavy half of the RE series (from Gd to Lu) are considered as prototypes of an ideal HEA, stabilized by the entropy of mixing with completely random distribution of the elements on an almost undistorted hexagonal close-packed (hcp) lattice. Here we present a study of the Ce-Gd-Tb-Dy-Ho hexagonal HEA (abbreviated as HEA-Ce), where a light-RE element Ce is alloyed with four heavy-RE elements. Since the binary mixing enthalpies of Ce with these elements are all zero, random mixing of the elements and an ideal solid solution can also be expected. Contrary to the expectations, a two-phase structure forms in the HEA-Ce, consisting of the majority hcp matrix and the rhombohedral precipitates that occupy a significant fraction of the sample's volume, with both phases having very similar composition. The “ideality” of the HEA-Ce solid solution is very likely compromised by the fact that the crystal structure of Ce is different from the structures of other elements. By performing measurements of the magnetic properties, the specific heat and the electrical resistivity in a magnetic field, we have determined the magnetic state of the HEA-Ce. Long-range-ordered periodic magnetic structures do not form (like they do in the hexagonal HEAs containing heavy-RE elements only), but the magnetic structure breaks up into ferromagnetically (FM) polarized spin domains distributed in size that orient randomly in zero field. The magnetically ordered state of the HEA-Ce can be described as a disordered FM state with a 2nd-order thermodynamic FM phase transition at 140 K. The introduction of Ce did not yield any of the phenomena that are exceptional for the Ce-containing alloys and compounds (mixed valence, heavy-fermion, unconventional superconductivity).

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Contributing Institute(s):

1. Mikrostrukturforschung (PGI-5)

Research Program(s):

1. 143 - Controlling Configuration-Based Phenomena (POF3-143) (POF3-143)

Appears in the scientific report 2018

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Database coverage:
; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Web of Science Core Collection

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