Journal Article

FZJ-2021-02531

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Segregation‐controlled densification and grain growth in rare earth‐doped Y 2 O 3

Kindelmann, M. (Corresponding author)FZJ* ; Ran, K.FZJ* ; Rheinheimer, W.FZJ* ; Morita, K.Extern* ; Mayer, J.FZJ* ; Bram, M.FZJ* ; Guillon, O.FZJ*

2021
Soc. Westerville, Ohio

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Please use a persistent id in citations: http://hdl.handle.net/2128/28417  doi:10.1111/jace.17907

Abstract: Cation doping of Y2O3 is an established approach for tailoring densification and grain growth during sintering. However, the segregation of doped cations to the grain boundary and their impact on processing are still not completely understood. Segregation can be driven by electrostatic effects due to charge mismatch with the host lattice or elastic effects induced by ion size mismatch. While segregation is caused by thermodynamics, it impacts diffusion and the kinetics of grain boundaries during densification and microstructure evolution. In this study, we utilize two isovalent dopants (La3+ and Gd3+), that is we focus on the elastic component of segregation. We investigate the densification as well as the grain growth kinetics of both doped and undoped Y2O3 during field-assisted sintering/spark plasma sintering (FAST/SPS). While Gd3+ is showing no significant effect on densification, La3+ resulted in a strongly reduced sintering activity. Furthermore, the analysis of the grain growth behavior during sintering and on predensified samples revealed a decrease in the grain growth coefficient, with La3+ having the strongest impact. The structure and chemistry at the grain boundary were observed by aberration-corrected TEM. While no structural change was caused by doping, the chemical analysis showed a strong segregation of La3+ to the grain boundary, which could not be observed for Gd3+. The results indicate that segregated La3+ causes a drastic decrease in grain boundary migration rates through solute drag as well as much slower sintering kinetics, likely caused by a decrease in the grain boundary self-diffusion due to segregation. This study further underlines the importance of the elastic contribution to cation segregation and establishes a clear relationship to grain growth and sintering kinetics, which are both decreased by segregation.

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Contributing Institute(s):

1. Werkstoffsynthese und Herstellungsverfahren (IEK-1)
2. Materialwissenschaft u. Werkstofftechnik (ER-C-2)

Research Program(s):

1. 535 - Materials Information Discovery (POF4-535) (POF4-535)

Appears in the scientific report 2021

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

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