Polymorphic transitions and phase stability of CeO2-δ·(Dy,La,Sm,Y)2O3 high-entropy oxides consolidated by spark plasma sintering

IF 5.8 2区材料科学 Q1 MATERIALS SCIENCE, CERAMICS

Journal of The European Ceramic Society Pub Date : 2025-05-21 DOI:10.1016/j.jeurceramsoc.2025.117552

Avnee Chauhan , Andreas Frickel , Kousik Papakollu , Sabine Begand , Mathias Herrmann , Enrico Bernardo , Dušan Galusek

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Abstract

The influence of spark plasma sintering (SPS) on the phase stability and bandgap of single-phase HEO ceramics with the composition CeO_2-δ·(Dy,La,Sm,Y)₂O₃ was studied. Single phase HEO powders were prepared by combustion synthesis. The powders were consolidated by SPS at temperatures 1300° C, 1400° C, and 1600° C to prepare dense bulk ceramics. At 1600° C, a complete cubic-to-monoclinic phase transformation occurred, driven by Ce^4 + to Ce³⁺ reduction under reducing SPS conditions. The change in the oxidation state of Ce resulted in an increase of the average ionic radius driving the cubic-to-monoclinic phase transition. Annealing the monoclinic samples at 1200° C in air led to a reversible transformation to the cubic structure. The phase transformations coupled with the presence of oxygen vacancies resulted in a bandgap energy reduction.

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放电等离子烧结法制备CeO2-δ·（Dy,La,Sm，Y）2O3高熵氧化物的相变与相稳定性

研究了放电等离子烧结（SPS）对CeO2-δ·（Dy,La,Sm，Y）2O3单相HEO陶瓷相稳定性和带隙的影响。采用燃烧合成法制备了单相HEO粉末。在1300°C、1400°C和1600°C的温度下，用SPS固结粉末，制备致密的块状陶瓷。1600℃时，在还原SPS条件下，Ce4 +向Ce3+的还原作用下，发生了完全的立方到单斜相变。Ce氧化态的变化导致平均离子半径的增加，驱动立方到单斜的相变。在空气中1200℃退火后，单斜晶向立方结构可逆转变。相变加上氧空位的存在导致带隙能量降低。

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来源期刊

Journal of The European Ceramic Society 工程技术-材料科学：硅酸盐

CiteScore

10.70

自引率

12.30%

发文量

863

审稿时长

35 days

期刊介绍： The Journal of the European Ceramic Society publishes the results of original research and reviews relating to ceramic materials. Papers of either an experimental or theoretical character will be welcomed on a fully international basis. The emphasis is on novel generic science concerning the relationships between processing, microstructure and properties of polycrystalline ceramics consolidated at high temperature. Papers may relate to any of the conventional categories of ceramic: structural, functional, traditional or composite. The central objective is to sustain a high standard of research quality by means of appropriate reviewing procedures.