Preparation and effect of grain size on the thermal stability, phase transition, mechanical property, and photocatalytic property of pyrochlore (La0.2Nd0.2Sm0.2Gd0.2Y0.2)2Zr2O7 high-entropy oxide

• Published in: Ceramics international 2022-07, Vol.48 (14), p.20667-20674
• Main Authors: Du, Mingrun, Liu, Shixin, Ge, Yanfeng, Li, Zepeng, Wei, Tong, Yang, Xiong, Dong, Jiajun
• Format: Article
• Language: English
• Subjects: Grain size; High-entropy oxide; Photocatalytic property; Structural and mechanical properties
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2022.04.046

In this work, pyrochlore (La0.2Nd0.2Sm0.2Gd0.2Y0.2)2Zr2O7 high-entropy oxide (p-RZHEO) powders with nanoscale grains have been synthesized using a simple coprecipitation–hydrothermal–calcination method. The effects of grain size on the thermal stability, mechanical property, phase transition, and photocatalytic property of p-RZHEO are investigated. The results show that decreasing the grain size yields poor thermal stability but a significant increase in the bulk modulus. Furthermore, as grain size increases, the dynamic process in the pressure-induced pyrochlore-cotunnite phase transition becomes more sluggish. The high-pressure cotunnite phase formed in the sample with small grains generates faster under pressure, significantly shortening the pyrochlore-cotunnite phase coexisting region. The photodegradation of Rhodamine B solution reveals that p-RZHEO powders exhibit good photocatalytic activity, which can be improved by reducing the powder grain size. The findings of this study could serve as a new guide for the development of novel high-entropy oxides with desirable properties. [Display omitted]