Thermal-Driven Fluorite-Pyrochlore-Fluorite Phase Transitions of Gd^sub 2^Zr^sub 2^O^sub 7^ Ceramics Probed in Large Range of Sintering Temperature

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 47; no. 1; p. 623
• Main Authors: Zhou, Li, Huang, Zhangyi, Qi, Jianqi, Feng, Zhao, Wu, Dengxue, Zhang, Wei, Yu, Xiaohe, Guan, Yongbing, Chen, Xingtao, Xie, Landong, Sun, Kai, Lu, Tiecheng
• Format: Journal Article
• Language: English
• Published: New York Springer Nature B.V 01.01.2016
• Subjects: Ceramics; Phase transitions; Temperature
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-015-3234-4

Fluorite (F)-pyrochlore (P)-fluorite (F) phase transitions of Gd^sub 2^Zr^sub 2^O^sub 7^ were investigated from 573 K to 1873 K (300 °C to 1600 °C), by means of X-ray diffraction, infrared spectra (IR), and Raman spectra. The low-temperature F phase can stably exist below 1523 K (1250 °C) and the F-P transition occurs at 1523 K to 1573 K (1250 °C to 1300 °C). The ordering process of P phase forms at 1573 K to 1773 K (1300 °C to 1500 °C) and the ordering degree increases with increasing sintering temperature and heat preservation period. High-temperature phase transition from P to F occurs between 1773 K and 1823 K (1300 °C and 1550 °C). IR spectra of samples with different ordering degrees show an interesting shift at 510 cm^sup -1^. Raman spectra show that only the A^sub 1g^ mode displays a significant change between F and P phases. This ordering degree and phase transition temperature studies would allow a more targeted experimental optimization of Gd^sub 2^Zr^sub 2^O^sub 7^ to use in nuclear waste host, thermal barrier coatings, and solid oxide fuel cells.