Thermal-Driven Fluorite-Pyrochlore-Fluorite Phase Transitions of Gd2Zr2O7 Ceramics Probed in Large Range of Sintering Temperature

摘要

Fluorite (F)-pyrochlore (P)-fluorite (F) phase transitions of Gd2Zr2O7 were investigated from 573 K to 1873 K (300 A degrees C to 1600 A degrees 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 A degrees C) and the F-P transition occurs at 1523 K to 1573 K (1250 A degrees C to 1300 A degrees C). The ordering process of P phase forms at 1573 K to 1773 K (1300 A degrees C to 1500 A degrees 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 A degrees C and 1550 A degrees C). IR spectra of samples with different ordering degrees show an interesting shift at 510 cm(-1). Raman spectra show that only the A(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 Gd2Zr2O7 to use in nuclear waste host, thermal barrier coatings, and solid oxide fuel cells. (C) The Minerals, Metals & Materials Society and ASM International 2015