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Pressure-induced order-disorder transition in Gd1.5Ce0.5Ti2O7 pyrochlore.

ABSTRACT: An experimental study on ordered pyrochlore structured Gd1.5Ce0.5Ti2O7 (Fd3¯m) was carried out up to 45 GPa by synchrotron radiation X-ray diffraction and Raman spectroscopy. Experimental results show that Gd1.5Ce0.5Ti2O7 transfers to a disordered cotunnite-like phase (Pnma Z = 4) at approximately 42 GPa. Compared with the end member Gd2Ti2O7, the substitution of Ce3+ for Gd3+ increases the transition pressure and the high-pressure stability of the pyrochlore phase. This pressure-induced structure transition is mainly controlled by cationic order-disorder modification, and the cationic radius ratio r A/r B may also be effective for predicting the pyrochlore oxides' high-pressure stability. Two isostructural transitions are observed at 6.5 GPa and 13 GPa, and the unit-cell volume of Gd1.5Ce0.5Ti2O7 as a function of pressure demonstrates its compression behaviour is rather complex.

SUBMITTER: Niu J

PROVIDER: S-EPMC6774973 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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Pressure-induced order-disorder transition in Gd1.5Ce0.5Ti2O7 pyrochlore.

Niu Jingjing J Wu Xiang X Zhang Haibin H Qin Shan S

Royal Society open science 20190904 9

An experimental study on ordered pyrochlore structured Gd1.5Ce0.5Ti2O7 ( F d 3 ¯ m ) was carried out up to 45 GPa by synchrotron radiation X-ray diffraction and Raman spectroscopy. Experimental results show that Gd1.5Ce0.5Ti2O7 transfers to a disordered cotunnite-like phase (Pnma Z = 4) at approximately 42 GPa. Compared with the end member Gd2Ti2O7, the substitution ...[more]

PMID: 31598308

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