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Pressure-induced phase transition of La₂Zr₂O₇ and La_0.5Gd_1.5Zr₂O₇ pyrochlore.

ABSTRACT: In situ high-pressure experiments on La₂Zr₂O₇ and La_0.5Gd_1.5Zr₂O₇ have been carried out at up to approximately 40 GPa using synchrotron X-ray diffraction and Raman spectroscopy combined with a diamond anvil cell technique. Both La₂Zr₂O₇ and La_0.5Gd_1.5Zr₂O₇ undergo a phase transition from a pyrochlore phase (Fd3̄m) into a cotunnite-like phase (Pnma) at 22.7 and 23.3 GPa, respectively. This type of phase transition is mainly controlled through the order-disorder occupancy of cations, and Gd³⁺ substitution of La³⁺ reduces the stability of zirconate pyrochlore. However, abnormal changes to the unit-cell volumes and vibrational modes observed at 5.5 GPa in La₂Zr₂O₇ and 6.5 GPa in La_0.5Gd_1.5Zr₂O₇ are attributed to an anion disorder in the pyrochlore.

SUBMITTER: Niu J

PROVIDER: S-EPMC9065121 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature

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Pressure-induced phase transition of La2Zr2O7 and La0.5Gd1.5Zr2O7 pyrochlore.

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

RSC advances 20190617 33

In situ high-pressure experiments on La2Zr2O7 and La0.5Gd1.5Zr2O7 have been carried out at up to approximately 40 GPa using synchrotron X-ray diffraction and Raman spectroscopy combined with a diamond anvil cell technique. Both La2Zr2O7 and La0.5Gd1.5Zr2O7 undergo a phase transition from a pyrochlore phase (Fd3̄m) into a co ...[more]

PMID: 35516883

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