Pressure-induced phase transition of Lu2Ti2O7and Lu1.5Ce0.5Ti2O7+ xpyrochlores

Min Xu; Jingjing Niu; Guanfeng Wu; Qian Liao; Xi Tan; Dongyan Yang; Longcheng Liu; Yuhong Li; Yue Xia

doi:10.1088/1361-648X/ad1d1e

Pressure-induced phase transition of Lu₂Ti₂O₇and Lu_1.5Ce_0.5Ti₂O_{7+ x}pyrochlores

J Phys Condens Matter. 2024 Jan 24;36(16). doi: 10.1088/1361-648X/ad1d1e.

Authors

Min Xu^{1

2}, Jingjing Niu³, Guanfeng Wu^{1

2}, Qian Liao^{1

2}, Xi Tan^{1

2}, Dongyan Yang⁴, Longcheng Liu^{2

5}, Yuhong Li⁴, Yue Xia^{1

2

4}

Affiliations

¹ School of Nuclear Science and Technology, University of South China, Hengyang 421001, People's Republic of China.
² R&D Center of Radioactive Waste Treatment, Disposal and Modeling, University of South China, Hengyang 421001, People's Republic of China.
³ State Key Laboratory of Tibetan Plateau Earth System Science, Resources and Environment (TPESRE), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, People's Republic of China.
⁴ School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, People's Republic of China.
⁵ China Institute of Atomic Energy, Beijing 102413, People's Republic of China.

PMID: 38198736
DOI: 10.1088/1361-648X/ad1d1e

Abstract

This study utilizes both experimental and computational approaches to investigate the performance of Lu₂Ti₂O₇(LTO) and Lu_1.5Ce_0.5Ti₂O_7+x(LCTO) pyrochlores under high pressure. The structural changes of LTO and LCTO pyrochlores were characterized usingin-situsynchrotron x-ray diffraction (SXRD) andin-situRaman spectroscopy at pressures up to 44.6 GPa. The kinks inP-aandP-Vcurves at around 5 GPa are mainly attributed to the interaction between the pressure medium and the isostructural changes. The onset pressures for transitioning from the cubic pyrochlore phase (Fd-3 m) to the monoclinic phase (P2₁) are observed at 32.5 GPa and 38.1 GPa, respectively. It is important to note that at the highest measured pressures, the phase transition remains incomplete. This partial transition is likely the result of oriented disorder among cations and anions under high pressure. In addition, introducing Ce as a dopant significantly enhances structural stability. This can be explained by the larger ionic radius of Ce, which hinders the disordering process.

Keywords: ceramic; crystallographic structure; defects; phase transformation.