2025/06/10 by Zhu, Zhichao, Li, Xin, Ma, Ziru +9
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci)
paper · doi:10.48550/arxiv.2506.08789
Ceria has been extensively studied since it has many applications in diverse research fields. However, the mechanism of the hydrogen dynamics, especially the diffusion kinetics on a microscopic level is still unclear as the experimental data has been very limited. In this work, the CeO2-H interaction has been comprehensively studied by a combination of 1H NMR transverse relaxation time (T2) measurement, neutron powder diffraction, quasi-elastic neutron scattering (QENS), X-ray total scattering, and ab initio calculations. Based on QENS measurements, the first direct evidence for hydrogen jump diffusions of the Chudley-Elliot type in the bulk ceria has been given, with a jump distance of ~3.98 angstrom. The theoretically calculated activation energy barriers Ea for hydrogen diffusion are relatively low (less than 0.1 eV), further supporting that such hopping can readily occur. A larger barrier value of Ea ~0.2 eV is directly estimated by T2 NMR data, suggesting possible slower hydrogen dynamics with the pre-exponential factor D0 of diffusion coefficient ~10-11 m2/s.