A team of scientists led by Dr. Thomas Meier from SHARPS has made significant progress in the study of lanthanum superhydrides (LaHx) under extreme pressure conditions. This study sheds new light on formerly unanswered questions on the long-term stability of metal superhydrides. The research, published in Nature Communications, introduces combined 1H- and 139La-NMR data on lanthanum superhydrides, LaHx, (x = 10.2 − 11.1), synthesized after laser heating at pressures above 160 GPa, and presents the Diffusion-driven transient hydrogenation in metal superhydrides.
Hydrogen-rich metal superhydrides are widely studied for their potential in high-temperature superconductivity, yet the atomic and electronic behavior of hydrogen in these systems remains poorly understood. In this study, Zhou et al. employ high-pressure nuclear magnetic resonance (NMR) spectroscopy to directly probe the hydrogen dynamics in lanthanum superhydrides (LaHₓ, x = 10.2–11.1) synthesized above 160 GPa. Their findings reveal an unexpectedly high hydrogen diffusion coefficient of ~10⁻⁶ cm²/s at room temperature, orders of magnitude higher than typical hydrides at ambient conditions.
This high hydrogen mobility is not predicted by ab-initio calculations, which assume relatively static hydrogen configurations in these dense metal lattices. The results suggest that quantum effects and anharmonic lattice vibrations may play a significant role in stabilizing a dynamically fluctuating hydrogen sublattice. Over time, this enhanced diffusion leads to gradual dehydrogenation of the synthesized compounds, shedding light on previously unexplained inconsistencies in metal superhydride experiments.
“These experiments have been conducted by an international research team from SHARPS, HPSTAR, the University of Bristol, and the University of Edinburgh,” says Dr. Thomas Meier, corresponding author from SHARPS. “The extreme mobility of hydrogen observed in this study suggests that future high-pressure experiments must account for real-time hydrogen dynamics. Understanding these effects could be key to stabilizing hydrogen-rich compounds under extreme conditions.”
“This work challenges the fundamental assumptions of hydrogen behavior in high-pressure hydrides,” adds Yishan Zhou, first author of the study. “Our results suggest that the hydrogen sublattice is far more dynamic than previously thought, which has profound implications for the synthesis and stability of these materials.”
Caption: Long-term evolution of NMR spectra in days after initial laser heating at 170 GPa. a) 139La-NMR spectra remain almost constant intensities while resonance frequencies gradually shift towards higher Hz/MHz values. b) A progressive decrease in signal-intensity of the 1H-NMR spectra of the metal hydride spin sub-system was observed while a simultaneous increase of molecular hydrogen in the sample cavity (c) was observed.
By demonstrating the transient nature of hydrogen in lanthanum superhydrides, this study opens new avenues for exploring the role of atomic diffusion in high-pressure materials and highlights the need for real-time spectroscopic techniques to capture these dynamic processes.
近日，由上海前瞻物质科学研究院、北京高压科学研究中心、北京大学、布里斯托大学和爱丁堡大学等组成的研究小组采用高压核磁共振（NMR）光谱技术，直接探测了在160 GPa以上压力下合成的镧超氢化物（LaHₓ，x = 10.2–11.1）中的氢动力学。相关成果以“Diffusion-driven transient hydrogenation in metal superhydrides at extreme conditions”为题发表于近期的《自然|通讯》。文章链接：https://doi.org/10.1038/s41467-025-56033-3。
