A team at the University of Tokyo has measured a 148 meV energy barrier that suppresses hydrogen quantum tunnelling through vanadium when the metal's lattice distorts, tying the effect directly to crystal symmetry. The work, reported in Nature Communications (DOI: 10.1038/s41467-026-75020-w), positions symmetry as a tunable design lever for hydrogen storage, permeation membranes, and catalysis R&D.

The research group, led by Katsuyuki Fukutani of the Institute of Industrial Science with Takahiro Ozawa and Sudhansu Sekhar Das, used vanadium as a model hydrogen-storage metal. They paired nuclear reaction analysis, which maps hydrogen depth profiles at sub-micron resolution, with electrical resistance measurements that track hydrogen redistribution over time. The two techniques delivered both spatial and kinetic data from the same samples.

What did the measurements show?

At temperatures near 70 K, hydrogen atoms began migrating through vanadium's body-centred cubic lattice, hopping between interstitial sites. In vanadium's highly symmetric α-phase, which forms at low hydrogen loading, atoms tunnel freely between neighbouring tetrahedral sites. As hydrogen concentration rises, the host lattice distorts into a β-phase, and tunnelling is blocked until atoms clear the 148 meV barrier the team quantified.

"We found that hydrogen undergoes pronounced quantum tunnelling in a highly symmetric crystal environment, whereas the tunnelling is strongly suppressed when the symmetry is lowered," Fukutani told Physics World.

How did the team distinguish tunnelling from thermal motion?

From the electrical resistance data, the researchers extracted a diffusion coefficient across a wide temperature range, including the cryogenic window where quantum motion dominates. They then fitted the temperature dependence against quantum-mechanical calculations of hydrogen motion in each phase:

• In the α-phase, hydrogen's ground states are delocalised across tetrahedral sites through tunnelling.
• In the β-phase, uniaxial strain from the lattice distortion localises those states around specific O_z sites.
• That localisation effectively converts tunnelling into classical thermal activation rather than suppressing motion altogether.

Diffusion-coefficient values were not disclosed in numerical form, but the phase-resolved behaviour leaves little interpretive ambiguity. Hydrogen's lightness makes pronounced quantum behaviour expected; the novelty is identifying a controllable variable.

What does this change for R&D?

The result recasts crystal symmetry as a design parameter rather than a fixed materials constant. External strain, alloying additions, or selection of oxide hosts could all shift the balance between tunnelling and thermal hopping, with downstream consequences for membrane selectivity, storage capacity targets, and catalytic turnover rates.

"Our findings suggest that hydrogen transport can be controlled by tuning quantum tunnelling through crystal symmetry — for example by applying external strain," Fukutani said. "This is particularly exciting because it identifies crystal symmetry as a fundamental principle for controlling the quantum behaviour of hydrogen in materials, opening new possibilities for tailoring hydrogen transport."

Caveats and scope

All data derive from a single model system — vanadium. The team did not yet report measurements across hydrogen isotopes, under applied strain in situ, or in alloyed hosts. Whether the 148 meV barrier scales predictably to other body-centred cubic metals remains untested. The work is framed as a proof of principle, not a materials-by-numbers recipe for hydrogen tank design.

The group plans to extend the framework to metal alloys and oxide storage media, aiming to build a universal model linking local atomic structure and crystal symmetry to hydrogen's quantum behaviour. "Ultimately, we hope to establish a universal framework describing how local atomic structure and crystal symmetry govern the quantum behaviour of hydrogen," Fukutani said.