New Boron Allotrope Is 10 Million Times More Conductive and Flexible

Engineers designing flexible electronics and resilient semiconductors now have access to a material that bends like a metal and conducts electricity seven orders of magnitude better than its conventional form. By restructuring pure boron—an element notorious in materials science for being extraordinarily hard, highly brittle, and electrically insulating—chemists have successfully synthesized a new phase that flows under mechanical stress instead of shattering. The breakthrough resolves a tension that has defined boron chemistry for more than half a century, proving that the element can be engineered to possess both high electrical conductivity and plastic deformability simultaneously without altering its fundamental chemical composition.[3][5]

The new allotrope, designated Imma-B60 and detailed in a September 2026 paper published in the journal Nature Chemistry, achieves this unprecedented flexibility by abandoning the dense, tightly packed atomic arrangements typical of elemental boron. Instead, the material forms a highly porous, open framework built from cage-like clusters of 12 boron atoms, known as B12 icosahedra. These complex geometric clusters are interconnected by triangular three-atom boron units through a combination of two-center and three-center sigma bonds. This specific architectural arrangement creates a lattice that balances structural rigidity with internal flexibility, resembling the open-framework clathrate forms of silicon more than it does traditional boron phases.[1][4]

This cage-like architecture leaves wide, open channels within the crystal lattice, fundamentally altering the material's mechanical limits and allowing it to absorb physical strain. When the Imma-B60 crystal is placed under intense mechanical stress, its atomic planes can slide smoothly past one another through a process known as a dislocation-mediated slip mechanism. Because the internal structure has the physical space to shift and accommodate the applied force, the material avoids the catastrophic failure typical of rigid covalent networks, allowing the atomic layers to glide without breaking the overall integrity of the crystal.[1][2]

As a direct result of this internal sliding mechanism, Imma-B60 can undergo plastic deformation of up to 23 percent without fracturing—a level of ductility that is essentially unheard of for an elemental solid built from covalently bonded boron. When conventional boron crystals, such as the widely studied beta-rhombohedral phase, are loaded past their elastic limit, they simply crack and shatter. However, during in situ uniaxial compression tests, video recordings of Imma-B60 nanopillars showed the material bending, yielding, and shearing in a manner characteristic of ductile metals, completely defying the brittle nature usually associated with covalent nonmetals.[1][5]

Beyond its mechanical resilience, the open framework also completely rewires the material's electronic properties, transforming it from an insulator into a highly efficient conductor. Calculations and physical measurements demonstrate that Imma-B60 possesses a remarkably narrow bandgap of less than 0.2 electronvolts, which is far smaller than the wide bandgaps typically found in conventional boron phases. This narrow gap allows electrons to transition easily into the conduction band, facilitating a smooth and continuous flow of electrical current through the material's porous lattice structure.[1][4]

This narrow bandgap yields an electrical conductivity of approximately 900 siemens per meter at room temperature, a staggering figure for a material composed entirely of boron. That rate is roughly 10 million times higher than the conductivity of beta-rhombohedral boron, representing a seven-order-of-magnitude increase in electrical performance. In practical terms, the researchers have taken a material that was previously considered an electrical near-insulator and restructured it into something that approaches the performance of a conducting semiconductor, opening up entirely new use cases for the element in advanced electronic applications.[2][3]

For decades, creating a plastic and highly conductive form of pure boron was a theoretical goal that consistently eluded chemists, largely because standard one-step, high-pressure synthesis methods naturally force boron atoms into dense, rigid, and brittle crystals. To bypass this thermodynamic trap, the research team—led by Xiang-Feng Zhou and Yongjun Tian at Yanshan University in China, working alongside collaborators at several other Chinese institutions—abandoned direct crystallization. Instead, they utilized a sophisticated two-step precursor strategy designed to build the open framework around a temporary chemical scaffold.[1][5]

In the first step of this process, the researchers synthesized a sodium-rich compound known as sodium boride (Na4B60) under extreme high-pressure and high-temperature conditions. During this phase, the sodium atoms acted as a vital temporary scaffold, sitting inside the open channels of the boron framework and physically preventing the structure from collapsing inward into a denser, more conventional phase. This allowed the boron atoms to organize into the desired B12 icosahedra and triangular connecting units while maintaining the porous architecture required for the material's unique properties.[1][2]

Once the sodium boride crystals were fully formed, the researchers placed them in a specialized vacuum furnace and baked them at 900 degrees Celsius for two consecutive days. The intense heat and vacuum environment effectively pulled the guest sodium atoms out through the open structural channels in a process called degassing. Because the boron framework had already stabilized, the removal of the sodium left the intact, pure boron architecture of Imma-B60 behind, successfully yielding the elusive open-framework allotrope without compromising its delicate internal geometry.[2][3]

The unprecedented combination of high electrical conductivity and physical ductility in a light-element framework invites entirely new directions in materials science and engineering. Researchers are already exploring the material's potential for next-generation thermoelectric devices, lightweight flexible electrodes, and mechanically resilient semiconducting components that can bend and stretch without losing their functionality. Because the material is composed of a single, abundant element, it avoids the complex supply chain issues associated with multi-element rare-earth semiconductors, making it a highly attractive candidate for scalable flexible electronics.[3][5]

Writing in their published study, the authors emphasized that the implications of their work extend far beyond this single material. They noted that the achievement "not only establishes a powerful precursor-based strategy for accessing metastable materials, but also substantially expands boron's application potential beyond conventional superhard, semiconducting phases." The team suggests that this two-step degassing technique can now be deployed as a template to hunt for other undiscovered metastable frameworks, proving that even the most familiar elements on the periodic table can still yield profound surprises when pushed into new structural regimes.[1][2]