The achievement matters because it resolves a tension that has defined boron chemistry for more than half a century. The known allotropes, including the familiar beta-rhombohedral phase and the high-pressure gamma-B28 form, are built from B12 icosahedra, cage-like clusters of twelve boron atoms that lock the structure into rigid, three-dimensional networks. That architecture delivers hardness and, in some phases, semiconducting behavior, but it also means the material has no easy way to relieve stress. When a conventional boron crystal is loaded past its elastic limit, it cracks rather than bends. Achieving a single boron phase that is simultaneously a good electrical conductor and capable of plastic flow has therefore been an explicit goal, and until now an unmet one, in the field.

The route to Imma-B60 is as interesting as the material itself. Rather than trying to crystallize pure boron directly into the desired framework, the team used a two-step precursor strategy. First, they synthesized a sodium boride, Na4B60, under high-pressure and high-temperature conditions, growing crystals large enough for single-crystal X-ray diffraction. In this compound, sodium atoms occupy channels within a boron framework, acting as a kind of structural scaffold. In the second step, the researchers removed the sodium by degassing the crystals at around 900 degrees Celsius under high vacuum for 48 hours. What remained was a pure boron framework that inherited the geometry of its sodium-containing parent, an approach the authors describe as a powerful way to access metastable materials that cannot be reached by direct synthesis.

The structure that survives the sodium extraction is remarkable in its own right. Imma-B60 adopts an orthorhombic open framework in which B12 icosahedra are interconnected by triangular B3 units through a combination of two-center and three-center sigma bonds. This is not the dense, space-filling arrangement of ordinary boron; it is a porous, cage-like architecture more reminiscent of the open-framework clathrate forms of silicon, which themselves were synthesized by a comparable precursor-removal strategy. The team confirmed the structure through a combination of single-crystal and powder X-ray diffraction, Rietveld refinement, micro-electron diffraction, and scanning transmission electron microscopy, and they benchmarked the diffraction pattern against every reported and predicted boron phase to show that Imma-B60 is genuinely new.

The electronic properties are where the material begins to look transformative. Calculations and measurements show that Imma-B60 has a narrow bandgap of less than 0.2 electronvolts, far smaller than the gap in conventional boron phases. The measured electrical conductivity is approximately 9 times 10 to the 2 siemens per meter, which the authors note is seven orders of magnitude higher than that of beta-boron. In practical terms, a material that was previously an electrical near-insulator has been restructured, without changing its chemical composition, into something approaching a conducting semiconductor. The bonding analysis, performed with a solid-state adaptation of adaptive natural density partitioning, confirms that the framework is held together by predominantly sigma-type bonding, with the open topology leaving the electronic structure in a regime where charge transport becomes facile.

Equally striking is the mechanical behavior. Using in situ uniaxial compression of nanopillars carved from the crystals, oriented along a specific crystallographic direction, the researchers observed that Imma-B60 deforms plastically to strains of about 23 percent. The deformation proceeds through a dislocation-mediated slip mechanism, meaning that planes of atoms slide past one another along defined crystallographic pathways rather than the material shattering. Video recordings of the compression experiments show the nanopillars bending and shearing in a way that looks more like a metal than a covalent nonmetal. Nanoindentation measurements on both the precursor Na4B60 and the final B60 phase provided complementary hardness and elastic modulus data, placing the new material well outside the superhard-but-brittle envelope that has characterized boron to date.

The precursor strategy itself may prove to be the study’s most consequential contribution. The idea of using a guest species, in this case sodium, to template a framework and then removing it to leave a metastable elemental structure echoes the celebrated synthesis of open-framework silicon from sodium silicide clathrates, and it has been proposed as a route to exotic phases of other elements, including polymeric nitrogen and superconducting allotropes of silicon and carbon. By demonstrating the approach for boron, the Yanshan University team adds a new entry to a growing catalog of metastable materials that are accessible only through chemical templating. The sodium diffusion pathway and its energy barrier were mapped computationally, showing how the guest atoms can migrate out of the framework without collapsing it.

The work also required considerable experimental ingenuity at the growth stage. The team found that inserting zinc interlayers between the sodium and boron starting layers in the high-pressure assembly dramatically improved crystal size and quality, a detail they verified with control experiments and scanning electron microscopy of hundreds of crystals. Residual sodium content after degassing was tracked with energy-dispersive spectroscopy and electron energy-loss spectroscopy, and the analysis revealed that lower degassing temperatures or argon-flow conditions left more sodium behind, underscoring how sensitive the final purity, and therefore the properties, are to the extraction protocol. Subtle defect motifs associated with interstitial boron sites were identified in the refined structures, and the authors show that these defects, rather than secondary phases, explain weak additional diffraction features.

For applications, the combination of high conductivity and ductility in a light-element framework opens doors that conventional boron could never approach. Thermoelectric devices, which depend on materials with unusual electronic transport and low thermal conductivity, are an obvious candidate given the narrow bandgap and porous structure; theoretical work has long suggested that doping boron icosahedra could even produce superconductivity. Flexible or deformable electronics, lightweight electrodes, and mechanically resilient semiconducting components are other directions the open framework invites. More broadly, the result is a reminder that the periodic table still holds surprises in its simplest entries: a single element, boron, whose known phases were cataloged over decades, has just yielded a form that is simultaneously transparent to none of its usual weaknesses and rich in properties its usual phases never displayed. The team, led by Xiang-Feng Zhou and Yongjun Tian, with Feng Chen, Lianfeng Zou, and Penghui Li as co-first authors, suggests that the precursor-based strategy can now be extended to hunt for further metastable frameworks, meaning Imma-B60 may be less an endpoint than a template for what comes next.

Subject of Research: Synthesis of a conductive and plastic open-framework boron allotrope via a high-pressure precursor route

Article Title: An open-framework boron allotrope exhibiting high conductivity and plasticity

Article References: Chen, F., Zou, L., Li, P., Fan, C., Liu, Y., Xu, B., Shao, X., Zhang, H., He, X.-L., Huang, M.-X., Chen, F., Nie, A., Ke, F., Zhao, Z., Dong, H., Yang, Y., Weng, X.-J., Wang, H.-T., Zhou, X.-F., & Tian, Y. (2026). An open-framework boron allotrope exhibiting high conductivity and plasticity. Nature Chemistry. https://doi.org/10.1038/s41557-026-02267-7

Image Credits: AI Generated

DOI: 10.1038/s41557-026-02267-7

Keywords: boron, allotrope, open framework, high pressure, plasticity, electrical conductivity, B12 icosahedra, sodium boride, dislocation slip, metastable materials, Nature Chemistry, bandgap

That bottleneck may finally be easing. A team led by Wei Zhai, Zhenyu Shi, Rui Tao, Zijian Li, Zhuangchai Lai and Hua Zhang, working across the City University of Hong Kong, The Hong Kong Polytechnic University and partner institutions, has published a detailed protocol in Nature Protocols describing a salt-assisted method that reliably converts ordinary 2H-phase crystals into phase-pure, highly crystalline 1T′-phase materials. The procedure covers a broad compositional palette, including MoS2, MoSe2, WS2, WSe2 and the mixed-chalcogen alloys MoS2xSe2(1−x) and WS2xSe2(1−x), and it does so at a scale that previous approaches could only dream of: gram quantities per batch, with individual crystals reaching hundreds of micrometers across.

The elegance of the method lies in its simplicity. Rather than building 1T′ crystals from scratch under exotic conditions, the protocol starts with commercially available 2H-phase transition metal dichalcogenides and co-anneals them with elemental chalcogen powders, such as sulfur or selenium, together with common alkali metal salts such as potassium oxalate hydrate or potassium carbonate. The reaction is carried out in a sliding tube furnace under a hydrogen-argon atmosphere. When the mixture is heated, the alkali metal salts act as the trigger for a remarkable structural transformation, coaxing the atomic layers of the stable 2H phase to slide and distort into the metastable 1T′ configuration. The chalcogen vapor maintains the correct chemical environment, preventing decomposition while the phase change proceeds.

Understanding why this works requires a brief tour of the underlying crystallography. In the 2H phase, each metal atom sits in a trigonal prismatic coordination environment, and the layers stack in a specific sequence that renders the material a semiconductor. The 1T′ phase, by contrast, features octahedral coordination with a periodic lateral displacement of the metal atoms, breaking the symmetry in a way that produces metallic conductivity. Because the 1T′ arrangement is metastable, it does not form spontaneously under ordinary synthesis conditions; it must be kinetically trapped. Alkali metal ions appear to facilitate this trapping by intercalating between the layers, weakening the interlayer bonding and lowering the energetic barrier for the intralayer atomic rearrangement. Subsequent deintercalation of these ions leaves behind the transformed lattice, now locked into its new metastable geometry.

The published protocol walks researchers through every stage of this process with unusual care. It specifies the setup of the sliding tube furnace, a configuration that allows the reactants to be rapidly moved into and out of the hot zone, giving precise control over reaction timing. It details the loading of the 2H-phase starting materials, the chalcogen powders and the salt, the purging and establishment of the hydrogen-argon atmosphere, the heating profile and the post-reaction washing steps that remove residual salts and recover the transformed crystals. The entire procedure takes approximately 37 hours and 20 minutes from start to finish, a time investment that is modest compared with the weeks of trial and error that often accompany attempts to grow metastable phases by conventional routes.

Equally important is the protocol’s emphasis on verification. Phase purity is not assumed; it is demonstrated. The authors prescribe a characterization workflow built on three complementary techniques. Raman spectroscopy probes the vibrational fingerprints of the lattice, which differ distinctly between the 2H and 1T′ arrangements. X-ray photoelectron spectroscopy examines the chemical states of the metal and chalcogen atoms, confirming that the transformation is complete and that no residual intercalants or decomposition products remain. X-ray diffraction provides the definitive structural verdict, revealing the characteristic peak positions of the 1T′ lattice and the absence of any detectable 2H-phase remnants. Together, these measurements give researchers the confidence that the material they are studying is genuinely the phase they intended to make.

The significance of gram-scale availability is difficult to overstate. Much of the early literature on metastable transition metal dichalcogenides relied on chemically exfoliated nanosheets produced through lithium intercalation, a method dating back to the 1980s that yields small, often defective flakes with variable phase content. Colloidal synthesis routes later offered better control but typically produced nanometer-scale particles rather than the large, well-ordered crystals needed for fundamental physics experiments and device fabrication. Hydrothermal and solution-phase approaches to 1T′ WSe2 and related compounds expanded the toolkit further, yet crystal size and phase purity remained persistent limitations. With crystals hundreds of micrometers wide available in gram batches, experiments that were previously impractical, such as building van der Waals heterostructures from 1T′ layers, performing detailed transport measurements, or loading industrial-scale electrocatalyst electrodes, become routine possibilities.

The applications that stand to benefit span an impressive range. In electrocatalysis, the metallic character of 1T′-phase materials makes them natural candidates for the hydrogen evolution reaction, the cathodic half of water splitting that underpins green hydrogen production. Previous work by members of the same team demonstrated that the phase of the support material dramatically influences how platinum catalysts grow and perform on molybdenum disulfide, achieving highly efficient hydrogen evolution when the metal deposited on metallic-phase surfaces. In electronics, 1T′ phases offer low-resistance contacts to semiconducting 2H layers, a strategy known as phase engineering that has been used to build better transistors. In photonics and sensing, 1T′ monolayers stabilized on gold nanowires have enabled ultrasensitive surface-enhanced Raman scattering detection. And in condensed matter physics, the metallic 1T′ phases of certain dichalcogenides host superconductivity, making high-purity crystals essential for studying emergent quantum phenomena.

The protocol also reflects a maturing view of what its authors call phase engineering of nanomaterials, a discipline that treats crystal phase as a design parameter on par with composition and dimensionality. Over the past decade, reviews in Chemical Reviews and Nature Reviews Chemistry have charted the rapid growth of this field, cataloguing unconventional phases across two-dimensional materials and the synthetic strategies developed to access them. The salt-assisted approach described here joins other recent innovations, including photoredox phase transformation driven by light, as part of a growing arsenal for navigating the energy landscapes of metastable matter. By codifying the method into a reproducible, step-by-step protocol, the team has effectively lowered the barrier to entry for laboratories worldwide.

For the broader materials community, the message is one of cautious optimism. Metastable phases have long been viewed as fragile curiosities, accessible only to specialists with finely tuned equipment and generous patience. A protocol that transforms shelf-stable commercial powders into gram quantities of phase-pure 1T′ crystals using a standard tube furnace and inexpensive salts suggests that these materials are ready to move from the margins of feasibility into the mainstream of research practice. Whether the next breakthrough comes in hydrogen catalysis, quantum devices or entirely unforeseen directions, the raw ingredients are now, quite literally, available by the gram.

Subject of Research: Salt-assisted synthesis of high phase-purity metastable 1T′-phase group VIB transition metal dichalcogenide crystals

Article Title: Salt-assisted synthesis of high phase-purity metastable 1T′-phase group VIB transition metal dichalcogenides

Article References: Zhai, W., Shi, Z., Tao, R., Li, Z., Dong, D., Tang, J., Wang, W., Wang, L., Yang, H., Zhai, L., Ruan, X., Wu, Y., Wang, J., Yao, Y., Zhao, C., He, Q., Lai, Z., & Zhang, H. (2026). Salt-assisted synthesis of high phase-purity metastable 1T′-phase group VIB transition metal dichalcogenides. Nature Protocols. https://doi.org/10.1038/s41596-026-01429-8

Image Credits: AI Generated

DOI: 10.1038/s41596-026-01429-8

Keywords: transition metal dichalcogenides, 1T′ phase, phase engineering, salt-assisted synthesis, metastable materials, two-dimensional materials, hydrogen evolution, electrocatalysis, MoS2, WS2, crystal growth, Nature Protocols