An open-framework boron allotrope exhibiting high conductivity and plasticity.

Boron allotropes have attracted interest due to their diverse structural motifs and unusual properties; however, despite the many phases identified so far, achieving a boron allotrope that simultaneously exhibits high electrical conductivity and plasticity remains challenging. Here we report the synthesis of Imma-B60, an allotrope that exhibits both high electrical conductivity and plastic deformability, via the high-pressure formation of a Na4B60 precursor followed by sodium degassing. This allotrope features an open-framework architecture comprising B12 icosahedra interconnected by triangular B3 units through two-centre and three-centre σ bonds. Imma-B60 exhibits a narrow bandgap (<0.2 eV) with a conductivity of ~9 × 102 S m-1, seven orders of magnitude higher than β-boron. Remarkably, it demonstrates exceptional plastic deformation (~23%) through dislocation-mediated slip mechanisms. This discovery 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.