Findings of ZZU team are published online in the journal Nature. [Photo/zzu.edu.cn]

A research team from Zhengzhou University (ZZU) has successfully synthesized bulk pure-phase hexagonal diamond and precisely resolved its crystal structure, revealing a novel phase transition mechanism. The findings were published online in the journal Nature on March 5, 2026, under the title “Bulk hexagonal diamond”

Diamond, renowned for its exceptional hardness, thermal conductivity, and wide bandgap, typically adopts a cubic structure. However, the existence of a hexagonal polymorph was first predicted theoretically in 1962 and later discovered in meteorites in 1967. Yet natural samples exist only as nanoscale grains embedded in meteorites, making isolation and property measurement extremely challenging. Moreover, the high formation energy barrier of hexagonal diamond under laboratory conditions has long hindered its synthesis, fueling debate over whether it can exist as a stable bulk material.