The androgynous twins of zinc

Zinc is a metal with the hcp structure. It is quite unsual among hcp metals in that the c/a ratio for zinc is very large at ambient pressure and then decreases and crosses √3 at ~10 GPa. Changes in c/a ratio are predicted to affect the plasticity of hcp metals, but is it really true?

The √3 threshold for c/a ratio is important for twinning as {10-12} twins can change in nature, switching from compressive to tensile, i.e. activated by compressive or tensile stress along the c axis. This is what we test with this series of experiments.  We confirm the androgynous nature of {10⁢-1⁢2} twin response at low and high pressures. When 𝑐/𝑎=√3, polycrystalline Zn does not display any evidence of twinning and its plastic behavior is controlled by mostly basal and pyramidal ⟨𝑐+𝑎⟩ slip activity, with a very small contribution of prismatic ⟨𝑎⟩ slip.

Want to know more? Have a look at our paper: Androgynous {10⁢-1⁢2} twin in zinc, published today in Physical Review Materials.