High-pressure powder x-ray-diffraction experiments have been carried out on Zn with a He-pressure medium up to 18 GPa at 40 K. No anomaly in the volume dependence of the $c/a$ axial ratio has been found within experimental errors. The $c/a$ anomaly, which has been predicted to appear associated with the electronic topological transitions, should be extremely small. Thermal expansion of Zn rapidly decreases under high pressure, yielding nearly identical axial ratios at room and low temperatures.

• Received 11 September 2001

DOI:https://doi.org/10.1103/PhysRevB.65.132107