Low-temperature thermal expansion of rock-salt ZnO

Lattice parameter of metastable high-pressure phase of zinc oxide, rock-salt ZnO, was measured in the 10–300 K temperature range using synchrotron X-ray powder diffraction. No phase transition was observed down to 10 K. The lattice parameter of rock-salt ZnO was found to increase from 4.266 Å in the 10–80 K range up to 4.2752(3) Å at 298 K, while the volume thermal expansion coefficient increases from slight negative values below 40 K up to 4.77×10-5 K-1 at 298 K.