Crystal structure of monoclinic hafnia (HfO) revisited with synchrotron X-ray, neutron diffraction and first-principles calculations.

A study on the crystal structure of monoclinic HfO has been performed using synchrotron X-ray and neutron diffraction data separately, as well as a combination of both. The precision of the structural parameters increases significantly due to application of the neutron diffraction technique. The experimental oxygen positions in HfO, derived precisely, are visualized only by semi-local density functional calculations in terms of the calculated electronic band gap, but are not captured as accurately by using hybrid functionals.