Structural and Electronic Properties of ZnWO₄(010) Cleaved Surface

A high-quality inclusion-free ZnWO 4 crystal 90 mm in diameter and with a mass of up to 8 kg was grown by the low thermal gradient Czochralski technique. Crystallographic properties of ZnWO 4 (010) cleaved surfaces were evaluated with reflection high energy electron diffraction (RHEED), and the electronic structure of the surface was studied using X-ray photoelectron spectroscopy (XPS). A system of Kikuchi lines was observed for cleaved ZnWO 4 (010) by RHEED confirming the high crystallographic state of the surface. The XPS valence-band and core-level spectra of ZnWO 4 (010) have been measured. The XPS measurements reveal that tungsten and zinc atoms are in the formal valences +6 and +2, respectively, on cleaved ZnWO 4 (010) surface. The 3.0 keV Ar + bombardment of the surface causes partial transformation of tungsten ions from W 6+ to lower valence states; however, no partial loss of oxygen atoms belonging to ZnO 6 octahedra occurs due to this bombardment of the ZnWO 4 (010) surface because after this treatment zinc remains exclusively in the formal valence +2. The W–O chemical bonding is considered in tungstates including ZnWO 4 .