Structural and Electronic Properties of ZnWO4(010) Cleaved Surface

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• 作者：Victor V. Atuchin ; Evgeny N. Galashov ; Oleg Yu. Khyzhun ; Anton S. Kozhukhov ; Lel D. Pokrovsky ; Vladimir N. Shlegel
• 刊名：Crystal Growth & Design
• 出版年：2011
• 出版时间：June 1, 2011
• 年：2011
• 卷：11
• 期：6
• 页码：2479-2484
• 全文大小：899K
• 年卷期：v.11,no.6(June 1, 2011)
• ISSN：1528-7505

文摘

A high-quality inclusion-free ZnWO₄ 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 ZnWO₄(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 ZnWO₄(010) by RHEED confirming the high crystallographic state of the surface. The XPS valence-band and core-level spectra of ZnWO₄(010) have been measured. The XPS measurements reveal that tungsten and zinc atoms are in the formal valences +6 and +2, respectively, on cleaved ZnWO₄(010) surface. The 3.0 keV Ar⁺ bombardment of the surface causes partial transformation of tungsten ions from W⁶⁺ to lower valence states; however, no partial loss of oxygen atoms belonging to ZnO₆ octahedra occurs due to this bombardment of the ZnWO₄(010) surface because after this treatment zinc remains exclusively in the formal valence +2. The W鈥揙 chemical bonding is considered in tungstates including ZnWO₄.